*2.2. Study Area and Data*

Hubei Province is located between northern latitudes 29◦05 and 33◦20 and eastern latitudes 108◦21 and 116◦07 within China. The province covers an area of 185,900 square kilometers, and includes a variety of topographical regions, including mountains, plains, and transitional topographic zones. The topography of Hubei Province exhibits the highest elevation of 3090 m in its western region, and lowest towards its eastern area, with a lowest elevation of −142 m [39]. Hubei Province lies within a north–south transitional climatic zone, belonging to the northeastern Asian monsoonal region, except for the higher elevations of the western mountainous areas. Most of the province features a subtropical monsoonal, humid climate. The warm temperature coincides with the rainy period, providing abundant rainfall to support agroforest production [39]. The spatial distribution of meteorological sites and the digital elevation model (DEM) are shown in Figure 2.

**Figure 2.** The spatial distribution of meteorological sites and digital elevation model (DEM) data representation.

The Hubei Meteorological Bureau provided annual and monthly precipitation data from 75 meteorological stations from 2006 through 2014 in Hubei Province. Figure 3 displays the average monthly precipitation distribution for the period of record.

**Figure 3.** *Cont.*

**Figure 3.** The monthly precipitation distribution from 2006 to 2014.

Many factors influence the spatial distribution of precipitation. Previous studies have demonstrated that topographic characteristics are the main controlling factor [40,41]. The Normalized Differential Vegetation Index (NDVI) is influenced by precipitation, and vice versa [42,43]. This work employs the Digital Elevation Model (DEM) Shuttle Radar Topography Mission (SRTM) data with 90 m resolution. The NDVI data are the MODND1M for China with 500 m resolution NDVI monthly synthesis products. All of the above data are available from the Geospatial Data Cloud website (http://www.gscloud.cn).

#### *2.3. Data Preprocessing*

All data were consolidated under the WGS-84 geographic coordinate system. The grid resolution employed was 0.1◦ × 0.1◦. Precipitation constitutes the dependent variable; longitude, latitude, DEM, and the NDVI are the independent variables. The timescale of precipitation data is divided into monthly and annual categories. The monthly data represent the time series data from January 2006 through December 2014. The yearly data denote the time series data from 2006 through 2014.

The interpolation accuracy of the GTWR models was evaluated by cross-verification (CV). The 75 meteorological sites were randomly divided into 60 sites (80% of the total number of sites) as the modeling set for interpolation; the remaining 15 sites (20% of the total number of sites) were chosen as the validation set, which was used to evaluate the models' accuracies. This paper employs the GTWR models corresponding to several timescales listed in Table 1.


**Table 1.** Listing of the geographically and temporally weighted regression (GTWR) models.
