Consistency of spatiotemporal variability of MODIS and ERA5-Land surface warming trends over complex topography.

In this study, the trend of widely used MODIS MxD11 and MxD21 Land Surface Temperature (LST) and ERA5-Land Skin Temperature (SKT) and 2 m air temperature products were validated using 2 m air temperature trends obtained by ground observations from 266 stations in 2000-2021 over Turkey, known to have complex topography. The results show that colder regions have substantially higher temporal temperature variability than warmer ones. MxD21 and MxD11 products are 4.4 °C and 2.9 °C warmer than ERA5-Land products, respectively, while ERA5-Land products (SKT and 2 m) have nearly similar averages (12.5 °C). The consistency between MODIS and ERA5-Land data is significantly lower over areas with more complex topography and irrigation activities, despite the fact that the products show a high linear relationship over the study area. While February trends are consistently much higher than other months (2.2 and 1.4 °C/decade for MODIS and ERA5-Land, respectively), overall MODIS skin temperature products (0.7 °C/decade) generally exhibit smaller trends than ERA5-Land skin and air temperature trends (0.94 °C/decade). The results suggested that MODIS and ERA5-Land trends, which are highly consistent with observations, might replace observations in the absence of long-term station-based records.