This paper was presented at the Art, Science and Applications of Reflectance Spectroscopy Symposium sponsored by ASD Inc. and IEEE GRSS, February 23-25, 2010 in Boulder, Colorado.

Authors: Dar Roberts¹, Eliza S. Bradley¹, Phillip E. Dennison², Ira Leifer³, Andrew Thorpe¹
Affiliations:
(1) Department of Geography, University of California, Santa Barbara, CA  USA
(2) Department of Geography, University of Utah, Salt Lake City, UT  USA
(3) Marine Science Institute, University of California, Santa Barbara, CA  USA

Abstract

Imaging spectrometers have a well established capability to map atmospheric trace gases. Examples include water vapor, carbon dioxide, and most recently methane. In this talk, I present research demonstrating the ability of AVIRIS to map methane over strong marine sources. Methane is an extremely important green house gas that has increased significantly in pre and post-industrial times. Due to strong absorptions in the Short Wave Infrared, the potential exists to use imaging spectrometers, such as the Airborne Visible Infrared Imaging Spectrometer (AVIRIS), to map methane emissions from strong sources. The study was conducted at Coal Oil Point, California one of the strongest marine sources globally. I present a radiative transfer inversion approach, in which surface albedo, estimated at 2139 nm, is used to estimate albedo-specific radiance for background methane, calculate a spectral residual between modeled background radiance and measured radiance, and develop an index, C, which increases in response to methane. This approach is applied to two AVIRIS data sets, one from August 2007, the other collected under different illumination and meteorological conditions in June 2008, and the results are compared. Methane estimates are evaluated using a suite of surface observations. I conclude the talk with a brief discussion of current and planned activities, including analysis of AVIRIS data acquired over urban targets, feedlots, and rice paddies.