# Comparison of Methods for Reconstructing MODIS Land Surface Temperature under Cloudy Conditions
## 3 Results
### Analysis of LST Variation Characteristics Based on Soil Moisture  
Among the many factors affecting surface temperature, soil moisture is an important factor, especially in arid areas. Both agricultural activities and geological surveys depend significantly on the moisture content of soil [37]. [PERSON] et al. [38] believed that there was a certain spatial correlation between soil moisture (SM) and land surface temperature. It is generally believed that SM has a positive relationship with thermal inertia at the surface. As a result, a drop in SM causes a decrease in thermal inertia and an increase in the diurnal range of LST. However, the actual changes need to be analyzed according to the specific environment. To analyze the influence of soil moisture on LST, we selected the data of 2 cm soil moisture, because the soil moisture in this layer is closer to the surface moisture, and is therefore more useful for analyzing the impact of soil moisture on LST. We selected three sites (Arou, Daman, and Huazhaizi) representing different underlying surfaces (alpine meadow, cropland, and bare land) to analyze the impact of soil moisture on LST. Figure 9 presents a comparison of SM with LST reconstructed by classification and adaptive window.  
The underlying surface of the Arou Site is grassland, and the surface type is relatively uniform, so the inter-annual change in soil moisture is also relatively uniform. During spring, with the increase in LST, the melting of frozen soil in winter is an important reason for the increase in SM. Summer is a hot and rainy season, but on days of high temperature with no rain, SM will decrease. With the arrival of autumn and winter, the precipitation will decrease, LST will gradually decrease, and SM will also decrease. The change in SM throughout the whole area mainly depends on the freeze-thaw cycle of water and rainfall. The underlying surface of the Daman Site is cropland. In around March, SM will usher in a  
Figure 8: Spatial distribution of the reconstructed LST based on temporal, spatial, and spatiotemporal methods from 2016 to 2019.  
peak, which is mainly due to irrigation for the upcoming sowing season. With the arrival of the summer rainy season, the LST reaches its maximum value in the year. When crops are harvested in autumn, the underlying surface of the ground gradually changes from crops to bare soil. On the soil surface without vegetation cover, soil moisture will accelerate the loss. SM decreases and LST decreases. However, in 2018, SM was significantly different from in other years, remaining at a low value for the whole year. This may be due to the heterogeneity of the irrigation area and the change in planting density. The change in SM throughout the whole area is mainly dependent on irrigation and rainfall. The underlying surface of the Huazhaizi Site is bare land, so the evaporation is at a high level and SM is at a low level throughout the year compared with the other two sites. However, SM will still reach its maximum in the rainy season. The change in SM throughout the whole region is mainly dependent on evaporation and precipitation.