Details

Autor(en) / Beteiligte

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

Titel

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

Ist Teil von

• International journal of climatology, 2020-03, Vol.40 (4), p.2062-2077

Ort / Verlag

Chichester, UK: John Wiley & Sons, Ltd

Erscheinungsjahr

2020

Quelle

Wiley Online Library All Journals

Beschreibungen/Notizen

• 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. Statistical downscaling algorithms based on weather regimes and past analogues are operated over Israel. The RCP8.5 ensembles mean precipitation drops by ~30% based on the weather regimes method and by ~50% with the analogues method by the end of the 21st century. It is suggested that the projected reduction in seasonal precipitation is not only the result of a decrease in the rain‐bearing systems frequencies, but also the result of a decrease in their average precipitation intensity.