Solar radiation enters the Earth's atmosphere with a portion being scattered by clouds and aerosols.

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Processing, archiving and distributing Earth science data
at the NASA Langley Research Center

Frequently Asked Questions and Information - ERBE Information

ERBE Frequently Asked Questions

Earth Radiation Budget Experiment (ERBE) is a NASA satellite measurement project that came about in the late 1970's as a result of NASA recognizing the importance of improving our understanding of the radiation budget and its effects on the Earth's climate, and a need to make accurate regional and global measurements of the components of the radiation budget. ERBE observations were collected from three satellites that measured global albedo, outgoing and reflected fluxes, and solar incidence. The first full calendar month of ERBE observation began on November 1984. The ERBE project officially ended after the decommission of the NASA ERBS satellite mission on August 2005. All ERBE data are permanently archived at the NASA Langley Atmospheric Science Data Center.

The three satellites ERBS, NOAA-9, NOAA-10 carrying two ERBE instrument packages (Scanner and NonScanner) were used. The NASA Goddard Space Flight Center built the Earth Radiation Budget Satellite (ERBS) on which the first ERBE instruments were launched by the Space Shuttle Challenger in 1984. ERBE instruments were also launched on two operational National Oceanic and Atmospheric Administration (NOAA) weather monitoring satellites, NOAA-9 and NOAA-10 in 1984 and 1986, respectively.

Earth Radiation Budget Satellite (ERBS) is a dedicated NASA research satellite launched by Space Shuttle Challenger in October 1984 and was the first spacecraft to carry ERBE instruments into orbit. ERBS is in a precessing orbit (57 degree) allowing the ERBE instruments on board this satellite to provide complete diurnal sampling in 72 days. The ERBS satellite mission came to an official end on August 2005 after 20+ years of continuous operations.

The Radiation Budget represents the balance between incoming energy from the Sun and outgoing thermal (longwave) and reflected (shortwave) energy from the Earth.

Global spatial coverage is provided by the ERBE instruments on board the NOAA-9 and NOAA-10 satellites. Coverage between 60 degrees north and south latitude is provided by ERBS satellite. ERBS is a precessing satellite and produces the best diurnally sampled data because it sees all 24 hours of local time in 72 days. NOAA-9 and NOAA-10 are sun-syn satellite and do not cover the entire diurnal cycle, however they see the entire globe. NOAA-9 is the afternoon (2:30 PM LST) satellite and NOAA-10 is the morning (7:30 AM LST) satellite.

The ERBE/ERBS instruments operated from November 1984 to August 2005. The ERBE/NOAA 9 instruments operated from February 1985 to November 1992. The ERBE/NOAA 10 instruments operated from January 1986 to November 1992. ERBE data availability depends on both instrument type and satellite.

These are two types of instruments specifically designed by a team of electronic, thermal, and mechanical experts, built and integrated with the ERBS and NOAA satellite platforms by TRW of Redondo Beach, CA.

Scanner
A set of three co-planar detectors (longwave, shortwave and total energy), all of which scan from one limb of the Earth to the other, across the satellite track (in its normal operational mode).

The scanner instrument has a smaller footprint (40 km at nadir) and scanned across the orbit plane to provide maximum spatial coverage. The scanner measures directional radiance, not hemispheric flux. The directional radiance is converted to hemispheric flux using empirical statistical model (ERBE ADM). The scanner is designed for regional to large scale analysis, and due to the smaller footprint, the scanner product is able to separate clear sky data from all-sky data to provide both clear-sky and all-sky estimates.

NonScanner
A set of five detectors; one which measures the total energy from the Sun, two which measure the shortwave and total energy from the entire Earth disk, and two of which measure the shortwave and total energy from a medium resolution area beneath the satellite.

The Nonscanner instrument did not scan and pointed straight down to measure hemispheric flux from the Earth. The large footprint (1000 km) is designed only for large scale analysis, thus products provide only all-sky data. Because the nonscanner had less moving parts, it lasted a lot longer than the scanner instrument.

  • Total Channel: 0.2 to 50 microns
  • Shortwave Channel: 0.2 to 5 microns
  • Longwave Channel: 5 to 50 microns
  • Albedo - The ratio of reflective shortwave flux to the solar incoming flux at top of atmosphere (TOA), where zero (0.0) represents total absorption, and one (1.0) represents total reflectance.
  • Net - Net Radiation (Net) is the amount of total radiative flux energy deposited into the Earth system at top of the atmosphere (TOA).
  • OLR - Outgoing Longwave Radiation (OLR) is an alias for longwave (LW) radiative flux energy leaving the Earth system at top of the atmosphere (TOA).
  • RSR - Reflected Shortwave Radiation (RSR) is an alias for shortwave (SW) radiative flux energy leaving the Earth system at top of the atmosphere (TOA).
  • Scene Identification - The twelve possible ERBE scene categories constructed from combinations of geography and cloud cover resulting in distinct Angular Distribution Models.
  • Solar Incidence - The time integrated value of solar incoming flux into the Earth system at top of the atmosphere (TOA).
  • Total Solar Irradiance - The average power received on a unit area at the mean Earth/Sun distance (Watts/square meter).

