Earth Radiation Budget Experiment (ERBE) Earth Radiant Fluxes and Albedo for Month Nonscanner (S-10N) Langley ASDC Data Set Document
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Earth Radiation Budget Experiment (ERBE) Earth Radiant Fluxes and Albedo for Month Nonscanner (S-10N) Langley ASDC Data Set Document |
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This document describes the Earth radiant flux and albedo data product for Nonscanner (S-10N) and provides the user with the necessary information to use the Earth Radiation Budget Experiment (ERBE) data for scientific research studies.
The S-10N contains the same science information arranged in the same order as the S-10 but with some differences in processing algorithms and data format. The data set, S-10N, consists of nonscanner data processed without scene identification information from the scanner instrument and with the numerical filter cross-track enhancement technique (see the Special Corrections/Adjustments Section of this document).
Earth Radiation Budget Experiment (ERBE) S-10N (Nonscanner-only) Radiant Flux and Albedo in Native Format.
This document supports the data sets:
| ERBE_S10N_WFV_NF_NAT: | Earth Radiation Budget Experiment (ERBE) S-10N (Nonscanner-only) Wide Field of View Numerical Filter Radiant Flux and Albedo in Native (NAT) Format (ERBE_S10N_WFV_NF_NAT) |
| ERBE_S10N_WFV_SF_NAT: | Earth Radiation Budget Experiment (ERBE) S-10N (Nonscanner-only) Wide Field of View Shape Factor Radiant Flux and Albedo in Native (NAT) Format (ERBE_S10N_WFV_SF_NAT) |
Data are archived as the Earth Radiant Fluxes and Albedo for Month Nonscanner (S-10N).
The S-10N contains regional hourly and daily monthly averages of radiant fluxes and albedo as well as actual individual hour box data.
The objectives of ERBE are:
The S-10N contains regional hourly and daily monthly averages as well as the actual individual hour box data which are the input data to the Monthly Time/Space Averaging Subsystem. The S-10N contains numerical filter data of 5 degree resolution and shape factor data of 10 degree resolution from the nonscanner instrument. The S-10N is available for single spacecraft and as a combination of all operational spacecraft for wide field-of-view (WFOV). The S-10N consists of two disk files per month, one for WFOV numerical filter and one for WFOV shape factor. The data values are represented in scaled 16-bit integers. The nonscanner data for each region observed during a month are collected into a 32 X 25 matrix representing days and hours of the month; monthly (day), monthly (hour), daily, and monthly hourly averages are determined for each region. The values contained for each region are as follows:
The goal of the ERBE is to produce monthly averages of longwave and shortwave radiation parameters on the Earth at regional to global scales. Preflight mission analysis led to a three-spacecraft system to provide the geographic and temporal sampling required to meet this goal. Three nearly identical sets of instruments were built and launched on three separate spacecraft. These instruments differ principally in the spacecraft interface electronics and in the field-of-view limiters for the nonscanner instruments required because of differences in the spacecraft orbit altitudes.
The ERBS spacecraft was launched by Space Shuttle Challenger in October 1984 and was the first spacecraft to carry ERBE instruments into orbit. The ERBS was designed and built by Ball Aerospace Systems under contract to NASA Goddard Space Flight Center (GSFC), and ERBS was the first spacecraft dedicated to NASA science experiments to be launched by the Space Shuttle. The ERBS carries the Stratospheric Aerosol and Gas Experiment (SAGE II) instrument in addition to the ERBE instruments. The Payload Operation and Control Center (POCC) at GSFC directs operations of the ERBS spacecraft and the ERBE and SAGE II instruments, employing both ground stations and the Tracking and Data Relay Satellite System (TDRSS) network. Spacecraft and instrument telemetry data are received at GSFC where the data are processed by the Information Processing Division that provides ERBE and SAGE II experiment data to the NASA Langley Research Center (LaRC).
The second and third spacecraft launched with ERBE instruments are Television Infrared Radiometer Orbiting Satellite (TIROS) N-class spacecraft, which are part of the NOAA operational meteorological satellite series. The NOAA-9 and NOAA-10 spacecraft were launched in December 1984 and September 1986, respectively. The NOAA spacecraft include other instruments, such as the Advanced Very High Resolution Radiometer (AVHRR) and the High-Resolution Infrared Radiometer Sounder (HIRS), which provide NOAA with data for near-real-time weather forecasting. Both spacecraft are in nearly sun-synchronous orbits. The equator-crossing times (at launch) of the orbital nodes for the NOAA-9 and NOAA-10 orbits were 1420 UT (ascending) and 1930 UT (descending), respectively, where UT denotes universal time. The Satellite Operations and Control Center (SOCC) at the National Environmental Satellite and Data Information Service (NESDIS) operates the NOAA spacecraft. NOAA also provides decommutation processing of the telemetry data.
NASA tracks the ERBS spacecraft, and the North American Aerospace Defense Command (NORAD) tracks the NOAA spacecraft. The tracking data are provided to GSFC where orbit ephemeris data are calculated for all three spacecraft and provided to LaRC.
| SRB_Daily | Surface Radiation Budget Daily Averages |
| SRB_Monthly | Surface Radiation Budget Monthly Averages |
Dr. Bruce R. Barkstrom
ERBE Principal Investigator
NASA Langley Research Center
Earth Radiation Budget Experiment (ERBE)
The theory behind the measurements made to collect the ERBE data is non-trivial and well beyond the scope of this document. However, interested readers are referred to the following publications: Suttles (Reference 26), Hoffman (Reference 14) and Smith (Reference 23).
All three sets of ERBE instruments were designed to collect data for one year but had a goal of two years. The nonscanner instruments continue to collect data for ERBS; however, the nonscanner instruments on-board NOAA-9 and NOAA-10 have been deactivated. Table 1 describes the nominal orbit parameters for each satellite at launch.
| Nominal Orbit Parameter | ERBS | NOAA-9 | NOAA-10 |
|---|---|---|---|
| Launch Date | October 5, 1984 | December 12, 1984 | September 17, 1986 |
| Planned Duration | 1 Year | 1 Year | 1 Year |
| Actual Duration Scanner | 5-1/2 years (February 28, 1990) |
3 years (January 20, 1987) |
2-1/2 years (May 22, 1989) |
| Actual Duration Nonscanner | Operating | Over 12 years, deactivated April 3, 1997 | Over 8 years, deactivated December, 1994 |
| Orbit | Precessing | Sun-synchronous | Sun-synchronous |
| Semi-major Axis | 6988 km | 7248 km | 7211 km |
| Mean Altitude | 610 km | 872 km | 833 km |
| Inclination | 57 deg | 98 deg | 98 deg |
| Nodal Period | 98 minutes | 102.08 minutes | 101.2 minutes |
| Equator Crossing Time (at launch) | Variable | 1430 Local Mean Solar Time, ascending | 0730 Local Mean Solar Time, descending |
The ERBE instruments are on the ERBS, NOAA-9, and NOAA-10 satellites.
ERBS was the first spacecraft dedicated to NASA science experiments to be launched by the Space Shuttle. ERBS carries SAGE II instruments in addition to the ERBE instruments. The NOAA spacecraft include other instruments, such as the Advanced Very High Resolution Radiometer (AVHRR) and the High-Resolution Infrared Radiometer Sounder (HIRS), which provide NOAA with data for near-real-time weather forecasting.
A complete list of the measured parameters is found in Table 2.
| CHANNEL | WAVELENGTH LIMITS (microns) |
MEASUREMENT | |
|---|---|---|---|
| Nonscanner Fixed Wide field of view | 1 | 0.2-50.0 | Total Radiance |
| 2 | 0.2 - 5.0 | Shortwave Reflected | |
| Nonscanner Fixed Medium field-of-view | 3 | 0.2 - 50.0 | Total Radiance |
| 4 | 0.2 - 5.0 | Shortwave Reflected | |
| Fixed Solar Monitor | 5 | 0.2 - 50.0 | Total Irradiance |
| Scanner Narrow field-of-view | 1 | 0.2 - 50.0 | Total Radiance |
| 2 | 0.2 - 45.0 | Shortwave Reflected | |
| 3 | 5.0 - 50.0 | Longwave Emitted |
The ERBE is a multisatellite system designed to measure the Earth's radiation budget. The ERBE instruments fly on a mid-inclination NASA satellite, (ERBS), and two sun-synchronous NOAA satellites, (NOAA-9 and NOAA-10). Each satellite carries both a scanner and a nonscanner instrument package.
The nonscanner instrument package contains four Earth-viewing channels and a solar monitor. The Earth-viewing channels have two spatial resolutions: a horizon-to-horizon view of the Earth, and a field-of-view limited to about 1000 km in diameter. The former are called the wide field-of-view (WFOV) and the latter the medium field-of-view (MFOV) channels. For each of the two fields of view, there is a total spectral channel which is sensitive to all wavelengths and a shortwave channel which uses a high purity, fused silica filter dome to transmit only the shortwave radiation from 0.2 to 5 microns. The solar monitor is a direct descendant of the Solar Maximum Mission's Active Cavity Radiometer Irradiance Monitor detector. Because of the concern for spectral flatness and high accuracy, all five of the channels on the nonscanner package are active cavity radiometers.
