Distribution and Variation of the Surface Sensible Heat Flux Over the Central and Eastern Tibetan Plateau: Comparison of Station Observations and Multireanalysis Products

Surface sensible heat fluxes (SH) over Tibetan Plateau (TP) dictate the seasonal conversion, onset and maintenance of the Asian monsoon. Spatiotemproal variability in SH over central and eastern TP (CETP) from reanalysis products (i.e., JRA55, ERA-Interim, NCEP1, and NCEP2) and derived using bulk transfer approximations applied to observations is characterized for all seasons during 1980-2015 and is diagnosed in the context of two important drivers of variability: wind speed and land-air temperature difference (Tg-Ta). In the climatological mean, SH from observations increases from east to west and exhibits obvious seasonality with highest value in spring and lowest in winter. Declines in SH prior to 2000 as manifest in the observations appears to have resulted from changes in wind speeds, and the subsequent recovery is attributable to increases in both wind speeds and air-surface temperature gradients. The intercomparison shows that ERA-Interim exhibits greatest accord with observations in terms of the climatological distribution and seasonality, and all reanalyses exhibit some aspects of the temporal variability and long-term trends as manifest in the observations. However, the root causes of the long-term variability in SH as manifest in the reanalysis products are not consistent with inferences derived from the observations.