Variability of the hydrometeorological conditions in Kerch Bay in 2007-2024

Aim of this work is to investigate the variability of the hydrometeorological conditions in Kerch Bay in 2007- 2024. Methods used: the methodology of this study involves plotting and analyzing the graphs for the long-term variability of the average monthly values of the hydrometeorological parameters for 2007-2024 based on the data collected over the course of weekly monitoring conducted from April 2017 to April 2024. Novelty: for the first time, the variability of the environmental conditions in this region has been investigated for 17-year time range, including the most recent years. Results: the analysis of the long-term (2007-2024) variability of the average monthly near-ground air and water surface temperature, upper water layer salinity, near-ground wind speed and direction, wave action, and water transparency in Kerch Bay has been conducted. The prevalence of positive anomalies of air and water temperature involving the increased number of hot summer days and reduction in the number of winter sub-zero cold days as compared to the preceding 50-year time range has been identified. Considerable increase in the salinity is recorded for 2007-2014, which is followed by the lowering rates of its increase and stabilization of its values after 2017, mainly due to the water advection via the Kerch Strait and the wind regime in this area. The long-term variability of the average monthly wave heights has been categorized into three time ranges: 2017-2019 characterized by medium values, 2020-2022 characterized by decreased values, and 2023-2024 characterized by increased values. It is shown that the lowest water transparency in the bay (≤1.0 m) is recorded mainly in February–March under variable winds; the highest one (>3.0 m) is observed from April to December (since July 2021) in the context of the northerly winds and the lowest average wind speed. Practical significance: results obtained and discussed in this article can be vital for the assessment of the ecosystem variability in Kerch Bay as a region heavily involved into industrial and fishing activity.