Spatial heterogeneity in CO2, CH4, and energy fluxes: insights from airborne eddy covariance measurements over the Mid-Atlantic region

Hannun, R. A., et al. (2020), Spatial heterogeneity in CO2, CH4, and energy fluxes: insights from airborne eddy covariance measurements over the Mid-Atlantic region, Environmental Research Letters., 15, 035008, doi:10.1088/1748-9326/ab7391.

The NASA Carbon Airborne Flux Experiment (CARAFE): instrumentation and methodology

Wolfe, G. M., et al. (2018), The NASA Carbon Airborne Flux Experiment (CARAFE): instrumentation and methodology, Atmos. Meas. Tech., 11, 1757-1776, doi:10.5194/amt-11-1757-2018.

NASA to Measure Greenhouse Gases Over the Mid-Atlantic Region

In May, a team of Goddard scientists will begin measuring greenhouse gases over the Mid-Atlantic region — an area chosen in part because it encompasses a range of vegetation, climate, and soil types that would influence the exchange of carbon dioxide and methane between the Earth and the atmosphere.

NASA Using Aircraft to Measure Mid-Atlantic Greenhouse Gases

NASA is conducting low-level aircraft flights measuring greenhouse gases over the mid-Atlantic region through September. The flights are for the CARbon Airborne Flux Experiment or CARAFE, which will measure the exchange of greenhouse gases such as carbon dioxide and methane between the Earth and the atmosphere in the region.

Diode Laser Hygrometer

The DLH has been successfully flown during many previous field campaigns on several aircraft, most recently ACTIVATE (Falcon); FIREX-AQ, ATom, KORUS-AQ, and SEAC4RS (DC-8); POSIDON (WB-57); CARAFE (Sherpa); CAMP2Ex and DISCOVER-AQ (P-3); and ATTREX (Global Hawk). This sensor measures water vapor (H2O(v)) via absorption by one of three strong, isolated spectral lines near 1.4 μm and is comprised of a compact laser transceiver and a sheet of high grade retroflecting road sign material to form the optical path. Optical sampling geometry is aircraft-dependent, as each DLH instrument is custom-built to conform to aircraft geometric constraints. Using differential absorption detection techniques, H2O(v) is sensed along the external path negating any potential wall or inlet effects inherent in extractive sampling techniques. A laser power normalization scheme enables the sensor to accurately measure water vapor even when flying through clouds. An algorithm calculates H2O(v) concentration based on the differential absorption signal magnitude, ambient pressure, and temperature, and spectroscopic parameters found in the literature and/or measured in the laboratory. Preliminary water vapor mixing ratio and derived relative humidities are provided in real-time to investigators.

Instrument Type: 
Laser absorption
Measurements: 
H2O
Aircraft: 
B200 - LARC, DC-8 - AFRC, Global Hawk - AFRC, P-3 Orion - WFF, WB-57 - JSC, Sherpa - WFF, HU25 Falcon - LaRC, Twin Otter - CIRPAS - NPS
Point(s) of Contact: 
Glenn S. Diskin (PI)
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