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ATom: L2 Measurements from CU High-Resolution Aerosol Mass Spectrometer (HR-AMS)

Documentation Revision Date: 2019-08-01

Dataset Version: 1

Summary

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 degrees 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.

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

  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 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:

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 chemistry78(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.