1961—2020年宁夏地区极端气候变化趋势及影响因素分析

ANALYSIS OF EXTREME CLIMATE CHANGE TRENDS AND INFLUENCING FACTORS FROM 1961 TO 2020 IN NINGXIA HUI AUTONOMOUS REGION, CHINA

关键词:  极端气候指数  极端气温  极端降水  小波分析  人类活动

Key words:  extreme climate index  extreme temperature  extreme precipitation  wavelet analysis  human activity

摘要:

目的 探明极端气候指数的时空变化特征，明确极端气候变化的影响因素。方法 文章基于1961—2020年宁夏19个气象站点的逐日平均气温、最高气温、最低气温和降水量等数据，采用国际气候诊断与指数小组（ETCDD－MI）定义的极端气候指数，运用线性趋势法、克里金插值法、小波分析等方法，明确宁夏极端气候变化趋势，并探讨人类活动与极端气温变化的关系。结果 （1）宁夏的极端气温指数中，暖夜、夏日日数、持续暖期日数和年最大日最高气温均呈现上升趋势；霜冻日数、冷昼、持续冷日日数均呈现下降趋势，年最大日最低气温呈上升趋势。（2）在空间分布上，暖夜、夏日日数、连续暖期日数和年最大日最高气温的变化率在引黄灌区变化率较大，指数均呈现上升趋势，霜冻日数、冷昼、连续冷期日数在全区均呈现下降趋势，引黄灌区和中部干旱区下降趋势变动较为明显。（3）极端高温指数的变化率在北部引黄灌区较高，全区呈现出升温态势。（4）宁夏4个极端降水指标变化并不显著，但区域间年际变化差异较大，南部山区大部分地区极端降水指数变化率较高且呈正向变化，而北部引黄灌区降水年际变化率远低于南部山区且降水趋于减少。（5）1987—1992年极端高温指数和极端低温指数存在显著共振周期，极端高温指数上升领先极端低温指数。（6）极端气温影响因素分析发现，人口的增长、能源消费碳排放量的增加、城市化率的上升和建筑面积的增加，与月最高温日值都存在线性相关关系，反映出随着人类活动的增加，极端高温指数也存在一定程度的正向关系。结论 极端气候变化特征表明，宁夏地区高温事件增加，低温事件减少，极端降水年际波动幅度较大，地区差异显著，并且人类活动可能与极端气候变化存在相应关系。

Abstract:

The purpose of this research is to ascertain the temporal and spatial variation characteristics of extreme climate indexes and to clarify the factors affecting extreme temperature changes. Climate data was collected from 19 weather stations in the Ningxia region of China for the period from 1961 to 2020. And the data included the daily average, maximum and minimum temperatures and precipitation data, then these data were used to calculate values for the extreme climate indexes defined by the CCl/CLIVAR/JCOMM Joint Expert Team on Climate Change Detection and Indices (ETCCDI). And the linear trend method, the kriging interpolation method, wavelet analysis and other methods were used to clarify the trend of extreme climate change in Ningxia and explore the relationships between human activities and changes in the extreme climate indices. The results were listed as follows. In Ningxia, indexes describing the number of warm nights and summer days, warm spell duration indexes, monthly minimum value of daily minimum temperatures and monthly maximum value of daily maximum temperatures all showed an upward trend. The numbers of frost days and cold days and cold spell duration indexes showed a downward trend. In terms of spatial distribution, the changes were largest in the Yellow River diversion irrigation area, and the indexes showed an upward trend. The number of frost days, cold days and the cold spell duration index showed a downward trend over the whole Ningxia region, but the downward trends in the Yellow River diversion irrigation area and the arid area in the central part of the region were more obvious. Overall, the four extreme precipitation indexes did not change significantly, but the interannual variation fluctuated greatly in Ningxia. The number of continuous precipitation days decreased slightly, but the total precipitation showed a weak upward trend. The precipitation related indexes in the southern mountainous area were high and showed an increase, and the interannual change rate of precipitation in the Northern Yellow River irrigation district was much lower than that in the Southern mountain and precipitation tends to decrease. The monthly maximum value of daily maximum temperature index and the monthly minimum value of daily minimum temperature showed a significant resonance period from 1987 to 1992, and the rise in the maximum temperature index was ahead of that of the minimum temperature index. The analysis of factors influencing the temperature indexes showed that growth in population, increase in carbon emission due to energy consumption, increase in urbanization and increase in built-up areas all showed linear correlations with the monthly maximum temperature. This showed that increases in human activity had affected the temperature related indexes. Therefore, the characteristics of extreme climate change indicates that high temperature events increases and low temperature events decreases, the interannual fluctuation ranges in precipitation are large, and there are significant regional differences and human activities may be related to extreme climate change in Ningxia.