Validation of gridded data set over semi-arid region of Syria

Abstract

Arid and semi-arid regions are particularly susceptible to climate change. However, precipitation and temperature reliable data for the long term are unavailable in many developing regions mainly in the conflict-affected regions of the world. Gridded Climate Data (GCD), in recent years, has emerged as a reliable data sets especially for the remote regions. The reliability and accuracy of these data sets vary from region to region. In this study, the GCD of precipitation global precipitation climatology center (GPCC) and temperature climate research unit (CRU) is validated using various statistical and spatial analysis over Syria. The quality of the observed data has been checked by the double mass curve and compared with the observed by time-series and residual analysis. CDF and PDF were plotted for the evaluation of GCD along with the comparison of the spatial distribution of precipitation and temperature. The double mass curve results showed that the annual rainfall time series showed no breakpoint in the graph representing the consistency of the observed data of various stations. The PDF and CDF of the observed and GPCC data were plotted to find the relationship of the GPCC with the observed data. The R2, PBIAS, NRMSE, NSE and md of GPCC with observed data shows that at the various station the gridded data is in close relationship with the gridded data, which strengthens the hypothesis that the GPCC can perform well over Syria. Time series analysis of 50 years (1951–2010) was compared along with the residual of each station. The comparison showed that the GPCC data matched well with the observed data with a slight under or overestimation at some stations. The spatial distribution of the annual mean rainfall over Syria was plotted for the observed as well as GPCC data. The spatial distribution of the GPCC was much more similar in most part of the country which represents the ability of the gridded data to replicate the annual mean precipitation over most part of the country.