Variability of Surface Sensible Heat Flux over Northwest China

The present study documents the variability of surface sensible heat flux over Northwest China using station observations for the period 1961-2000. It is found that the afternoon and nighttime sensible heat flux variations are remarkably different. The variability of the instant flux in the afternoon is much larger than in the nighttime. The afternoon and nighttime flux anomalies tend to be opposite. The diurnal and seasonal dependence of sensible heat flux variations is closely related to the diurnal cycle of mean land-air temperature difference. The relationship of sensible heat flux with land-air temperature difference based on the instant value differs from that based on the daily mean. The present study indicates the importance for the models to properly simulate mean land-air temperature difference and its diurnal and seasonal variations in order to capture surface sensible heat flux variability over Northwest China and predicts its plausible impacts on climate.