The nonscanner elevation beams can be rotated to any of three positions: launch/stow/internal calibration position (180 degrees), solar calibration position (78 degrees), and Earth-viewing (nadir) position (0 degrees). The WFOV detectors view the Earth from limb-to-limb (plus a small ring of space). The MFOV detectors are designed to include approximately an Earth view of 10 geocentric degrees within the unencumbered field of view (FOV).
The ERBE instruments were developed by TRW, Inc.
This section is not applicable for this data set.
The tolerance is 1 percent for the total channel and 2 percent for the shortwave channel.
In-flight calibrations of the nonscanners were normally performed on a bi-weekly basis.
The ERBE instruments were developed by TRW, Inc. Laboratory calibrations of the ERBE nonscanner and solar monitor instruments were completed in the TRW calibration facility at Redondo Beach, California in 1984. The fundamental standards used for the ERBE instruments were the International Pressure and Temperature Standard of 1968 (IPTS-68) and the World Radiation Reference (WRR). The TRW master reference blackbody (MRBB) was calibrated using these, and the MRBB was subsequently used to transfer the calibrations to the internal blackbody (IBB) and to the shortwave channels via an integrating sphere. The results of the calibrations were reported in detail in TRW calibration documents.
In-flight calibrations are performed in order to maintain the accuracy of radiometric measurements by accounting for internal instrument component parametric changes brought about by the spacecraft's environmental variables. In-flight calibrations of the nonscanners were normally performed on a bi-weekly basis. These included internal calibrations, space looks, and solar calibrations. Internal calibrations consist of cycling of IBB temperatures (total sensors) and shortwave internal calibration source (SWICS) voltages. Space looks consist of observations of "cold" space, both before and after solar calibrations. Solar calibrations consist of measurements made while the solar disc is within the instrument's field-of-view.
On days when internal calibrations are performed, shortwave offsets are independently determined in four ways:
In cases where the first option is not viable, the second option is used, along with a linearly-fitted delta based upon the historical differences between method 1 and method 2. The offsets determined using options 3 and 4 have never been used in production processing.
The ERBE nonscanner instrument consists of four Earth-viewing detectors and one solar monitor detector located on the head assembly. The four Earth-viewing detectors are unchopped active cavity radiometers (ACR), whereas the solar monitor is an unfiltered chopped ACR designed to measure direct solar radiation for calibrating the Earth-viewing detectors. Two of these detectors have wide field-of-view (WFOV) apertures allowing the detectors to view the entire disk of the Earth; the other two detectors have medium field-of-view (MFOV) apertures allowing the detectors to view an area about 1000 km in diameter. Two of the Earth-viewing detectors, one WFOV and one MFOV, and the solar monitor detector measure total radiation, whereas the other two Earth-viewing detectors measure shortwave radiation. The total radiation detectors are unfiltered, and the shortwave spectral bands are achieved by use of fused silica dome filters placed over the detectors.
The nonscanner instrument microprocessor processes and executes ground-commanded and stored commands to direct and control the instrument operations. The instrument can operate in several modes so that radiation measurements can be made over a wide range of operational conditions. The instrument can operate at azimuth angles between 0 and 180 degrees, and at fixed elevation beam positions of 0(nadir), 78 (solar ports), and 180 (stow or internal calibration position) degrees. Normal Earth-viewing operation is at the nadir elevation position and at an azimuth position of 180 degrees for NOAA-10, 170 degrees for NOAA-9, and 0 degrees for ERBS. The ERBE nonscanner instrument output consists of a complete cycle of radiometric and housekeeping measurements every 16 seconds. There are 20 radiometric measurements every 16 seconds, while the frequency of housekeeping measurements is either 1, 2, or 4 measurements per 16 seconds, depending on the type of measurement.
Telemetry data from the ERBE instruments on the NOAA-9 and NOAA-10 spacecraft are transmitted to Control and Data Acquisition (CDA) ground stations at Gilmore Creek, Alaska, and Wallops Island, Virginia that relay the data through a geostationary communications satellite to the SOCC at NESDIS in Suitland, Maryland. NOAA provides decommutation processing of the telemetry data and provides the data to LaRC. During portions of the ERBE mission, telemetry data from the NOAA spacecraft were transmitted to GSFC for decommutation processing and delivery to LaRC. Telemetry and tracking data from the ERBE instrument on ERBS are transmitted to the NASA ground terminal at White Sands, New Mexico through the Tracking and Data Relay Satellite System (TDRSS). The data are transmitted from the ground terminal to the NASA communications center at GSFC, where the data are processed by the Information Processing Division (IPD) that provides ERBE data to LaRC.
This section is not applicable for this data set.
This section is not applicable for this data set.
The spatial coverage differs with the channel and the spacecraft, as described below.
WFOV Instruments: these two fixed detectors continuously view the earth disc (plus a small ring of space). The measurements are continuous over the entire globe for NOAA-9 and NOAA-10, and between 57 degrees north and south latitudes for ERBS which precesses approximately 3.95 degrees west per day.
MFOV Instruments: these two fixed detectors continuously view an area about 1000 km in diameter (nominally, a 5 degree earth central angle at the top of the Earth atmosphere, TOA). The measurements are continuous over the entire globe for NOAA-9 and NOAA-10, and between 57 degrees north and south latitude for ERBS.
ERBE scanner instruments on board the NOAA-9 and NOAA-10 satellites provide global coverage, while the ERBE scanner instrument onboard ERBS provides coverage between 67.5 degrees north and south latitude.
Though a map is not available, the limits of coverage are discussed in the Spatial Coverage Section (above).
The spatial resolution differs with the four types of instruments and the two types of spacecraft (ERBS and NOAA). The WFOV instruments have 136 degree FOV on ERBS and 126 degree FOV on the NOAA satellites. The MFOV instruments have footprints of approximately 5 geocentric degree radius or 1000 km at the TOA. The solar instrument has an unencumbered FOV which observes the entire solar disk.
The S-10N contains data which have been averaged to 5.0 degree or 10.0 degree grid scales.
Gridding is an equal-angle projection of 5.0 X 5.0 degree (MFOV, 2592 bins), and 10.0 X 10.0 degree (WFOV, 648 bins).
Binning of the data is based on an equal-angle grid of 5.0 X 5.0 degree (MFOV, 2592 bins), and 10.0 X 10.0 degree (WFOV, 648 bins). In each resolution, the bin number 1 is found at 90 degree N, 0 degree W with the bin number increasing in an easterly direction.
The layout of a 2.5 system is given; the 5.0 and 10.0 systems are designed similarly. In this grid system, L = longitude and λ = latitude is replaced with colatitude, where λco = 90 - λ, so that 0° <= λco <= 180°.
The following list shows the number of regions for each resolution:
| Resolution | Total No. of Regions |
|---|---|
| 5.0 | 2,592 |
| 10.0 | 648 |
Instruments on the three satellites (ERBS, NOAA-9, and NOAA-10) began acquiring Earth viewing data in November 1984, February 1985, and October 1986, respectively. All of the Earth-viewing nonscanner instruments collect measurements continuously except during calibrations. The solar instrument collects about 20 minutes of usable data during bi-weekly solar calibration periods. Additional solar measurement data are sometimes obtained for special projects.
This is an ongoing experiment, and the data are being processed out of sequence. Please consult the Langley ASDC IMS for available data granules.
Data records for the Level 2 products are instantaneous measurements and estimates. Gridded data (the S-10N, S-4N, and S-4GN products) are daily, monthly hour (hourly averages for a month), monthly day (daily averages for a month), and hourly. Individual hour box estimates are also in S-10N.
There are two data records for each region processed. The data records are written as 16-bit words. Some values are too large to be placed in one 16-bit word and, therefore, occupy two 16-bit words. The method of restoring the values in these words is discussed in the Variable Description/Definition Section of this document.
The first record for a region is of fixed length and contains the averaged data. There are 990 words in this record for S-10N. The second record is of variable length and contains the "actual" hour box data passed from the Inversion Subsystem (Reference 8) through the Daily Data Base Subsystem (Reference 6). The length of this record in words can be calculated by multiplying the number of hour boxes (978th word of record 1 for the nonscanner) by the number of values passed per hour box. The number of values is 38 for the nonscanner.
