Observation of tropospheric ozone in urban areas using TANSO-FTS on GOSAT

Tropospheric ozone is thirdly important greenhouse gas as well as harmful for human health, agricultural crops and natural vegetation. It also plays an important roll that drives the chemistry in the lower atmosphere. Recently, tropospheric ozone is increased by human activity, particularly in urban areas. For these reasons, monitoring of tropospheric ozone is important. The objective of this study is to retrieve tropospheric ozone by satellite remote sensing. The Greenhouse gases Observing SATellite (GOSAT), which was launched in January 2009, and its main sensor called TANSO-FTS has a spectral band in the thermal infrared (TIR) region whose spectral resolution is 0.2cm^-1 in the range 700-1800cm^-1(5.5-14.3μm) including ozone absorption bands at 9.6μm. The spectral resolution is sufficiently high for retrieving tropospheric ozone as well as IMG, TES and IASI. Furthermore, TANSO-FTS has been operated in a "specific operation mode" to measure carbon dioxide, methane, and tropospheric ozone at 4 × 4 (totally 16) mesh points over the Kanto Plain, the center of which is Tokyo. This specific observation covers about 100 km × 100 km of the plain. In this study, we improved the retrieval algorithm so as that the tropospheric ozone in urban areas, especially Kanto Plain can be retrieved more precisely. Particularly we have improved the procedure to estimate the surface properties such as surface types, surface temperature, and surface emissivity using several databases and libraries. We will discuss the results from comparison between in-situ measurements and retrieved results using our improved method.