Net Primary Productivity (NPP) is not only the main parameter for estimating carbon sequestration and oxygen release in ecosystems and measuring terrestrial carbon cycle, but also the main index for evaluating ecosystem health. In view of the limited application of domestic satellites in remote sensing monitoring of grassland NPP, a set of NPP inversion model of grassland NPP in Inner Mongolia was constructed based on FY-3D/MERSI2 data. The NPP of grassland under clear sky condition in Inner Mongolia was obtained by using a strict cloud detection algorithm, which was driven by remote sensing data products and CLDAS meteorological assimilation data, combined with light energy utilization model and ecological process model. In this study, lattice meteorological data with high resolution are introduced, which greatly improves the precision of inversion results. At the same time, based on the observation data and MODIS products, multiple relationship models of above-ground biomass, the Fraction Photosynthetic Active Radiation Absorption Ratio (FPAR) and Normalized Difference Vegetation Index (NDVI) in different months (from May to August) of grassland growth period in Inner Mongolia were constructed, and process parameters such as Leaf Area Index (LAI) and FPAR could be directly estimated based on FY-3D data. By comparing several key ecological process parameters with MODIS products, it is found that they have good correlation and spatial consistency. Finally, the grass observation data of 18 ecological meteorological observation stations in June 2021 were compared with the estimated results, showing that there was a good consistency between them, with a correlation coefficient of 0.86. The NPP inversion using FY-3D/MERSI2 can fully present the general state of vegetation productivity in Inner Mongolia.

Based on the monthly soil moisture of GLDAS Noah 2.0 from 1950 to 2009, the temporal and spatial variation characteristics of soil moisture at each layer of the Tibetan Plateau in summer were analyzed. The results are as follows: (1) In summer, the soil moisture at each layer of the Tibetan Plateau decreased gradually from south to north, and there was an extreme value center at the middle and deep layers in the central of the Tibetan Plateau, respectively. (2) The difference of soil moistures between the surface, shallow, middle and deep layers (except for the deep and middle layers) in summer appeared a vertical distribution of ‘wet upper and dry lower’ in the mid-eastern part of the Plateau, while that showed a vertical distribution of ‘wet lower and dry upper’ in the mid-western part. (3) The first mode of soil moisture at different layers of the Plateau in summer appeared a reverse distribution from southwest to northeast, and the zero line moved to northeast with the increase of soil depth. (4) The annual variation characteristics of soil moisture at different layers of the main part of the Plateau were obvious in summer during 1950-2009. The soil moisture except for the deep layer had significant downward trend as a whole, and it was higher in the early stage and lower in the later stage from 1950 to 2009, while for the deep layer it appeared non-significant increasing trend. Spatially, the decreasing trend of soil moisture at different layers except for deep layer of the Plateau dominated during 1950-2009, while the soil moisture at deep layer of the central part of the Plateau tended to increase. (5) After removing trend, the maximum variation range of annual average soil moisture at each layer except for the deep layer decreased with the increase of soil depth in the central part of the Plateau, while it increased with the increase of soil depth in the central and eastern part of the Plateau.