A detailed record structure of the S-10N output product is shown in Table 3, and a pictorial summary of the product is shown in Table 4. The scale factors given in Table 3 are typical values. The actual values used to scale the data are recorded in the first record as discussed in the Data Format Section of this document. These are the values that should be used to scale the integer data and not the values in Table 3.
| Scale Factor | |||||||
|---|---|---|---|---|---|---|---|
| Temporal Scale |
Record Index |
Parameter Name | Units | Name | Value | No. of Data Values in Record |
Cumulative Total Bits |
| - | 1 | Region number | --- | SCALE1(1) | 1 | - | 16 |
| 2 | Geographic scene type | --- | SCALE1(2) | 100 | - | 32 | |
| 3-11 | Scene fraction histogram(9) | --- | SCALE1(3) | 100 | - | 176 | |
| Monthly (day) |
12 |  |
Wm-2 | SCALE1(4) | 10 | 1 | 192 |
| 13 | MMINSW | Wm-2 | SCALE1(5) | 10 | 1 | 208 | |
| 14 | MMAXSW | Wm-2 | SCALE1(6) | 10 | 1 | 224 | |
| 15 |  |
Wm-2 | SCALE1(7) | 100 | 1 | 240 | |
| 16 | NSW | --- | SCALE1(8) | 1 | 1 | 256 | |
| 17 |  |
Wm-2 | SCALE1(9) | 10 | 1 | 272 | |
| 18 | MMINLW | Wm-2 | SCALE1(10) | 10 | 1 | 288 | |
| 19 | MMAXLW | Wm-2 | SCALE1(11) | 10 | 1 | 304 | |
| 20 |  |
Wm-2 | SCALE1(12) | 100 | 1 | 320 | |
| 21 | NLW | --- | SCALE1(13) | 1 | 1 | 336 | |
| 22 |  |
--- | SCALE1(14) | 10000 | 1 | 352 | |
| 23 |  |
Wm-2 | SCALE1(15) | 100 | 1 | 368 | |
| 24 | TSOLRD(1) | W-hm-2 | SCALE1(16) | 1 | 1 | 384 | |
| 25 | TSOLRD(2) | W-hm-2 | SCALE1(17) | 10 | 1 | 400 | |
| Monthly (hour) |
26 | |
Wm-2 | SCALE1(18) | 10 | 1 | 416 |
| 27 | MMINSW | Wm-2 | SCALE1(19) | 10 | 1 | 432 | |
| 28 | MMAXSW | Wm-2 | SCALE1(20) | 10 | 1 | 448 | |
| 29 | |
Wm-2 | SCALE1(21) | 100 | 1 | 464 | |
| 30 | NSW | --- | SCALE1(22) | 1 | 1 | 480 | |
| 31 | |
Wm-2 | SCALE1(23) | 10 | 1 | 496 | |
| 32 | MMINLW | Wm-2 | SCALE1(24) | 10 | 1 | 512 | |
| 33 | MMAXLW | Wm-2 | SCALE1(25) | 10 | 1 | 528 | |
| 34 | |
Wm-2 | SCALE1(26) | 100 | 1 | 544 | |
| 35 | NLW | --- | SCALE1(27) | 1 | 1 | 560 | |
| 36 | |
--- | SCALE1(28) | 10000 | 1 | 576 | |
| 37 | |
Wm-2 | SCALE1(29) | 100 | 1 | 592 | |
| 38 | TSOLRH(1) | W-hm-2 | SCALE1(30) | 1 | 1 | 608 | |
| 39 | TSOLRH(2) | W-hm-2 | SCALE1(31) | 10 | 1 | 624 | |
| Daily | 40 thru 473 |
DEO | Wm-2 | SCALE1(32) | 10 | 14x31 | - |
|
Wm-2 | SCALE1(33) | 10 | - | - | ||
| MMINSW | Wm-2 | SCALE1(34) | 10 | - | - | ||
| MMAXSW | Wm-2 | SCALE1(35) | 10 | - | - | ||
|
Wm-2 | SCALE1(36) | 100 | - | - | ||
| NSW | --- | SCALE1(37) | 1 | - | - | ||
|
Wm-2 | SCALE1(38) | 10 | - | - | ||
| MMINLW | Wm-2 | SCALE1(39) | 10 | - | - | ||
| MMAXLW | Wm-2 | SCALE1(40) | 10 | - | - | ||
|
Wm-2 | SCALE1(41) | 100 | - | - | ||
| NLW | --- | SCALE1(42) | 1 | - | - | ||
|
--- | SCALE1(43) | 10000 | - | - | ||
| SOLARD(1) | W-hm-2 | SCALE1(44) | 1 | - | - | ||
| SOLARD(2) | W-hm-2 | SCALE1(45) | 10 | - | 7568 | ||
| Monthly Hourly |
474 thru 977 |
|
Wm-2 | SCALE1(46) | 21x24 | - | - |
| MMINSW | Wm-2 | SCALE1(47) | 10 | - | - | ||
| MMAXSW | Wm-2 | SCALE1(48) | 10 | - | - | ||
|
Wm-2 | SCALE1(49) | 100 | - | - | ||
| NSW | --- | SCALE1(50) | 1 | - | - | ||
| SUMSW(1) | W-hm-2 | SCALE1(51) | 1 | - | - | ||
| SUMSW(2) | W-hm-2 | SCALE1(52) | 1 | - | - | ||
| SUM2SW(1) | W-hm-22 | SCALE1(53) | 1 | - | - | ||
| SUM2SW(2) | W-hm-22 | SCALE1(54) | 10 | - | - | ||
|
Wm-2 | SCALE1(55) | 10 | - | - | ||
| MMINLW | Wm-2 | SCALE1(56) | 10 | - | - | ||
| MMAXLW | Wm-2 | SCALE1(57) | 10 | - | - | ||
|
Wm-2 | SCALE1(58) | 100 | - | - | ||
| NLW | --- | SCALE1(59) | 1 | - | - | ||
| SUMLW(1) | W-hm-2 | SCALE1(60) | 1 | - | - | ||
| SUMLW(2) | W-hm-2 | SCALE1(61) | 10 | - | - | ||
| SUM2LW(1) | W-hm-22 | SCALE1(62) | 1 | - | - | ||
| SUM2LW(2) | W-hm-22 | SCALE1(63) | 10 | - | - | ||
|
--- | SCALE1(64) | 10000 | - | - | ||
| SOLARH(1) | W-hm-2 | SCALE1(65) | 1 | - | - | ||
| SOLARH(2) | W-hm-2 | SCALE1(66) | 10 | - | 15632 | ||
| Monthly | 978 | NHR-DAY | --- | SCALE1(67) | 1 | 1 | - |
| 979 | NOAA-9 Deadscanner Flag** | --- | SCALE1(67) | 1 | 1 | - | |
| 980 | ERBS Deadscanner Flag** | --- | SCALE1(67) | 1 | 1 | - | |
| 981 | NOAA-10 Deadscanner Flag** | --- | SCALE1(67) | 1 | 1 | - | |
| 982 | Half-sine Flag** | --- | SCALE1(67) | 1 | 1 | - | |
| 983 - 990 | Spares | - | - | 0 | 9 | 15840 | |
| Hourly/ Day* |
1 | Hour box | --- | SCALE2(1) | 1 | 1 | 16 |
| 2 | Whole Julian date(1) | day | SCALE2(2) | 1 | 1 | 32 | |
| 3 | Whole Julian date(2) | day | SCALE2(3) | 1 | 1 | 48 | |
| 4 | Fractional Julian date | day | SCALE2(4) | 10000 | 1 | 64 | |
| 5-13 | Scene fraction(9) | --- | SCALE2(5) | 10000 | 1 | 208 | |
| 14-22 | (9) |
--- | SCALE2(6) | 10000 | 1 | 352 | |
| 23 | COS(ZEN)SUN | --- | SCALE2(7) | 10000 | 1 | 368 | |
| 24 | Satellite zenith angle | degrees | SCALE2(8) | 100 | 1 | 384 | |
| 25 | Azimuth angle | degrees | SCALE2(9) | 100 | 1 | 400 | |
| 26 | SOLAR | Wm-2 | SCALE2(10) | 10 | 1 | 416 | |
| 27 | |
Wm-2 | SCALE2(11) | 10 | 1 | 432 | |
| 28 | MMINSW | Wm-2 | SCALE2(12) | 10 | 1 | 448 | |
| 29 | MMAXSW | Wm-2 | SCALE2(13) | 10 | 1 | 464 | |
| 30 | |
Wm-2 | SCALE2(14) | 100 | 1 | 480 | |
| 31 | NSW | --- | SCALE2(15) | 1 | 1 | 496 | |
| 32 | |
Wm-2 | SCALE2(16) | 10 | 1 | 512 | |
| 33 | MMINLW | Wm-2 | SCALE2(17) | 10 | 1 | 528 | |
| 34 | MMAXLW | Wm-2 | SCALE2(18) | 10 | 1 | 544 | |
| 35 | |
Wm-2 | SCALE2(19) | 10 | 1 | 560 | |
| 36 | NLW | --- | SCALE2(20) | 1 | 1 | 576 | |
| 37 | MDIFFSW | Wm-2 | SCALE2(21) | 100 | 1 | 592 | |
| 38 | MDIFFLW | Wm-2 | SCALE2(22) | 100 | 1 | 608* | |
|
* Repeated NHR-DAY times ** See Section 9.3.1 | |||||||
| Output Structure | |||
|---|---|---|---|
| Temporal Scale | Statistics/Parameters | No. of Data Values | Record |
| - | Regional number, Geographic scene type, Scene fraction histogram(9) | 11 | 1 |
| Monthly (Day) |
,
MMINSW,
MMAXSW,
,
NSW,
,
MMINLW, MMAXLW, ,
NLW,
, ,
TSOLRD(2)
|
28 x 1 | |
| Monthly (Hour) |
,
MMINSW,
MMAXSW,
,
NSW,
,
MMINLW, MMAXLW, ,
NLW,
,
,
TSOLRH(2)
|
||
| Daily |
DEO,
,
MMINSW, MMAXSW,
,
NSW,
,
MMINLW, MMAXLW, ,
NLW,
,
SOLARD(2)
|
14 x 31 | |
| Monthly Hourly |
,
MMINSW,
MMAXSW,
,
NSW,SUMSW(2),
SUM2SW(2), ,
MMINLW,
MMAXLW,
,
NLW,
SUMLW(2), SUM2LW(2), ,
SOLARH(2)
|
21 x 24 | |
| Monthly | NHR-DAY | 1 | |
| NOAA-9 Deadscanner Flag | 1 | ||
| ERBS Deadscanner Flag | 1 | ||
| NOAA-10 Deadscanner Flag | 1 | ||
| Half-sine Flag | 1 | ||
| Spares | 9 | ||
| Hourly/Day |
Hour box, Whole Julian date(2), Fractional Julian date, Scene fraction (9),
(9),
COS(ZEN)SUN,
Satellite zenith angle,
Azimuth angle, SOLAR, ,
MMINSW,
MMAXSW, ,
NSW,
,
MMINLW,
MMAXLW, ,
NLW,
|
38 x NHR-DAY | 2 |
In the following definitions, some values are listed as occupying two words. These parameters require two 16-bit words to represent a sufficient number of significant digits. To restore the value in the two words, multiply the value of the first 16-bit word by the appropriate scale factor (see Table 3 and add on the value in the second 16-bit word.
