Development of daily gridded Penman-Monteith reference crop evapotranspiration data for Karnataka State, India

ABSTRACTReference crop evapotranspiration (ET0) estimates are often unavailable at fine spatial resolutions due to the lack of dense climatic networks. The present study was taken up to develop a methodology for obtaining a gridded Penman-Monteith (PM) ET0 dataset for Karnataka State, India, through spatial interpolation of estimates obtained at climate stations. Three interpolation techniques, Inverse Distance Weighted (IDW), Kriging, and Point-Based Sentinel Hospitals Area Distance (P-BSHADE), were employed to derive PM ET0 estimates. Considering the historical climate records of 67 stations located in Karnataka State for the period of 2006–2016, the interpolation methodologies were evaluated using a cross-validation procedure. Results showed that the performance of IDW was better with significant error reduction at validation sites. Subsequently, the IDW algorithm was used to derive daily PM ET0 values at 0.25° × 0.25° grids over the Karnataka State, India. Finally, the comparative analysis of developed PM ET0 gridded data product against three global ET0 products indicated the developed gridded ET0 to be most accurate across different agroclimatic zones. Web links of the developed product have been created in an effort to share the data on ET0, which is a critical input in a variety of studies in earth sciences.KEYWORDS: Penman-Monteithspatial interpolationIDWKrigingP-BSHADE AcknowledgementsWe are grateful to the Water Resources Development Organization (WRDO), Government of Karnataka, for providing the climate dataset used in the study and to three anonymous reviewers whose critical comments improved the quality of the manuscript.Disclosure statementNo potential conflict of interest was reported by the authors.Data availability statementData are openly available in a public repository that does not issue DOIs.The dataset developed in this study is stored in a repository and available in-text data citation.