Documentation Revision Date: 2019-12-30
Dataset Version: 1
Summary
This dataset includes 47 files in comma-delimited text (ICARTT) format, with one data file per flight date.
Figure 1. Measurements of atmospheric acetone concentration from samples collected by the Trace Organic Gas Analyzer (TOGA) during ATom-3 flights in 2017.
Citation
Apel, E.C., E.C. Asher, A.J. Hills, and R.S. Hornbrook. 2019. ATom: L2 Volatile Organic Compounds (VOCs) from the Trace Organic Gas Analyzer (TOGA). ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1749
Table of Contents
- Dataset Overview
- Data Characteristics
- Application and Derivation
- Quality Assessment
- Data Acquisition, Materials, and Methods
- Data Access
- References
Dataset Overview
This dataset provides concentrations of volatile organic compounds (VOCs) measured by the Trace Organic Gas Analyzer (TOGA) during airborne campaigns conducted by NASA's Atmospheric Tomography (ATom) mission. Specific data were obtained for radical precursors, tracers of anthropogenic and biogenic activities, tracers of urban and biomass combustion emissions, products of oxidative processing, precursors to aerosol formation, and compounds important for aerosol modification and transformation. TOGA measures a wide range of VOCs with high sensitivity (ppt or lower), frequency (2.0 min.), accuracy (often 15% or better), and precision (<3%). ATom deployed 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.
Project: Atmospheric Tomography Mission (ATom)
The Atmospheric Tomography Mission (ATom) was a NASA Earth Venture Suborbital-2 mission. It studied the impact of human-produced air pollution on greenhouse gases and on chemically reactive gases in the atmosphere. ATom deployed 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 four seasons over a 4-year period.
Related Data
ATom: Merged Atmospheric Chemistry, Trace Gases, and Aerosols. Data from all ATom instruments and all four flight campaigns, including aircraft location and navigation data, merged to several different time bases: https://doi.org/10.3334/ORNLDAAC/1581
ATom Flight Track and Navigational Data. Flight path (location and altitude) data for each of the four campaigns provided in KML and csv format: https://doi.org/10.3334/ORNLDAAC/1613
Data Characteristics
Spatial Coverage: Global. Flights circumnavigate the globe, primarily over the oceans
Spatial Resolution: Point measurements
Temporal Coverage: Periodic flights occurred during each campaign
Table 1. Flight campaign schedule
| Deployment | Date Range |
|---|---|
| ATom-1 | July 29 - August 23, 2016 |
| ATom-2 | January 26 - February 21, 2017 |
| ATom-3 | September 28 - October 28, 2017 |
| ATom-4 | April 24 - May 21, 2018 |
Temporal Resolution: 35-second integrated sampling time
Data File Information
This dataset includes 47 files in comma-delimited text (ICARTT) format, with one file per flight date for all four ATom flight campaigns. Data files conform to the ICARTT File Format Standards V1.1.
File names are structured as TOGA_DC8_YYYYMMDD_R#.ict, where YYYYMMDD is the start date (in UTC time) of the flight, and R# is the file version or revision number.
Data Variables
Table 2. Variables in the data files. Missing data are indicated by -999. Upper limit of detection flag: -777 and Lower limit of detection flag: -888.
