# Analyzing the Characteristics of Soil Moisture Using GLDAS Data: A Case Study in Eastern China
## 3 Results and Discussion
### The Relationship between Precipitation, Temperature and Soil Moisture  
Soil moisture is an important meteorological element for keeping the balance of global water and energy. Due to the delayed changes to the characteristics of the soil, it became the hydrologic cycle \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Category** & **Spring** & **Summer** & **Autumn** & **Winter** & **Yearly** \\ \hline
0–10 cm & 1.319 & 1.259 & \(-\)1.418 & 0.624 & \(-\)0.019 \\
10–40 cm & 0.177 & 3.717 & \(-\)2.278 & \(-\)0.378 & \(-\)0.107 \\
40–100 cm & 0.181 & 5.642 & \(-\)3.074 & \(-\)0.992 & \(-\)0.269 \\
100–200 cm & 0.848 & 5.398 & \(-\)3.837 & \(-\)2.024 & \(-\)0.332 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The climate tendency rate of soil moisture in four layers (Unit: kg/m\({}^{2}\)/10a). Figure 8: The average changes of soil moisture in different years in eastern China from 1961 to 2011: (a): 0–10 cm; (b) 10–40 cm; (c) 40–100 cm; (d) 100–200 cm. storage buffer area, which thus mastered the surface heat flux between the latent and sensible heat flux. More analysis shows that the deviation of soil moisture adversely affects climate change. The lower than normal value of soil moisture can lead to a drop in precipitation, thus reducing the ground air humidity and causing a rise in temperature. This means that reducing the water content of soil makes temperature rise [27]. In eastern China, precipitation and temperature both have a large impact on the regional soil water content. Looking at the data on soil moisture, precipitation and temperature, it is noted that the inter-annual variability of precipitation and different layers of soil moisture is very significant. Both present declining trends, and the annual average temperature increases, yet minimum temperatures in 1969, 1976, and 1984 correspond to the El Nino year in Chinese history. The maximum temperatures fell in 1998, 2003, and 2007. Again, it is significant that 1998 follows the strongest El Nino year in the 20 th century, 2003 was a rare high temperature year and 2007 was the warmest year since 1951. Each layer of soil moisture also displays such extremes. This shows that there is a connection between soil moisture, precipitation and temperature. Therefore, the above data reveals that warming and drying phenomena are related to decreasing soil moisture. In order to examine the previous assumptions, we examine links between the 51 years of soil moisture anomalies in each layer and the annual average precipitation anomaly, and also assess the relevance of the soil moisture, temperature and precipitation. Comparing the average annual precipitation anomaly in eastern China with the soil moisture anomalies (Figure 9), it is evident that although all layers of soil moisture are not the same, each layer of soil moisture and precipitation have a positive correlation. Its correlation coefficient shows a decline with the increase of soil depth from 0.78 in the 0-10 cm layer to 0.46 in the 100-200 cm layer. Thus, precipitation strongly influences soil moisture in the 0-10 cm layer, though it is not clear whether this can be said for the other layers. The main cause of this phenomenon is that water in the 0-10 cm layer mainly comes from natural precipitation, whereas  
Figure 9: The relationship of annual average precipitation anomaly (red line) and the layers of soil moisture (blue line) from 1961 to 2011 in eastern China: (**a**) 0–10 cm; (**b**) 10–40 cm; (**c**) 40–100 cm; (**d**) 100–200 cm. the water in 10-40 cm, 40-100 cm, and 100-200 cm layers is from penetration. Figure 10 compares annual average temperature anomalies with the layers of soil moisture from 1961 to 2011 in eastern China, and it proves that temperature and different layers of soil moisture have a negative correlation. From shallow to deep soil (0-10 cm, 10-40 cm, 40-100 cm, and 100-200 cm), the correlation coefficient of soil moisture and temperature is 0.32, 0.51, 0.47 and 0.52, respectively.