Possible Linkage Between Spring Surface Sensible Heat Flux Anomalies Over The Mid-Hgh Latitudes Of The Eurasian Continent And Summer Climate In The Middle-Lower Reaches Of The Yangtze River

In the summer, the middle-lower reaches of the Yangtze River(MLRYR) were often threatened by the sustainable heat wave and droughts and floods, which had caused tremendous impacts on people’s lives and properties, and the social developments. To explore the potential linkage between spring surface sensible heat flux anomalies over the mid-high latitudes of the Eurasian continent (MHLEC) and summer climate in MLRYR, therefore, was very vital and meaningful for improving the accuracies of the summer weather prediction. Herein, the daily precipitation and temperature observed at753stations provided by the National Climate Data Center of China, the monthly surface sensible heat flux from (ERA-40)and ERA-interim and the monthly NCEP/NCAR reanalysis data as well as the NSIDC snow water equivalent data were collected for exploring:(1) characteristics of the spring surface sensible heat flux anomalies in MHLEC;(2) possible linkage between the spring surface sensible heat flux anomalies and the summer climate in MLRYR, and even their potential physical mechanism and (3) relationship between the spring surface sensible heat flux in MHLCE and the corresponding snow anomalies. Conclusions can be summarized as below:1) During the past50years, the spring surface sensible heat flux in MHLEC fluctuated obviously at interannual and decadal scales, with the opposite spatial patterns in the west and the east regions. For instance, it habited that spring surface sensible heat flux decreased in the mid-1970s, increased during the end of1970s and the beginning of2000s, and then decreased after2000s.2) A closer linkage existed between the spring surface sensible heat flux anomalies over MHLEC and the summer climate in MLRYR. Moreover, the spring surface sensible heat flux anomalies over MHLEC positively and negatively related to the summer precipitation and temperature, respectively, with the given significant level. Strong (weak) spring surface sensible heating over MHLEC usually resulted in more (less) precipitation and cooling (warming) in summer of MLRYR. Notably, the decadal anomalies of the spring surface sensible heat flux anomalies over MHLEC also related to similar to those of summer precipitation in MLRYR to some extent.3) The potential mechanism of the influences of the spring surface sensible heat flux anomalies over MHLEC in the summer climate of MLRYR were controlled by the significant changes in the general circulation due to the anomalous surface sensible heat. For example, given the weaker sensible heat over MHLEC, the subtropical westerly jet of the East Asia would be weaken followed by the subtropical high to east with the lower magnitude, leading to be more difficult for raining due to the anticyclone and to be warmer. By contrast, if the sensible heat over MHLEC was stronger, the subtropical westerly jet of the East Asia would be enhanced followed by the subtropical high to east with the higher magnitude, leading to be easier for raining due to the anticyclone and to be cooler.4) To some extent, there were some decadal fluctuations of the spring snow over MHLEC in the past30years. Less (more) spring snowmelt as well as more (less) snow over MHLEC usually accompanied with the stronger (weaker) spring surface sensible heating. So, the anomalous spring sensible surface heat might be induced by the MHLEC snowmelt.