Evolution law of atmospheric boundary layer in Gurbantünggüt Desert based on reanalysis dataset and in situ observation data.

As a special geographical unit on the earth, deserts have certain differences in planetary boundary layer (PBL) characteristics from other surface types. In order to find out the long-term evolution law of the Gurbantünggüt Desert, on the basis of evaluating the availability of reanalysis data, using the most effective reanalysis data and situ measured data in this area, the evolution law of the atmospheric boundary layer in the desert area was studied. The results show that among the ERA5, MERRA2, JRA-55 and NCEP-FNL reanalysis data, the ERA5 data has the smallest error with the measured data in the comparison of ground elements or high-altitude meteorology parameters, and can be used for the long-term evolution of the atmospheric boundary layer in desert areas. Based on the ERA5 dataset, the annual planetary boundary layer height (PBLH) of the desert fluctuated between 1979 and 1985, but showed a downward trend overall. From 1986 to 2019, the PBLH generally shows an upward trend, and by 2020, the PBLH decreases again. The PBLH in the summer of the desert was contrary to the inter-annual change trend of the PBLH throughout the year. The spatial distribution shows that the PBLH has the characteristics of north-south anisotropy. The characteristics of the ABL in the Gurbantünggüt Desert in different thermal states in summer vary greatly. Based on the sounding observational data, the average PBLH of the stable boundary layer in the Gurbantünggüt Desert in summer is 496 m, the average PBLH of the convective boundary layer is 1693 m, and the average PBLH of the neutral boundary layer is 1208 m. The ABL in desert areas from 02:00 to 08:00 and 23:00 is dominated by stable boundary layers, of which the proportion of stable boundary layers at 05:00 is as high as 67%. During the day, the boundary layer from 14:00 to 17:00 is mainly the convective boundary layer, accounting for more than 50%, and the boundary layer at 20:00 is mainly a neutral boundary layer, accounting for 55%.