The land-atmosphere coupling (LAC) strength can be used to characterize how the land surface influences precipitation, temperature or other atmospheric physical processes, and can be used to identify the hotspot of land-atmosphere interactions, which can deepen the understanding of landatmosphere interaction and climate system. In order to quantify the LAC strength in China, the spatial-temporal distribution characteristics of the LAC index of soil moisturelatent heat flux and latent heat flux-lifting condensation level, the Pearson and Kendall’s Tau correlation of soil moisturetemperature and soil moistureprecipitation were analyzed by using ERA5 reanalysis data. The results are as follows: (1) The latent heat flux increased with soil moisture increasing, providing water vapor for precipitation. The increase in latent heat flux led to the decrease of sensible heat flux, then temperature decreased, which weakened the drive of boundary layer and was not conducive to the uplift and condensation of air mass over arid and semiarid areas of northern China. This region was a hotspot of landatmosphere interaction in China. (2) There were obvious seasonal differences in LAC strength in China. The LAC strength over arid and semiarid regions was stronger in spring and summer, but weaker in autumn and winter. The soil was relatively dry in dry season over southwest China where LAC was significant. For landatmosphere coupling, we should not only consider the division of traditional climate zones, but also ponder the influence of rain belt dynamic changes.

Based on ERA reanalysis data during 1979-2017, the spatial-temporal variation characteristics of surface sensible and latent heat flux in Southwest China were analyzed by using empirical orthogonal function (EOF) and power spectrum methods. The results are as follows: (1) In Southwest China, the sensible heat flux in spring was larger than that in summer, while latent heat flux was larger in summer than in spring. The sensible heat flux in spring and summer began to weaken after 2000, while the latent heat flux in spring and summer had increased significantly since 2000. (2) There were three spatial patterns of sensible heat flux in spring, which were mainly characterized by east-west reverse, region-wide uniform and negative and positive dipole spatial distribution. There were mainly two spatial patterns in summer, which showed the consistency of spatial distribution. The corresponding time coefficients characterized the significant inter-decadal and inter-annual periodic variations of sensible heat fluxes in summer. There were three spatial patterns of latent heat flux in spring, which were mainly characterized by uniform region-wide, reverse east-west and decreasing outward in all directions from the center. There were mainly two spatial patterns of latent heat flux in summer. The first mode characterized the consistency in spatial distribution. The second mode indicated that the flux increased gradually from northwest to southeast in a trapezoidal manner. The change of corresponding time coefficients characterized that latent heat flux in spring and summer had significant inter-annual and inter-decadal variation characteristics. The sensible heat fluxes in spring and summer were characterized by inter-annual variations about 3 years and inter-decadal variations more than 10 years, and inter-decadal variations were stronger than inter-annual variations. The latent heat flux in spring and summer mainly had inter-decadal variations over 10 years in Southwest China.