Conference Proceedings Paper Atmospheric Methane over Arctic Ocean Observed from Thermal IR Sounders AIRS and IASI. Leonid Yurganov 1, *, Ira Leifer 2 , Thomas McClimans 3 , and Frank Muller-Karger 4 1 University of Maryland Baltimore County (ret), Baltimore, MD, USA; leonid.yurganov@gmail.com 2 Bubbleology Research International, Inc., Solvang, CA, USA; Ira.Leifer@bubbleology.com 3 SINTEF Ocean, Trondheim, Norway; mccliman@online.no 4 University of Southern Florida, St. Petersburg, FL, USA; carib@usf.edu * Correspondence: leonid.yurganov@gmail.com; Tel.: +1-443-315-1344 Published: date Academic Editor: name Abstract: Seven operational Thermal Infrared (TIR) spectrometers launched at sun-synchronous polar orbits supply huge amounts of information about Arctic methane (CH 4 ) year-round, day and night. The TIR data are unique for estimating CH 4 emissions in a warming Arctic, both terrestrial and marine. This report is based on publicly available CH 4 concentrations retrieved by NOAA and NASA from spectra of TIR radiation delivered by EU IASI and US AIRS sounders. Data with low thermal contrast were discarded. Validation versus aircraft measurements at three US continental sites reveal a reduced, but still signifcant sensitivity to CH 4 anomalies in the lower troposphere. The focus area is the Barents and Kara Seas (BKS). BKS is impacted with warm Atlantic water and mostly free of sea ice. It is a shelf area with deposits of oil and natural gas (~90% CH4), as well as submarine permafrost and methane hydrates. Although AIRS and IASI observe no signifcant diference in CH 4 between summer BKS and N. Atlantic, a strong, monthly positive CH 4 anomaly of up to 30 ppb occurs during late autumn-winter. We suggest that this diference is explained by stable summer thermal stratifcation and its fall/winter breakdown that enhances BKS emissions due to deeper winter mixing. Keywords: Satellite Data; Greenhouse Gases; Arctic. 1. Introduction The Arctic has experienced the fastest warming on Earth over recent decades, termed Arctic amplifcation with the Arctic Ocean warming at nearly double the rate of the world’s oceans [1]. Due to Arctic amplifcation, there is concern about the vast stores of the important GHG methane (CH4), in hydrates, permafrost, and other reservoirs. The radiative impact of CH 4 is second after carbon dioxide The 3nd International Electronic Conference on Remote Sensing (ECRS 2018), 22 May–5 June 2019; Sciforum Electronic Conference Series, Vol. 2, 2019