ERBE net radiation is defined at top of the atmosphere (TOA) as the following:
Net (TOA) = Solar_down (TOA) - SW_up (TOA) - LW_up (TOA)

where Solar_down (TOA) is the solar incoming flux at TOA, SW_up (TOA) is the reflected shortwave flux at TOA, and LW_up (TOA) is outgoing longwave flux at TOA. The sign convention for ERBE net radiation is that positive/negative sign represents a net radiative energy surplus/deficit of the Earth system, respectively.

Cloud radiative forcing (CRF) is not an ERBE parameter. However, it can be calculated from the ERBE scanner data set using the all-sky and the clear-sky parameters as the following:

Cloud Radiative Forcing = Clear-sky Flux - All-sky Flux

Cloud radiative forcing can not be calculated from the ERBE nonscanner data set due to the lack of clear-sky parameters.

ERBE data are available in many different resolutions; ranging from instantaneous satellite footprint data (40km spatial scale), to monthly mean regional averaged gridded data (2.5-degree, 5-degree, and 10-degree grid), to global-monthly mean data. In addition, daily mean regional averages and monthly-hourly regional averages are also available.

  • ERBE uses a regular equal-angle grid system. The ERBE regional gridded data is available in three different resolutions (2.5-degree, 5-degree, and 10-degree) depending on the instrument type.
  • For the ERBE 2.5-degree regional data set, the ERBE grid contains 10,368 2.5-degree regions. This maps to 72 latitude zones with 144 regions in each (72 * 144 = 10368). The first ERBE 2.5 degree region is located at the North Pole - Greenwich meridian. The center location of region 1 is at 88.75N and 1.25E. The 2.5 degree grid extends eastward, one 2.5 degree region at a time, around the entire 2.5-degree latitude circle and then step southward, one 2.5-degree latitude zone at a time, until it reaches region 10368, which is centered at 88.75S and 358.75E.
  • For the ERBE 5-degree regional data set, the ERBE grid contains 2592 5-degree regions. This maps to 36 latitude zones with 72 regions in each (36 * 72 = 2592). The first ERBE 5-degree region is located at the North Pole - Greenwich meridian. The center location of region 1 is at 87.5N and 2.5E. The 5-degree grid extends eastward, one 5-degree region at a time, around the entire 5-degree latitude circle and then step southward, one 5-degree latitude zone at a time, until it reaches region 2592, which is centered at 87.5S and 357.5E.
  • For the ERBE 10-degree regional data set, the ERBE grid contains 648 10-degree regions. This maps to 18 latitude zones with 36 regions in each (18 * 36 = 648). The first ERBE 10-degree region is located at the North Pole - Greenwich meridian. The center location of region 1 is at 85N and 5E. The 10-degree grid extends eastward, one 10-degree region at a time, around the entire 10-degree latitude circle and then step southward, one 10-degree latitude zone at a time, until it reaches region 648, which is centered at 85S and 355E.

The ERBE region number can be easily determined with the following:

2.5-degree Data: Region number = int(colat / 2.5) * 144 + (lon / 2.5)

5-degree Data: Region number = int(colat / 5) * 72 + (lon / 5)

10-degree Data: Region number = int(colat / 10) * 36 + (lon / 10)

where colat = 90 - latitude

For users working with regional data needing global averages, area weighting needs to be applied to the regional averages because of the equal-angle grids. Global data are also available in the S4 data sets.

Compilation successful but values read seem off:
Check to see what bit machine you're running on. If it is a 64-bit machine, check to see if the is a 32-bit compile option available. Other issues affecting compilation would be differing versions of the operating system and compilers the read software are being run on.

Big Endian Little Endian:
Unix machines are Big Endian architecture while Linux systems are Little Endian architecture. Data generated on a Unix machine are byte swapped on the Linux machine when data files are transferred.

Zipped files:
Any zip files need to be unzipped before use. Most programs only read one file at a time.
Example:
filename: s9_8502_5.zip
unzip s9_8502_5.zip

More information is in the Data Access Questions section.

Please submit your science questions directly to the NASA Langley Atmospheric Science Data Center's (ASDC's) User Services. They will forward them to the volunteer scientists assigned to the ERBE data sets. Since the ERBE project has officially ended, the science support is very limited and depends on the availability of our volunteer scientists. It may take a few days to receive your answers.

  • Level 1: NonScanner data: TSI
  • Level 2: Instantaneous unfiltered satellite footprint data: S-7, S-8
  • Level 3: Monthly Averaged gridded data: S-4, S-4N, S-4G, S-4GN, S-9, S-10, S-10N
S-4 Regional, Zonal, and Global Averages
S-4N NonScanner Regional, Zonal, and Global Averages
S-4G Regional, Zonal, and Global Averages
S-4GN NonScanner Regional, Zonal, and Global Averages
S-9 Scanner Earth Radiant Flux and Albedo
S-10 NonScanner Earth Radiant Flux and Albedo
S-10N NonScanner Earth Radiant Flux and Albedo
S-7 NonScanner Medium-Wide FOV Data Tape
S-8 Processed Archive Tape
TSI Total Solar Irradiance

 

The data are available in both native format (NAT), and Hierarchical Data Format (HDF) as listed and described in the Earth Radiation Budget Experiment (ERBE) Langley ASDC Project Document. The following provide a quick summary of the available data.
 