Nonscanner Output Product (S-10N) values are represented by Table 4. For each parameter listed below, the units are given in parentheses and the numbers in brackets identify the possible range.
An integer from 1 to 2592 denotes one of the 5.0 x 5.0 degree
ERBE regions. Region 1 lies in the range
85.0° < lat <= 90° (0° <= colat < 5.0°), 0° <= long < 5.0°.
The regions are numbered consecutively, west to east, 72 per latitude band. The
last row of regions includes a latitude of -90 degrees (colat=180
degrees).
An integer from 1 to 648 denotes one of the 10.0 x 10.0 degree ERBE
regions. Region 1 lies in the range
80.0° < lat <= 90° (0° <= colat < 10.0°), 0°
<= long < 10.0°.
The regions are numbered consecutively, west to east, 36 per latitude band. The
last row of regions includes a latitude of 90 degrees (colat = 180
degrees).
The fraction denoting the cloud-free land + desert geotype. If greater than 0.5, the longwave model is applied.
These are the sum of all scene fractions for one month for clear, partly cloudy, mostly cloudy, and overcast scenes. The scene fraction histograms and scene fraction vectors have a dimension of nine. (See Table 8.)
These are monthly means based on daily calculations of flux. For longwave quantities, the daily means are obtained from the extrapolation, interpolation, and diurnal modeling algorithms that operate on the existing longwave estimates. The extrapolation and interpolation algorithms will, in general, cross daily boundaries, but the longwave diurnal model applied to land scenes operates on a specific day.
The shortwave quantities are based on calculations for specific days. The days are defined to be symmetric about solar noon.
the monthly mean SWF based on monthly mean albedo and the sum of integrated
solar incidence over the entire month. (Wm-2)
where N = all days of month.
MMINSW: minimum daily mean for days with at least one SWF estimate. (Wm-2)
MMAXSW: maximum daily mean for days with at least one SWF estimate. (Wm-2)
standard deviation of daily means for days with at least one SWF estimate.
(Wm-2)
NSW: the number of days with at least one SWF estimate. [1-31]
the monthly mean LWF based on all extrapolated, interpolated, and modeled LWF
values for the month in this region. (Wm-2)
where N = all days of month. (Reference 4)
MMINLW: the minimum daily mean of the LWF for the month. (Wm-2)
MMAXLW: the maximum daily mean for the LWF for the month. (Wm-2)
standard deviation for the LWF daily means for every day in the month.
(Wm-2)
NLW: number of days with at least one LWF estimate. [1-31]
the monthly mean albedo from daily values, based on the sum of all integrated
daily SWF is calculated for days with at least one SWF estimate. [0-1.0]
The solar incidence is integrated from sunrise to sunset for each day with SWF data, assuming a sun position for the day that is fixed at its position for 0h0m0s UT. (Reference 4)
the
monthly net flux defined from
the sum of
integrated solar incidence over the entire month, and monthly net
LWF. (Wm-2)
TSOLRD (2 words): the monthly total integrated solar incidence for the entire month. The multiple of 10 used to separate this value is 1000. (W-hm-2)
These are monthly means based on values averaged over the month at each local hour. In general, they result in different values for the same radiometric quantity compared to the monthly (day) means.
the monthly mean SWF based on the monthly mean albedo and the sum of integrated
solar incidence over the entire month. (Wm-2)
where N = all days of month.
MMINSW: the minimum monthly hourly mean SWF as calculated for days with at least one SWF estimate. It can be zero if there is at least one nighttime hour during the month. (Wm-2)
MMAXSW: the maximum monthly hourly mean SWF as calculated for days with at least one SWF estimate. (Wm-2)
the standard deviation of all monthly (hour) mean SWF including nighttime
values. This value may be a large number without much physical significance.
(Wm-2)
NSW: the number of hours that had at least one SWF estimate during the month. [1-24]
the monthly mean LWF based on all extrapolated, interpolated, and modeled LWF
values only for days during the month that had at least one actual LWF
estimate. (Wm-2) (Reference
4)
MMINLW: the minimum LWF for days with at least one LWF estimate. (Wm-2)
MMAXLW: the maximum LWF for days with at least one LWF estimate. (Wm-2)
the standard deviation of all monthly (hour) mean LWF for days with at least
one LWF estimate. (Wm-2)
NLW: the number of hours that had at least one LWF estimate during the month. [1-24]
the monthly mean albedo from monthly hourly values, based on the sum of all SWF
calculated for days with at least one SWF estimate.
where Dsw = days with at least one SWF measurement. (Reference 4)
There is no correction for integrated solar incidence in the monthly hourly albedo calculations. Since the albedo is in the form of a dimensionless ratio, the monthly (hour) albedo will generally be very close to the monthly (day) albedo. [0-1.0]
the monthly net flux defined from
the sum of integrated solar incidence over the entire month, and monthly net
LWF defined from days with at least one LWF estimate.
(Wm-2)
TSOLRH (2 words): the monthly total integrated solar incidence for the entire month. The multiple of 10 used to separate this value is 1000. (W-hm-2)
These are quantities calculated for each day in the month; i.e., there are 31 sets of values on the file. A set consists of the following values.
DEO: the distance-corrected solar constant for the day. (Wm-2)
for each day with at least one SWF estimate, the sum of all estimates and
modeled SWFs, divided by 24, and corrected by the ratio of integrated to summed
solar incidence. This value is called the integrated SWF.
(Wm-2)
where S(d) and S'(d) are the integrated and summed solar radiances, respectively. (Reference 4)
MMINSW: the minimum estimated or modeled SWF for the day. This value will be zero for days with at least one nighttime hour. (Wm-2)
MMAXSW: the maximum estimated or modeled SWF for the day. (Wm-2)
the standard deviation of all modeled or estimated SWF values for the day.
This may be a large number without much physical significance for days having
at least one nighttime hour. (Wm-2)
NSW: the number of hours with SWF estimates for the day. [1-24]
daily LWF consisting of estimates and extrapolated, interpolated, and modeled
values. (Wm-2) If the half-sine fit was applied, all
daily LWF quantities will contain fill values.
MMINLW: the minimum estimated or modeled LWF for the day. (Wm-2)
MMAXLW: the maximum estimated or modeled LWF for the day. (Wm-2)
the standard deviation of all modeled or estimated LWF for the day.
(Wm-2)
NLW: the number of hours with LWF estimates for the day. [1-24]
the daily albedo defined as the ratio of integrated daily SWF to the integrated
daily solar incidence. [0-1.0]
where S(d) = integrated daily solar incidence.(Reference 4)
SOLARD (2 words): integrated solar incidence over a day. The multiple of 10 used to separate this value is 1000. (W-hm-2)
These are calculated for the month at each local hour, i.e., there are 24 sets of values on the file. A set consists of the following values.
the monthly hourly mean SWF for this hour. (Wm-2)
MMINSW: the minimum estimated SWF for this hour. This value will be zero for nighttime hours. (Wm-2)
MMAXSW: the maximum SWF for this hour. (Wm-2)
the standard deviation for SWF at this hour.
(Wm-2)
NSW: the number of days with SWF estimates for the hour. [1-31]
SUMsw (2 words), SUM2sw (2 words): the sum and sum squared of actual SWF estimates at this hour. These values are intended for doing tests of statistical significance for diurnal variability. The multiple of 10 used to separate these values is 1000. (W-hm-2), ((W-hm-2)-2)
the monthly hourly average LWF for this hour.
