Bias Correction of the Ratio of Total Column CH4 to CO2 Retrieved from GOSAT Spectra

Remote Sensing

Laura T. Iraci¹  Haruki Oshio²  Hirofumi Ohyama²  Yukio Yoshida²  Tsuneo Matsunaga²  Isamu Morino²  David W.T. Griffith³  Nicholas M. Deutscher³  Voltaire A. Velazco³  Young-Suk Oh⁴  Debra Wunch⁵  Coleen Roehl⁶  Justus Notholt⁷  Thorsten Warneke⁷  Christof Petri⁷  Frank Hase⁸  Ralf Sussmann⁹  Kei Shiomi^1,10  Cheng Liu^1,11  Yao Té^1,12  Manvendra Dubey^1,13  David F. Pollard^1,14  Rigel Kivi^1,15 

[1] Atmospheric Science Branch, NASA Ames Research Center, Moffett Field, CA 94035, USA;Center for Global Environmental Research, National Institute for Environmental Studies, Tsukuba, Ibaraki 305-8506, Japan;Centre for Atmospheric Chemistry, School of Earth, Atmospheric and Life Sciences, Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, NSW 2522, Australia;Climate Research Division, National Institute of Meteorological Sciences, Seogwipo, Jeju-do 63568, Korea;Department of Physics, University of Toronto, Toronto, ON M5S 1A7, Canada;Division of Geology and Planetary Science, California Institute of Technology, Pasadena, CA 91125, USA;Institute of Environmental Physics, University of Bremen, 28359 Bremen, Germany;Institute of Meteorology and Climate Research IMK-ASF, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany;Institute of Meteorology and Climate Research – Atmospheric Environmental Research (IMK-IFU), Karlsruhe Institute of Technology, 82467 Garmisch-Partenkirchen, Germany;Japan Aerospace Exploration Agency (JAXA), Tsukuba, Ibaraki 305-8505, Japan;Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China;Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères (LERMA-IPSL), Sorbonne Université, CNRS, Observatoire de Paris, PSL Université, 75005 Paris, France;Los Alamos National Laboratory, Los Alamos, NM 87545, USA;National Institute of Water and Atmospheric Research, Lauder, Omakau 9352, New Zealand;Space and Earth Observation Centre, Finnish Meteorological Institute, 99600 Sodankylä, Finland;

关键词: methane;    proxy method;    GOSAT;    TCCON;   

DOI  :  10.3390/rs12193155

来源: DOAJ

【 摘 要 】

The proxy method, using the ratio of total column CH₄ to CO₂ to reduce the effects of common biases, has been used to retrieve column-averaged dry-air mole fraction of CH₄ from satellite data. The present study characterizes the remaining scattering effects in the CH₄/CO₂ ratio component of the Greenhouse gases Observing SATellite (GOSAT) retrieval and uses them for bias correction. The variation of bias between the GOSAT and Total Carbon Column Observing Network (TCCON) ratio component with GOSAT data-derived variables was investigated. Then, it was revealed that the variability of the bias could be reduced by using four variables for the bias correction—namely, airmass, 2 μm band radiance normalized with its noise level, the ratio between the partial column-averaged dry-air mole fraction of CH₄ for the lower atmosphere and that for the upper atmosphere, and the difference in surface albedo between the CH₄ and CO₂ bands. The ratio of partial column CH₄ reduced the dependence of bias on the cloud fraction and the difference between hemispheres. In addition to the reduction of bias (from 0.43% to 0%), the precision (standard deviation of the difference between GOSAT and TCCON) was reduced from 0.61% to 0.55% by the correction. The bias and its temporal variation were reduced for each site: the mean and standard deviation of the mean bias for individual seasons were within 0.2% for most of the sites.

【 授权许可】

Unknown