Global Tropospheric Experiment Pacific Exploratory Mission-Tropics A (GTE PEM Tropics A) Langley ASDC Document Data Set Document
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Global Tropospheric Experiment Pacific Exploratory Mission-Tropics A (GTE PEM Tropics A) Langley ASDC Document Data Set Document |
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This document provides information on data products obtained during the GTE Pacific Exploratory Mission-Tropics A atmospheric science expedition conducted over the tropical Pacific during August-September 1996. The major objective of the mission was to understand the factors controlling tropospheric ozone and its precursors (NOx, CO and hydrocarbons) over the South Pacific, and to assess the implications for the global oxidizing power of the atmosphere. There was also a need to improve understanding of atmospheric sulfur chemistry over the Pacific. Measurements were made primarily by investigators' instruments located on the NASA DFRC DC-8 and WFF P-3B airplanes. Also provided are a list of principal investigators, a brief summary of measurement techniques and a list of publications. PEM-Tropics A was the first of two studies in the South Tropical Pacific region conducted through the GTE Project Office at NASA's Langley Research Center. The second study, PEM-Tropics B, was conducted during the March - April 1999 time period. Data from PEM-Tropics B is also available through the Langley ASDC.
This document provides information for the following PEM Tropics A data sets: (XX indicates the DC-8 or P-3B flight number.)
| gte_pemta_dc8mXX.zip: | Aircraft Data |
| gte_pemta_dc8trajmXX.zip: | Backward Air Mass Trajectories Associated With The DC-8 Flights |
| gte_pemta_sgfvpdXX.zip: | Fast Response H2O Measurements |
| gte_pemta_merge_dXX.zip: | Merged data files |
| gte_pemta_dc8_sat_trkm06.zip: | Selected Satellite Images with DC-8 Aircraft Flight Track |
| gte_pemta_p3mXX.zip: | Aircraft Data |
| gte_pemta_p3btrajmXX.zip: | Backward Air Mass Trajectories Associated With the P-3B Flights |
| gte_pemta_merge_pXX.zip: | Merged data files |
| gte_pemta_sat_trk_p3bmXX.zip: | Selected Satellite Images with P3-B Aircraft Flight Track |
| gte_pemta_ozonesondes_as.zip: | Ozone Sondes Launched From American Samoa |
| gte_pemta_ozonesondes_nz.zip: | Ozone Sondes Launched From New Zealand |
| gte_pemta_ozonesondes_ei.zip: | Ozone Sondes Launched From Easter Island |
| gte_pemta_ozonesondes_ta.zip: | Ozone Sondes Launched From Tahiti |
| gte_pemta_ozonesondes_fj.zip: | Ozone Sondes Launched From Fiji |
| gte_pemta_sst_1996_mmdd_MMDD.zip: | Equatorial Pacific Sea Surface Temperature Analysis for time period from month mm day dd to month MM day DD |
| gte_pemta_total_ozone.zip: | Total Ozone from TOMS |
| gte_pemta_g9wv_1996_mmdd.zip: | GOES-9 Water Vapor Satellite Images for month mm and day dd |
| gte_pemta_pre_1996_mmdd.zip: | SSM/I Rain Rate for month mm and day dd |
| gte_pemta_firecount_africa.zip: | Fire counts from AVHRR for Africa |
| gte_pemta_firecount_Austra.zip: | Fire counts from AVHRR for Australia |
| gte_pemta_firecount_samerica.zip: | Fire counts from AVHRR for South America |
| gte_pemta_radiosondes.zip: | Radiosonde Data |
| gte_pemta_dc8_modeling_amc.zip: | Air Mass Characterization |
| gte_pemta_dc8_modeling_hu_1min.zip: | Harvard point model calculations based upon 1-minute merge |
| gte_pemta_dc8_modeling_hu_hc.zip: | Harvard point model calculations based upon HC-merge |
| gte_pemta_dc8_modeling_hu_hno3.zip: | Harvard point model calculations based upon HNO3-merge |
The following files are from AER's point model;
| gte_pemta_dc8_modeling_aer1.zip: | fixed: acetone (400 ppm); H2O2 & MeOH (climatology) |
| gte_pemta_dc8_modeling_aer2.zip: | acetone (from CO correlation); H2O2 & MeOH (from climatology) |
| gte_pemta_dc8_modeling_aer3.zip: | fixed: acetone (from CO correlation); free: H2O2 & MeOH |
| gte_pemta_dc8_modeling_aer4.zip: | fixed: acetone = 0.0; free: H2O2 & MeOH |
The investigators involved in the PEM Tropics A mission were funded by NASA. The funded investigators, their organization and grant, agreement or contract number was:
| Investigator | Organization | Number |
|---|---|---|
| Aircraft: | ||
| B. Anderson | NASA Langley | N/A |
| E. Atlas | NCAR | L-62926D |
| A. Bandy | Drexel U | NAG-1-1770 |
