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ABoVE/ASCENDS: Merged Atmospheric CO2, CH4, and Meteorological Data, 2017

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Documentation Revision Date: 2022-12-02

Dataset Version: 1

Summary

This dataset provides in situ airborne measurements of atmospheric carbon dioxide (CO2), methane (CH4), water vapor concentrations, air temperature, pressure, and wind speed and direction as well as airborne remote sensing measurements of column average CO2 collected during Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) deployments from 2017-07-20 to 2017-08-08 over Alaska, US, and the Yukon and Northwest Territories of Canada. CO2 and CH4 were measured with NASA's Atmospheric Vertical Observations of CO2 in the Earth's Troposphere (AVOCET) instrument. Water vapor and relative humidity were measured with Diode Laser Hydrometer. Measurements were taken onboard a DC-8 aircraft. The ASCENDS flights were coordinated with the 2017 Arctic-Boreal Vulnerability Experiment (ABoVE) campaign. The data are provided in ICARTT format along with an archive of flight videos.

These data are a merge of files from two ABoVE/ASCENDS datasets: Abshire et al. (2022) and Sun et al (2022).

There are four data files in ICARTT (.ict) format and one compressed zip file (.zip) with this dataset; the .ict files contain the data and the .zip file contains flight videos.

 

Figure 1. A map showing the ground tracks for the airborne campaign with a table summarizing each flight. The colors in the table match those shown in the ground tracks. Image is from the related dataset Abshire et al. (2022).

Citation

Abshire, J.B., J. Mao, H. Riris, S.R. Kawa, and X. Sun. 2022. ABoVE/ASCENDS: Merged Atmospheric CO2, CH4, and Meteorological Data, 2017. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/2114

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 in situ airborne measurements of atmospheric CO2, CH4, water vapor concentrations, air temperature, pressure, relative humidity, and wind speed and direction, as well as airborne remote sensing measurements of column averaged CO2 collected during ASCENDS deployments from 2017-07-20 to 2017-08-08 over Alaska and the Yukon and Northwest Territories of Canada. CO2 and CH4 were measured with NASA's Atmospheric Vertical Observations of CO2 in the Earth's Troposphere (AVOCET) instrument. Water vapor and relative humidity were measured with a Diode Laser Hydrometer. These data are a merge of files in the Related Datasets listed below.

Project: Arctic-Boreal Vulnerability Experiment

The Arctic-Boreal Vulnerability Experiment (ABoVE) is a NASA Terrestrial Ecology Program field campaign based in Alaska and western Canada between 2016 and 2021. Research for ABoVE links field-based, process-level studies with geospatial data products derived from airborne and satellite sensors, providing a foundation for improving the analysis and modeling capabilities needed to understand and predict ecosystem responses and societal implications.

Related Datasets

Abshire, J.B., J. Mao, H. Riris, S.R. Kawa, and X. Sun. 2022. ABoVE/ASCENDS: Active Sensing of CO2, CH4, and Water Vapor, Alaska and Canada, 2017. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/2050

  • One of the two input datasets used to generate the current merged dataset

Sun, X., P.T. Kolbeck, J.B. Abshire, S.R. Kawa, and J. Mao. 2022. ABoVE/ASCENDS: Atmospheric Backscattering Coefficient Profiles from CO2 Sounder, 2017. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/2051

  • One of the two input datasets used to generate the current merged dataset

Related Publications

Abshire, J. B., A.K. Ramanathan, H. Riris, G.R. Allan, X. Sun, W.E. Hasselbrack, J. Mao, S. Wu, J. Chen, K. Numata, S.R. Kawa, M.Y.M. Yang, and J. DiGangi. 2018. Airborne measurements of CO2 column concentrations made with a pulsed IPDA lidar using multiple-wavelength-locked laser and HgCdTe APD detector. Atmospheric Measurement Techniques (AMT) 11:2001-2025. https://doi.org/10.5194/amt-11-2001-2018

Allan, G.R., J.B. Abshire, H. Riris, J. Mao, W.E. Hasselbrack, K. Numata, J. Chen, R. Kawa, M. Rodriguez, and M. Stephen. 2018. Lidar measurements of CO2 column concentrations in the Arctic region of North America from the ASCENDS 2017 airborne campaign. SPIE Proceedings volume 10779, Lidar Remote Sensing for Environmental Monitoring XVI, 1077906 (24 October 2018). https://doi.org/10.1117/12.2325908

Sun, X., J.B. Abshire, A. Ramanathan, S.R. Kawa, and J. Mao. 2021. Retrieval algorithm for the column CO2 mixing ratio from pulsed multi-wavelength lidar measurements. Atmospheric Measurement Techniques 14:3909–3922. https://doi.org/10.5194/amt-14-3909-2021

Acknowledgement

This research was funded by the NASA Terrestrial Ecology Program: Arctic-Boreal Vulnerability Experiment.

