CLIMADAT-GRid: A high-resolution daily gridded precipitation and temperature dataset for Greece

Abstract

We introduce the development of CLIMADAT-GRid, the first publicly available daily air temperature and precipitation gridded climate dataset for Greece at a high resolution of 1 km × 1 km, covering the period 1981-2019. The dataset is derived from quality-controlled and homogenized daily measurements from an extensive network of meteorological stations: 122 for temperature and 312 for precipitation. Several approaches are evaluated for generating daily gridded datasets, including fixed random Kriging, generalized additive models, k-nearest neighbors, and support vector machines. Based on the evaluation analysis against withheld observational data, fixed random Kriging is selected as the method for the CLIMADAT-GRid construction. To address the lack of a dense temperature observational network, high-resolution simulations from the Weather Research and Forecasting (WRF) model are blended with observational data to produce the gridded temperature datasets. CLIMADAT-GRid is benchmarked against the CHELSA-W5E5, a global climate product with a similar resolution, for the overlapping period 1981-2016. While both datasets show comparable results for temperature, CLIMADAT-GRid demonstrates superior spatial performance and closer agreement with observational data for both the mean and the extreme values. Regarding precipitation, CLIMADAT-GRid consistency indicates higher values than CHELSA-W5E5, especially during the rainy season, but exhibits better agreement with observations. In terms of the number of wet days, both datasets overestimate spatial means relative to observations, with CLIMADAT-GRid showing a more pronounced orographic pattern than CHELSA-W5E5. Both datasets show similar results for the number of days with precipitation amounts equal to or higher than 10 mm, with CLIMADAT-GRid indicating better overall agreement with the observations. The CLIMADAT-GRid dataset is publicly available at 10.5281/zenodo.14637536 and can be cited as Varotsos et al. (2025).