Objective selection of model run from regional climate models ensemble

Abstract

In this paper, a method was developed in relation to the north-western coast of the Black Sea in order to determine the optimal model run from regional climate models ensemble. As a result of climate change, which has been observed since the late 1980s in Ukraine, various natural objects changes have been also transformed. The study of such changes in the future is possible only by using runs of global or regional climate models. Moreover, the step of the spatial grid in the climate model must be comparative with the spatial size of a natural object under study. In the north-western coast of the Black Sea, climate change is characterized by increasing aridity of climate and a corresponding decrease in freshwater inflows into coastal lagoons from their catchments, making ecosystems of these lagoons sensitive and vulnerable to climate change. Using numerical models in order to study climate change impact on these natural objects requires input hydrometeorological information in the spatial grid points, the distance between which should correspond to the horizontal size of lagoons, i.e. several kilometers. In this paper, data from the scenarios RCP4.5 and RCP8.5 of the ensemble from 14 model runs with different regional climatic models of the CORDEX project were used to simulate the future changes of the temperature and precipitation regime. For each grid point and scenario, a single simulation was selected from the ensemble, which best reproduces the intra-annual changes of temperature, precipitation, and evaporation compared to the ensemble means. Despite the sufficiently large distance between the estuaries, the method allowed the selection of a single optimal model run, which shows the significant differences in spring and summer precipitation as well as year-around evaporation in the southern and northern parts of the northwestern coast of the region. This run well reproduces the relationship between temperature, precipitation, and evaporation in the southern and northern parts of the northwestern coast of the Black Sea.

Keywords

• climate change
• cordex
• temperature
• precipitation
• evaporation