Data Characteristics

Spatial Coverage: Alaska; Yukon; Northwest Territories

ABoVE Reference Locations

Domain: Core and extended
State/Territory: Alaska; Yukon; Northwest Territories
Grid cells: Ah000v000, Ah000v001, Ah001v000, Ah001v001, Ah001v002, Ah002v001, Ah002v002

Spatial Resolution: Point locations. At an aircraft speed of 170 knots (87.5 m/s), one 1-second averaging interval covers a distance of ~87 m. Profiles cover a vertical range from the surface up to 6 km altitude at ~15 m vertical resolution.

Temporal Coverage: 2017-07-20 to 2017-08-08 with 8 single-day flights during the period.

Temporal Resolution: 1, 5, 10, and 60-seconds

Study Areas: Latitude and longitude are given in decimal degrees.

Site Westernmost Longitude Easternmost Longitude Northernmost Latitude Southernmost Latitude
Alaska and Canada -165.6848 -98.1479 71.2664 34.5939

Data File Information

There are four data files in ICARTT format (*.ict) and one .zip file with flight videos.

The .ict files are named ascends-mrgXX-dc8_merge_20170720_R2_thru20170808.ict where XX is 01, 05, 10, and 60 (second intervals). The files used to create this dataset from the two Related Datasets in Section 2 of this document are listed in Table 2. These files put all individual measurements on a common time base and coordinates. These co-located measurements will facilitate the analysis of the co-variations of the parameters.

The .zip file is named flight_videos.zip.

Table 1. Variables in the merge data files.

User note: A "Unit Conversion" field is provided which shows one unit "to" another unit contained in parentheses (e.g. "(degC to K)") if the units changed between the PI data and the merge file at all, even if just the case differs. If the units of a variable changed but no conversion was necessary, the unit text was changed or clarified from that in the raw file (e.g. to standardize units across a variable/measurement type). Where the field is empty, no unit change was made from the raw file.

If any portion of the averaging period contains a Limit of Detection (LOD) value for a given measurement, the average is marked with an LOD flag: Lower LOD= -888888, Upper LOD= -777777. For the merge period, if all data are missing, the missing flag is set to = -999999.

