基于湿润指数的甘肃省1967—2016年地表湿润特征

Surface humidity index in Gansu Province during 1967 to 2016 based on humidity index

基于甘肃32个气象站点近50 a气象数据,应用世界粮农组织Penman-Monteith模型计算潜在蒸散量,并计算湿润指数。以划分出的干湿气候区为研究对象,采用Bernaola-Galván(B-G)分割法、经验正交分解法、滑动T检验、累积距平、Morlet小波变换、IDW空间插值等方法,对各干湿气候区的湿润指数的变化趋势进行分析比较,确定了研究区地表湿润状况的空间分异,并探究了湿润指数变化的驱动因素。结果表明:①研究区湿润指数总体上呈西增东减趋势,增加和减少地区的面积分别占研究区总面积的28.6%和71.4%,EOF空间分布模态主要为全区一致分布模态和以乌鞘岭为界东西反向分异模态。②半湿润区以−0.018∙(10a)^(−1)(p<0.05)的速率呈显著下降趋势,3个分割阶段均值呈依次递减趋势,存在12 a左右的主周期,并在1994年发生由多到少的突变,地表暖干化趋势明显;半干旱区以0.002∙(10a)^(−1)的速率呈上升趋势(p>0.05),4个分割阶段均值呈波动变化趋势,存在14 a左右的周期,并在1996年后地表呈暖干化趋势,但未发生突变;干旱区以0.003∙(10a)−1的速率呈上升趋势(p>0.05),3个分割阶段均值呈依次递增趋势,存在22 a左右的周期,并在1992年后地表湿润指数以0.006∙(10a)−1的速度显著上升(p<0.01),但未发生突变。③降水量、相对湿度、潜在蒸散是影响湿润指数的主要驱动因素,而气温要素的影响较弱,不同气候区地表湿润指数的驱动因素具有明显的季节差异。

Background,aim,and scope With global warming becoming more and more prominent,water vapor transport is accelerated,in recent years,the rate and magnitude of climate change has increased significantly,and the uncertainty of climate wet and dry change has increased.In this paper,the change of wet index in Gansu in the past 50 years is studied in order to find out the changes of surface wet and wet on the time scale and spatial scale of different wet and dry climate zones and their transformation characteristics under the background of global warming.Materials and methods Based on the data of 32 climate stations in Gansu,this paper selected the World FAO P-M model to calculate the potential evapotranspiration,and then calculate the surface humidity index.We used the methods of B-G segmentation,cumulative distance leveling,IDW and other methods to analyze the climate-change trend and characteristics of humidity index in each dry-wet climate region.Results The humidity index of Gansu Province was increasing in the west and decreasing in the east.The EOF spatial distribution mode is mainly the consistent distribution mode of the whole region and the reverse division of the isomorphism of east and west with the Wushaoling as the boundary.The semi-humid region showed a significant downward trend at the rate of−0.018∙(10a)−1,the mean of the three segmentation stages decreased in turn,the mutation from much to few occurred in 1994.The semi-arid region was on the rise of 0.002∙(10a)^(−1),the mean of the four segmentation stages showed a trend of fluctuation,and the surface dried after 1996,but no mutation occurred;The arid region showed an upward trend of 0.003∙(10a)−1,with the mean of the three segmentation stages increasing in turn,and the surface moisture index increased significantly at 0.006∙(10a)−1 after 1992,but no mutation occurred.Discussion In recent years,the arid region in the west shows a clear trend of transition from warm to warm and humid,which is closely related to the increase of precipitation,has a positive impact on the sustainable development of agricultural production and natural environment in the future.As a transitional area of climate transformation,the central semi-arid zone has a weak humidity trend,and with the improvement of surface moisture,the fragile ecological environment of Hexi corridor and Qilian mountain area can be further improved.With the decrease of rainfall,rising temperature,increasing the shortage of surface moisture and increasing the degree of climate drought,the arid area of crops increases,leads to the decline of production and destroys the sustainable and stable development of agriculture.Conclusions Under the background of the transition of climate from warm dry to warm and humid in northwest China,the whole region of climate warm-up change in the study area has consistent,and the warming trend is developing,but the change of surface moisture characteristics has significant spatial difference.The semihumid zone not only did not change to warm and humid,but also had a clear trend of warm drying in the past half century,especially since 1994,the trend of surface drying was significant,and it was an untransformed area.The semi-arid region showed a weak trend of warm-up and humidity,and the surface moisture index increased and decreased alternately,which was a weak transformation area.The arid zone showed a more obvious trend of warm-up,especially after 1992 the surface at 0.006·(10a)^(−1) rate showed a significant upward trend,which is a transformation zone.Recommendations and perspectives On the basis of consistent with the results of previous research,this paper classified the characteristics of climate wet and wet changes in the study area,and made an indepth study on the specific process of climate wet and wet transformation in northwest China.As a climate dry-wet index which considers the combined effect of various factors,the humidity index is an ideal index for characterizing the change of surface wet and wet in arid areas,and the regional differences of surface wet index in different areas of the study area play an important role in guiding the agricultural development,ecological environment and economic development of the study area.