| D. Blake | U of California-Irvine | NAG-1-1777 |
| J. Bradshaw | Georgia Tech | NAG-1-1767 |
| E. Browell | NASA Langley | N/A |
| M. Carroll | U of Michigan | NAG-1-1755 |
| A. Clarke | U of Hawaii | NAG-1-176 |
| F. Eisele | Georgia Tech | NAG-1-1766 |
| G. Gregory | NASA Langley | N/A |
| B. Heikes | U of Rhode Island | NAG-1-1757 |
| B. Hubert | U of Hawaii | NAG-1-1763 |
| M. Rodgers | Georgia Tech | NAG-1-1768 |
| G. Sachse | NASA Langley | N/A |
| R. Shetter | NCAR | L-63198D |
| H. Singh | NASA Ames | N/A |
| R. Talbot | U of New Hampshire | NAG-1-1761 |
| Modeling: | ||
| D. Davis | Georgia Tech | NAG-1-1769 |
| D. Jacob | Harvard | NAG-1-1759 |
| T. Krishnamurti | Florida State U | NAG-1-1771 |
| D. Lenschow | NCAR | L-63196D |
| S. Liu | Georgia Tech | NAG-1-1822 |
| R. Newell | Mass Inst of Tech | NAG-1-1758 |
| J. Rodriguez | AER, Inc. | NAS1-20592 |
The major objective of the PEM-Tropics A mission was to understand the factors controlling tropospheric ozone and its precursors (NOx, CO and hydrocarbons) over the South Pacific, and to assess the implications for the global oxidizing power of the atmosphere. A secondary objective was to improve the understanding of atmospheric sulfur chemistry over the Pacific. PEM-Tropics A was implemented with the NASA DC-8 and P-3B aircraft as the primary measurement platforms, supported by radiosonde and ozonesonde launches from sites in the South Pacific region. Airborne measurements were typically obtained at a constant altitude over the tropical Pacific during transit flights (i.e. "survey" flights), and over multiple altitudes closer to the intensive sites during flights from the intensive sites. Flight missions were conducted during PEM Tropics A from August 5, 1996 through October 5, 1996. Section 4.b lists the flight dates. Flight tracks are shown in Hoell et al., [1999]. The duration, altitude range, ascent and descent rate, and flight path for each mission varied depending on mission objectives and environmental conditions. Ground-based measurements were made at sites shown in Hoell et al., [1999]. The automated ground sites provided daily measurements during the time frame when airborne measurements were being made and weekly averaged samples before and after. Further information about the measurement region and time frame may be found in the Journal of Geophysical Research, Vol. 104, No. D5, 5567-5583, March 20, 1999, and PEM Tropics A, Part 2, Vol. 104, No. D13, July 20, 1999.
This data set contains all of the data submitted to the GTE data archive by the PEM Tropics A investigators listed in Section 1.d and includes merges of the various measurements aboard each aircraft. Data from radiosondes launches, kinematic trajectories analysis, satellite images, and fire count are also included.
Tables 1a and 1b from Hoell et al., [1999] list the DC-8 and P-3B aircraft investigations, respectively. Table 1c also from Hoell et al., [1999] lists the modeling and meteorological investigations, along with the Mission Meteorologists and Scientists.
PEM Tropics A investigators have individually reported the results of their investigations in the Journal of Geophysical Research, Vol. 104, No. D5, March 20, 1999, and PEM Tropics A, Part 2, Vol. 104, No. D13, July 20, 1999.
There are data sets available from the Langley ASDC for 13 other GTE missions conducted from 1983 to 2001. See the GTE home page at http://www-gte.larc.nasa.gov and/or http://eosweb.larc.nasa.gov/PRODOCS/gte/table_gte.html for a description of the available data.
Global Tropospheric Experiment Pacific Exploratory Mission Tropics A (PEM Tropics A)
If the person is known to be retired, deceased or no longer at their respective organization, it is noted and the contact information may be omitted. The contact information provided was current during the mission, but may no longer be current.
John Bradshaw (deceased)
Scott Sandholm (Co-I)Stephanie Vay -- Responsible for the measurement of carbon dioxide
MS 483
NASA Langley Research Center
Hampton VA 23681-0001
Telephone: 757-864-1574
Fax: 757-864-5841
E-mail: s.a.vay@larc.nasa.gov
Glen W. Sachse Responsible for CO and CH4
(See prior listing under DC-8)
Stephanie Vay Responsible for CO2
(See prior listing under DC-8)
The following persons have more specialized knowledge than the investigators listed in Section 1.d, as indicated, about the data in the data sets.
