Documentation Revision Date: 2021-10-28
Dataset Version: 1
There are 48 data files in ICARTT (*.ict) format included in this dataset
Yang, M.M., and J.R. Bennett. 2021. ATom: Flight Dynamics and Environmental Parameters of the NASA DC-8 Aircraft. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1909
Table of Contents
- Dataset Overview
- Data Characteristics
- Application and Derivation
- Quality Assessment
- Data Acquisition, Materials, and Methods
- Data Access
This dataset contains flight dynamics and environmental parameters (often referred to as housekeeping) specific to the DC-8 aircraft as collected from an assortment of instruments across all four ATom campaigns flown from 2016 through 2018. Measurements include aircraft position, altitude, speed, wind parameters, air temperature, and atmospheric and cabin pressure. These data can be used to understand the interior and exterior conditions and positioning of the DC-8 aircraft at 1-second resolution.
Project: Atmospheric Tomography Mission
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.
Wofsy, S.C., S. Afshar, H.M. Allen, E.C. Apel, E.C. Asher, B. Barletta, J. Bent, H. Bian, B.C. Biggs, D.R. Blake, N. Blake, I. Bourgeois, C.A. Brock, W.H. Brune, J.W. Budney, T.P. Bui, A. Butler, P. Campuzano-Jost, C.S. Chang, M. Chin, R. Commane, G. Correa, J.D. Crounse, P. D. Cullis, B.C. Daube, D.A. Day, J.M. Dean-Day, J.E. Dibb, J.P. DiGangi, G.S. Diskin, M. Dollner, J.W. Elkins, F. Erdesz, A.M. Fiore, C.M. Flynn, K.D. Froyd, D.W. Gesler, S.R. Hall, T.F. Hanisco, R.A. Hannun, A.J. Hills, E.J. Hintsa, A. Hoffman, R.S. Hornbrook, L.G. Huey, S. Hughes, J.L. Jimenez, B.J. Johnson, J.M. Katich, R.F. Keeling, M.J. Kim, A. Kupc, L.R. Lait, K. McKain, R.J. Mclaughlin, S. Meinardi, D.O. Miller, S.A. Montzka, F.L. Moore, E.J. Morgan, D.M. Murphy, L.T. Murray, B.A. Nault, J.A. Neuman, P.A. Newman, J.M. Nicely, X. Pan, W. Paplawsky, J. Peischl, M.J. Prather, D.J. Price, E.A. Ray, J.M. Reeves, M. Richardson, A.W. Rollins, K.H. Rosenlof, T.B. Ryerson, E. Scheuer, G.P. Schill, J.C. Schroder, J.P. Schwarz, J.M. St.Clair, S.D. Steenrod, B.B. Stephens, S.A. Strode, C. Sweeney, D. Tanner, A.P. Teng, A.B. Thames, C.R. Thompson, K. Ullmann, P.R. Veres, N.L. Wagner, A. Watt, R. Weber, B.B. Weinzierl, P.O. Wennberg, C.J. Williamson, J.C. Wilson, G.M. Wolfe, C.T. Woods, L.H. Zeng, and N. Vieznor. 2021. ATom: Merged Atmospheric Chemistry, Trace Gases, and Aerosols, Version 2. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1925.
- Data from all ATom instruments and all four flight campaigns, including aircraft location and navigation data, merged to several different time bases
Wofsy, S.C., and ATom Science Team. 2018. ATom: Aircraft Flight Track and Navigational Data. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/1613
- Flightpath (location and altitude) data for each of the four campaigns provided in KML and CSV format.
Spatial Coverage: Global. Flights circumnavigate the globe, primarily over the oceans
Spatial Resolution: Point measurements
Temporal Coverage: Periodic flights occurred during each campaign
|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
There are 48 data files in ICARTT (*.ict) format included in this dataset that contain flight dynamics and environmental parameters. Data files conform to the ICARTT File Format Standards V1.1. The files are named Hskping _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 File Details
Missing data are represented by -9999.
