Estimating Surface Heat Source in the Tibetan Plateau With the Maximum Entropy Production Model

It is of practical significance to develop a dataset of the Tibetan Plateau (TP) surface heat sources (including surface sensible heat flux (SH) and latent heat flux (LE) with long coverage time and high accuracy, which can meet the time requirement of climate monitoring and prediction. Among various atmospheric reanalysis data, NCEP-II atmospheric reanalysis data can meet the operational time of climate monitoring and prediction, but its SH and LE calculated based on the classic Monin-Obukhov similarity theory have large errors. Previous studies have developed the SH and LE datasets over the TP using the newly proposed Maximum Entropy Production (MEP) model and the multi-source datasets including satellite remote sensing data and atmospheric reanalysis data. However, these SH and LE datasets are short in time and can not meet the timeliness requirements. In this paper, using the MEP model and the daily average net radiation, surface temperature, and soil moisture data of the NCEP-II atmospheric reanalysis dataset which can meet the timeliness of climate monitoring and prediction operations, we establish SH and LE in the TP area from 1980 to 2023. We verify the reliability of the new dataset by using the TP intensive observation data and analyze the temporal and spatial variation characteristics of the new dataset. The evaluation shows that the correlation coefficients between the monthly mean MEP SH (SHMEP) and LE (LEMEP) and the observations are 0.93 and 0.82, respectively, and the root mean square errors are 11.91 W/m2 and 13.80 W/m2, respectively, which are better than those of the SH and LE of the ERA5, ERA-Interim, MERRA-2, JRA-55, and NCEP-II atmospheric reanalysis data, especially better than the accuracy of the NCEP-II reanalysis, and can meet the timeliness and quality needs of climate monitoring and prediction operations. For the period 1980-2023, summer SHMEP exhibits a significant downward trend, with a linear trend of -0.48 W m–2 10a-1, while LEMEP shows unsignificant upward trend.