尼洋河流域极端气候时空分布特征及其可能成因

探究全球变暖下的尼洋河流域极端气候变化特征及原因,对于科学支撑西藏地区的极端气候灾害防治和生态安全保障等具有重要意义。本文基于尼洋河流域1960—2019年逐日降水及气温数据,采用极端气候指标法、Sen's斜率估计法、MK趋势及突变检验法、GIS空间分析法从降水、气温两个角度分析近60年尼洋河流域极端气候时空分布特征,并结合大气环流因子,使用地理探测器方法探讨时空分布特征的可能成因。结果表明：在时间上,尼洋河流域极端气候整体呈现暖湿化的变化趋势。极端降水的降水量、降水强度、降水日数均呈现增加趋势,极端气温的高温极值、低温极值均呈现增大趋势,低温日数呈现减少趋势。在空间上,尼洋河流域极端气候变化存在明显的空间分异性。极端降水整体自东向西逐渐减少、极端气温整体自东南向西北逐渐降低。尼洋河河道作为水汽通道,有一定的增温、保温作用,各极端气候指标沿着河道呈现出连续的极值点。副热带高压、青藏高压对尼洋河流域暖湿化的变化起到了正向增强作用,极涡、北大西洋涛动则相反。以坡度为代表的地形因子、以NDVI为代表的下垫面因子分别是影响极端降水、极端气温空间分布的最主要的环境因子,高程对极端降水、气温的空间分布均起到了重要的作用。

Spatio-temporal distribution characteristics and possible causes of extreme climate in the Niyang River Basin

Exploring the characteristics and causes of extreme climate change in the Niyang River Basin under global warming has important significance for scientific support of extreme climate disaster prevention and ecological security in Tibet. Based on the precipitation and temperature data of the Niyang River Basin from 1960 to 2019, we used the extreme climate index method, Sen's slope method, Mann-Kendall tendency and abrupt change test and GIS spatial analysis method to explore the spatio-temporal distribution characteristics of extreme climate in the basin in the past 60 years from the perspectives of precipitation and temperature. Combined with atmospheric circulation factors, we used the Geodetector method to investigate the possible causes of spatio-temporal characteristics. The results showed that the Niyang River Basin showed a trend of warming and wetting on the time scale. Precipitation amount, precipitation intensity, and the number of days of extreme precipitation all showed an increasing trend. High-temperature and low-temperature extremes all showed an increasing trend, and the number of low temperature days showed a decreasing trend. On the space scale, there was an obvious spatial heterogeneity in the study basin. The extreme precipitation overall gradually decreased from the east to the west, and the extreme temperature overall gradually cooled from the southeast to the northwest. As a water vapor channel, the Niyang River had effects of warming and heat-preserving, thus the extreme climate indexes showed continuous extreme points along the river. The Subtropical High and the Qinghai-Xizang High had a positive effect on the warming and humidification of the Niyang River Basin, while the Polar Vortex and North Atlantic Oscillation were the opposite. Topographic factors represented by slope and underlying surface factors represented by NDVI were the most important environmental factors that respectively influenced the spatial distribution of extreme precipitation and extreme temperature. Elevation played an important role in the spatial distribution of both extreme precipitation and temperature.