“蒸发悖论”在云南省的探讨

Evaporation Paradox in Yunnan Province

利用云南省1981—2011年52个站点候气象数据,通过分析云南省各站点季、年潜在蒸散量与气温变化趋势,探讨了"蒸发悖论"在云南省的时空分布。结果表明,(1)全省年潜在蒸散量t-ET0,y经历了先下降后上升的变化过程。1981—1990年,t-ET0,y以4.45mm/a的速率下降,有"蒸发悖论"存在;1991—2011年,t-ET0,y以2.42 mm/a的速率上升,不存在"蒸发悖论";(2)不同时间段内存在"蒸发悖论"的站点数量不同,分布区域差异明显。1981—1990年主要分布于中部和东南地区,1991—2011年集中分布在西部地区,且站点数量变少;(3)1981—1990年,存在"蒸发悖论"的站点在春、夏、秋、冬四季均有成片分布,其中冬季主要分布于云南省西北和中部地区,春季集中于中部,夏季和秋季主要分布于西南地区。1991—2011年,各季节也有一定数量的站点存在"蒸发悖论",但站点分布较无序,空间趋势变化不明显;(4)"蒸发悖论"的有无与时间段的长短选取有关,长时段的研究序列可能会掩盖短时段的"蒸发悖论"现象。因此,"蒸发悖论"在云南省具有阶段性、季节性和区域性。

Based on the climatic data of the 52 meteorological stations in Yunnan province from 1981 to 2011, the spatial-temporal variations of ＂Evaporation paradox＂ in Yunnan province were discussed by analyzing the seasonal and yearly potential evapotranspiration （ETo） and temperature tendency of each station in Yunuan prov- ince. The results indicated that, ~the t-ETo,y showed a decreasing-increasing trend in Yunnan province, which de- creased with the rate of 4.45 mm/a over 1981--1990 with ＂evaporation paradox＂, while the t-ETo,y increased with the rate of 2.42 mm/a from ! 991 to 201 ! without ＂evaporation paradox＂. ~ The numbers and regional distribu- tion of station which existed ＂evaporation paradox＂ were different in different periods, they mainly distributed in the middle and southeast from 1981 to 1990, while they intensively distributed in the western from 1991 to 2011 with less number stations. ~Over 1981--1990, the stations, which existed ＂evaporation paradox＂, had the cen- tralizing distribution in all seasons. The ＂evaporation paradox＂ stations mainly distributed in the middle and northwest areas in winter, and concentrated in the middle area in spring, while mainly located in the southwest in summer and autumn. Over 1991--2011, there were also a number of stations which existed ＂evaporation para- dox＂ in all seasons, but the stations distributed disorderly and theirs spatial change trends were not obvious. @ The ＂evaporation paradox＂ depended on the length of time and the long time of studying sequence might cover the ＂evaporation paradox＂ phenomenon which existed in the short period. So, the ＂evaporation paradox＂ in Yun- nan province had the characteristics of stage, seasonal and regional.