Documentation Revision Date: 2018-03-23
Data Set Version: 1
This dataset includes 306 data files: 152 ICARTT (*.ict) and 152 NetCDF (*.nc) files. The ICARTT and NetCDF files contain the same data. Files are organized by file type (either netcdf or icartt), and further grouped into seven directories, one for each merge type, with one file per flight date. There were 11 flights in the ATom 1 deployment (July-August 2016) and 11 in ATom 2 (January-February 2017).
Wofsy, S.C., E. Apel, D.R. Blake, C.A. Brock, W.H. Brune, T.P. Bui, B.C. Daube, J.E. Dibb, G.S. Diskin, J.W. Elkiins, K. Froyd, S.R. Hall, T.F. Hanisco, L.G. Huey, J.L. Jimenez, K. McKain, S.A. Montzka, T.B. Ryerson, J.P. Schwarz, B.B. Stephens, B. Weinzierl, and P. Wennberg. 2018. ATom: Merged Atmospheric Chemistry, Trace Gases, and Aerosols. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1581
Table of Contents
- Data Set Overview
- Data Characteristics
- Application and Derivation
- Quality Assessment
- Data Acquisition, Materials, and Methods
- Data Access
Data Set Overview
This dataset provides information on greenhouse gases and human-produced air pollution, including atmospheric concentrations of carbon dioxide (CO2), methane (CH4), tropospheric ozone (O3) and black carbon (BC) aerosols, collected during airborne campaigns conducted by NASA's Atmospheric Tomography (ATom) mission. This dataset includes merged data from all instruments. A variety of merged file types have been created for each flight date. The merge files include additional data such as numbered profiles and distance flown. In the case of data obtained over longer time intervals (e.g. flask data), the merge files provide (weighted) averages of 1-second data to match the sampling intervals. ATom deploys an extensive gas and aerosol payload on the NASA DC-8 aircraft for systematic, global-scale sampling of the atmosphere, profiling continuously from 0.2 to 12 km altitude. Flights occurred in each of 4 seasons over a 4-year period from 2016 to 2018. Flights originate from the Armstrong Flight Research Center in Palmdale, California, fly north to the western Arctic, south to the South Pacific, east to the Atlantic, north to Greenland, and return to California across central North America. ATom establishes a single, contiguous global-scale dataset. This comprehensive dataset will be used to improve the representation of chemically reactive gases and short-lived climate forcers in global models of atmospheric chemistry and climate. Profiles of the reactive gases will also provide critical information for validation of satellite data, particularly in remote areas where in situ data is lacking. Complete aircraft flight information including, but not limited to, latitude, longitude, and altitude are also provided.
This dataset provides results from the Summer 2016 and Winter 2017 flight campaigns. Data from subsequent campaigns will be added when it is finalized.
The Atmospheric Tomography Mission (ATom) is a NASA Earth Venture Suborbital-2 mission. It will study the impact of human-produced air pollution on greenhouse gases and on chemically reactive gases in the atmosphere. ATom deploys an extensive gas and aerosol payload on the NASA DC-8 aircraft for systematic, global-scale sampling of the atmosphere, profiling continuously from 0.2 to 12 km altitude. Flights will occur in each of 4 seasons over a 4-year period.
HIAPER Pole-to-Pole Observations (HIPPO) of Carbon Cycle and Greenhouse Gases Study (2009-2011). Data available at: https://www.eol.ucar.edu/field_projects/hippo
Spatial Coverage: Flights begin in California, fly north to the western Arctic, south to the South Pacific, east to the southern Atlantic, north to Greenland, and return to California across central North America.
Spatial Resolution: Point measurements
Temporal Coverage: Periodic flights occurred during each deployment. ATom-1 was from July 29, 2016 - August 23, 2016 and ATom-2 was from January 26, 2017 - February 21, 2017. Additional deployments are scheduled.
Temporal Resolution: < 1 - 2 seconds, depending on instrument and flight. Merge files present the data from different instruments averaged to various time bases, including 10-seconds and 1-second.
