Insights on the climate of Bhutan from a new daily 1 km gridded data set for temperature and precipitation

Abstract

Gridded climatological data derived for Bhutan from internationally available data sets either come at a very low spatial resolution, or do not provide daily data, or contain few in situ measurements. We present a newly developed daily high-resolution (1 km) gridded data set for Bhutan covering the years 1996–2019 for precipitation and maximum and minimum temperature (BhutanClim). As input, we used quality-controlled and homogenized data from up to 67 weather stations from the National Center for Hydrology and Meteorology of Bhutan. The spatial interpolation of daily temperature consists of a non-linear vertical profile combined with an inverse-distance interpolation of the residuals. The interpolation uses a non-Euclidian distance that takes elevation differences between grid cells and topographic obstacles into account. The daily coverage allows the calculation of climate indicators that need daily data such as frost days or precipitation days. The new climatology benefits from the use of local measurements and shows plausible small-scale spatial patterns. It shows a distinct dry region in the valleys in central Bhutan bordering a dry climate classification according to Köppen–Geiger which is not visible in other data sets.