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ATom: Merged Atmospheric Chemistry, Trace Gases, and Aerosols

Documentation Revision Date: 2018-03-23

Data Set Version: 1

Summary

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 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.

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).

Figure 1: ATom flights continuously sample atmospheric profiles. In this flight from Pago Pago, American Samoa to Christchurch, New Zealand, on August 8, 2016, the aircraft sampled 12 profiles from about 50 to 11,000 meters above mean sea level.

Citation

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

  1. Data Set Overview
  2. Data Characteristics
  3. Application and Derivation
  4. Quality Assessment
  5. Data Acquisition, Materials, and Methods
  6. Data Access
  7. References

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.

Project: Atmospheric Tomography Mission (ATom)

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.

Related Data:

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

Data Characteristics

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:

MER-TYPE_aircraft_YYYYMMDD_R#.ext

where:

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

 

Merge Types:

Merge Type Description
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.

 

Data Variables:

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.

 

Companion Files:

Filename Description
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:

Tier 1

  • 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?

Tier 2

  • 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?

Significance

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

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

Project Overview:

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.

flight pattern for ATom

Figure 2: Generalized flight plan for ATom showing continuous pole-to-pole profiling.

Table 2: Flight deployment schedule

Deployment

Date Range

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).

Data Access

These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

ATom: Merged Atmospheric Chemistry, Trace Gases, and Aerosols

Contact for Data Center Access Information:

References

ICARTT File Format Standards V1.1. https://www-air.larc.nasa.gov/missions/etc/IcarttDataFormat.htm