Documentation Revision Date: 2019-08-01
Dataset Version: 1
Summary
This dataset includes 94 files in comma-delimited text (ICARTT) format.
Figure 1. The HR-AMS instrument installed on the NASA DC-8 for the ATom-1 deployment.
Citation
Jimenez, J.L., P. Campuzano-Jost, D.A. Day, B.A. Nault, D.J. Price, and J.C. Schroder. 2019. ATom: L2 Measurements from CU High-Resolution Aerosol Mass Spectrometer (HR-AMS). ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1716
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 the concentrations of separated ions from inorganic and organic species measured by the High-Resolution Aerosol Mass Spectrometer (HR-AMS). The HR-AMS detects non-refractory submicron aerosol composition by impaction on a vaporizer at 600°C, followed by electron ionization and time-of-flight mass spectral analysis. The measurements include chemically speciated submicron non-refractory particulate mass at a one second and 60 second resolution, and the size distribution of chemically speciated submicron non-refractory particulate mass at 60 second resolution.
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.
Acknowledgements:
The ATom HR-AMS team would like to thank the following individuals for their contributions to the success of the ATom Mission: D. Sueper (U. Colorado CIRES and Dept. of Chemistry) and D.S. Thomson (U. Colorado CIRES and Dept. of Chemistry and Original Code Consulting, Boulder, CO).
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 deployment.
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: 1 second
Data File Information
This dataset includes 94 files in comma-delimited text (ICARTT) format. Data files conform to the ICARTT File Format Standards V1.1.
File names are structured as indicated in Table 2, where YYYYMMDD is the start date (in UTC time) of the flight and R# is the file version or revision number.
Table 2. Quantity and measurements given each file name.
| File Name Type | Number of Files | Measurment |
|---|---|---|
| AMS_DC8_YYYMMDD_R#.ict | 35 | one second resolution of chemically speciated submicron non-refractory particulate mass |
| AMS-60s_DC8_YYYMMDD_R#.ic | 35 | 60 second resolution of chemically speciated submicron non-refractory particulate mass |
| AMSSD_DC8_YYYMMDD_R#.ict | 24 | size distribution of chemically speciated submicron non-refractory particulate mass at 60 second resolution |
Table 3. Variables in the data files AMS_DC8_YYYYMMDD_R#.ict. The variables for AMS-60s_DC8_YYYYMMDD_R#.ict are the same except for "_60s" added to the end of each variable name. Missing data are indicated by -9999.000.
| Variable Name | Units | Description |
|---|---|---|
| AMS_Starttime | seconds | seconds since midnight UTC |
| AMS_Stoptime | seconds | seconds since midnight UTC |
| AMS_MidPointTime | seconds | seconds since midnight UTC |
| AMS_LAT | deg | aircraft latitude at time of sampling |
| AMS_LON | deg | aircraft longitude at time of sampling |
| AMS_ALT | m | aircraft GPS altitude at time of sampling |
| OA_lt_1um_AMS | ug sm-3 | mass concentration of organic aerosol in air for particle diameter less than 1um measured by HRAMS |
| OA_lt_1um_AMS_prec | ug sm-3 | 1s precision error of the mass concentration of organic aerosol in air for particle diameter less than 1um measured by HRAMS |
| OA_lt_1um_AMS_DL | ug sm-3 | detection limit for the mass concentration of organic aerosol in air for particle diameter less than 1um measured by HRAMS |
| Sulfate_lt_1um_AMS | ug sm-3 | mass concentration of sulfate aerosol in air for particle diameter less than 1um measured by HRAMS |
| Sulfate_lt_1um_AMS_prec | ug sm-3 | 1s precision error of mass concentration of sulfate aerosol in air for particle diameter less than 1um measured by HRAMS |
| Sulfate_lt_1um_AMS_DL | ug sm-3 | detection limit for the mass concentration of sulfate aerosol in air for particle diameter less than 1um measured by HRAMS |
| Nitrate_lt_1um_AMS | ug sm-3 | mass concentration of nitrate aerosol in air for particle diameter less than 1um measured by HRAMS |
| Nitrate_lt_1um_AMS_prec | ug sm-3 | 1s precision error of mass concentration of nitrate aerosol in air for particle diameter less than 1um measured by HRAMS |
| Nitrate_lt_1um_AMS_DL | ug sm-3 | Detection limit for the mass concentration of nitrate aerosol in air for particle diameter less than 1um measured by HRAMS |
| Ammonium_lt_1um_AMS | ug sm-3 | mass concentration of ammonium aerosol in air for particle diameter less than 1um measured by HRAMS |
| Ammonium_lt_1um_AMS_prec | ug sm-3 | 1s precision error of mass concentration of ammonium aerosol in air for particle diameter less than 1um measured by HRAMS |
