COMPENDIUM OF NASA DATA BASE FOR THE GLOBAL TROPOSPHERIC EXPERIMENT'S ARCTIC BOUNDARY LAYER EXPERIMENTS ABLE-3A AND ABLE-3B By Gerald L. Gregory and A. Donald Scott, Jr. Langley Research Center SUMMARY The report provides a compendium of NASA aircraft data that are available from NASA's Global Tropospheric Experiment's (GTE) Arctic Boundary Layer Experiments (ABLE) conducted in July and August of 1988 (ABLE-3A) and 1990 (ABLE-3B). ABLE-3A flight experiments were primarily based at Barrow and Bethel, Alaska, and included survey/transit flights to Thule, Greenland; northward of Thule; and eastward of Goose Bay, Labrador. ABLE-3B flight experiments were based at North Bay (Ontario) and Goose Bay, Canada, and included flights northward to Frobisher Bay, Canada. The primary purposes of the experiments were (1) the measurement of the flux of various trace gases (e.g., methane, carbon monoxide, ozone, and water vapor) from high-arctic (tundra and boreal) and Canadian (Hudson Bay lowlands, forest/wetlands) ecosystems, (2) the elucidation of factors important to the production and destruction of ozone at high northern latitudes, and (3) the documentation of the types (source and chemical signature) of air common to and transported into the regions. The format of the report utilizes data plots--time series and altitude profiles--of selective data acquired aboard the NASA/Wallops Electra aircraft. The purpose of the report is to provide a representation of aircraft data that are available in archived format via NASA Langley's Distributed Active Archive Center (DAAC). The data format is not intended to support original research/analyses, but to assist the reader in identifying data that are of interest. This compendium is for only the NASA aircraft data. The archived data bases include numerous supporting data including meteorological observations/products, results from surface studies, satellite observations, and sondes releases. INTRODUCTION The goal of the NASA Tropospheric Chemistry Program is to develop an understanding of the chemical cycles that control the composition of the troposphere and to assess the susceptibility of the global atmosphere to chemical change. A major component of the NASA program is the Global Tropospheric Experiment (GTE), which consists of a series of field experiments designed to (1) evaluate the capability of instrument techniques to measure, under field condition, the minute concentrations of key chemical species in the atmosphere, and (2) systematically address tropospheric chemistry issues relevant to global change, through airborne sampling expeditions, coupled with modeling and laboratory studies. GTE is primarily an aircraft-based program supplemented by ground-based measurements. Satellite data also play important roles. Space Shuttle observations of tropospheric carbon monoxide distributions have been used to plan and direct the course of expeditions, for example, over tropical rain forests and for continental outflow into the tropical Atlantic Ocean. Landsat land-surface images have facilitated the extrapolation of regional Arctic-tundra measurements into global-scale conclusions. Total Ozone Measurements from Satellites (TOMS) have helped place GTE observed ozone distributions/budgets into a global perspective (temporal and spatial). Weather data returned by environmental satellites have guided flight planning for research flights. The Distributed Active Archive Center (DAAC) data include many of the satellite, surface, and meteorological products used to support GTE missions or analyses. The GTE airborne expeditions have focused on studies of the remote global atmosphere in order to provide well-documented baseline measurements of the unperturbed environment and to fully understand the chemical cycles underlying the natural environment. Table 1 and Figure 1 summarize GTE missions conducted through March 1994. The GTE expeditions have been conducted in a diverse range of environments and with different scientific goals. The Chemical Instrument Test and Evaluation (CITE) series was designed to study our ability to measure key tropospheric gaseous species by exposing selected instrumentation to a wide range of measurement conditions. The Atmospheric Boundary Layer Experiments were designed to study the emission, chemical processes, and dynamics of the boundary layer, and have been conducted over ecosystems known to have significant influence on the global troposphere. The importance of long-range transport of natural and anthropogenic emissions on the global troposphere has been investigated in the Pacific Exploratory Missions (PEM) and the Transport and Atmospheric Chemistry Experiment in the Atlantic (TRACE-A). The GTE, managed through the Tropospheric Chemistry Program in the Mission to Planet Earth Office, NASA Headquarters, was initiated in the early 1980s. Implementation of the GTE Project is via a Project Office at the NASA Langley Research Center, Atmospheric Sciences Division. SYMBOLS AND UNITS ABLE Arctic Boundary Layer Experiment CITE Chemical Instrument Test and Evaluation CO carbon monoxide C2Cl4 tetrachloroethylene DAAC Distributed Active Archive Center deg. degree dp dew point temperature, degree Centigrade Ga.Inst. of Tech Georgia Institute of Technology, Atlanta, Georgia GTE Global Tropospheric Experiment LaRC Langley Research Center m mission NASA National Aeronautics and Space Administration NO nitric oxide NOx nitric oxides (nitric oxide + nitrogen dioxide) NOy total odd nitrogen no./cm3 number of aerosols (0.12 to 3.12 @Lm diameter) per cm3 of air 03 ozone PAN peroxyacetyl nitrate PEM Pacific Exploratory Mission