Data File Information:
This dataset includes 306 data files: 152 ICARTT (*.ict) and 152 NetCDF (*.nc) files. The ICARTT and NetCDF files contain the same data. All ICARTT files have detailed header information and follow the standards established and summarized in the ICARTT File Format Standards V1.1. NetCDF files are structured as GeoTrajectory files, where the observations for a flight segment are connected along a one-dimensional track in space, with time increasing monotonically along the track.
Files are organized by file type (either netcdf or icartt), and further grouped into seven directories, one for each merge type, with one file per flight date. There were 11 flights in the ATom 1 deployment (July-August 2016) and 11 in ATom 2 (January-February 2017). Note, however, that data from the ATom-2 flight on February 13, 2017 is not available for the MER-MED merge type.
File Naming Conventions:
Naming conventions are the same for both file formats. Files are organized by merge type and flight date, such as:
TYPE = merge type
aircraft = DC8
YYYYMMDD = flight date (beginning of flight, UTC time)
R# = revision number of data. A higher number indicates a more recent revision.
ext = file extension. either '.nc' for NetCDF or '.ict' for ICARTT
|MER-1HZ||Merge of flight data at one second intervals across all instruments.|
|MER-MED||Data merge to MEDUSA sampling interval.|
|MER-PFP||Data merge to PFP sampling interval.|
|MER-SAGA-AERO||Data merge to SAGA-AERO sampling interval.|
|MER-TOGA||Data merge to TOGA sampling interval, from 1s merge file.|
|MER-WAS||Data merge to WAS sampling interval.|
|MER10||Merge of flight data with 10 second means.|
There are over 450 individual variables measured by the 24 instruments onboard the NASA DC-8. A list of all data variables is provided in the companion file ALLNAMES.txt and in the header information of the ICARTT and NetCDF files themselves.
|ALLNAMES.txt||A list of all data variables included in the merge files.|
|ATom_merge.pdf||A pdf copy of this user's guide.|
|ATom_merging_Rcode_20170628.pdf||A script in the R language that takes data from all the instrument ICARTT files and merges them to the various temporal bases provided here.|
|atom1.kmz||A KMZ file for viewing in Google Earth showing all ATom-1 flight paths. Latitude, longitude, altitude, and time are included.|
|atom2.kmz||A KMZ file for viewing in Google Earth showing all ATom-2 flight paths. Latitude, longitude, altitude, and time are included.|
Application and Derivation
ATom builds the scientific foundation for mitigation of short-lived climate forcers, in particular methane (CH4), tropospheric ozone (O3), and Black Carbon aerosols (BC).
ATom Science Questions:
- What are chemical processes that control the short-lived climate forcing agents CH4, O3, and BC in the atmosphere? How is the chemical reactivity of the atmosphere on a global scale affected by anthropogenic emissions? How can we improve chemistry-climate modeling of these processes?
- Over large, remote regions, what are the distributions of BC and other aerosols important as short-lived climate forcers? What are the sources of new particles? How rapidly do aerosols grow to CCN-active sizes? How well are these processes represented in models?
- What type of variability and spatial gradients occur over remote ocean regions for greenhouse gases (GHGs) and ozone depleting substances (ODSs)? How do the variations among air parcels help identify anthropogenic influences on photochemical reactivity, validate satellite data for these gases, and refine knowledge of sources and sinks?
ATom delivers unique data and analysis to address the Science Mission Directorate objectives of acquiring “datasets that identify and characterize important phenomena in the changing Earth system.” and “measurements that address weaknesses in current Earth system models leading to improvement in modeling capabilities.” ATom will provide unprecedented challenges to the CCMs used as policy tools for climate change assessments, with comprehensive data on atmospheric chemical reactivity at global scales, and will work closely with modeling teams to translate ATom data to better, more reliable CCMs. ATom provides extraordinary validation data for remote sensing.
Quality assessment procedures differ by instrument. Quality flags are provided within the data files for many of the measured parameters.
