Impact of Sensible Heat Flux Anomaly over Qinghai-Tibet Plateau on Low Cloud Amount over the Subtropical Northeastern Pacific
[Objective]To investigate the influence of Qinghai-Tibet Plateau(QTP)sensible heat flux anomaly on the low cloud amount over the Subtropical Northeastern Pacific(SNEP)in spring.[Method]Based on satellite observations and reanalysis data,linear regression,correlation analysis,composite analysis and numerical model simulation were used to analyze the relationship between QTP sensible heat flux and SNEP low cloud amount.[Result and Conclusion](1)The variance of leading mode of singular value decomposition between the QTP sensible heat flux and SNEP low cloud amount is 33.76%,and the correlation coefficient between the two time series is 0.84.(2)Strengthened surface sensible heat in spring can generate a barotropic wave train from QTP to the SNEP,presenting an atmospheric circulation anomalies like"+-+-+".The anomalous anticyclonic circulation on the SNEP intensifies the subtropical high in the North Pacific and then shift northeastward.Meanwhile,the anomalous barotropic anticyclone strengthens the downward motion and low level inversion strength,reducing low cloud height.(3)The increased northeasterly winds on the southeast flank of the anticyclone intensifies the prevailing northeasterly,leading to an increase in surface sensible heat,a reduction in the atmospheric stability at air-sea interface,and an enhancement of turbulent mixing.As a result,increased water vapor supply facilitates low cloud formation.(4)The composite analysis reveals an asymmetric response between anomalous strong and weak years.This study discusses the physical relationship between QTP sensible heat flux anomaly and SNEP low cloud changes,which could be a potential reference for the low cloud prediction over the SNEP.