Assess Surface Energy Balance at ten Sites over the Tibetan Plateau and implication for LSMs modeler

Using the observed surface heat fluxes to evaluate land-surface model (LSMs) is a common step to improving LSMs, but there are significant uncertainties in the measured surface energy budgets, especially for the Tibetan Plateau (TP) region where the observation conditions are harsh. In this study, summer (from July 2013 to October 2016) observations obtained from ten sites over the TP during the 3rd TP Experiment (TIPEX III) were used to access the surface energy balance ratio (SEBR) and associated uncertainties. The ten-site averaged SEBR is 75.1±5.4%, largely on par with reported SERB for other regions. The soil heat storage term represents a more significant source of uncertainty (12.7%) than the canopy storage term (0.2%) for the energy closure. The SEBR shows a strong diurnal cycle and their midday (10:00 15:00 local time) values are higher than their values around the sunrise and sunset time. The late-night SEBR (00:00 6:00 local time) at sites located at higher elevations are more reliable than that at lower elevation sites, because of the stronger outgoing long wave radiation in the former. In general, SEBR improves with increasing near-surface layer instability, but the maximum SEBR for meadow sites correspond to u*=0.25 m s-1. Measured latent heat fluxes have more substantial uncertainties than sensible heat fluxes. Considering all uncertainty sources, we derive an uncertainty range for measured surface heat fluxes, which provides a useful guidance for applying these observations to evaluate LSMs.