| Ammonium_lt_1um_AMS_DL | ug sm-3 | detection limit for the mass concentration of ammonium aerosol in air for particle diameter less than 1um measured by HRAMS |
| Chloride_lt_1um_AMS | ug sm-3 | mass concentration of chloride aerosol in air for particle diameter less than 1um measured by HRAMS |
| Chloride_lt_1um_AMS_prec | ug sm-3 | 1s precision error of mass concentration of chloride aerosol in air for particle diameter less than 1um measured by HRAMS |
| Chloride_lt_1um_AMS_DL | ug sm-3 | detection limit for the mass concentration of chloride aerosol in air for particle diameter less than 1um measured by HRAMS |
| Seasalt_lt_1um_AMS | ug sm-3 | mass concentration of seasalt aerosol in air for particle diameter less than 1um measured by HRAMS |
| Seasalt_lt_1um_AMS_prec | ug sm-3 | 1s precision error of mass concentration of seasalt aerosol in air for particle diameter less than 1um measured by HRAMS |
| Seasalt_lt_1um_AMS_DL | ug sm-3 | detection limit for the mass concentration of seasalt aerosol in air for particle diameter less than 1um measured by HRAMS |
| MSA_lt_1um_AMS | ug sm-3 | mass concentration of MSA aerosol in air for particle diameter less than 1um measured by HRAMS |
| MSA_lt_1um_AMS_prec | ug sm-3 | 1s precision error of mass concentration of MSA aerosol in air for particle diameter less than 1um measured by HRAMS |
| MSA_lt_1um_AMS_DL | ug sm-3 | detection limit for the mass concentration of MSA aerosol in air for particle diameter less than 1um measured by HRAMS |
| StdtoVol_AMS | m3 sm-3 | conversion factor from std to ambient volume and pressure |
| IceFlag_AMS | unitless | data points suspected to be impacted by artifacts due to ice impaction on the inlet |
| AmmBalance_lt_1um_AMS | unitless | Ammonium Molar Balance for non refractory inorganic species less than 1um measured by HRAMS |
| Density_lt_1um_AMS | g cm-3 | estimated aerosol density assuming internally mixed aerosol for particle diameter less than 1um measured by HRAMS |
| OADensity_lt_1um_AMS | g cm-3 | estimated density of the organic aerosol fraction assuming internally mixed aerosol for particle diameter less than 1um measured by HRAMS |
| O_C_lt_1um_AMS | unitless | O/C atomic ratio of the organic mass fraction of the aerosol for particle diameter less than 1um measured by HRAMS |
| H_C_lt_1um_AMS | unitless | H/C atomic ratio of the organic mass fraction of the aerosol for particle diameter less than 1um measured by HRAMS |
| OA_OC_lt_1um_AMS | unitless | organic aerosol to organic carbon ratio of the organic mass fraction of the aerosol for particle diameter less than 1um measured by HRAMS |
| OSc_lt_1um_AMS | unitless | estimated average oxidation state of carbon of the organic mass fraction of the aerosol for particle diameter less than 1um measured by HRAMS |
| f43_lt_1um_AMS | unitless | fractional contribution of m/z 43 to total organic mass for particle diameter less than 1um measured by HRAMS |
| f44_lt_1um_AMS | unitless | fractional contribution of m/z 44 to total organic mass for particle diameter less than 1um measured by HRAMS |
| f57_lt_1um_AMS | unitless | fractional contribution of m/z 57 to total organic mass for particle diameter less than 1um measured by HRAMS |
| f60_lt_1um_AMS | unitless | fractional contribution of m/z 60 to total organic mass for particle diameter less than 1um measured by HRAMS |
| f82_lt_1um_AMS | unitless | fractional contribution of m/z 82 to total organic mass for particle diameter less than 1um measured by HRAMS |
| f91_lt_1um_AMS | unitless | fractional contribution of m/z 91 to total organic mass for particle diameter less than 1um measured by HRAMS |
| fC2H3O_lt_1um_AMS | unitless | fractional contribution of C2H3O+ to total organic mass for particle diameter less than 1um measured by HRAMS |
| fCO2_lt_1um_AMS | unitless | fractional contribution of CO2+ to total organic mass for particle diameter less than 1um measured by HRAMS |
| fC4H9_lt_1um_AMS | unitless | fractional contribution of C4H9+ to total organic mass for particle diameter less than 1um measured by HRAMS |
| fC2H4O2_lt_1um_AMS | unitless | fractional contribution of C2H4O2+ to total organic mass for particle diameter less than 1um measured by HRAMS |
| fC5H6O_lt_1um_AMS | unitless | fractional contribution of C5H6O+ to total organic mass for particle diameter less than 1um measured by HRAMS |
| fC7H7_lt_1um_AMS | unitless | fractional contribution of C7H7+ to total organic mass for particle diameter less than 1um measured by HRAMS |
| OrgNitr_Fraction_lt_1um_AMS | unitless | estimated organic nitrate fractional contribution to total aerosol nitrate mass by HRAMS |
Table 4. Variables in the data files AMSSD_DC8_YYYMMDD_R#.ict.