  Scanner and Nonscanner
(Scanner-dependent)
Original Nonscanner
(Scanner-independent)
Newer Nonscanner
(Scanner-independent)
Total Solor Irradiance
Temporal Coverage 11/1984 - 02/1990: 11/1984 - 11/1995: 11/1984 - 09/1999: 10/1984 - 03/2003:
Data Sets
  • ERBE_S4/S7/S9_NAT
  • ERBE_S4G_/SC/MFOV/WFOV
  • ERBE_S10_MFOV/WFOV
  • ERBE_S4N_NAT
  • ERBE_S4GN_WFOV
  • ERBE_S10N_WFV
  • ERBE_S10N_WFOV
  • Edition2 & Edition3 products
  • ERBE_S7_NAT
  • ERBE_TSI_ERBS_NAT

 

There are single satellite and combined-satellite scanner products. The best source for these data is to order the ERBE scanner CD which gives all the S4G monthly mean 2.5 degree gridded data from both single satellite and combined-satellite product in ASCII format. Also, ordering the S4G HDF data online and using the ncdump utility to perform a straight ASCII dump is another option. NOAA-9 and NOAA-10 provide global coverage at different local sampling times. These do not provide the full diurnal coverage, which can affect the quality of the shortwave and longwave estimate. ERBS covers all 24-hour local time, but only for regions between 60N and 60S.

Scanner and Nonscanner instruments are processed independently using separated instrument calibration procedure and data processing algorithm. Because of these differences, it is best to work with these two data sets separately.

  • ERBE/ERBS scanner operated for ~5 years: November 1984 - February 1990
  • ERBE/NOAA-9 scanner operated for ~2 years: February 1985 - January 1987
  • ERBE/NOAA-10 scanner operated for ~2 years: January 1987 - April 1989

Even though NOAA-9 and NOAA-10 continued to fly mid to late 1990's, the ERBE Nonscanner record stopped due to instrument failure. Currently only the ERBE/ERBS noncanner data have been reprocessed to correct for satellite altitude drift and other instrument related issues. These new data are only released as the ERBE/ERBS S10N Edition3 product. More information is available in the Edition3 Data Quality Summary, including a special website to obtain user-applied corrected and ASCII formatted data. No S4GN data is available for this latest data. NOAA-9 and NOAA-10 data have not been reprocessed to correct for the satellite altitude drift issue with no plans for a future fix. The satellite altitude drift only affects the Noncanner data set. The scanner data set is not affected by this issue.

Scanner and Nonscanner instruments are processed independently using separated instrument calibration procedure and data processing algorithm. Because of these differences, it is best to work with these two data sets separately.

ERBE/ERBS Nonscanner operated for ~20 years November 1984 - August     2005
ERBE/ERBS S10N Ed3 Nonscanner operated for ~14 years January     1985 - September 1999
ERBE/NOAA-9 Nonscanner operated for ~8 years February    1985 - November 1992
ERBE/NOAA-10 Nonscanner operated for ~8 years February    1985 - November 1992

** Note** : ERBE/ERBS nonscanner TOA flux data from October 1999 to August 2005 is unavailable to the public due to unresolved instrument anomaly issues.

NFOV narrow field-of-view   2.5 degree resolution
MFOV-NF medium field-of-view numerical filter 5.0 degree resolution
WFOV-NF wide field-of-view numerical filter 5.0 degree resolution
MFOV-SF medium field-of-view shape factor 10.0 degree resolution
WFOV-SF wide field-of-view shape factor 10.0 degree resolution

Sample Filename: s4gn_wnf5._yymm_s
"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

  • Telemetry - Process data from NOAA and GSFC to a common format, interpret the instrument and spacecraft housekeeping data, and analyze instrument commands and in-orbit environment.
  • Ephemeris - Analyze orbit position data from GSFC for each of the three satellite platforms.
  • Merge/Count Conversion - Combine telemetry and ephemeris data to produce Earth location geometry and convert radiometric counts produced by the instruments into satellite-altitude radiances.
  • Inversion - Identify the scene viewed by the instruments and interpret the measurements at the top of the Earth's atmosphere using shape factor and numerical filter inversion techniques.
  • Daily and Monthly Time/Space Averaging - Convert from time-ordered to regionally-accessible data sets and apply diurnal models to estimate hourly, daily, and monthly averages of radiation budget components.
  • Data Products - Generate well-documented science archival products in an easily accessible format.

The ERBE data product documentations can be found at the links below:

Visualize ERBE data with view_hdf:

  • view_hdf a visualization and analysis tool for accessing data stored in Hierarchical Data Format (HDF) and HDF-EOS.

Visualize ERBE data with HDFView:

Short QuickTime movies of ERBE data can be found at the links below: