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Atmos Chem Phys

Title:		"Observing atmospheric formaldehyde (HCHO) from space: validation and intercomparison of six retrievals from four satellites (OMI, GOME2A, GOME2B, OMPS) with SEAC(4)RS aircraft observations over the Southeast US"
Author(s):		Zhu L; Jacob DJ; Kim PS; Fisher JA; Yu K; Travis KR; Mickley LJ; Yantosca RM; Sulprizio MP; De Smedt I; Abad GG; Chance K; Li C; Ferrare R; Fried A; Hair JW; Hanisco TF; Richter D; Scarino AJ; Walega J; Weibring P; Wolfe GM;
Address:		"John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA. Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA. Centre for Atmospheric Chemistry, School of Chemistry, University of Wollongong, Wollongong, NSW, Australia. School of Earth and Environmental Sciences, University of Wollongong, Wollongong, NSW, Australia. Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA. Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland, USA. NASA Goddard Space Flight Center, Greenbelt, Maryland, USA. NASA Langley Research Center, Hampton, VA 23681, USA. Institute of Arctic and Alpine Research, Univ. of Colorado, Boulder, CO, USA. Science Systems and Applications, Inc., Hampton, VA, USA. Joint Center for Earth Systems Technology, University of Maryland Baltimore County, Baltimore, Maryland, USA"
Journal Title:		Atmos Chem Phys
Year:		2016
Volume:		20161101
Issue:		21
Page Number:		13477 - 13490
DOI:		10.5194/acp-16-13477-2016
ISSN/ISBN:		1680-7316 (Print) 1680-7324 (Electronic) 1680-7316 (Linking)
Abstract:		"Formaldehyde (HCHO) column data from satellites are widely used as a proxy for emissions of volatile organic compounds (VOCs) but validation of the data has been extremely limited. Here we use highly accurate HCHO aircraft observations from the NASA SEAC(4)RS campaign over the Southeast US in August-September 2013 to validate and intercompare six retrievals of HCHO columns from four different satellite instruments (OMI, GOME2A, GOME2B and OMPS) and three different research groups. The GEOS-Chem chemical transport model is used as a common intercomparison platform. All retrievals feature a HCHO maximum over Arkansas and Louisiana, consistent with the aircraft observations and reflecting high emissions of biogenic isoprene. The retrievals are also interconsistent in their spatial variability over the Southeast US (r=0.4-0.8 on a 0.5 degrees x0.5 degrees grid) and in their day-to-day variability (r=0.5-0.8). However, all retrievals are biased low in the mean by 20-51%, which would lead to corresponding bias in estimates of isoprene emissions from the satellite data. The smallest bias is for OMI-BIRA, which has high corrected slant columns relative to the other retrievals and low scattering weights in its air mass factor (AMF) calculation. OMI-BIRA has systematic error in its assumed vertical HCHO shape profiles for the AMF calculation and correcting this would eliminate its bias relative to the SEAC(4)RS data. Our results support the use of satellite HCHO data as a quantitative proxy for isoprene emission after correction of the low mean bias. There is no evident pattern in the bias, suggesting that a uniform correction factor may be applied to the data until better understanding is achieved"
Keywords:
Notes:		"PubMed-not-MEDLINEZhu, Lei Jacob, Daniel J Kim, Patrick S Fisher, Jenny A Yu, Karen Travis, Katherine R Mickley, Loretta J Yantosca, Robert M Sulprizio, Melissa P De Smedt, Isabelle Abad, Gonzalo Gonzalez Chance, Kelly Li, Can Ferrare, Richard Fried, Alan Hair, Johnathan W Hanisco, Thomas F Richter, Dirk Scarino, Amy Jo Walega, James Weibring, Petter Wolfe, Glenn M eng Germany 2016/01/01 Atmos Chem Phys. 2016; 16(21):13477-13490. doi: 10.5194/acp-16-13477-2016. Epub 2016 Nov 1"