第4回極域科学シンポジウム横断セッション：[IA] 「急変する北極気候システム及びその全球的な影響の総合的解明」―GRENE北極気候変動研究事業研究成果報告2013―11月12日（火） 国立極地研究所 ２階大会議

原 政之

徐健青

野沢 徹

高田 久美子

National Institute of Polar Research Repository

  高緯度陸上の広域地表面熱水収支の長期変動特性～気候湿潤度による解析～   高田久美子 1,2,3、徐健青 3、原政之 3、野沢徹 4 1国立極地研究所、2国立環境研究所、3海洋研究開発機構、4岡山大学  Long-term variations of the large-scale energy-water balance on land at high latitudes  - Analysis using a wetness index -  Kumiko Takata1,2,3, Jianqing Xu3, Masayuki Hara3 and Toru Nozawa4 1National Institute of Polar Research 2Natinal Institute for Environmental Research 3Japan Agency for Marine-Earth Science and Technology 4Okayama University  Long-term variations of the large-scale energy-water balance on land were examined using a wetness index (WI) calculated as a ratio of precipitation to potential evaporation (Kondo and Xu, 1997; Xu et al., 2005). Potential evaporation (Ep) was calculated from the energy balance equation at the surface, using the latest ECMWF global atmospheric reanalysis data (ERA interim) from 1979 to 2010; and the global precipitation analysis product of GPCC was used for precipitation (Pr).  The trends during the period were analyzed in each terrestrial region (after Sheffield and Wood, 2007). An attempt to quantify the contribution of the factors to those trends was made. There are increasing trends in Ep and Pr for most of the regions in northern high latitudes. In particular, the increasing trend in Ep and Pr for eastern Siberia is significant (i.e., larger than RMSE), and the both offset each other to show no trend in WI.  On the other hand, the increasing trend in Ep and the decreasing trend in Pr seemed to bring about the decreasing trend in WI, though each trend was similar to its RMSE respectively.  The increasing trends in Ep were also shown in many regions in the northern mid-latitudes (six regions out of eight). There were decreasing trend in WI for monsoon Asia and Central Asia, where there were almost no trend in Pr. Wet and dry conditions on land have been discussed mostly on the basis of precipitation, but it is shown that the contribution of Ep is significant in some regions (e.g., monsoon Asia) or the changes in Ep offset the changes in Pr in other regions (e.g., eastern Siberia, western Siberia, northern Europe).   Acknowledgements This study is partly supported by the GRENE project for Arctic Climate Change..   References Kondo, J. and J. Xu, Potential evaporation and climatological wetness index. Tenki, 44(12), 875-883, 1997. Xu, J., S. Haginoya, K. Saito, and K. Motoya: Surface heat balance and pan evaporation trends in Eastern Asia in the period 1971-2000. Hydrological Processes, vol. 19, 2161-2186, DOI:10.1002/hyp.5668, 2005.  Sheffield, J. and E.F. Wood, Characteristics of global and regional drought, 1950–2000: Analysis of soil moisture data from off-line simulation of the terrestrial hydrologic cycle. J. Geophys. Res. (Atmos.), 112, D17115, doi:10.1029/2006JD008288, 2007.  

Long-term variations of the large-scale energy-water balance on land at high latitudes - Analysis using a wetness index -

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Long-term variations of the large-scale energy-water balance on land at high latitudes - Analysis using a wetness index -

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