*2.4. MODIS Surface Reflectance and Land Surface Temperature*

The daily Aqua MODIS surface reflectance at 500 m (MYD09GA v.6) acquired in bands 1 (620–670 nm), 2 (841–876 nm), 3 (459–479 nm), 4 (545–565 nm), 5 (1230–1250 nm), and 7 (2105–2155 nm) were used. The MODIS reflectance is measured at ground level in the absence of atmospheric scattering or absorption and is already corrected for atmospheric gases, aerosols, and thin cirrus clouds [52]. Regarding the LST, daily Aqua MODIS LST (MYD11A1 v.6) and Terra MODIS LST (MOD11A1 v.6)—both at 1 km spatial resolution—were used. They have an accuracy specification of 1 ◦C under clear-sky conditions [53].

The three MODIS products are provided into a tile-based sinusoidal projection. The four tiles corresponding to the Iberian Peninsula (h17v04, h17v05, h18v04 and h18v05) were selected. These four tiles of the reflectance maps were first mosaicked. The resulting maps were resampled from the sinusoidal grid to a regular 500 m grid using the nearest neighbor approach. The same processing was applied to the LST but for a regular 1 km grid. The reflectance in all bands was filtered using their corresponding flags (land and highest quality). Finally, the reflectance maps at 500 m were aggregated to the same 1 km grid for the LST using a simple average.