| Variable Name | Units | Description |
|---|---|---|
| AMSSD Starttime | seconds | seconds since midnight UTC |
| AMSSD Stoptime | seconds | seconds since midnight UTC |
| AMSSD MidPoint | seconds | seconds since midnight UTC |
| LAT AMSSD | deg | aircraft latitude at time of sampling |
| LON AMSSD | deg | aircraft longitude at time of sampling |
| GALT AMSSD | m | aircraft GPS altitude at time of sampling |
| StdToVol AMSSD | m3 sm-3 | conversion factor from std to ambient volume and pressure |
| OA Total | ug sm-3 | total submicron aerosol mass measured in size segregated mode of OA by AMS less than 1 um |
| SO4 Total | ug sm-3 | total submicron aerosol mass measured in size segregated mode of sulfate by AMS less than 1 um |
| NO3 Total | ug sm-3 | total submicron aerosol mass measured in size segregated mode of ammonium by AMS less than 1 um |
| NH4 Total | ug sm-3 | total submicron aerosol mass measured in size segregated mode of nitrate by AMS less than 1 um |
| Chl Total | ug sm-3 | total submicron aerosol mass measured in size segregated mode of chloride by AMS less than 1 um |
| OA dMdlogDva XtoYnm | ug sm-3 | submicron aerosol mass size distribution of OA in air per dlogDva for vacuum aerodynamic diameter from X to Ynm |
| SO4 dMdlogDva XtoYnm | ug sm-3 | submicron aerosol mass size distribution of SO4 in air per dlogDva for vacuum aerodynamic diameter from X to Ynm |
| NO3 dMdlogDva XtoYnm | ug sm-3 | submicron aerosol mass size distribution of NO3 in air per dlogDva for vacuum aerodynamic diameter from X to Ynm |
| NH4 dMdlogDva XtoYnm | ug sm-3 | submicron aerosol mass size distribution of NH4 in air per dlogDva for vacuum aerodynamic diameter from X to Ynm |
| Chl dMdlogDva XtoYnm | ug sm-3 | submicron aerosol mass size distribution of Chl in air per dlogDva for vacuum aerodynamic diameter from X to Ynm |
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
Accuracy estimate (2sdev): Inorganics +/-34%, Organics +/-38%, dominated by uncertainty in particle collection efficiency due to particle bounce, and absolute and relative ionization efficiency. Precision error (1sdev) for each species is provided as a variable.
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.
High-Resolution (Time-of-Flight) Aerosol Mass Spectrometer (HR-AMS):
| Instrument | Full Name | Contact Person | Type | Measurements |
|---|---|---|---|---|
| HR-AMS | CU Aircraft High-Resolution Aerosol Mass Spectrometer | Jose-Luis Jimenez | spectrometer (in situ) | aerosol mass |
The High-Resolution (Time-of-Flight) Aerosol Mass Spectrometer (HR-AMS) detects non-refractory submicron aerosol composition by impaction on a vaporizer at 600°C, followed by electron ionization and time-of-flight mass spectral analysis. Size-resolved composition can be quantified by measuring the arrival times of the aerosol at the vaporizer. For more information, see DeCarlo et al. (2006).
Data Access
These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).
ATom: L2 Measurements from CU High-Resolution Aerosol Mass Spectrometer (HR-AMS)
Contact for Data Center Access Information:
- E-mail: uso@daac.ornl.gov
- Telephone: +1 (865) 241-3952
References
DeCarlo, P.F., Kimmel, J.R., Trimborn, A., Northway, M.J., Jayne, J.T., Aiken, A.C., Gonin, M., Fuhrer, K., Horvath, T., Docherty, K.S. and Worsnop, D.R., 2006. Field-deployable, high-resolution, time-of-flight aerosol mass spectrometer. Analytical chemistry, 78(24), pp.8281-8289.
J.L. Jimenez, P. Campuzano-Jost, D.A. Day, B.A. Nault, J.C. Schroder, M.J. Cubison, Frequently Asked Questions for AMS Data Users, http://cires.colorado.edu/jimenez-group/wiki/index.php?title=FAQ_for_AMS_Data_Users, accessed July-2019.