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ATom: L2 Volatile Organic Compounds (VOCs) from the Trace Organic Gas Analyzer (TOGA)

Documentation Revision Date: 2019-12-30

Dataset Version: 1

Summary

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.

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

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

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