Assessment of climatic season changes in Ukraine during 21st century based on an ensemble of 34 RCM projections of Euro-CORDEX

Abstract

<p>The last decade proved to be the warmest in Ukraine for the whole period of instrumental weather observations. Recent and projected future warming will cause changes in the duration of climatic seasons in Ukraine with corresponding shifts in dates of their start and end.</p> <p>As specified by the Expert Team on Climate Change Detection and Indices, climatic seasons are determined as periods from the first day after the start of a year to the first date after 1 July when at least 6 consecutive days mean daily temperature (t) exceeds (drops under) different thresholds. We analysed four climatic periods: warm period (t>0<sup>o</sup>C), growing season (t>5<sup>o</sup>C), active vegetation (t>10<sup>o</sup>C), and summer season (t>15<sup>o</sup>C).</p> <p>To assess these projected changes bias-adjusted daily data of EuroCORDEX were used from 34 regional climate models for RCP4.5 and RCP8.5 scenarios for 3 future periods: near-term 2021-2040, mid-term 2041-2060 and far-term 2081-2100. Data of ensemble mean for two scenarios firstly were compared with E-Obs v20.0e results in the base period 1991-2010 and showed different biases for different climatic seasons, but very similar behaviour for both scenarios and both variables (length and start of climatic seasons). The least biases (< 0.5 days) were obtained for growing season, while biases reached -10 days for length of warm season and were within 1-3 days for other two seasons.</p> <p>In general by the end of the century, under the RCP4.5 scenario in Ukraine, all analysed climatic season lengths may be the same as in the middle of the century under the RCP8.5 scenario.</p> <p>By the end of the century, for the RCP8.5 scenario, the changes in the climatic seasons range from 40 to almost 70 days, increasing from east to west. As a result, in the coldest in Ukraine region winter is projected to last only from 10 to 30 days, and the vegetation will last throughout the year not only at the southern coast of the Black Sea but also the steppe part of the Crimea and some southern parts of Odesa region. There are almost no differences between scenarios for growing season length, start and end days in the near-term. The area with the longest growing season (from 240 to 260 days) will extend almost 200 km to the north.  </p> <p>Under the RCP8.5 scenario, the length of active vegetation at the end of the century can range from 200 to 240 days, and in the Crimea and the south of Odesa region - 240-285 days, and summer length can vary from 140 days in the north to over half-year in the Crimea and southern Odesa. At the end of the 21<sup>st</sup> century, projected summer in Polissya will be as in the Crimea now - 140-160 days. Such climatic conditions were not observed in Ukraine previously. Increasing the length of the growing season and the period of active vegetation will strengthen the agro-climatic potential of Ukraine and contribute to obtaining higher yields of crops if corresponding measures in providing enough water supply will be implemented.</p>

Analysis of the dynamics and precipitation regime in the cross-border region Poland-Belarus- Ukraine (2010-2018)

“…The forecasts of scientists (Krakovska et al, 2017), (Martazinova & Shchehlov, 2018) predict some further increase in precipitation in the study region.…”

“…According to estimates of mathematical modeling of regional climate processes in Ukraine, Poland, and in the Central European region as a whole, trends in the growth of precipitation amounts will persist in the study region, most forecasts do not foresee a significant decrease in the amount of precipitation (Krakovska et al, 2017;Zolina et al al., 2014;Didovets et al, 2020).…”

“…Most of the modern models predict further preservation or a slight increase in the amount of precipitation in the region (Krakovska et al, 2017), (Kamyshenko, 2012.). At the same time, a change in the precipitation regime in combination with higher evaporation costs in the warm period of the year can contribute to a decrease of the territory in the water content and, as a result, to a decrease in the levels of groundwater and surface water bodies.…”

Performances of Holiday Climate Index (HCI) for Urban and Beach Destinations in Sri Lanka under Changing Climate

“…Nevertheless, Fang et al [47] stated that for hydrological modeling aspects, bias correction for relative humidity and wind has the least significance. Additionally, the findings of Krakovska et al [48] mentioned RCMs and that the satellite-observed cloud cover product has the least biases. Therefore, as the present study focuses on climate conditions at ground level, bias-corrected climate variables (temperature, precipitation, and relative humidity) were taken into consideration, with raw climate variables such as cloud cover and wind.…”