Variable Unit Conversion, if changed Original Name Description Data-ID
UTC ("seconds (from midnight UTC)" to "s") N/A Mid-time of the interval in seconds since midnight UTC on the flight date Merge code
JDAY   N/A Julian day of the flight start date Merge code
INDEX 1 N/A Sequential index of the data record starting with the flight number Merge code
FLIGHT 1 N/A Flight number Merge code
LOCAL_SUN_TIME degrees N/A Local sun time at the sampling longitude and time Merge code
LATITUDE degrees_north N/A Latitude Ascends-Hskping
LONGITUDE degrees (0-360) Longitude Longitude Ascends-Hskping
ALTP ("ft" to "km") Pressure_Altitude Aircraft pressure altitude derived from air pressure sensor Ascends-Hskping
PRESSURE ("mb" to "hPa") Static_Pressure Static air pressure Ascends-Hskping
TEMPERATURE ("Celcius" to "K") Static_Air_Temp Static air temperature Ascends-Hskping
THETA K N/A Potential temperature Merge code
O3COLUMN Du N/A Ozone column OMI
SZA 1 N/A Solar zenith angle Merge code
WNS ("m/s (limited to where Roll_Angle <= 5 degrees)" to "m/s") Wind_Speed  Wind speed, limited to where Roll_Angle <= 5 degrees Ascends-Hskping
WND ("deg (0-360" to "deg") Wind_Direction Wind direction, 0-360 degrees, clockwise from +y Ascends-Hskping
DOY ("day beginning January 1" to "DOY") Day_Of_Year Fight day of year, beginning January 1 Ascends-Hskping
MSL_GPS_ALT ("m (height above mean sea level)" to "km") MSL_GPS_Altitude Aircraft GPS altitude above mean sea level Ascends-Hskping
HAE_GPS_ALT ("m (height above ellipsoid WGS84)" to "km") HAE_GPS_Altitude Aircraft GPS altitude above WGS84 ellipsoid Ascends-Hskping
RadarAlt ("ft" to "km") Radar_Altitude Aircraft radar altitude Ascends-Hskping
GRD_SPD ("m/s" to "m s-1") Ground_Speed Aircraft ground speed Ascends-Hskping
TAS ("kts" to "m/s") True_Air_Speed Aircraft true airspeed Ascends-Hskping
IAS ("kts" to "m/s") Indicated_Air_Speed Aircraft indicated airspeed Ascends-Hskping
MachNumber   Mach_Number Aircraft speed in mach number Ascends-Hskping
VerticalSpeed ("m/s" to "m s-1") Vertical_Speed Aircraft vertical speed Ascends-Hskping
HDG ("deg (0-360" to "degs") True_Heading Aircraft true heading, 0-360 degrees, clockwise from +y Ascends-Hskping
TRK ("deg (0-360" to "degs") Track_Angle Aircraft track angle, 0-360 degrees, clockwise from +y Ascends-Hskping
DriftAngle ("deg (+-180" to "degs") Drift_Angle Aircraft drift angle, +/-180 degrees, clockwise from +y Ascends-Hskping
PITCH ("deg (+-180" to "degs") Pitch_Angle Aircraft pitch angle, +/-180 degrees, up+ Ascends-Hskping
ROLL ("deg (+-180" to "degs") Roll_Angle Aircraft roll angle, +/-180 degrees, right+ Ascends-Hskping
PotentialTemp ("Kelvin" to "degK") Potential_Temp Potential temperature Ascends-Hskping
Dewpoint ("Celcius" to "K") Dew_Point Dew point temperature
(data are missing or not included for all files)		 Ascends-Hskping
TotalAirTemp ("Celcius" to "K") Total_Air_Temp An intermediate product of air temperature measurement, not corrected for air motion Ascends-Hskping
IR_SurfTemp ("Celcius" to "K") IR_Surf_Temp Surface temperature Ascends-Hskping
CabinPressure ("hpa" to "hPa") Cabin_Pressure Aircraft cabin pressure Ascends-Hskping
SolarZenithAngle ("deg" to "degs") Solar_Zenith_Angle Solar zenith angle Ascends-Hskping
AircraftSunElevation ("deg" to "degs") Aircraft_Sun_Elevation Sun elevation angle with respect to aircraft Ascends-Hskping
SunAzimuth ("deg" to "degs") Sun_Azimuth Sun azimuth angle Ascends-Hskping
AircraftSunAzimuth ("deg" to "degs") Aircraft_Sun_Azimuth Sun azimuth angle with respect to aircraft Ascends-Hskping
MixingRatio ("g/kg" to "g kg-1") Mixing_Ratio Atmospheric water mass mixing ratio
(data are missing or not included for all files)		 Ascends-Hskping
VaporPresWater ("mb" to "hPa") Part_Press_Water_Vapor Partial pressure of water vapor
(data are missing or not included for all files)		 Ascends-Hskping
SatVaporPresWater ("mb" to "hPa") Sat_Vapor_Press_H2O Saturated vapor pressure over liquid water Ascends-Hskping
SatVaporPresIce ("mb" to "hPa") Sat_Vapor_Press_Ice Saturated vapor pressure over ice Ascends-Hskping
RelativeHumidity ("percent (with respect to water)" to "%") Relative_Humidity Relative humidity
(data are missing or not included for all files)		 Ascends-Hskping
CH4_ppmv ("ppmv" to "ppbv") CH4_ppmv Measurements of dry methane (CH4) in volumetric mixing ratio
(from the AVOCET instrument)		 ASCENDS-AVOCET-CH4
CO2_MixingRatio ppmv CO2_ppmv Measurements of dry carbon dioxide (CO2) in volumetric mixing ratio
(from the AVOCET instrument)		 ASCENDS-AVOCET-CO2
XCO2_Sounder ppm XCO2_Sounder Measurements of column-averaged dry-air mole fraction (XCO2)
(from the CO2 Sounder Lidar instrument)		 ASCENDS-CO2SOUNDER-XCO2
Aircraft_Altitude ("m" to "km") Aircraft_Altitude GPS height above mean sea level ASCENDS-CO2SOUNDER-XCO2
H2O_vapor_DLH ppmv H2O_ppmv Water vapor mixing ratio ASCENDS-DLH
RHi_pct_DLH % RHi_pct Relative humidity with respect to ice ASCENDS-DLH
RHw_pct_DLH % RHw_pct Relative humidity with respect to liquid ASCENDS-DLH

 


Table 2. These data are a merge of files from the two datasets listed in the Overview Section of this document under Related Datasets. Files used to create this dataset are listed below.