| Name | Units | Description |
|---|---|---|
| Time_Start | seconds | seconds since midnight UTC on flight date |
| Time_Stop | seconds | seconds since midnight UTC on flight date |
| CFC11_TOGA | ppt | CFC-11 gas dry volume mixing ratio |
| CFC113_TOGA | ppt | CFC-113 gas dry volume mixing ratio |
| CH3Cl_TOGA | ppt | Methyl chloride gas dry volume mixing ratio |
| CH2Cl2_TOGA | ppt | Dichloromethane gas dry volume mixing ratio |
| CHCl3_TOGA | ppt | Chloroform gas dry volume mixing ratio |
| C2Cl4_TOGA | ppt | Tetrachloroethene gas dry volume mixing ratio |
| ClBenzene_TOGA | ppt | Chlorobenzene gas dry volume mixing ratio |
| CHBrCl2_TOGA | ppt | Bromodichloromethane gas dry volume mixing ratio |
| CHBr2Cl_TOGA | ppt | Dibromochloromethane gas dry volume mixing ratio |
| CH3Br_TOGA | ppt | Methyl bromide gas dry volume mixing ratio |
| CH2Br2_TOGA | ppt | Dibromomethane gas dry volume mixing ratio |
| CHBr3_TOGA | ppt | Bromoform gas dry volume mixing ratio |
| CH2ClI_TOGA | ppt | Chloroiodomethane gas dry volume mixing ratio |
| CH2BrI_TOGA | ppt | Bromoiodomethane gas dry volume mixing ratio |
| CH3I_TOGA | ppt | Methyl iodide gas dry volume mixing ratio |
| CH2I2_TOGA | ppt | Diiodomethane gas dry volume mixing ratio |
| Propane_TOGA | ppt | Propane gas dry volume mixing ratio |
| iButane_TOGA | ppt | Isobutane gas dry volume mixing ratio |
| nButane_TOGA | ppt | n-Butane gas dry volume mixing ratio |
| iPentane_TOGA | ppt | Isopentane gas dry volume mixing ratio |
| nPentane_TOGA | ppt | n-Pentane gas dry volume mixing ratio |
| x2MePentane_TOGA | ppt | 2-Methylpentane gas dry volume mixing ratio |
| x3MePentane_TOGA | ppt | 3-Methylpentane gas dry volume mixing ratio |
| nHexane_TOGA | ppt | n-Hexane gas dry volume mixing ratio |
| x224TrimePentane_TOGA | ppt | 2,2,4-Trimethylpentane gas dry volume mixing ratio |
| nHeptane_TOGA | ppt | n-Heptane gas dry volume mixing ratio |
| iButene1Butene_TOGA | ppt | Isobutene + 1-Butene gas dry volume mixing ratio |
| Isoprene_TOGA | ppt | Isoprene gas dry volume mixing ratio |
| Benzene_TOGA | ppt | Benzene gas dry volume mixing ratio |
| Toluene_TOGA | ppt | Toluene gas dry volume mixing ratio |
| EthBenzene_TOGA | ppt | Ethylbenzene gas dry volume mixing ratio |
| mpXylene_TOGA | ppt | m-Xylene + p-Xylene gas dry volume mixing ratio |
| oXylene_TOGA | ppt | o-Xylene gas dry volume mixing ratio |
| aPinene_TOGA | ppt | alpha-Pinene gas dry volume mixing ratio |
| Tricyclene_TOGA | ppt | Tricyclene gas dry volume mixing ratio |
| Camphene_TOGA | ppt | Camphene gas dry volume mixing ratio |
| bPineneMyrcene_TOGA | ppt | beta-Pinene + Myrcene gas dry volume mixing ratio |
| LimoneneD3Carene_TOGA | ppt | Limonene + D3-Carene gas dry volume mixing ratio |
| CH2O_TOGA | ppt | Formaldehyde gas dry volume mixing ratio |
| CH3CHO_TOGA | ppt | Acetaldehyde gas dry volume mixing ratio |
| Propanal_TOGA | ppt | Propanal gas dry volume mixing ratio |
| Butanal_TOGA | ppt | Butanal gas dry volume mixing ratio |
| Acrolein_TOGA | ppt | Acrolein gas dry volume mixing ratio |
| MAC_TOGA | ppt | Methacrolein gas dry volume mixing ratio |
| Acetone_TOGA | ppt | Acetone gas dry volume mixing ratio |
| MEK_TOGA | ppt | Methyl ethyl ketone gas dry volume mixing ratio |
| MVK_TOGA | ppt | Methyl vinyl ketone gas dry volume mixing ratio |
| CH3OH_TOGA | ppt | Methanol gas dry volume mixing ratio |
| C2H5OH_TOGA | ppt | Ethanol gas dry volume mixing ratio |
| MTBE_TOGA | ppt | Methyl tert-butyl ether gas dry volume mixing ratio |
| DMS_TOGA | ppt | Dimethyl sulfide gas dry volume mixing ratio |
| HCN_TOGA | ppt | Hydrogen cyanide gas dry volume mixing ratio |
| CH3CN_TOGA | ppt | Acetonitrile gas dry volume mixing ratio |
| EthONO2_TOGA | ppt | Ethyl nitrate gas dry volume mixing ratio |
