Spatiotemporal Variation and its Attribution of Observed Surface Sensible Heat Flux in Mainland China over the Last 60 Years

Abstract Surface sensible heat fluxes (SHFs) influence atmosphere–land energy, thermal transport, and multiscale atmospheric circulation within the boundary layer. However, few studies have systematically estimated the spatiotemporal variability of SHF and its attribution on large scales, among which the precise estimation of the bulk heat transfer coefficients is challenging. Here, we quantify SHF changes and disclose the impacts of driving forces over mainland China from 1960 to 2019, combining 2454 meteorological observation stations and six global atmospheric reanalysis products. Based on the observed and reanalysis datasets, we first initiate one set of monthly ensembled bulk heat transfer coefficients C h for each station in mainland China. The SHF intensity shows remarkable spatial heterogeneity and temporal fluctuation at a 20-yr scale nationally: relatively slightly decrease (−2.15 W m −2 decade −1 , 1960–79), decrease (−4.59 W m −2 decade −1 , 1980–99), and increase (4.05 W m −2 decade −1 , 2000–19). The large-scale surface SHF variations exhibit dramatic interdecadal variability primarily due to confounding effects associated with hydrometeorological (i.e., ground–air temperature difference, wind velocity, air density, soil moisture, precipitation, and potential evapotranspiration) and external environmental factors (i.e., elevation, vegetation, climate zone, and urbanization). The applicability assessment further highlights large deviations in global atmospheric reanalysis SHFs (compared to station estimates) at the regional scale over mainland China. This comprehensive study will provide new insights for future large-scale SHF estimation initiatives and the exploration of spatiotemporal patterns of global SHF variation and their attributions. Significance Statement This study aims to comprehensively elucidate the spatiotemporal patterns of SHF and their drivers over decades in mainland China. We design a new scheme to estimate the bulk heat transfer coefficient in calculating SHF at 2454 stations in China using meteorological observation stations and atmospheric reanalysis products. The temporal variations of SHF are dramatic at the national scale from 1960 to 2019 and are closely linked to changes in forcing factors such as ground–air temperature differences, precipitation, wind velocity, air density, and soil moisture. In addition, diversified environmental conditions disrupt SHF patterns, including altitude, vegetation, climate zone, and urbanization rate. In particular, the applicability assessment reveals that SHF derived from several atmospheric reanalysis products is highly biased over large regions. These results will improve our understanding of the spatiotemporal patterns of large-scale SHF and the applicability of reanalysis products in mainland China.