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  • 1
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    Understanding summer wind systems over the eastern Mediterranean in a high‐resolution climate simulation (2022)
    Latt, Melissa R. ; Hochman, Assaf ; Caldas‐Alvarez, Alberto ; [et al.]
    John Wiley & Sons, Ltd. | Chichester, UK
    Details
    Publication Date: 2024-01-12
    Description: Regional and local wind systems are often complex, particularly near coastal areas with a highly variable orography. Thus, the realistic representation of regional wind systems in weather and climate models is of strong relevance. Here, we evaluate the ability of a 13‐year convection‐permitting climate simulation in reproducing the interaction of several regional summer wind systems over the complex orography in the eastern Mediterranean region. The COSMO‐CLM simulations are driven by hourly ERA‐5 reanalysis and have a spatial resolution of 2.8 and 7.0 km. The simulated near‐surface wind fields are compared with unique very high‐resolution wind observations collected within the “Dead Sea Research Venue” project (DESERVE) and data from the Israel Meteorological Service synop network. The high‐resolution COSMO‐CLM simulations largely reproduce the main characteristics of the regional wind systems (Mediterranean and Dead Sea breeze, slope winds in the Judean Mountains and winds along the Jordan Rift valley), whereas ERA‐5 is only able to represent the Mediterranean Sea breeze. The high‐resolution simulations substantially improve the representation of regional winds, particularly over complex orography. Indeed, the 2.8 km simulation outperforms the 7.0 km run, on 88% of the days. Two mid‐July 2015 case studies show that only the 2.8 simulation can realistically simulate the penetration of the Mediterranean Sea Breeze into the Jordan Rift valley and complex interactions with other wind systems like the Dead Sea breeze. Our results may have profound implications for regional weather and climate prediction since very high‐resolution information seems to be necessary to reproduce the main summertime climatic features in this region. We envisage that such simulations may also be required at other regions with complex orography.
    Description: In this paper we show that COSMO‐CLM regional climate model simulations at 7.0 (CLM‐7.0) and 2.8km (CLM‐2.8) resolution can realistically reproduce near‐surface regional and local wind systems over the complex orography of the eastern Mediterranean as opposite to coarser resolutions (ERA‐5, 31 km). The Mediterranean and local Dead Sea breezes, slope winds over the Judean Mountains, and winds along the Jordan Rift valley are well represented both climatologically and on individual days. CLM‐2.8 captures the small‐scale variability of the wind field better than CLM‐7.0 particularly near the Dead Sea and on 88% of the days CLM‐2.8 represents wind speed even more realistically than CLM‐7.0. image
    Description: German Helmholtz Association (“Changing Earth” program)
    Description: AXA Research Fund http://dx.doi.org/10.13039/501100001961
    Description: Ministry of Science, Research and Arts
    Description: Helmholtz Association of German Research Centers
    Keywords: ddc:551.6 ; complex orography ; convection permitting ; COSMO‐CLM ; Dead Sea ; eastern Mediterranean ; grid spacing ; regional climate modelling ; sea breeze
    Language: English
    Type: doc-type:article
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    CITATION GEO-LEO
  • 2
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    Future projections of Mediterranean cyclone characteristics using the Med-CORDEX ensemble of coupled regional climate system models (2022)
    In:  EPIC3Climate Dynamics, 58(9-10), pp. 2501-2524, ISSN: 0930-7575
    Details
    Publication Date: 2022-05-01
    Description: Here, we analyze future projections of cyclone activity in the Mediterranean region at the end of the twenty-first century based on an ensemble of state-of-the-art fully-coupled Regional Climate System Models (RCSMs) from the Med-CORDEX initiative under the Representative Concentration Pathway (RCP) 8.5. Despite some noticeable biases, all the RCSMs capture spatial patterns and cyclone activity key characteristics in the region and thus all of them can be considered as plausible representations of the future evolution of Mediterranean cyclones. In general, the RCSMs show at the end of the twenty-first century a decrease in the number and an overall weakening of cyclones moving across the Mediterranean. Five out of seven RCSMs simulate also a decrease of the mean size of the systems. Moreover, in agreement with what already observed in CMIP5 projections for the area, the models suggest an increase in the Central part of the Mediterranean region and a decrease in the South-eastern part of the region in the cyclone-related wind speed and precipitation rate. These rather two opposite tendencies observed in the precipitation should compensate and amplify, respectively, the effect of the overall reduction of the frequency of cyclones on the water budget over the Central and South-eastern part of the region. A pronounced inter-model spread among the RCSMs emerges for the projected changes in the cyclone adjusted deepening rate, seasonal cycle occurrence and associated precipitation and wind patterns over some areas of the basin such as Ionian Sea and Iberian Peninsula. The differences observed appear to be determined by the driving Global Circulation Model (GCM) and influenced by the RCSM physics and internal variability. These results point to the importance of (1) better characterizing the range of plausible futures by relying on ensembles of models that explore well the existing diversity of GCMs and RCSMs as well as the climate natural variability and (2) better understanding the driving mechanisms of the future evolution of Mediterranean cyclones properties.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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    PAPER (OA)
  • 3
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    Weather regimes and analogues downscaling of seasonal precipitation for the 21st century: A case study over Israel (2021)
    Details
    Publication Date: 2021-09-06
    Description: 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.
    Keywords: 551.6 ; analogues downscaling ; climate change ; CMIP5 predictions ; Eastern Mediterranean ; seasonal precipitation ; synoptic classification ; weather regimes
    Language: English
    Type: article
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    CITATION GEO-LEO
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