AVOCET CH2 Files
ASCENDS-AVOCET-CH4_DC8_20170720_R0.ict,2018-04-26
ASCENDS-AVOCET-CH4_DC8_20170721_R0.ict,2018-04-26
ASCENDS-AVOCET-CH4_DC8_20170727_R0.ict,2018-04-26
ASCENDS-AVOCET-CH4_DC8_20170731_R0.ict,2018-04-26
ASCENDS-AVOCET-CH4_DC8_20170803_R0.ict,2018-04-26
ASCENDS-AVOCET-CH4_DC8_20170805_R0.ict,2018-04-26
ASCENDS-AVOCET-CH4_DC8_20170806_R0.ict,2018-04-26
ASCENDS-AVOCET-CH4_DC8_20170808_R0.ict,2018-04-26
AVOCET CO2 Files
ASCENDS-AVOCET-CO2_DC8_20170720_R0.ict,2018-04-26
ASCENDS-AVOCET-CO2_DC8_20170721_R0.ict,2018-04-26
ASCENDS-AVOCET-CO2_DC8_20170727_R0.ict,2018-04-26
ASCENDS-AVOCET-CO2_DC8_20170731_R0.ict,2018-04-26
ASCENDS-AVOCET-CO2_DC8_20170803_R0.ict,2018-04-26
ASCENDS-AVOCET-CO2_DC8_20170805_R0.ict,2018-04-26
ASCENDS-AVOCET-CO2_DC8_20170806_R0.ict,2018-04-26
ASCENDS-AVOCET-CO2_DC8_20170808_R0.ict,2018-04-26
CO2SOUNDER-XCO2 Files
ASCENDS-CO2SOUNDER-XCO2_DC8_20170720_R0.ict,2019-08-30
ASCENDS-CO2SOUNDER-XCO2_DC8_20170721_R0.ict,2019-09-10
ASCENDS-CO2SOUNDER-XCO2_DC8_20170727_R0.ict,2019-09-10
ASCENDS-CO2SOUNDER-XCO2_DC8_20170731_R0.ict,2019-09-10
ASCENDS-CO2SOUNDER-XCO2_DC8_20170803_R0.ict,2019-09-10
ASCENDS-CO2SOUNDER-XCO2_DC8_20170805_R0.ict,2019-09-10
ASCENDS-CO2SOUNDER-XCO2_DC8_20170806_R0.ict,2019-09-10
ASCENDS-CO2SOUNDER-XCO2_DC8_20170808_R0.ict,2019-09-10
DLH Files
ASCENDS-DLH_DC8_20170720_R0.ict,2018-07-23
ASCENDS-DLH_DC8_20170721_R0.ict,2018-07-26
ASCENDS-DLH_DC8_20170727_R0.ict,2021-11-05
ASCENDS-DLH_DC8_20170731_R0.ict,2018-07-09
ASCENDS-DLH_DC8_20170803_R0.ict,2018-07-09
ASCENDS-DLH_DC8_20170805_R0.ict,2018-07-09
ASCENDS-DLH_DC8_20170806_R0.ict,2018-07-09
ASCENDS-DLH_DC8_20170808_R0.ict,2018-07-09
HSKPING Files
Ascends-Hskping_DC8_20170720_R1.ict,2019-07-16
Ascends-Hskping_DC8_20170721_R1.ict,2019-07-16
Ascends-Hskping_DC8_20170727_R2.ict,2019-07-15
Ascends-Hskping_DC8_20170731_R1.ict,2019-07-16
Ascends-Hskping_DC8_20170803_R1.ict,2019-07-16
Ascends-Hskping_DC8_20170805_R1.ict,2019-07-16
Ascends-Hskping_DC8_20170806_R1.ict,2019-07-16
Ascends-Hskping_DC8_20170808_R1.ict,2019-07-16

Application and Derivation

These data contribute to our understanding and predictive capabilities for modeling the land-atmospheric exchange of CO2 and CH4 in the ABoVE study region.

