# Analyzing the Characteristics of Soil Moisture Using GLDAS Data: A Case Study in Eastern China
## 3 Results and Discussion  
### Characteristics of Climate Change in East China  
#### 3.1.1 The Changes of Temperature and Precipitation  
The eastern China area roughly tends to grow hotter between 1961 and 2011, as Table 1 and Figure 3 display.  
The Mann-Kendall test results show the average temperatures rise (slope 0.0267) in 51 years, and \(Z_{c}\) value passes the test of significance of 99%, which means the increasing trend is obvious. The average annual climate tendency rate in eastern China is 0.266 \({}^{\circ}\)C/10a, which is higher than centurial average global climate tendency rate (0.104 \({}^{\circ}\)C/10a) [26]. The 50-year temperature data can be divided into two characteristic phases: from 1961 to 1986, when the temperature in eastern China was colder than normal (negative temperature departure) and the climate tendency rate was \(-\)0.0283 \({}^{\circ}\)C/10a; and from 1987 to 2011, when the temperature increased (positive temperature departure). The temperature shows a rising trend, with a climate trend rate of 0.268 \({}^{\circ}\)C/10a. In particular, the average temperature rose to hit 9.91 \({}^{\circ}\)C in 1998, later reaching 9.94 \({}^{\circ}\)C in 2007, which is a high point over the previous 50 years, as shown in Figure 4.  
Compared with temperature, precipitation in eastern China shows different trends. From Mann-Kendall test precipitation results we know that in the last 50 years, precipitation in eastern China declined overall (i.e., here slope is \(-\)0.03), but is not in an obvious manner because the \(Z_{c}\) value doesn't pass the significance test. Inter-annual change is also very different. The largest annual average precipitation value reached 73.8 mm in 1998. This large precipitation corresponds to the heavy flood in 1998 which caused many rivers' water levels to rise sharply in the middle and low reaches of the Yangtze River, and seriously exceeded the safety level. The smallest average annual precipitation value appeared in 2011 at only 58.03 mm. Average annual precipitation of course varied in different years, as Figures 5 and 6 show.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Category** & **Value \(Z_{c}\)** & **Slope** \\ \hline Precipitation & \(-\)1.0072 & \(-\)0.0318 \\ Temperature & 5.4744 *** & 0.0267 \\ \hline \hline \end{tabular} Note: *** Represent passed 99% significance testing.  
\end{table}
Table 1: Mann-Kendall test of temperature and precipitation change trends  
Figure 3: Annual average temperature change in eastern China from 1961 to 2011.  
From the comparison of temperature and precipitation, the temperature in eastern China has evidently increased, while precipitation has slightly declined. In order to further analyze the climate change in eastern China, it is necessary to consider the characteristics of soil moisture in this region. Although there are many factors that influence changes in soil moisture, its characteristics are complicated due to the effect of non-unitary. Temperature, evaporation, light intensity, precipitation and other climate factors can lead to some changes in soil moisture. Long-term climate evolution can also cause changes in soil moisture at different times.  
Figure 4: The inter-annual variability of average temperature anomaly in eastern China from 961 to 2011.  
Figure 5: The inter-annual variability of average annual precipitation in eastern China from 1961 to 2011.  
Figure 6: The inter-annual variability of average annual precipitation anomaly in eastern China from 1961 to 2011.