## 2 Data and Methods
### Application of GIS Technologies for Climatic Atlas Compilation
#### 2.4.2 Climatic Atlas Structure  
The final version of the climatic atlas is a set of digital maps of hydrometeorological parameters, divided into categories. The scheme of the atlas compilation is presented in Figure 8.  
Figure 8: Scheme of the climatic atlas compilation.  
Figure 7: Example of the map design. Average air temperature changes (°C) between the periods 1980–1999 and 2000–2021 for the winter season (December–February).  
For each category of data, source maps were obtained (459 files in total) and subsequently processed. At the initial stage of processing, these source cartographic materials do not represent a valuable cartographic unit. The processing and preparation of maps of hydrometeorological parameters for the subsequent atlas compilation was mentioned above.  
The raster layers were combined into MXD files consisting of raster layers of basic data categories (air temperature at ground surface, total precipitation, wind speed at ground surface), as well as auxiliary data (soil temperature and moisture content, air humidity, snow cover thickness), divided into groups:  
* Average values for the entire period 1950-2021 and separately for the periods 1950-1979, 1980-1999, and 2000-2021.
* Average changes between the periods 1950-1979 and 1980-1999, 1950-1979 and 2000-2021, 1980-1999 and 2000-2021 (difference in average values between these periods, with the earlier period always subtracted from the later one).
* The rate of change of mean monthly anomalies relative to the annual rate for the periods 1950-2021, 1950-1979, 1980-1999, and 2000-2021, estimated using the 1 st derivative.
* Mean values for the winter (December-February) and summer (June-August) seasons and for the 12 months of the year for the entire period 1980-2021 and separately for the periods 1980-1999 and 2000-2021.
* Average changes for the winter (December-February) and summer (June-August) seasons and for the 12 months of the year between the periods 1980-1999 and 2000-2021 (the difference of average values between these periods, with the earlier period always subtracted from the later one).  
In each data category group, auxiliary data are presented. Thus, each data category group represents a separate MXD project. The total amount of files of merged raster layer projects was 52, each available for processing in ESRI ArcGIS (ArcMap).  
This approach is flexible, i.e., additional data (at the user's discretion) can be added to each of the prepared projects for more detailed data analysis/comparison. In this version of the climatic atlas, data editing, color palette changes, and data analysis tools are also available. As the main analysis tool, a raster calculator can be used [40; 41]. The principle of the tool is to perform pixel-by-pixel arithmetic operations with two raster layers. An example of this tool operation is shown in Figure 9.  
Along with this, the data isoline overlay mentioned above can be used as a tool for spatial data analysis.  
The atlas maps were also presented in high resolution TIFF (Tagged Image File Format) format that can be applied for further analysis in other geographic information software. Although ArcMap is an optimal software solution with many built-in tools to address a wide range of tasks, it also has certain disadvantages. The obvious one is the commercial distribution of this software. The TIFF format is universal, ready for handling in any GIS software, including the open source one. The TIFF maps were converted into PDF (Portable Document Format) files. This format is intended for convenient visual assessment of cartographic information and can serve as illustrative material for a variety of purposes.  
Figure 9: _Cont._