Yonghoon Choi | National Institute of Aerospace

Tel: +1 (757)864-5512, FAX: +1 (757) 864-4343

Education

Ph.D. in Geochemistry, Florida State University, 2002
M.S. in Geophysics, Yonsei University, 1991
B.S. in Geological Sciences, Yonsei University, 1989

Research Interests

Measurement of the high precision, in-situ CO2 concentration aboard NASA DC-8;
Development of the CO2 measurement systems for the validation flights for the newly evolving remote CO2 sensors;
Data Analysis for the tropospheric CO2 measurement for the aircraft missions; and
C-13 and C-14 isotope mass spectrometric measurement and data analysis.

Current Research

DC-8 and P-3 Aircraft measurements and data analysis of atmospheric CO2: The AVOCET (Atmospheric Vertical Observation of CO2 in the Earth’s Troposphere) in-situ CO2 measurement system (high precision and fast response) aboard P-3 conducted the successful flights for the DISCOVER-AQ (Deriving Information on Surface Conditions from Column and VERtically Resolved Observations Relevant to Air Quality) field mission over Washington DC and the Baltimore area to monitor the air quality, and to enable more effective use of current and future satellites to diagnose ground level conditions influencing air quality. The ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) field mission was conducted with three NASA aircraft (DC-8, P-3, and B200). ARCTAS includes studies for the California Air Resources Board (CARB) as part of a scientific collaborative effort. ARCTAS and CARB mission data analysis will contribute to several objectives, including: 1) large-scale characterization of the spatiotemporal distributions of atmospheric CO2 needed to resolve seasonal and annual CO2 budget, 2) quantifying North American CO2 source/sinks and contributions from Asian emissions 3) evaluating inverse techniques that assimilate surface observations to derive regional to continental scale CO2 flux estimates 4) providing integrated measures of atmospheric column amounts from vertical soundings for retrieval algorithm development and validation of remotely-sensed data products, 5) offering an independent assessment of anthropogenic emission inventories (bottom-up approaches), and 6) quantifying and trace the pollution source with carbon isotopes (C-13 and C-14).

Validation for newly evolving remote CO2 sensors: The ACCLAIM (Advance Carbon and Climate Laser Intercontinental Mission) and ASCENDS (Active Sensing of CO2 Emissions over Nights, Days, and Seasons) field missions have been performed to investigate the feasibility of measuring total column CO2 from space with NASA LaRC in-situ CO2 measurement team in partnership with ITT. A series of field experiments with NASA Langley, Goddard, and JPL teams have been conducted to validate the performance of a laser instrument with the in-situ CO2 instrument. The newly developed fast and high precision in-situ CO2 measurement systems have been integrated at NASA UC-12B, NASA DC-8, and Learjet aircraft, and have been flying successfully for ASCENDS CAL/VAL field missions.

Recent Publications

S. Vay, Y. Choi, K. P. Vadrevu, et al., Patterns of CO₂ and radiocarbon across high northern latitudes during International Polar Year 2008, J. Geophys. Res., 116, D14301, 2011, doi:10.1029/2011JD015643

J. Simpson, S. K, Akagi, S. Vay, Y. Choi, et al., Boreal forest fire emissions in fresh Canadian smoke plumes: C₁-C₁₀ volatile organic compounds (VOCs), CO₂, CO, NO₂, NO, HCN, and CH₃CN, Atmos. Chem. Phys., 2011, 11, 6445-6463, doi:10.5194/acp-11-6445-2011.

G. D. Spiers, R. T. Menzies, Y. Choi, E. V. Browell, et al., Atmospheric CO₂ Measurements with a 2-micrometer airborne laser absorption spectrometer employing coherent detection, Applied Optics, 2011, Vol. 50, No. 14, Applied Optics, 2098-2111.

K. P. Vadrevu and Y. Choi, Wavelet analysis of airborne CO₂ measurements and related meteorological parameters over heterogeneous landscapes, Atmos. Res., 2011, 102, 77-90, doi:10.1016/j.atmosres.2011.06.008.

T. Refaat, S. Ismail, G. Koch, Y. Choi, et al., Backscatter 2mm Lidar Validation for Atmospheric CO₂ DIAL Applications, IEEE Transactions on Geoscience and Remote Sensing, 2011, Vol. 49, No. 1, 572- 580.

J. Abshire, H. Riris, E. Browell, Y. Choi and many others, A lidar approach to measure CO₂ concentrations from space for the ASCENDS Mission, Proc. SPIE, Vol 7832, 78320D, doi:10.1117/12.868567, 2010.

S. Vay, S. Tyler, Y. Choi, et al., 2009, Sources and transport of ¹⁴C on CO₂ within the Mexico City Basin and vicinity, Atmos. Chem. Phys., 9, 4973-4985.

Yonghoon Choi, Stephanie Vay, and many others, 2008, Characteristics of the atmospheric CO₂ signal as observed over the conterminous United States during INTEX-NA, Journal of Geophysical Research – Atmospheres, Vol. 113, D07301, doi:10.1029/2007JD008899

E. Browell, M. Dobbs, J. Dobler, S. Kooi, Y. Choi, et al., 2008, Airborne demonstration of 1.57 micron laser absorption spectrometer for atmospheric CO2 measurements, Proc. 24^th International Laser Radar Conf. I, 697-700.

J. E. Campbell, S. A. Vay, Y. Choi, and many others, 2007, Analysis of anthropogenic CO₂ singal in ICARTT using a regional chemical transport model and observed tracers, Tellus, 59B, doi:10.1111/j.1600—889.2006.00239.x

Yonghoon Choi and Yang Wang, 2004, Dynamics of carbon sequestration in a Coastal wetland using radiocarbon measurements, Global Biogeochemical Cycles, 18, GB4016, doi:10.1029/2004GB002261

Y. Wang, Y. P. Hseih, W.M. Landing, Y. H. Choi, V. Salters and D. Campbell, 2002, Chemical and carbon isotopic evidence for the source and fate of dissolved organic matter in the Florida Everglades, Biogeochemistry, Vol 61, pages 269-289

Y. Choi, et. al., 2001, Vegetation Succession and carbon sequestration in a coastal wetland in northwest florida : Evidence from carbon isotopes, Global Biogeochemical Cycles, Vol 15, No 2, pages 311-319