pptv parts-per-trillion, by volume ppbv parts-per-billion, by volume Rel. Humidity relative humidity, percent T air temperature, degree Centigrade TAMMS Turbulent Air Motion Monitoring System Theta potential temperature, degree Kelvin TOMS Total Ozone Measurements from Satellites TRACE-A Transport and Atmospheric Chemistry Experiment in the Atlantic Univ.of Calif. University of California at Irvine, California at Irvine Univ.of New Hamp. University of New Hampshire, Durham, New Hampshire PROGRAM AND DATA DESCRIPTIONS Arctic Boundary Layer Experiment: ABLE-3A The Arctic Boundary Layer Experiment (ABLE-3A) was conducted in Arctic and sub-Arctic regions of North America and Greenland during July and August 1988. This was the first comprehensive investigation of sources, sinks, and distribution of trace gas and aerosol chemical species in a northern high- latitude region during summer months. The experimental design placed emphasis on the role of biosphere-atmosphere interactions in determining the chemical composition of the troposphere, on processes which influence the tropospheric ozone budget, and the importance of long-range transport as a source of pollutants in the remote Arctic regions. The centerpiece of ABLE-3A was a series of 33 research flights with the instrumented NASA Wallops Electra aircraft. A core set of measurements aboard the aircraft focused on eddy correlation flux measurements (methane, carbon monoxide, and ozone) with instrumentation of 10-Hz response. NASA's boom-mounted turbulent air motion system provided correlation data for the fast-response chemical sensors. A sizable amount of mission flight time was dedicated to low-altitude (150 to 1000 m) flight in support of flux studies. Figure 2 shows the study region as well as flight lines for survey/transit flights northward to Alert and eastward to Frobisher and Goose Bay, Canada. An intensive surface site (tower and chamber flux studies) was established at Bethel, Alaska, and provided information on the interpretation of fluxes from the micro (chamber) to the regional (aircraft) scale. The ABLE-3A data archive includes (1) data taken aboard the NASA Wallops Electra aircraft; (2) data measured at the Bethel surface site; (3) sondes released from multiple locations in support of the aircraft flights; and (4) numerous meteorological, land-use, and satellite data products used in flight (field) planning and post-mission analyses. The aircraft data included the following suite of chemical measurements: methane, carbon monoxide, carbon dioxide, nonmethane hydrocarbons, acetic acid, formic acid, nitric oxide, nitrogen dioxide, total odd or "reactive" nitrogen gaseous species, peroxyacetyl nitrate, peroxypropionly nitrate, ozone, radon gas, and aerosol chemical composition and size distribution. Table 2 identifies investigators responsible for the measurements, and Figure 3 shows a schematic of the aircraft instrument plan. The aircraft platform as configured for ABLE-3A had a cruise speed at altitude of about 6 km/min and a maximum flight duration and ceiling of about 6 hours and 7 km, respectively. Table 3 summarizes each of the 33 flights. Survey flights were generally long-duration flights at high altitude (5 to 74 km) with (generally) at least one descent (spiral or ramp) to about 150 m above local terrain. Flux missions consisted of numerous short-duration (30 to 45 minute), low (below 1 km), and level flight legs, and included at least two altitude soundings to about 6 km. Other flights combined numerous profiles and level-flight legs to meet planned objectives. Generally, altitude profiles (spirals or ramps) were flown with ascent/descent rates of 150 to 200 m/min. The data plots for the ABLE-3A missions are given in Appendix A. For each flight, three pages of time series plots are provided: page 1 - altitude, temperature, dew point temperature, relative humidity, potential temperature, aerosol; page 2 - ozone, carbon monoxide, nitric oxide, nitrogen oxides, total odd or "reactive" nitrogen gas species, peroxyacetly nitrate; and page 3 - methane, acetylene, ethane, propane, tetrachloroethylene. The species were selected to provide the reader with information on both the source and photochemical history of the air. Figure numbers correspond to flight numbers; i.e., Figure Al.2 represent the page 2 plots for flight #1. Selected profile plots follow the time series plots as, for example, Figure Al.4. Profile plots include temperature, dew point temperature, ozone, carbon monoxide, and methane data plotted to the same altitude scale. One to three profile plots are provided for each flight. Table 4 summarizes the profiles selected. Data plots are in standardized format as discussed in the Introduction to the Appendices. The archive includes other aircraft specie data which have not been plotted in Appendix A. Arctic Boundary Layer Experiment: ABLE-3B The Arctic Boundary Layer Experiment (ABLE-3B) was conducted in north- central and northeastern regions of Canada during July and August 1990 and included a longitudinal survey of trace gas and aerosol species along the east coast of North America from 370 N to 650 N. ABLE-3B used ground, aircraft, and satellite measurements to study source, sink, and transport processes which influence the chemical climate of relatively remote sub-Arctic and Arctic regions of Canada. As was the case for ABLE-3A, the experimental design placed emphasis on the role of biosphere-atmosphere interactions in determining the chemical composition of the troposphere and on processes which influence the tropospheric ozone budget. An important piece of ABLE-3B was a series