Development of satellite retrieval algorithm of near surface air specific humidity
using in-situ observations over the Kuroshio Extension region
Hiroyuki Tomita1, Masahisa Kubota2 and Masanori Konda3
1. Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology,
Natsusimacho 2-15, Yokosuka, Kanagawa, JAPAN. tomitah@jamstec.go.jp
2. School of Marine Science and Technology, Tokai University, Orido 3-20-1, Shizuoka, Japan
3. Department of Geophysics, Graduate School of Science, Kyoto University, Kitashirakawa
Oiwake-cho, Kyoto, Japan
Air-sea heat fluxes over the Kuroshio Extension region have crucial role in the
global climate system. Accurate information of air-sea heat flux over the Kuroshio
Extension region, therefore, is indispensable for better under standing of global
climate system. However, most of present satellite air-sea heat flux products have
significant issues. Particularly, inaccurate estimations of near surface (at 10m above
sea surface) air specific humidity causes problematic air-sea latent heat flux
estimation. In order to investigate the cause of errors in several satellite retrieval
algorithms of near surface air specific humidity, recently, we have carried out in-situ
observations by surface moored buoys and research vessels over the Kuroshio
Extension region. Surface moored buoys observe relatively accurate and continuous
time series of air-sea heat fluxes during several years. In order to observe
atmospheric vertical profiles, observations by many radiosondes were conducted by
research vessels. One of the purposes of this study is to compare present satellite
products of near surface air specific humidity with these recent in situ observations.
Second purpose is to develop new satellite retrieval algorithm for better estimation of
air-sea heat flux over the Kuroshio Extension region. As a result, we found
significant differences in error characteristics of satellite near surface air specific
humidity depending on season and atmospheric conditions. Finally, we have
developed new satellite retrieval algorithm of near surface air specific humidity taken
account seasonal differences in error characteristics. The comparison with in situ
observations reveals that newly developed algorithm show better performance
compared with previous algorithms.