Table 1. Instruments used for data collection and their associated variables.
|Instrument Name||Variables Measured|
|LN251 EGI||Positional parameters, altitude parameters, ground_speed, and vertical_speed|
|LN251 EGI, Aircraft Data System-85||Wind_Speed and Wind_Direction|
|Rosemount 102||Total_Air_Temperature, used to derive Static_Air_Temperature and Potential_Temperature|
|MKS Baratron 220D||Cabin_Pressure|
|Edgetech hygrometer||Dew_Point, used to derive associated water vapor parameters|
|Aircraft Data System-85||Pressure_Altitude, Indicated_Air_Speed, True_Air_Speed, Mach_Number, Static_Pressure|
Table 2. Variables and descriptions for the 46 data files named Hskping _DC8_YYYYMMDD_R#.ict.
|Start_UTC||Seconds||Seconds from 0000 UTC|
|Day_Of_Year||Numeric||Day beginning January 1|
|Latitude||Decimal degrees||Degrees North|
|Longitude||Decimal degrees||Degrees East|
|MSL_GPS_Altitude||Meters||Height above mean sea level|
|HAE_GPS_Altitude||Meters||Height above ellipsoid WGS84|
|Pressure_Altitude||Feet||Height above a standard datum plane|
|Radar_Altitude||Feet||Height above ground|
|Ground_Speed||Meters/second||Aircraft speed relative to ground|
|True_Air_Speed||Knots||Aircraft speed relative to air|
|Indicated_Air_Speed||Knots||Aircraft speed relative to air as indicated on instrument panel|
|Mach_Number||Mach||Air speed: speed of sound ratio|
|Vertical_Speed||Meters/second||Rate of ascent/decent|
|True_Heading||Degrees||Aircraft orientation relative to due north, 0-360, clockwise from North|
|Track_Angle||Degrees||Projection of the aircraft path onto the earth’s surface, 0-360, clockwise from North|
|Drift_Angle||Degrees||Angle difference between True_Heading and Track_Angle. +/-180, clockwise from North|
|Pitch_Angle||Degrees||Angle between aircraft longitudinal axis and the horizon, +/-180, up+|
|Roll_Angle||Degrees||Angle measurement where aircraft lateral axis is horizontal, +/-180, rt+|
|Static_Air_Temp||Celsius||Temperature of undisturbed air. Reduction from Total_Air_Temp|
|Potential_Temp||Kelvin||Potential temperature, derived from Static_Air_Temp and Static_Pressure|
|Dew_Point||Celsius||Temperature where dew/ice may begin to form|
|Total_Air_Temp||Celsius||Temperature within aircraft boundary layer (including dynamic effects)|
|IR_Surf_Temp||Celsius||Aircraft infrared surface temperature|
|Static_Pressure||Millibar||Pressure of aircraft static pressure system|
|Cabin_Pressure||Millibar||Pressure inside cabin|
|Wind_Speed||Meters/second||Derived horizontal wind speed|
|Wind_Direction||Degrees||Derived wind direction|
|Solar_Zenith_Angle||Degrees||Angle between the sun and the vertical direction|
|Aircraft_Sun_Elevation||Degrees||Elevation (altitude, in angle) of the sun with respect to the aircraft.|
|Sun_Azimuth||Degrees||Angle between the sun and solar noon|
|Aircraft_Sun_Azimuth||Degrees||Sun azimuth angle with respect to the aircraft.|
|Mixing_Ratio||Gram/kilogram||Mixing ratio of water in the air|
|Part_Press_Water_Vapor||Millibar||Partial pressure of water vapor|
|Sat_Vapor_Press_H2O||Millibar||Pressure where water will begin to condense|
|Sat_Vapor_Press_Ice||Millibar||Pressure where ice will begin to deposit|
|Relative_Humidity||Percent||Humidity with respect to water|
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
- 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?
- 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?
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.
Table 3. Uncertainties of variables according to instrument manufacturer’s specifications.
|Start_UTC||Low order milliseconds|
|Latitude||5 meters spherical error probable|
|Longitude||5 meters spherical error probable|
|HAE_GPS_Altitude||5 meters spherical error probable|
|Pressure_Altitude||20 feet, increasing to 138 feet with altitude|
|Radar_Altitude||2 feet, +- 2% at altitude|
|Indicated_Air_Speed||5 kts at TAS 50 kts; 2 kts at TAS 100 kts; 2.8 kts at TAS 300 kts|
|Vertical_Speed||Greater of 0.152 m/s or 5%|
|Static_Air_Temp||0.5 degree C|
|Dew_Point||0.2 degree C|
|Total_Air_Temp||0.3 degree C|
|IR_Surf_Temp||0.5 degree C + 0.7%*(target-housing)|
|Wind_Speed||1 m/s during straight and level flight legs|
|Relative_Humidity||2 – 5 %|
Data Acquisition, Materials, and Methods
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.
Flight Dynamics & Environmental Parameters
This dataset contains measurements from multiple instruments on the DC-8 aircraft. Additional information about instrumentation built into DC-8 can be found in the Experimenter’s Handbook on the ESPO DC-8 Description page.
These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).
Contact for Data Center Access Information:
- E-mail: firstname.lastname@example.org
- Telephone: +1 (865) 241-3952