Lithuanian Energy Institute, Lithuania.
Lithuanian Energy Institute, Lithuania.
Sci Total Environ. 2024 Feb 25;913:169669. doi: 10.1016/j.scitotenv.2023.169669. Epub 2024 Jan 2.
Based on the physical and geographical conditions, the Baltic Region is categorised as a humid climate zone. This means that, there is usually more precipitation than evaporation throughout the year, suggesting that droughts should not occur frequently in this region. Despite the humid climate in the region, the study focused on assessing the spatio-temporal patterns of droughts. The drought events were analysed across the Baltic Region, including Sweden, Finland, Lithuania, Latvia, and Estonia. This analysis included two drought indices, the Standardized Precipitation Index (SPI) and the Streamflow Drought Index (SDI), for different accumulation periods. Daily data series of precipitation and river discharge were used. The spatial and temporal analyses of selected drought indices were carried out for the Baltic Region. In addition, the decadal distribution of drought classes was analysed to disclose the temporal changes and spatial extent of drought patterns. The Pearson correlation between SPI and SDI was applied to investigate the relationship between meteorological and hydrological droughts. The analysis showed that stations with more short-duration SPI or SDI cases had fewer long-duration cases and vice versa. The number of SDI cases (SDI ≤ -1) increased in the Western Baltic States and some WGSs in Sweden and Finland from 1991 to 2020 compared to 1961-1990. The SPI showed no such tendencies except in Central Estonia and Southern Finland. The 6-month accumulation period played a crucial role in both the meteorological and hydrological drought analyses, as it revealed prolonged and widespread drought events. Furthermore, the 9- and 12-month accumulation periods showed similar trends in terms of drought duration and spatial extent. The highest number of correlation links between different months was found between SPI12-SDI9 and SPI12-SDI12. The results obtained have deepened our understanding of drought patterns and their potential impacts in the Baltic Region.
基于自然和地理条件，波罗的海地区被归类为湿润气候区。这意味着，该地区全年的降水量通常多于蒸发量，这表明该地区不应频繁发生干旱。尽管该地区气候湿润，但该研究侧重于评估干旱的时空模式。干旱事件分析涵盖了波罗的海地区，包括瑞典、芬兰、立陶宛、拉脱维亚和爱沙尼亚。该分析包括两个干旱指数，即标准化降水指数（SPI）和流量干旱指数（SDI），用于不同的累积期。使用了降水和河流流量的日数据系列。对选定的干旱指数进行了空间和时间分析，以了解波罗的海地区的干旱模式。此外，还分析了干旱等级的十年分布情况，以揭示干旱模式的时间变化和空间范围。应用 SPI 和 SDI 之间的皮尔逊相关性来研究气象和水文干旱之间的关系。分析表明，具有更多短持续时间 SPI 或 SDI 情况的站点具有较少的长持续时间情况，反之亦然。与 1961-1990 年相比，1991 年至 2020 年期间，波罗的海西部各州以及瑞典和芬兰的一些 WGS 站点的 SDI 情况（SDI ≤ -1）有所增加。SPI 除了在爱沙尼亚中部和芬兰南部外，没有出现这种趋势。6 个月的累积期在气象和水文干旱分析中起着至关重要的作用，因为它揭示了长期和广泛的干旱事件。此外，9 个月和 12 个月的累积期在干旱持续时间和空间范围方面显示出相似的趋势。不同月份之间发现的相关性链接数量最多的是 SPI12-SDI9 和 SPI12-SDI12。所获得的结果加深了我们对波罗的海地区干旱模式及其潜在影响的理解。