The following persons have either specialized knowledge in their field or general knowledge about the mission, its execution and the data sets.
OR Contact:
Airborne Science Program OfficeOR Contact:
Wallops Flight Facility Aircraft OfficeFred Reisinger (no longer with SAIC)
P-3B: James L. Raper, Sr. (retired)
NASA Langley Research Center
DC-8: James M. Hoell, Jr. (retired)
(See prior listing)
Potential usage and applications of the described data sets can be seen in the articles that comprise the Journal of Geophysical Research PEM Tropics A Special Sections (Vol. 104 No. D5 and D13, March 20 and July 20, 1999.
For convenience of the users, the equations used to calculate project provided variables Mach Number (M), Static Air Temperature (Ts), True Air Speed (TAS), Potential Temperature (θ), Vapor Pressure (e), Specific Humidity (q), Mixing Ratio (r), and Relative Humidity (%) are given below.
Mach Number, M: |
|
 |
M = Mach Number Ps = Static Pressure Qc = Differential Pressure |
Static Air Temperature, Ts: | |
 |
TS = Static Air Temperature (°K) TT = Total Air Temperature (°K) γ = 1.4, ratio of specific heat of air at constant pressure and volume |
True Air Speed, TAS: | |
 |
TAS = True Air Speed (knots) TS = Static Air Temperature (°K) M = Mach Number a = Speed of Sound |
Potential Temperature, θ: | |
 |
θ = Potential Temperature (°K) TS = Static Air Temperature (°K) Ps = Static Pressure (mb) |
Vapor Pressure, e :
ewater (mb) = [1.0007 + (3.46 * 10-6 * PS)] * 6.1121* EXP[17.502 * T/(240.97 + T)]
eice (mb) = [1.0003 + (4.18 * 10-6 * PS)] * 6.1115* EXP[22.452 * T/(272.55 + T)]
e = Partial Pressure of Water Vapor (mb)
PS = Static Pressure (mb)
T = Static Air Temperature (°C) for Saturation Vapor Pressure
or
T = Dew/Frost Point (°C) for Partial Pressure of Water Vapor
ProjDP of zero or greater should be used to derive the partial pressure of water vapor w.r.t water (ewater) and the ProjDP less than zero should be used to derive the partial pressure of water vapor w.r.t ice (eice).
StatTempDegC and ProjDP parameters recorded in the P-3B data set are substituted to calculate saturation vapor pressure and partial pressure of water vapor, respectively.
TSDEGC and ProjDP parameters recorded in the DC-8 data set are substituted to calculate saturation vapor pressure and partial pressure of water vapor, respectively. Also notice in the DC-8 data set there is a redundant static air temperature measurement, TSCALC, which is calculated by DADS. Although TSDEGC and TSCALC track closely they can diverge by ≈ 1° at the low and high ends of the measurement range.
Specific Humidity, q: | |
 |
 |
Mixing Ratio, r: | |
 |
 |
| Note: ppmv = 1.608 * ppmw ppmw = 0.622 * ppmv | |
Relative Humidity, %: | |
w.r.t. water, |
w.r.t. ice, |
Interested readers should see the Journal of Geophysical Research, Vol.104, No.D5, March 20, 1999 and documents therein, for plots and the results of analysis of data.
A general description of data granularity as it applies to the IMS appears in the EOSDIS Glossary. Aircraft data sets are available for each investigation for each flight.
All measurements aboard the DC-8 and P-3B aircraft, ozonesonde and radiosondes data for the PEM Tropics A mission are contained in the archive. Additionally kinematic backward air mass trajectories, satellite images, aircraft data merge to common time periods, and fire count data are also available in the archive. No additional data products relevant to PEM Tropics A are anticipated.
This data is available online or on a CDROM via the LaRC ASDC at http://eosweb.larc.nasa.gov. Additional information on PEM-Tropics A and other GTE field missions can be found on the GTE home page at http://www-gte.larc.nasa.gov/GTE_CD.html. Users may also order data by letter, telephone, and electronic mail from the ASDC (see 3e).
The Atmospheric Science Data Center at NASA's Langley Research Center.
Publication of a portion(s) of the data archive should acknowledge the principal investigator(s) responsible for the data by referencing the appropriate manuscript in the Journal of Geophysical Research, Vol. 104, No. D5, March 20, 1999, and PEM Tropics A, Part 2, Vol. 104, No. D13, July 20, 1999.
Airborne measurements were made over the central Pacific, as indicated in Hoell et al., [1999]. A more detailed description of the environmental characteristics for the experiment region is provided in the papers included in the Journal of Geophysical Research, Vol. 104, No. D5, March 20, 1999, and PEM Tropics A, Part 2, Vol. 104, No. D13, July 20, 1999. Additional information may be found in other publications authored by the principal investigators or on the GTE homepage at http://www-gte.larc.nasa.gov.