Quality Assessment

The AVOCET measurements of CO2 and CH4 were calibrated using the WMO X2007 scale (https://gml.noaa.gov/ccl/co2_scale.html) and WMO X2004A scale ( https://gml.noaa.gov/ccl/ch4_scale.html), respectively. Please refer to user guides of the two input ABoVE/ASCENDS datasets, Abshire et al. (2022) and Sun et al (2022), for more details on calibration process and quality assessment.

Data Acquisition, Materials, and Methods

ASCENDS deployments were from 2017-07-20 to 2017-08-08 over Alaska, US, and the Yukon and Northwest Territories of Canada. The flights were designed to assess the accuracy of airborne lidar measurements of column-averaged dry-air CO2 mixing ratio (XCO2) and to extend lidar measurements to the ABoVE study area in the Arctic. Eight flights with a NASA DC-8 aircraft were conducted with XCO2 measurements from the lidar along with in-situ CO2 measurements made at the aircraft. Forty-seven spiral-down maneuvers were conducted in locations over California, the Northwest Territories Canada, the Arctic Ocean, and Alaska, along with the transit flights from California to Alaska and return. Each spiral maneuver allowed comparing the XCO2 retrievals from the lidar against those computed from CO2 measured at the aircraft. In addition to the XCO2 measurement, the lidar receiver also recorded the time-resolved atmospheric backscatter signal strength continuously as the laser pulses propagated through the atmosphere.

In situ concentrations of atmospheric carbon dioxide and methane were measured with an infrared absorption spectrometer on NASA's Atmospheric Vertical Observations of CO2 in the Earth's Troposphere (AVOCET) instrument. Water vapor and relative humidity were measured with Diode Laser Hydrometer. Column-averaged dry-air CO2 mixing ratio (XCO2) measurements were taken with the CO2 Sounder Lidar instrument (Abshire et al., 2017). Sounder is a pulsed, multi-wavelength Integrated Path Differential Absorption (IPDA) lidar that estimates XCO2 in the nadir path from the aircraft to the scattering surface by measuring the shape of the 1572.33 nm CO2 absorption line (Abshire et al., 2018). The XCO2 observations are available in the related dataset Abshire et al. (2022). The meteorological data are available in the related dataset Sun et al (2022).

For additional details refer to the publications listed in the Overview Section of this document.

Data Access

These data are available through the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

ABoVE/ASCENDS: Merged Atmospheric CO2, CH4, and Meteorological Data, 2017

Contact for Data Center Access Information:

References

Abshire, J.B., J. Mao, H. Riris, S.R. Kawa, and X. Sun. 2022. ABoVE/ASCENDS: Active Sensing of CO2, CH4, and Water Vapor, Alaska and Canada, 2017. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/2050

Abshire, J. B., A.K. Ramanathan, H. Riris, G.R. Allan, X. Sun, W.E. Hasselbrack, J. Mao, S. Wu, J. Chen, K. Numata, S.R. Kawa, M.Y.M. Yang, and J. DiGangi. 2018. Airborne measurements of CO2 column concentrations made with a pulsed IPDA lidar using multiple-wavelength-locked laser and HgCdTe APD detector. Atmospheric Measurement Techniques (AMT) 11:2001-2025. https://doi.org/10.5194/amt-11-2001-2018

Allan, G.R., J.B. Abshire, H. Riris, J. Mao, W.E. Hasselbrack, K. Numata, J. Chen, R. Kawa, M. Rodriguez, and M. Stephen. 2018. Lidar measurements of CO2 column concentrations in the Arctic region of North America from the ASCENDS 2017 airborne campaign. SPIE Proceedings volume 10779, Lidar Remote Sensing for Environmental Monitoring XVI, 1077906 (24 October 2018). https://doi.org/10.1117/12.2325908

Sun, X., P.T. Kolbeck, J.B. Abshire, S.R. Kawa, and J. Mao. 2022. ABoVE/ASCENDS: Atmospheric Backscattering Coefficient Profiles from CO2 Sounder, 2017. ORNL DAAC, Oak Ridge, Tennessee, USA. https://doi.org/10.3334/ORNLDAAC/2051

Sun, X., J.B. Abshire, A. Ramanathan, S.R. Kawa, and J. Mao. 2021. Retrieval algorithm for the column CO2 mixing ratio from pulsed multi-wavelength lidar measurements. Atmospheric Measurement Techniques 14:3909–3922. https://doi.org/10.5194/amt-14-3909-2021