Downscaled simulations of the ECHAM5, CCSM3 and HadCM3 global models for the eastern Mediterranean–Black Sea region: evaluation of the reference period

Abstract

The outputs of three GCMs, ECHAM5, CCSM3 and HadCM3, are downscaled for the eastern Mediterranean-Black Sea region for the period 1961-1990 using a regional climate model, RegCM3, to assess the capability of these models in simulating the climatology of the region. In addition, the NCEP/NCAR Reanalysis data are also downscaled for the same period to display the performance of the regional climate model for the same region, which constitutes a relatively complex terrain and rich variety of climates. The gridded observational dataset of CRU is primarily used in the evaluation of the models, however, a regional dataset, which is based on a relatively dense gauging network, is also used to see how it affects the performance measures of the models. The reanalysis simulation indicates that RegCM3 is able to simulate the precipitation and surface temperature as well as the upper level fields reasonably well. However, it tends to overestimate the precipitation over the mountainous areas. All three GCM models are found to be highly skilled in simulating the winter precipitation and temperature in the region. The two models, ECHAM5 and HadCM3, are also good at simulating the summer precipitation and temperature, but the CCSM3 simulation generates dryer and warmer conditions than the observations for the whole region, which are most likely a result of the dryness in the upper levels of the original outputs. The use of the regional observational dataset does not necessarily improve the pattern correlations, but it yields better match between the modeled and observed precipitation in terms of variability and root-mean-square difference. It could be said that the outputs of these GCMs can be used in the climate change downscaling and impact assessment studies for the region, given that their strengths and weaknesses that are displayed in the present study are considered.

Evaluation of regional COSMO‐CLM climate simulations over the Eastern Mediterranean for the period 1979–2011

“…The low bias value of ISR715 winter precipitation represents a significant improvement with respect to earlier studies (e.g. Önol and Semazzi, ; Smiatek et al, ; Bozkurt et al, ), which displayed winter precipitation biases of ∼30 − 40 mm month −1 . Improvement in temperature is also shown for the cold months, but a worsening of performance is observed for the warm months.…”

“…The results display substantial improvement from earlier RCM studies in the region (e.g. Önol and Semazzi, ; Samuels et al, ; Smiatek et al, ; Bozkurt et al, ). Nevertheless, some model deficiencies are still evident.…”

High‐resolution projection of climate change and extremity over Israel using COSMO‐CLM

“…For the 99th percentile of daily precipitation (99p) indications of increases (i.e., extremity) are also seen for the northern part of the country. This features can be captured only by high-resolution simulations, and could not be captured by the global models in earlier projections of extreme precipitation (e.g., Samuels et al, 2013Samuels et al, , 2017 but also with regional models at lower resolution (e.g., Önol and Semazzi, 2009;Smiatek et al, 2011;Bozkurt et al, 2012). The general decrease in precipitation probably results from the decrease already seen and projected in cyclones occurrence (e.g., Tamarin-Brodsky and Kaspi, 2017;Hochman et al, 2017b), which mainly influence the northern and central parts of Israel.…”

Validation of newly designed regional earth system model (RegESM) for Mediterranean Basin

“…The standalone regional climate models (RCMs) are also widely employed to investigate and validate the present (i.e. Bozkurt et al 2012), and future climate (i.e. Onol et al 2013) of the Mediterranean Basin driven by GCM results.…”