Features of atmospheric circulation and thermal structures are discussed using the NCAR/NCEP data to reveal the reasons for the late onset and anomalous southward persistence of the South China Sea Summer Monsoon(SCSS...Features of atmospheric circulation and thermal structures are discussed using the NCAR/NCEP data to reveal the reasons for the late onset and anomalous southward persistence of the South China Sea Summer Monsoon(SCSSM) in 2005.The results show that three factors are crucial.First,a strong Arabian High overlaps with a high-latitude blocking high and channels strong cold air to southern Asia.Second,the Tibetan Plateau has a bigger snow cover than usual in spring and the melting of snow cools down the surface.Third,the Somali Jet breaks out at a much later date,being not conducive to convection over Indochina.The former two factors restrict atmospheric sensible heating over the Tibetan Plateau and nearby regions while the third one limits latent heating over Indochina.All of the factors slow down atmospheric warming and postpone the onset of SCSSM.Long after the onset of SCSSM,strong cold air over India advances the Southwest Monsoon northward slowly,resulting in weaker convection and latent heating over the Tibetan Plateau and nearby areas.The negative feedback conversely inhibits further northward movement of Southwest Monsoon.展开更多
基金National Key Fundamental Research Development Project (2004CB418302)
文摘Features of atmospheric circulation and thermal structures are discussed using the NCAR/NCEP data to reveal the reasons for the late onset and anomalous southward persistence of the South China Sea Summer Monsoon(SCSSM) in 2005.The results show that three factors are crucial.First,a strong Arabian High overlaps with a high-latitude blocking high and channels strong cold air to southern Asia.Second,the Tibetan Plateau has a bigger snow cover than usual in spring and the melting of snow cools down the surface.Third,the Somali Jet breaks out at a much later date,being not conducive to convection over Indochina.The former two factors restrict atmospheric sensible heating over the Tibetan Plateau and nearby regions while the third one limits latent heating over Indochina.All of the factors slow down atmospheric warming and postpone the onset of SCSSM.Long after the onset of SCSSM,strong cold air over India advances the Southwest Monsoon northward slowly,resulting in weaker convection and latent heating over the Tibetan Plateau and nearby areas.The negative feedback conversely inhibits further northward movement of Southwest Monsoon.
