Select and preprocess input data

Hourly air temperature measurements from four data sources has been selected (figure 1): Romanian National Meteorological Administration Network (ANM), Romanian National Air Quality Monitoring Network (RNMCA), Regional Basic Synoptic Networks (RBSN) and Meteorological Aerodrome Report Network (METAR).

Figure 1 Spatial distribution of weather stations.

In total, data from 354 stations were obtained from the four archives (78888 hours ×  354 stations = 27926352 possible values) (table 1).

Table 1 Availability of the hourly air temperature measurements (2009-2017).
Missing data ANM RNMCA METAR RBSN Total
No 11694123 6785612 308202 2071297 20859234
Yes 1006845 2444284 86238 3529751 7067118