Production of a combined land surface data set and its use to assess land‐atmosphere coupling in China

Land-atmosphere interactions play an important role in shaping regional climate and its variability. In land-atmosphere coupling study, a fundamental challenge is data limitation, such as the sparsity of long-term land observations and uncertainty in individual model simulations. This study produces a multisource combined land surface data set using a Bayesian model averaging method, for the assessment of land-atmosphere coupling across China. We employ the newly produced soil moisture and evapotranspiration, together with satellite-derived soil moisture and observation-based evapotranspiration to assess spatiotemporal characteristics of the coupling with observed precipitation and temperature. We also define a coupling index to identify region-specific regimes. The results have shown that strong coupling occurs over northern China, particularly in the transition zone between dry and wet climate. Here summer coupling is dominated by land evaporative water storage. Over the southern humid regions and regions at high altitudes, land-atmosphere coupling in summer is characterized by an energy-limited regime. Estimated coupling strengths vary with season and variable used. Precipitation-related couplings are generally stronger in summer; temperature-related couplings are stronger in summer in dry areas but stronger in winter in humid areas. These findings provide a multisource combined representation and cross validation of spatial and temporal characteristics of land-atmosphere coupling across China. The implications are that northern China is a critical region for climate change/variability impact and adaptation assessment.