(Wm-2)
MMINLW: the minimum LWF for days with LWF estimates for this hour. (Wm-2)
MMAXLW: the maximum LWF for days with LWF estimates for this hour. (Wm-2)
the standard deviation for LWFs for days with LWF estimates at the hour.
(Wm-2)
NLW: the number of days with LWF estimates at the hour. [1-31]
SUMLW (2 words), SUM2LW (2 words): the sum and sum squared of actual LWF estimates at this hour. These values are intended for doing tests of statistical significance on diurnal variability. The multiple of 10 used to separate these values is 1000. (W-hm-2), ((W-hm-2)-2)
monthly hourly albedo defined as the ratio of monthly hourly SWF to the
integrated solar incidence. [0-1.0]
SOLARH (2 words): integrated solar incidence over those days with SWF data for a given hour. The multiple of 10 used to separate this value is 1000. (W-hm-2)
The total number of hours in the month with one or more estimates of any kind. Record 2 length is determined by NHR-DAY times 38.
This is an integer with a value of zero or one. Zero indicates data from a month when the scanner was operating, or there is no NOAA-9 data in the data set. One indicates data from a month when the NOAA-9 scanner was not operating.
This is an integer with a value of zero or one. Zero indicates data from a month when the scanner was operating, or there is no ERBS data in the data set. One indicates that this is data from a month when the ERBS scanner was not operating.
This is an integer with a value of zero or one. Zero indicates data from a month when the scanner was operating, or there is no NOAA-10 data in the data set. One indicates data from a month when the NOAA-10 scanner was not operating.
This is an integer with a value of zero or one. Zero indicates that the half-sine algorithm for longwave was not used. One indicates that the half-sine algorithm for longwave was used.
The Hourly/Day estimates constitute the individual estimates
which are adjusted to the conditions at the local solar half hour with the aid
of directional models appropriate to the scene types represented
(See Table 8), Table 9), and
Table 10). The Hourly/Day statistics apply to the
averaging procedures done by Monthly Time/Space Averaging. For example,
applies not to a mean value, but to the result of a running average applied to
nonscanner estimates in the same region and local solar hour box. The standard
deviation applies as well to these (few) measurements.
This is an integer from 1-744 designating the local solar hour box to which the estimate has been assigned. (Hours run from 1-24 on the first day of the month, 25-48 on the second day of the month, etc.). If this is a multiple satellite product, the hour box number is adjusted by 1000 times the number of satellites which have data for the region.
This is the whole part of the Julian date. The multiple of 10 used to separate this value is 10000. (day) [2440000-2460000]
This is the fractional part of the Julian date. (day) [0-1]
These values form a normalized vector giving the distribution of clear, partly cloudy, mostly cloudy, and overcast pixels inverted by the Inversion/DDB Subsystems for this hour box. [0-1.0]
vectorThese are the albedos for clear, partly cloudy, mostly cloudy, or overcast scene types within this hour box. [0-1.0]
This is the average cosine of the solar zenith angle in the range of 0 - 90 degrees for the pixels, as a result of a running average applied in Monthly Time/Space Averaging. COS(ZEN) is defined as 0 for all zenith angles greater than 90 degrees. [0-1.0]
This is the average satellite-viewing zenith angle for the
pixels. (degrees) [0-180]
NOTE: This value is meaningless for products derived from multiple
satellites.
This is the average relative azimuth angle (0 in the forward
scattering direction) for the pixels. (degrees) [0-360]
NOTE: This value is meaningless for products derived from multiple
satellites.
This is the solar incidence for the local solar hour box. (Wm-2)
This is the average SWF adjusted to the local solar hour box and averaged by Monthly Time/Space Averaging. (Wm-2)
This is the minimum SWF estimate for the local solar hour box. (Wm-2)
This is the maximum SWF estimate for the local solar hour box. (Wm-2)
This is the standard deviation of SWF estimates for the local solar hour box. (Wm-2)
This is the number of individual SWF estimate records provided to the local solar hour box.
This is the average LWF estimate as averaged by Monthly Time/Space Averaging. (Wm-2)
This is the minimum LWF estimate for the local solar hour box. (Wm-2)
This is the maximum LWF estimate for the local solar hour box. (Wm-2)
This is the standard deviation of LWF estimates for the local solar hour box. (Wm-2)
This is the number of individual LWF estimate records provided to the local solar hour box.
These values, used for processing multiple satellites only, are the maximum difference between individual mean SWF or LWF. For single satellite products, these values are zero. (Wm-2)
Units of measurement for the calculated and measured science variables for the S-10N data product can be found in the Variable Description/Definition Section of this document.
Please refer to the Summary of Parameters Section of this document.
Please refer to the Temporal Coverage Map Section of this document for the archival status of the ERBE S-10N product.
ERBE data records are stored as binary integers in the ERBE native format. When ordering this data set, the user has the option of receiving the sample read software for this data set. The "README" file for executing this software provides the necessary information to obtain data records from this data set.
A general description of data granularity as it applies to the IMS appears in the EOSDIS Glossary.
Each archived granule contains data of a defined spatial resolution, as described in Table 5, for one month.
| Product | Data Sets | Data Filename* | Description of Data Sets |
|---|---|---|---|
| S-10N | ERBE_S10N_WFV_NF_NAT | s10n_wfov_nf_yymm_s | Nonscanner wide field-of-view numerical filter 5.0 deg. regional averages |
| ERBE_S10N_WFV_SF_NAT | s10n_wfov_sf_yymm_s | Nonscanner wide field-of-view shape factor 10.0 deg. regional averages | |
|
* yy represents the year (e.g., 89 - 1989); mm represents the
number value of a month (e.g., 01 = January, 12 = December) s represents the satellite code: 1 = NOAA-9 2 = ERBS 3 = NOAA-10 4 = NOAA-9/NOAA-10 5 = ERBS/NOAA-9 6 = ERBS/NOAA-10 7 = NOAA-9/ERBS/NOAA-10 | |||
The S-10N products contain a header record, a scale factors record, and data records. The S-10N for one month consists of one to four files. The products can be obtained on 9-track, 8mm, or 4mm tape media or electronically as disk files (i.e., a stream of bits) from the Langley ASDC. Read software is also provided. When a user is connected to the on-line Langley ASDC system, a particular data set pertaining to the type of ERBE S-10N data of interest can be selected.
Table 5 depicts the data sets produced each data month. Column one lists the type of S-10N product, column two lists the names of data sets which the user will see as he orders his data from the ASDC, column three represents the names of the files of the data that the user will receive from the ASDC and column four gives a description of each data set.
The header record identifies the data and also serves as an identifying number for any correspondence between a user and the ERBE Data Management Team. It is a 30-byte record formatted as 8-bit bytes and defined in Table 6. An example of the information in this header for an S-10N is given in Table 7.
