2.2.1. Meteorological Data

There are seven meteorological stations in XRB (Figure 1). Monthly meteorological data, e.g., temperature (T) and precipitation(P) are provided by the National Climate Center of China (http: //ncc.cma.gov.cn) for time series analysis. As most of these stations were built in the late 1950s, only monthly data from 2002 to 2014 were used in this study to ensure that the lengths of the data from multiple satellite data (GRACE) were consistent. Detailed meteorological stations' information is shown in Table 1.


**Table 1.** Meteorological stations' information in XRB.

China's annual average temperature and annual precipitation spatial interpolation data set (1980–2015) was based on daily observation data of more than 2400 meteorological stations across the country, and generated through sorting, calculation and spatial interpolation processing, which is provided by Data Center of Resources and Environmental Sciences, Chinese Academy of Sciences (http://www.resdc.cn) for analyzing spatial distribution and variation characteristics. The annual average temperature and precipitation units were 0.1 degrees Celsius and 0.1 mm, respectively. Interpolation of climatic factors such as temperature and precipitation use the Australian ANUSPLIN interpolation software. ANUSPLIN is a tool that uses smoothing spline functions to analyze and interpolate multivariate data, e.g., a method of approximating a curved surface using a function [32]. Mask extraction and resampling analysis of spatial interpolation data sets from 2002 to 2014 were carried out by ArcGIS software, and then to extract annual precipitation and temperature average values of the study area for analysis of spatial distribution and change trends.