Data Acquisition, Materials, and Methods
ATom makes global-scale measurements of the chemistry of the atmosphere using the NASA DC-8 aircraft. Flights span the Pacific and Atlantic Oceans, nearly pole-to-pole, in continuous profiling mode, covering remote regions that might have been regarded as pristine 20 years ago but today receive long-range inputs of pollution from expanding industrial economies. The payload has proven instruments for in situ measurements of reactive and long-lived gases, diagnostic chemical tracers, and aerosol size, number, and composition, plus spectrally resolved solar radiation and meteorological parameters.
Figure 2: Generalized flight plan for ATom showing continuous pole-to-pole profiling.
Table 2: Flight deployment schedule
|ATom-1 (Summer 2016)||July 29, 2016 - August 23, 2016|
|ATom-2 (Winter 2017)||January 26, 2017 - February 21, 2017|
|ATom-3 (Fall 2017)||September 28, 2017 - October 26, 2017|
|ATom-4 (Spring 2018)||planned for Apr - May, 2018|
ATom measures more than 100 distinct chemical, aerosol, radiative, and physical parameters. Fast instrument sampling rates provide spatially resolved, simultaneous, and contiguous observational data, providing a nearly complete chemical description of each air parcel.
Combining distributions of aerosols and reactive gases with long-lived GHGs and ODSs enables disentangling of the processes that regulate atmospheric chemistry: emissions, transport, cloud processes, and chemical transformations. ATom analyzes measurements using customized modeling tools to derive daily averaged chemical rates for key atmospheric processes and to critically evaluate Chemistry-Climate Models (CCMs). ATom also differentiates between hypotheses for the formation and growth of aerosols over the remote oceans.
Table 3: Instruments onboard the NASA DC-8 for ATom
|Instrument||Full Name||Contact Person||Type||Measurements||Data Variables|
|AMP||In Situ Measurements of Aerosol Microphysical Properties||Charles Brock||Spectrometer (in situ)||Dry aerosol particle size distribution, Cloud droplet size distribution, Dust size distribution, Precipitation Size, Cloud Liquid Water Content||NAerosol|
|AO2||NCAR Airborne Oxygen Instrument||Britt Stephens||O2, CO2||AO2|
|ATHOS||Airborne Tropospheric Hydrogen Oxides Sensor||William H. Brune||Fluorescence||OH, Napthalene, HO2, NO||ATHOS-HOx|
|CAFS||CCD Actinic Flux Spectroradiometers||Samuel R. Hall||Spectrometer (in situ)||Actinic Flux||CAFS-FLUX-N, CAFS-FLUX-Z, CAFS-JV, CAFS-JV-Z|
|CAPS Vienna||Cloud Aerosol and Precipitation Spectrometer - U Vienna||Bernadett Weinzierl||Aerosol, Particle size distribution, Cloud Liquid Water Content||Cloudindicator, NCoarseAerosol|
|CIT-CIMS||Chemical Ionization Mass Spectrometer||Paul Wennberg||CIMS||HNO3, H2O2, CH3OOH, HCN, PAA, PNA, SO2||CIT-H2O2, CIT-HCN, CIT-HNO3, CIT-MHP, CIT-PAA, CIT-PNA, CIT-SO2|
|DLH||Diode Laser Hygrometer||Glenn S. Diskin||Laser absorption||H2O||DLH-H2O|
|GT-CIMS||Chemical Ionization Mass Spectrometer||L. Greg Huey||CIMS||HNO3, SO2, HNO4, HCl, Br2, BrO, PAN||GTCIMSPANS|
|HR-AMS||CU Aircraft High-Resolution Time-of-Flight Aerosol Mass Spectrometer||Jose-Luis Jimenez||Spectrometer (in situ)||Cl, NH4, NO3, Organic Aerosol, SO4||AMS, AMS-60s, AMSSD|
|ISAF||In Situ Airborne Formaldehyde||Thomas F. Hanisco||Fluorescence||CH2O||ISAF-H2CO|
|Medusa||Medusa Whole Air Sampler||Britt Stephens||Whole Air Sampling||O2, CO2, N2, Argon, CO2 isotopes||MEDUSA, MEDUSA-Kernel|