| Bytes | Description | Value | Interpretation |
|---|---|---|---|
| 1-2 | Subsystem Indicator | 1-7 | The subsystem outputting the data product is: 1 - Telemetry 2 - Ephemeris 3 - Attitude 4 - Merge/FOV/Count Conversion 5 - Inversion 6 - Daily Data Base and Monthly Time/Space Averaging 7 - Output Products |
| 3-4 | Product Code | 1-99 | Each subsystem assigns its output (tape, disc, paper, plot, etc.) a unique number for identification. See Table 1 in Data Products Catalog for individual subystem definitions. |
| 5-6 | Spacecraft Indicator | 1-7 | The data is from the following combination of spacecraft: 1 - NOAA-9 only 2 - ERBS only 3 - NOAA-10 only 4 - NOAA-9 and NOAA-10 5 - NOAA-9 and ERBS 6 - NOAA-10 and ERBS 7 - NOAA-9 and NOAA-10 and ERBS |
| 7-8 | Whole Julian date (high-order part) | e.g., 244 | Leftmost 3 digits of the 7-digit whole part of the intiial Julian date. |
| 9-10 | Whole Julian date (low-order part) | e.g., 5700 | Rightmost 4 digits of the 7-digit whole part of the initial Julian date. |
| 11-12 | Fractional Julian date | e.g., 5000 | First 4 digits of the fractional part of the initial Julian date times 10000. |
| 13-14 | Processed Version Counter | 1-99 | A counter initially set to 1 and incremented by one each time the product is reprocessed. |
| 15-16 | Year Processed | e.g., 84 | The last two digits of the year of process date. The process date is the date (local time) when the data product was processed (or reprocessed) at Langley Research Center, Hampton, VA. |
| 17-18 | Month Processed | 1-12 | Month of the process date. January is 1 and December is 12. |
| 19-20 | Day Processed | 1-31 | Day of the process date. |
| 21-22 | Hour Processed | 0-23 | Hour of the process date. |
| 23-24 | Minute Processed | 0-59 | Minute of the process date. |
| 25-25 | Second Processed | 0-59 | Second of the process date. |
| 27-30 | Spares | 0 | Zero-filled spares to produce a record which is multiple of 8-, 16-, and 60- bits. |
| Bytes | Description | Example | Note |
|---|---|---|---|
| 1-2 | Subsystem Indicator | 6 | The S-9 or S-10 is output from the Monthly Time/Space Averaging Subsystem and will always have a 6 as the subsystem indicator. |
| 3-4 | Product Code | 60, 62, 64, 66, 68, 82, 84, 86, 88 | The Monthly Time/Sapce Averaging Subsystem has defined the product
codes as follows: 60: S-9 scanner 62, 82: S-10, S-10N numerical filter MFOV* 64, 84: S-10, S-10N numerical filter WFOV* 66, 86: S-10, S-10N shape factor MFOV* 68, 88: S-10, S-10N shape factor WFOV* |
| 5-6 | Spacecraft Indicator | 2 | A number 1-7 will appear here depending on whether data is for a single satellite or a combination of satellites. |
| 7-8 | Whole Julian date (high-order part) | 244 | The initial Julian date for this example is 6005.5. |
| 9-10 | Whole Julian date (low-order part) | 6005 | The whole Julian date for the first day of the month of actual data. |
| 11-12 | Fractional Julian date | 5000 | The fractional Julian date will be 0.5. |
| 13-14 | Processed Version Counter | 1 | A value of 1 means that the product has been processed one time and not reprocessed. |
| 15-16 | Year Processed | 84 | For this example, the product was processed on February 3, 1984 at 9 P.M. 48M54S. |
| 17-18 | Month Processed | 2 | |
| 19-20 | Day Processed | 3 | |
| 21-22 | Hour Processed | 21 | |
| 23-24 | Minute Processed | 48 | |
| 25-25 | Second Processed | 54 | |
| 27-30 | Spares | 0 | |
|
* After all ERBE scanners were inoperative, nonscanner data were processed
with an algorithm known as the "Time/Space Averaging Deadscanner
Option" (see Section 9.3.1). Product codes 82, 84, 86, and 88 indicate S-10N data processed using this algorithm. | |||
Following the header record are the scale factors which are used to pack the data. The record is written in 16-bit words. The first 67 values of this record are used to pack Record Type 1. The next 38 values are used to pack Record Type 2. The correspondence of the scale factors to the data values is discussed in the Parameter/Variable Section of this document. They are used to unscale the integer data quantities as follows:
Real Quantity = (Integer Scaled Quantity From Type) / (Scale Factor)
There are a number of steps in the processing of the ERBE data (see Figure 2). The mathematics involved in each of these steps is beyond the scope of this document. However, interested readers are referred to the following: Suttles (Reference 26), Hoffman (Reference 14) and Smith (Reference 23).
The Langley Research Center (LaRC) has the responsibility of processing and validating all science data from the ERBE mission and of distributing the resulting data products to the science community. The ERBE data processing system at LaRC uses a modular software subsystems approach to process the ERBE data, starting with the input telemetry and ephemeris data from Goddard Space Flight Center (GSFC) and NOAA and ending with the production of the required science data products.
The diagram in Figure 2 shows the major steps in the science data processing, together with the primary input and output data products. The first step in this processing procedure is to ingest 24 hours of telemetry data from the ERBS, NOAA-9, or NOAA-10 spacecraft into the front-end processing subsystem of the Data Processing System. The processing at this step accounts for spacecraft differences and for differences in the data acquisition and handling systems of the ERBS and TIROS N satellites. The data are organized into a format that is common to data from GSFC and NOAA. Extensive data quality editing and evaluation are performed, including the checking of quality flags appended by the tracking networks and processing systems at GSFC and NOAA. The operational status of the instruments is determined, and all instrument housekeeping data and selected spacecraft housekeeping measurements are converted to engineering units and edited. Pointing vectors for the optical axes of the detectors are calculated in a local horizon coordinate system at the spacecraft.
The 8-day ephemeris data sets are processed and validated separately before combining them with the corresponding telemetry data. Orbital data are tested for consistency with data from the previous week, and tests are performed to verify the consistency of the orbit calculations between 1-minute data points. The tests include checks for in-plane and out-of-plane consistency and precision. The routine verification processing and other analyses performed to verify the accuracy of the ephemeris data have generally demonstrated accurate orbit determination for both the ERBS and NOAA spacecraft.
The next major processing stage begins with the merging of the output data from telemetry processing with data output from the ephemeris processing. The FOV locations on a surface at the TOA are determined for every radiometric measurement. The FOV locations are more critical for the scanner measurements than those of the nonscanner because of the small FOV of the scanner instrument. A FOV accuracy analysis has shown that the calculated locations of the scanner measurements are well within the FOV footprint of the instrument on the Earth.
At this processing stage, the raw measurements for each radiometric detector are also converted to incident radiances at the spacecraft. The conversion algorithms employ calibration coefficients that are based primarily on ground-based calibration data, but which are updated with results from in-flight calibrations.
In the inversion processing stage, the spacecraft altitude radiances are inverted or reduced to radiant fluxes at the TOA by both a numerical filter technique and a shape factor technique. The shortwave radiances are inverted by both techniques based on the mostly-cloudy over ocean angular distribution model. The longwave radiances are inverted based on precomputed inversion weights (numerical filter technique) and precomputed shape factors (shape factor technique). An archival product, called the S-7, is produced at this point to retain detailed time histories of estimates of the radiant fluxes at the TOA.
The time-ordered estimates of TOA fluxes are sorted into spatial sequences for both the scanner and nonscanner measurements, grouping all estimates for a month together on a regional basis. A full calendar month of estimates is then retrieved for each region of the Earth. Hourly, daily, and monthly estimates of several different parameters are derived by interpolation using directional models that describe the temporal variation of the radiation budget components. Archival products of monthly averages of radiation components for the nonscanner are produced at this point.
Several archival products are produced at the final stage of data processing (Figure 2). The nested averages product gives values of the nonscanner fluxes from each instrument averaged over various spatial scales. The processing at this stage also combines data from all available spacecraft to produce a combined-satellite product of TOA fluxes averaged over the same spatial scales. An archival product for solar monitor measurements is also produced to provide time histories of solar calibration data. All archival data products are distributed first to the ERBE Science Team for review and validation and then to LaRC ASDC for archival.
Processing changes are discussed in the Special Corrections/Adjustments Section below.
Since the publication of Reference 4, several modifications have been made to Monthly Time/Space Averaging Algorithms which affected the S-10N product in the following areas:
Monthly shortwave averages are calculated using the monthly mean albedo and the sum of the integrated daily solar incidence of all days (N) of the month:
(6)
(
and S(d) are defined in Reference 4)
An alternate definition of monthly average values may be expressed in terms of monthly hourly averages. In this case, calculate the average for each of the 24 local hours using only the days with measurements and then take the mean of the local hour averages. The calculation of the monthly hourly average albedo and SWF are the same as Equation 12 (Reference 4) and Equation 6 respectively, whether one first sums through the days or the hours of the month. Obviously, shortwave interpolation cannot take place on a given day if there are no shortwave measurements for that day.
In general,
is not equal to
as defined by Equations 18 and 13 (Reference 4)
respectively, differing by the usage of the longwave interpolated values on
days for which there were no longwave measurements. This difference can be
significant if several days of measurements are missing. If there are no
shortwave measurements for a given month and the monthly total integrated solar
incidence is greater than zero, the solar and net parameters of these regions
are not used in the global averages. Some of these regions lie on the latitude
belt where the solar terminator occurs with the seasonal movement of the solar
declination. Naturally, if the monthly total integrated solar incidence equals
zero, the shortwave portion of Equations 18 and 13 (Reference
4) is zero. The sampling problems outlined in this paragraph will
ultimately have to be dealt with outside the context of ERBE operational
software.
The shortwave parameters of the monthly clear-sky averages are the same as the monthly averages, except that clear-sky measurements are used. The same holds true for the longwave parameters for ocean, snow, and coast geotypes. Over land and desert geotypes, however, the lack of clear-sky longwave measurements on a daily basis or even on a monthly time-scale as in tropical convective regions, discourages any type of daily modeling. Therefore, a half-sine model is best applied after the clear-sky longwave measurements have been sorted by local hour. This will better account for the clear-sky diurnal variation, assuming that the clear-sky longwave diurnal range exceeds the day-to-day fluctuations for a given local hour. This way, the bias toward either daytime or night time clear-sky measurements has been reduced. First, the monthly hourly LWF MLW(h) as defined by Equation 16 (Reference 4) is calculated, but only clear-sky longwave measurements are used. The same conditions as defined by the LW half-sine model section apply, except that the least squares fit is weighted by the number of measurements for the local hour, and the night time average is the mean of all night time clear-sky longwave measurements. This method is used for both the monthly daily and monthly hourly clear-sky longwave averages for land and desert regions.