of 22 research flights with the instrumented NASA Wallops Electra aircraft. As was the case for ABLE-3A, a core set of measurements aboard the aircraft focused on eddy correlation flux measurements (methane, carbon monoxide, and ozone) with instrumentation of 10-Hz response, and NASA's boom- mounted turbulent air motion system provided correlation data for the fast-response chemical sensors. A sizable amount (not as much as ABLE-3A) of mission flight time was dedicated to low-altitude (150 to 1000 m) flight in support of flux studies. Figure 4 shows the study regions as well as flight lines for survey/transit flights northward to Frobisher Bay. Intensive surface sites (flux measurements) were established at Kinosheo Lake in the Hudson Bay lowlands and in forest\wetlands near Scheffervillee (Quebec), Canada. Similar to the ABLE-3A archives the ABLE-3B data archive include (1) data taken aboard the NASA Wallops Electra aircraft; (2) data measured at the Kinosheo and Schefferville sites; (3) sondes released from multiple locations in support of the aircraft flights; and (4) numerous meteorological, land-use, and satellite data products used in flight (field) planning and post-mission analyses. The aircraft data included the following suite of chemical measurements: methane, carbon monoxide, carbon dioxide, nonmethane hydrocarbons, acetic acid, formic acid, nitric acid, nitric oxide, nitrogen dioxide, total odd or "reactive" nitrogen gaseous species, peroxyacetyl nitrate, peroxypropionly nitrate, ozone, and aerosol chemical composition and size distribution. Table 2 identifies investigators responsible for the measurements and Figure 5 shows a schematic of the aircraft instrument plan. The aircraft as configured for ABLE-3B had similar flight characteristics as discussed for ABLE-3A. Table 5 summarizes the 22 research flights. Description of the various flights (survey, flux, etc.) are similar to those of ABLE-3A. The data plots for the ABLE-3B missions are given in Appendix B. For each flight, three pages of time series plots are provided: page 1 - altitude, temperature, dew point temperature, relative humidity, potential temperature, aerosol; page 2 - ozone, carbon monoxide, methane, tetrachloroethylene, benzene, acetone; page 3 - nitric oxide, nitrogen oxides, total odd nitrogen gas, peroxyacetly nitrate, nitric acid; and page 4 - acetylene, ethane, propane. The species were selected to provide the reader with information on both the source and photochemical history of the air. Figure numbers and plot formats are similar to those previously discussed for ABLE-3A. Table 6 summarizes the profiles selected. Again, data plots are in standardized format and not all data (species) measured on the aircraft have been plotted. CONCLUDING REMARKS This compendium of data from NASA's Global Tropospheric Experiment's (GTE) Arctic Boundary Layer Experiments (ABLE-3A, 1988; ABLE-33, 1990) provides only a representation of aircraft data that are available in archived format from NASA Langley's Distributed Active Archive Center (DAAC). The presented data are not intended to support original research/analyses, but serve to assist the reader in identifying data that are of interest and may be obtained from Langley's DAAC archives This compendium is for only selected NASA aircraft data. The archived data bases include other data measured on board the aircraft as well as numerous supporting data including meteorological observations/products, results from surface studies, satellite observations, and sondes releases. GTE-sponsored analyses/results from the ABLE-3A and ABLE-3B expeditions have been published in Special Issues of the Journal of Geophysical Research - Atmospheres, Volume 97, Number D15, October 1992, and Volume 99, Number Dl, January 1994, respectively. Questions or information regarding the Langley DAAC archive should be directed to the Data Manager, DAAC, Atmospheric Sciences Division, Langley Research Center, Hampton, Virginia 23681-0001. INTRODUCTION TO APPENDICES Plots are presented in a standardized format, and the data (unedited) are from the GTE Project archives Relative humidity and potential temperature have been calculated from the archived data as early GTE missions did not archive these data. in some cases (mostly for moist, boundary layer conditions) relative humidity exceeds 100% (not plotted) as dew point temperature exceeded air temperature by a few degrees (assumed to be the result of instrument measurement/calibration uncertainty). For each expedition and for time series plots, abscissa time scales for a given flight are identical, and ordinate scales (for a given parameter) are identical among all flights. Ordinate scales were selected to best represent all the data from the expedition and for that specie; thus, some data may be off-scale. As a result of the software used for the plots and the data archive use of codes in place of data during calibration, when measurements were at "detection limit" and/or when measurements were made but data invalid, it is sometimes difficult to distinguish from the plots if data are off-scale or missing. For example, a symbol without an attached line may either mean that adjacent data are off-scale or have been coded as invalid. Inspection of the other plotted data often provides information which resolves the uncertainty. For each expedition and for profile plots, all altitude scales are identical and the specie scales are those selected for the time series plots. In order to maintain the standardized format, plots for flights in which a specie data were not reported are plotted with the axes and a "NO DATA" entry.