Role of land surface processes associated with interannual variability of broad-scale Asian summer monsoon as simulated by the CCSR/NIES AGCM.

摘要: The interannual variability of the South Asian summer monsoon and associated land-surface processes over Eurasian continent in a ten-year integration (1979-88) an atmospheric general circulation model (AGCM) forced by observed sea surface temperatures (SSTs) is examined. AGCM has been developed jointly Center for Climate System Research (CCSR), University Tokyo, National Institute Environmental Studies (NIES). A intensity index, based on magnitude summer-mean vertical shear zonal wind south region, used to classify weak strong years. It found that simulated broad-scale shows good correlation with observations. Furthermore, distinct precursory signals, including snow winter soil moisture anomalies spring, have pre-monsoon seasons There sharp contrast between years; excessive Eurasia 50°N increased spring are prior monsoon. These results consistent evidence observational data analyses some experiments. detailed analysis heat budget snow-albedo feedback dominates Tibetan Plateau. On other hand, its west central Asia, relatively lower land, effective cloud albedo due rainfall evaporation influence conditions. numerical experiment land initial conditions interchanged years, indicates positive roles played influencing subsequent circulations during 10-year period. However, such feedbacks not enough change sign anomalies. direct El Nino/Southern Oscillation through changes Walker appears predominate.