Weather regimes and analogues downscaling of seasonal precipitation for the 21st century: A case study over Israel

Assaf Hochman, Pavel Kunin, Pinhas Alpert, Tzvi Harpaz, Hadas Saaroni, Dorita Rostkier-Edelstein

Research output: Contribution to journalArticlepeer-review

Abstract

Global climate models provide only partial information on local-scale phenomenon, such as precipitation, primarily due to their coarse resolution. In this study, statistical downscaling algorithms, based on both weather regimes and past analogues, are operated for 18 Israeli rain gauges with an altitude ranging between −200 and ~1,000 m above sea level (ASL). To project seasonal precipitation over Israel and its hydrologic basins, the algorithms are applied to six Coupled Model Inter-comparison Project Phase 5 (CMIP5) models for the end of the 21st century, according to the RCP4.5 and RCP8.5 scenarios. The downscaled models can capture quite well the seasonal precipitation distribution, though with underestimation in winter and overestimation in spring. All models display a significant reduction of seasonal precipitation for the 21st century according to both scenarios. The winter reductions for the end of the century and the RCP8.5 scenario are found to be ~22 and ~37% according to the weather regimes and the analogues downscaling methods, respectively. Spring reductions are found to be ~10–20% larger than winter reductions. It is shown that the projected reduction results from a decrease in the frequency of the rain-bearing systems, as well as a decrease in the average daily precipitation intensity. The areas with the largest reductions in seasonal precipitation are found over the central mountains, the Mediterranean coastal area, and the Sea of Galilee hydrologic basins, which are the main fresh-water aquifers and reservoirs of Israel. The statistical downscaling methods applied in this study can be easily transferred to other regions where long-term data sets of observed precipitation are available. This study and others may serve as a basis for priority and policy setting toward better climate adaptation with associated uncertainties related to the methods used and nonstationary of the climate system.

Original languageEnglish
Pages (from-to)2062-2077
Number of pages16
JournalInternational Journal of Climatology
Volume40
Issue number4
DOIs
StatePublished - 30 Mar 2020

Keywords

  • CMIP5 predictions
  • Eastern Mediterranean
  • analogues downscaling
  • climate change
  • seasonal precipitation
  • synoptic classification
  • weather regimes

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