Two decades of distributed global radiation time series across a
mountainous semiarid area (Sierra Nevada, Spain)
Abstract. The main drawback of the reconstruction of high resolution distributed global radiation (Rg) time series in mountainous semiarid environments is the common lack of station-based solar radiation registers. This work presents nineteen years (2000–2018) of high spatial resolution (30 m × 30 m) monthly and annual global radiation maps derived using the model proposed by Aguilar et al. (2010), driven by in situ daily global radiation measurements, from sixteen weather stations with historical records in the area, and a high resolution digital elevation model in a mountainous area in southern Europe: Sierra Nevada (SN) Mountain Range (Spain). The applicability of the modeling scheme was validated against daily global radiation registers at the weather stations with mean RMSE values of 2.63 MJ m−2 day−1 and best estimations on clear-sky days. Filled daily Rg at weather stations revealed quite stable minimum daily Rg values and greater variations in the maximum daily Rg, but no clear trends with altitude in any of the statistics unlike the analysis at the monthly and annual scale when there is an increase in the high extreme statistics with the altitude of the weather station, especially above 1500 m a.s.l. Monthly distributed Rg time series showed significant spatial differences of up to 200 MJ m−2 month−1 that clearly followed the terrain configuration. July and December were clearly the months with the highest and lowest values of Rg received and the highest dispersion in the monthly Rg values was found in the spring and fall months. The great heterogeneity found in the monthly distribution of Rg along the study period (2000–2018), especially at the wet season, finally determined the inter annual differences of up to 800 MJ m−2 year−1 in the incoming global radiation in SN. The time series of the surface global radiation datasets here provided can be used to analyze trends, inter-annual and seasonal variation characteristics of the global radiation received in SN with high spatial detail (30 m). Datasets are available at https://doi.pangaea.de/10.1594/PANGAEA.921012 (Aguilar et al., 2020).