| iPropONO2_TOGA | ppt | Isopropyl nitrate gas dry volume mixing ratio |
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
| Species | Uncertainty |
|---|---|
| CH2Cl2 | 15% |
| CHCl3 | 15% |
| C2Cl4 | 15% |
| ClBenzene | 15% |
| CHBrCl2 | 20% |
| CHBr2Cl | 15% |
| CH2Br2 | 15% |
| CHBr3 | 30% |
| CH2ClI | 20% |
| CH2BrI | 30% |
| CH3I | 50% |
| CH2I2 | 40% |
| Propane | 30% |
| iButane | 15% |
| nButane | 15% |
| iPentane | 15% |
| nPentane | 15% |
| x2MePentane | 15% |
| x3MePentane | 15% |
| nHexane | 15% |
| x224TrimePentane | 15% |
| nHeptane | 30% |
| iButene1Butene | 20% |
| Isoprene | 15% |
| Benzene | 15% |
| Toluene | 15% |
| EthBenzene | 20% |
| mpXylene | 20% |
| oXylene | 20% |
| aPinene | 30% |
| Tricyclene | 50% |
| Camphene | 30% |
| bPineneMyrcene | 30% |
| LimoneneD3Carene | 30% |
| CH2O | 40% |
| CH3CHO | 20% |
| Propanal | 20% |
| Butanal | 30% |
| Acrolein | 30% |
| MAC | 20% |
| Acetone | 20% |
| MEK | 30% |
| MVK | 30% |
| CH3OH | 30% |
| C2H5OH | 30% |
| MTBE | 30% |
| DMS | 30% |
| HCN | 20% |
| CH3CN | 40% |
| iPropONO2 | 20% |
LLOD values are provided within the ICARTT files. The LLOD values are for sea-level, and are nearly constant to 12km, and increase above 12 km linearly to double sea-level LLOD by 14.6 km.
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 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.
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.
Trace Organic Gas Analyzer
TOGA measures volatile organic compounds (VOCs). Specific data will be obtained for radical precursors, tracers of anthropogenic and biogenic activities, tracers of urban and biomass combustion emissions, products of oxidative processing, precursors to aerosol formation, and compounds important for aerosol modification and transformation. TOGA measures a wide range of VOCs with high sensitivity (ppt or lower), frequency (2.0 min.), accuracy (often 15% or better), and precision (<3%). Over 50 species are routinely measured throughout the full altitude range. The major components of the instrument are the inlet, cryogenic pre-concentrator, gas chromatograph, mass spectrometer detector, zero air/calibration system, and the control/data acquisition system. All processes and data acquisition are computer controlled. For more information, refer to the references: Apel et al., 2010, and Apel et al., 2015.
Data Access
These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).
ATom: L2 Volatile Organic Compounds (VOCs) from the Trace Organic Gas Analyzer (TOGA)
Contact for Data Center Access Information:
- E-mail: uso@daac.ornl.gov
- Telephone: +1 (865) 241-3952
References
Apel, E. C., L. K. Emmons, T. Karl, F. Flocke, A. J. Hills, S. Madronich, J. Lee-Taylor, A. Fried, P. Weibring, J. Walega, D. Richter, X. Tie, L. Mauldin, T. Campos, A. Weinheimer, D. Knapp, B. Sive, L. Kleinman, S. Springston, R. Zaveri, J. Ortega, P. Voss, D. Blake, A. Baker, C. Warneke, D. Welsh-Bon, J. de Gouw, J. Zheng, R. Zhang, J. Rudolph, W. Junkermann and D. D. Riemer. (2010), Chemical Evolution of Volatile Organic Compounds in the Outflow of the Mexico City Metropolitan Area, Atmospheric Chemistry and Physics Vol. 10, No. 5, pp. 2353-2375, https://doi.org/10.5194/acp-10-2353-2010
Apel, E. C., R. S. Hornbrook, A. J. Hills, N. J. Blake, M. C. Barth, A. Weinheimer, C. Cantrell, S. A. Rutledge, B. Basarab, J. Crawford, G. Diskin, C. R. Homeyer, T. Campos, F. Flocke, A. Fried, D. R. Blake, W. Brune, I. Pollack, J. Peischl, T. Ryerson, P. O. Wennberg, J. D. Crounse, A. Wisthaler, T. Mikoviny, G. Huey, B. Heikes, D. O'Sullivan and D. D. Riemer. (2015), Upper Tropospheric Ozone Production from Lightning Nox-Impacted Convection: Smoke Ingestion Case Study from the DC3 Campaign, Journal of Geophysical Research: Atmospheres, https://doi.org/10.1002/2014JD022121