An additional change was made to the clear-sky averaging algorithm that corrects the misclassification of nighttime clear pixels as partly cloudy. For each nighttime hour box over land regions, a new clear-sky percentage is estimated by assuming that 100f the pixels classified as clear and partly cloudy are actually clear. If this new clear percentage exceeds 5 and represents an increase over the original clear-sky percentage, then the clear-sky longwave flux is recalculated using the mean and standard deviation of the total longwave flux.
| Solar Zenith Angle Bin Number | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Scanner Index | 0.95 | 0.85 | 0.75 | 0.65 | 0.55 | 0.43 | 0.35 | 0.25 | 0.15 | 0.05 | Nonscanner Index |
| (Clear) 1 | 1.00000 | 1.07895 | 1.19737 | 1.32895 | 1.51316 | 1.75000 | 2.11842 | 2.67105 | 3.52632 | 4.39474 | 1 (Ocean) |
| 2 | 1.00000 | .97813 | 1.01875 | 1.04375 | 1.09375 | 1.16438 | 1.28125 | 1.44375 | 1.68750 | 2.03750 | 2 (Land) |
| 3 | 1.00000 | 1.00450 | 1.00899 | 1.01289 | 1.01588 | 1.01738 | 1.01514 | 1.00525 | .97437 | .92747 | 3 (Snow) |
| 4 | 1.00000 | 1.02000 | 1.04800 | 1.08300 | 1.12600 | 1.17600 | 1.23400 | 1.30000 | 1.37200 | 1.45300 | 4 (Desert) |
| 5+ | 1.00000 | 1.01059 | 1.07627 | 1.13559 | 1.22881 | 1.35297 | 1.55085 | 1.83898 | 2.27966 | 2.79661 | Clear |
| (Partly Cloudy) 6 | 1.00000 | 1.12000 | 1.20000 | 1.36000 | 1.48000 | 1.72000 | 2.00000 | 2.40000 | 2.92000 | 3.56000 | 5 (Ocean) |
| 7* | 1.00000 | 1.03756 | 1.07981 | 1.13146 | 1.19249 | 1.29108 | 1.41315 | 1.59624 | 1.77465 | 2.01174 | 6 (Land/Desert)++ Partly Cloudy |
| 8* | 1.00000 | 1.03756 | 1.07981 | 1.13146 | 1.19249 | 1.29108 | 1.41315 | 1.59624 | 1.77465 | 2.01174 | |
| 9* | 1.00000 | 1.03756 | 1.07981 | 1.13146 | 1.19249 | 1.29108 | 1.41315 | 1.59624 | 1.77465 | 2.01174 | |
| 10+ | 1.00000 | 1.06805 | 1.12426 | 1.21598 | 1.29882 | 1.44970 | 1.63018 | 1.89349 | 2.19822 | 2.58432 | |
| (Mostly Cloudy) 11 | 1.00000 | 1.07843 | 1.13725 | 1.23529 | 1.29412 | 1.43137 | 1.56863 | 1.75686 | 1.96078 | 2.19608 | 7 (Ocean) |
| 12* | 1.00000 | 1.04700 | 1.10300 | 1.17000 | 1.24400 | 1.33200 | 1.42800 | 1.53400 | 1.65000 | 1.77500 | 8 (Land/Desert)++ Mostly Cloudy |
| 13* | 1.00000 | 1.04700 | 1.10300 | 1.17000 | 1.24400 | 1.33200 | 1.42800 | 1.53400 | 1.65000 | 1.77500 | |
| 14* | 1.00000 | 1.04700 | 1.10300 | 1.17000 | 1.24400 | 1.33200 | 1.42800 | 1.53400 | 1.65000 | 1.77500 | |
| 15* | 1.00000 | 1.08468 | 1.16216 | 1.25586 | 1.35135 | 1.46613 | 1.61171 | 1.77658 | 1.94685 | 2.14775 | |
| (Overcast) 16 | 1.00000 | 1.02353 | 1.07059 | 1.12941 | 1.17647 | 1.24706 | 1.31765 | 1.38824 | 1.45882 | 1.51765 | 9 Overcast |
Directional Model Index Selection for Scanner Measurements
Geotype(G) = 1 (Ocean) and fi = 1 (Clear) Then if fi = 1,
INDEX = G
Geotype(G) = 2 (Land) and fi = 2 (Partly cloudy) Then if
fi = 2, INDEX = G + 5
Geotype(G) = 3 (Snow) and fi = 3(Mostly cloudy) Then if
fi = 3, INDEX = G + 10
Geotype(G) = 4 (Desert) and fi = 4 (Overcast) Then if fi
= 4, INDEX = 16
Geotype(G) = 5 (Land/Ocean)+
* Storing separate but identical models for land, snow, desert, and
land/desert mix makes easier the generation of a scanner model index from cloud
and geotype information.
+ These are lienar composite models (50-50 for each constituent),
not independent models, which function as separate scene tyeps for scanner
processing.
++ Snow geotypes must be either clear or overcast.
Some of the directional models have been altered since the publication of Reference 4.
| Solar Zenith Angle Bin Number | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Model No. | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| 1 | .0760 | .0820 | .0910 | .1010 | .150 | .1330 | .1610 | .2030 | .2680 | .3340 |
| 2 | .1600 | .1565 | .1630 | .1670 | .1750 | .1863 | .2050 | .2310 | .2700 | .3260 |
| 3 | .6673 | .6703 | .6733 | .6759 | .6779 | .6789 | .6774 | .6708 | .6502 | .6189 |
| 4 | .2369 | .2388 | .2411 | .2437 | .2471 | .2517 | .2581 | .2683 | .2864 | .3098 |
| 5 | .1180 | .1193 | .1270 | .1340 | .1450 | .1597 | .1830 | .2170 | .2690 | .3300 |
| 6 | .1250 | .1400 | .1500 | .1700 | .1850 | .2150 | .2500 | .3000 | .3650 | .4450 |
| 7 | .2130 | .2210 | .2300 | .2410 | .2540 | .2750 | .3010 | .3400 | .3780 | .4285 |
| 8 | .1690 | .1805 | .1900 | .2055 | .2195 | .2450 | .2755 | .3200 | .3715 | .4368 |
| 9 | .2550 | .2750 | .2900 | .3150 | .3300 | .3650 | .4000 | .4480 | .5000 | .5600 |
| 10 | .3000 | .3270 | .3550 | .3820 | .4200 | .4487 | .4945 | .5380 | .5805 | .6320 |
| 11 | .2775 | .3010 | .3225 | .3485 | .3750 | .4069 | .4473 | .4930 | .5403 | .5960 |
| 12 | .4250 | .4350 | .4550 | .4800 | .5000 | .5300 | .5600 | .5900 | .6200 | .6450 |
Some of the directional albedo models have been improved since the publication of Reference 4.
| Model No. | Scene | Cloud Cover (Percent) |
|---|---|---|
| 1 | Ocean | 0 < C < 5 |
| 2 | Land | 0 < C < 5 |
| 3 | Snow | 0 < C < 5 |
| 4 | Desert | 0 < C < 5 |
| 5 | Mixed, Land-Ocean | 0 < C < 5 |
| 6 | Partly cloudy over ocean | 5 < C < 50 |
| 7 | Partly cloudy over land or desert | 5 < C < 50 |
| 8 | Partly cloudy over land-ocean mix | 5 < C < 50 |
| 9 | Mostly cloudy over ocean | 50 < C < 95 |
| 10 | Mostly cloudy over land or desert | 50 < C < 95 |
| 11 | Mostly cloudy over land-ocean mix | 50 < C < 95 |
| 12 | Overcast | 95 < C < 100 |
ERBE Albedo Directional Models for Ocean Scenes (See Graph 1)
ERBE Albedo Directional Models for Land Scenes (See Graph 2)
ERBE Albedo Directional Models for Clear Over Snow and Clear Over Desert Scenes (See Graph 3)
Region-Specific Directional Model for the Deadscanner Option (See Graph 4)
The main difficulty for the time/space averaging algorithm is that there is no scene identification information when a scanner is inoperative. This condition is caused by the lack of scanner data which are necessary to apply the proper directional models when extrapolating shortwave data to hours with no observations. In order to process data retrieved during periods with no scanner, an alternative method for selecting scene identification information has been developed which is called the Deadscanner Option.
The data needed to perform the Deadscanner Option are the observed total albedo and the percentage of each geotype (ocean, land, snow, and desert) for the region where the measurement was made. By combining the non-normalized directional albedo models proportionally by geotype percentage, a set of regionally specific directional models can be produced. The relationship of the observed albedo with the albedos predicted by these models is then used to establish which elements of the scene fraction array are filled. As an example, for a region that is 600cean, 30and, and 10 0esert, the region-specific directional models are shown in Graph 4. If the observed total albedo in this region is 21.4 at a cos (solar zenith angle) of 0.4 (represented by the X on Graph 4), it can be seen that this albedo lies halfway between the partly cloudy and clear directional models. The scene fraction array, sf, will be filled in the following manner:
| sf(1) = .30 = .5 * .6 | (clear ocean) |
| sf(2) = .15 = .5 * .3 | (clear land) |
| sf(3) = 0. | (clear snow) |
| sf(4) = .05 = .5 * .1 | (clear desert) |
| sf(5) = .30 = .5 * .6 | (partly cloudy ocean) |
| sf(6) = .20 = .5 * (.3 + .1) | (partly cloudy land/desert) |
| sf(7) = 0. | (mostly cloudy ocean) |
| sf(8) = 0. | (mostly cloudy land/desert) |
| sf(9) = 0. | (overcast) |
In nonscanner data, in some land regions like deserts and arid mountains, longwave flux exhibits a pronounced diurnal variation. A single diurnal fit to the monthly ensemble of all longwave data points based on a half-sine curve has been added to the nonscanner algorithm. Rather than daily fits, a fit is performed on monthly hourly averages. Given a month of data, there are five criteria which are applied to determine whether or not a good fit can be obtained:
If any of these criteria are not met, the fit will not be performed and the already calculated averages will be retained.