Hoell et al., [1999] shows flight missions that were conducted during PEM Tropics A. The duration, altitude range, assent and descent rate, and flight path of each mission varied depending on mission objective and environmental conditions. The nominal air speed ranged from 500 knots (approximately 575 mph) at 13 km altitude for the DC-8 to 270 knots (approximately 310 mph) at 8 km for the P-3B. Intensive measurement regions and aircraft flight paths, along which measurements were also made, are shown in papers in the PEM Tropics B Special Section, Journal of Geophysical Research, Vol. 104, No. D5, March 20, 1999.
| Data Set | Min Lat | Max Lat | Min Lon | Max Lon |
|---|---|---|---|---|
| Measurements onboard the DC-8 | -73S | 45N | -109E | 153E |
| Measurements onboard the P-3B | -35S | 39N | -165E | -75E |
| Ozonesonde station | Latitude | Longitude |
|---|---|---|
| Fiji | 18.10S | 178.20E |
| New Zealand | 45.05S | 169.68E |
| Samoa | 14.23S | 170.56W |
| Tahiti | 18.00S | 149.00W |
| Easter Island | 27.17S | 109.42W |
Resolution varies for each measurement. See the DC-8 and P-3B Instrument Characteristics Tables from Hoell et al., [1999] for the nominal characteristics of the instruments aboard each aircraft. The file header records associated with each data file will provide additional information.
No data gridding or binning of data to a geographic grid occurred during data processing.
Thirty-five aircraft missions were conducted from August 5 to October 5, 1996. (17 for the DC-8 and 18 for the P-3B. See Hoell et al., [1999] for additional information.)
| Data Set | Begin Date | End Date |
|---|---|---|
| Measurements onboard the DC-8 | August 30, 1996 | October 5, 1996 |
| Measurements onboard the P-3B | August 5, 1996 | September 26, 1996 |
| Sondes Data | January 4, 1995 | December 30, 1997 |
| Ozonesonde Station | Begin Date | End Date |
|---|---|---|
| Fiji | February 6, 1997 | December 26, 1997 |
| New Zealand | January 4, 1995 | December 30, 1997 |
| Samoa | August 8, 1995 | December 18, 1997 |
| Tahiti | July 31, 1995 | October 7, 1997 |
| Easter Island | August 20, 1995 | June 28, 1997 |
Not all of the parameters are in each data set granule. Also, the ranges vary between data sets and between granules within each data set. Tables 1a and 1b from Hoell et al., [1999] list the investigators and measurements made aboard the DC-8 and P-3B aircraft, respectively.
The variables measured are standard atmospheric, chemical and meteorological species requiring no further elaboration here.
The units of measure vary widely depending on species and measurement environment and are addressed in the individual papers for each investigation included in the Journal of Geophysical Research, Vol. 104, No. D5, March 20,1999, and PEM Tropics A, Part 2, Vol. 104, No. D13, July 20, 1999.
The instruments used in making the measurements are listed the DC-8 and P-3B Instrument Characteristics Tables from Hoell et al., [1999].
The ranges of data vary widely depending on species and measurement environment and are addressed in the individual papers for each investigation included in the Journal of Geophysical Research, Vol. 104, No. D5, March 20,1999, and PEM Tropics A, Part 2, Vol. 104, No. D13, July 20, 1999.
The GTE Data Format Document (http://www-gte.larc.nasa.gov/pem/GTE_FMT98.htm) contains examples of each data set type.
None reported for the current archive version. See readme files and/or header records included with each data set for information provided by the responsible investigator.
The data sets submitted to the ASDC are considered final and no further updates are anticipated.
Details of data acquisition and materials are addressed in the papers contained in the Journal of Geophysical Research PEM Tropics-A Special Issue (Vol. 104, No. D5 and D13, March 20 and July 20, 1999.
GTE Bibliography (http://www-gte.larc.nasa.gov/gte_pubs_update.htm)
Hoell, J. M., D. D. Davis, D. J. Jacob, M. O. Rodgers, R. E. Newell, H. E. Fuelberg, R. J. McNeal, J. L. Raper, and R. J. Bendura, Pacific Exploratory Mission in the tropical Pacific: PEM-Tropics A, August-September 1996, J. Geophys. Res., Vol. 104, No. D2, 5567-5583, 20 March, 1999.
PEM Tropics A Special Section, Journal of Geophysical Research, Vol. 104, No. D5, March 20, 1999, and PEM Tropics A, Part 2, Vol. 104, No. D13, July 20, 1999.