|MMS||Meteorological Measurement System||T. Paul Bui||Wind, Turbulence, Temperature, Aircraft position||MMS-1HZ, MMS-20Hz|
|NOAA CIMS||Chemical Ionization Mass Spectrometer||Thomas B Ryerson||CIMS||H2O, HNO3, HCl|
|NOAA Picarro||NOAA Picarro||Kathryn McKain||Spectrometer (in situ)||CO2, CH4, CO||NOAA-Picarro-CO2-CH4-CO|
|NOyO3||NOAA Nitrogen Oxides and Ozone||Thomas B Ryerson||Chemiluminescence||NO, NO2, NOy, O3||NOyO3-NO, NOyO3-NO2, NOyO3-NOy, NOyO3-O3|
|PALMS||Particle Analysis By Laser Mass Spectrometry||Karl Froyd||Spectrometer (in situ)||Particle Composition, Aerosol||PALMS|
|PANTHER||PAN and Trace Hydrohalocarbon ExpeRiment||James W. Elkins||Gas chromatography||(CH3)2CO, PAN, H2, CH4, CO, N2O, SF6, CFCl3, CF2Cl2, Halon-1211||GCECD, GCMSD|
|PFP||Programmable Flask Package Whole Air Sampler||Steve Montzka||Whole Air Sampling||N2O, SF6, H2, CS2, OCS, CO2, CH4, CO, CFCs, HCFCs, HFCs, Solvents, Methyl Halides, Hydrocarbons, Perfluorocarbons||PFP|
|QCLS||Quantum Cascade Laser System||Bruce Daube||Laser absorption||CO2, CO, CH4, N2O||QCLS-CH4-CO-N2O, QCLS-CO2|
|SAGA||Soluble Acidic Gases and Aerosols||Jack Dibb||Ion Chromatography||Na, NH4, K, Mg, Ca+2, Cl, Br-, NO3, SO4, C2O4-2, Be-7, Pb-210, HNO3, Fine Aerosol SO4, Fine Aerosol NO3||SAGA-AERO, SAGA-MC|
|SP2||Single Particle Soot Photometer (NOAA)||Joshua Schwarz||Photometer||Black Carbon, Scattering Aerosols||SP2-BC|
|TOGA||Trace Organic Gas Analyzer||Eric Apel||Gas chromatography, Spectrometer (in situ)||VOCs||TOGA|
|UCATS||UAS Chromatograph for Atmospheric Trace Species||James W. Elkins||Gas chromatography, Spectrometer (in situ), Photometer||N2O, SF6, CH4, CO, O3||UCATS-GC, UCATS-H2O, UCATS-O3|
|WAS (UCI)||Whole Air Sampler||Donald R. Blake||Whole Air Sampling||NMHCs, Halocarbons, Alkyl Nitrates, OCS, DMS, CS2||WAS|
Additional information about each instrument and the DC-8 platform is available at https://espo.nasa.gov/atom/instruments.
ATom is closely linked to satellites measuring atmospheric chemical composition: (i) ATom provides unique data for validation and algorithm development for OCO-2, GOME-2, TROPOMI, GOSAT, plus those planned for geostationary orbit (TEMPO), and the TCCON network. (ii) ATom uses satellite data to extend its airborne in-situ observations to global scale. (iii) ATom directly engages CCM groups and delivers a single, large-scale, contiguous in-situ dataset for model evaluation and improvement.
Merge File Methods:
This dataset includes merged data from all instruments. A variety of merged file types have been created for each flight date. The merge files include additional data such as numbered profiles and distance flown. In the case of data obtained over longer time intervals (e.g. flask data), the merge files provide (weighted) averages of 1-second data to match the sampling intervals. The merge procedure was executed in the R language and the merge script (ATom_merging_Rcode_20170628.pdf ) is provided as a companion file with this dataset.
For more information, please see the ATom website on the NASA Earth Science Project Office (ESPO) site (https://espo.nasa.gov/atom).
These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).
Contact for Data Center Access Information:
- E-mail: email@example.com
- Telephone: +1 (865) 241-3952
ICARTT File Format Standards V1.1. https://www-air.larc.nasa.gov/missions/etc/IcarttDataFormat.htm