The daytime curve is a least squares sine fit weighted by the number of measurements at each local hour. The nighttime data are simply averaged and the constant value is used for all night hours. These monthly hourly values for day and night are then stored. The resulting averages of longwave are stored in the arrays formerly used for the Monthly Hourly Longwave Average. The Daily Longwave Average values are replaced with the Monthly Hourly Longwave average values over land and deserts, if a fit is made. These Daily Longwave Average values over land are then used to calculate net radiation for the land regions. The algorithm and data products for other scene types are unchanged.
A flag to indicate whether the half-sine fit was used in a given region was added to the first data record for each region.
The monthly hourly averaged results and the corresponding statistics (minima, maxima, standard deviations) are a combination of measurements and models. The maximum and minimum values for the monthly hourly parameters should be handled with caution because they include extrapolation or interpolation between measurements having many missing hours of data.
A test to allow use or nonuse of the numerical filter cross-track expansion algorithm used by the Inversion Subsystem (Reference 8) has been added to Monthly Time/ Space Averaging nonscanner code.
Please refer to the Variable Description/Definition Section of this document.
There are no graphs or plots available for the S-10N product.
A discussion of various factors that may lead to errors are discussed in the Confidence Level/Accuracy Judgement Section of this document.
The measurement of radiation budget requires a massive data processing system. ERBE's system uses about 250,000 lines of FORTRAN code. This system also uses an additional 150,000 lines of off-line diagnostic work. The stringent requirements for accuracy in the budget dictate an acute attention to detail.
The ERBE data processing system uses about 25,000 coefficients. These coefficients are conveniently arranged in three groups. The first group is the set of "calibration coefficients" that appear in the algorithms converting telemetry counts to instrument irradiation. Ground- and in-flight-calibration sources provided these coefficients. The second group includes the angular distribution models (ADMs) and spectral unfiltering coefficients needed for inversion. A categorization of the Nimbus-7 ERB measurements forms the base for the ADM's. Missing bins were filled using the reciprocity principle. A combination of radiative transfer results and measurements of the instrument spectral responses provides the spectral correction coefficients. The third and final group of parameters consists of the coefficients needed for time averaging, mainly the directional models. These models describe the dependence of each scene type's albedo upon solar zenith angle. These directional models also came from the Nimbus-7 ERB, but have been suitably supplemented by Geostationary Operational Environmental Satellite (GOES) observations where needed. The majority of the coefficients are used in the inversion process.
The earth's radiation budget is not easy to measure, even indirectly. The ERBE Science Team has relied on consistency and measurement intercomparisons for validation. Fortunately, ERBE data provides a number of these checks. These criteria provide a way of judging the consistency of the various parameters in the data processing system.
The ERBE data products are complex assemblages of data and models. Thus, their uncertainties are difficult to compute. The following numbers represent estimates of the standard deviations about a given data point within which the true measurement might lie. They are not definitive confidence intervals, but are intuitively based on the observed discrepancies in the intercomparisons. It is also important to remember that different measurements have different uncertainties. First, for instantaneous radiances, we expect uncertainties of about 10f longwave observations of filtered radiance and 2 0.000000or shortwave. Radiative transfer comparison and spectral consistency provide the basis for this uncertainty estimate. Second, on an instantaneous observation of flux from 2.5 X 2.5 degree geographic regions, the ERBS/NOAA-9 intercomparisons offer reasonable estimates of uncertainty. These are 5 Wm-2 in the longwave and 15 Wm-2 in the shortwave. Third, on a monthly average, regional basis, the uncertainties in the scanner data are about 5 Wm-2 for shortwave and 5 Wm-2 for longwave. These come from simulations with GOES data. This uncertainty represents no change from the preflight estimate. The nonscanner averages may be somewhat more uncertain because of sampling and diurnal averaging process. Fourth, the uncertainty in global, annual average net radiation is probably about 5 Wm-2. This estimate is based on the imbalance obtained using scanner data from the four validation months (April, July, and October 1985; January 1986).
Measurement errors are mentioned in the Confidence Level/Accuracy Judgement Section of this document.
None.
This data are being processed at the Langley ASDC on the Product Generation System (PGS). Before the data are archived, the ASDC checks all granules to ensure that the size of the granules matches that which was on the PGS. The version number of the granules was also checked so that the most current version of the data is available to the user community. Granule level metadata are extracted from the granules such as the product ID, satellite(s) ID, and data date.
There are no known limitations or unreliable aspects in the algorithms implemented to generate the ERBE science data.
There are no known problems or inconsistencies in the ERBE data.
The monthly hourly averaged results and the corresponding statistics (minimums, maximums, standard deviations) are a combination of measurements and models. The mean and standard deviation of these results, which are on the S-10N, represent the best estimate of the monthly hourly results. However, the maximum and minimum values for the monthly hourly parameters should be handled with caution because they include the extrapolation or interpolation between measurements having many missing hours of data. Also note that one should not just average the measurements alone to determine the monthly hourly means, because it will give a misleading diurnal cycle. The combination of measurements and models gives a more reasonable estimate when compared to full-time sampling of the GOES.
Flux values and standard deviation values may contain a fill value (2^15 - 1). If a fill value was found during packing, the scale factor was not applied. A test for the presence of a fill value in any flux value should be made before the scale factor is applied. Also, when shortwave data are not available for calculation of albedos, these albedo values are set to zero in the S-10N products.
Measurements of the radiation budget provide one of the important tools for the validation of numerical models of the atmosphere. They also provide possibilities for "climate experiments" by allowing the sensitivity of the radiation budget to various forcings to be studied empirically.
The use of cloud discrimination has provided a significant new source of information on the influence of clouds and the characteristics of clear-sky fluxes. This information is particularly important in understanding cloud forcing. It is also important in describing the response of clouds to climate change: the climate cloud sensitivity.
The ERBE project plans to complete the reprocessing, which is currently in progress, of the nonscanner data using inversion and time/space averaging processes which do not use scanner scene identification information.
To continue the measurements of the radiation budget, a second project, the Clouds and the Earth's Radiant Energy System (CERES), is currently being developed. CERES is a key component of the Earth Observing System (EOS). The CERES instruments are improved models of the Earth Radiation Budget Experiment (ERBE) scanner instruments. The strategy of flying instruments on Sun-synchronous, polar orbiting satellites, such as NOAA-9 and NOAA-10, simultaneously with instruments on satellites that have precessing orbits in time sampling errors. CERES will continue that strategy by flying instruments on the polar orbiting EOS platforms simultaneously with an instrument on the Tropical Rainfall Measuring Mission (TRMM) spacecraft, which has an orbital inclination of 35 degrees. In addition, to reduce the uncertainty in data interpretation and to improve the consistency between the cloud parameters and the radiation fields, CERES will include cloud imager data and other atmospheric parameters. The first CERES instrument is scheduled to be launched on the TRMM spacecraft in 1997. Additional CERES instruments will fly on the EOS-AM platforms, the first of which is scheduled for launch in 1998, and on the EOS-PM platforms, the first of which is scheduled for launch in 2000.
There is read software available for this data set.
The read software can be obtained through the Langley ASDC.
Langley ASDC User and Data Services OfficeData, programs for reading the data, and user's guides can be obtained through the EOSDIS Langley ASDC on-line system which will allow users to search through the data inventory and place orders on-line. The Langley ASDC User and Data Services staff provides technical and operational support for users ordering data.
Langley ASDC User and Data Services OfficeOn a regular basis, individual ERBE data granules are reviewed by local members of the ERBE Science Team. Upon Science Team approval, the ERBE Data Management Team releases the data granule to the LaRC ASDC for archive.
There are no S-10N output products available other than the data granules.
ERBE Data Management System Reference Manual, Volumes Va and Vb, Inversion, August 1987.
ERBE Data Management System Reference Manual, Volume VII, Output Products, September 1986.
Monthly Medium-Wide Data Tape S-7 User's Guide, Revision 1, February 1993.
Processed Archival Tape S-8 PAT User's Guide, December 1987.
The Regional, Zonal, and Global Gridded Averages S-4G User's Guide, Revision 1, March 1993.
The Regional, Zonal, and Global averages, S-4/S-4N User's Guide, Revision 1, June 1993.
Sorlie, S. Langley DAAC Handbook. NASA/Langley Research Center, Hampton, Virginia, February 1993.
