太行山南麓蒸发皿蒸发量的变化特征及影响因子——以济源站为例

Variation characteristics and influencing factors of pan evaporation at the southern foot of Taihang Mountain:A case study in Jiyuan station

蒸发皿蒸发量(PE)是估算陆地蒸发量及农业水资源管理的重要参数之一。太行山南麓是我国黄河重点生态区的重要组分,研究该区域蒸发皿蒸发量的变化特征及影响因子对我国林业生态工程建设及维护我国黄河流域生态安全具有重要意义。依托河南黄河小浪底地球关键带国家野外科学观测研究站、黄河小浪底森林生态系统定位研究站,以太行山南麓济源市为研究区,基于近34 a逐日气象资料,分析该地区气象要素及蒸发皿蒸发量的变化特征,通过多元回归分析蒸发皿蒸发量的影响因子。结果表明:济源市气候变化趋势整体为趋于暖湿化,升温变化率为-1.966 mm/a春夏季增温幅度高于秋冬季。该地区蒸发皿蒸发量存在明显的“蒸发悖论”现象,整体变化呈下降趋势,变化率为0.041℃/a。春季PE为增加趋势,其余季节为下降趋势,并且秋冬季PE下降趋势比夏季显著。PE在2002—2003年左右发生显著性的突变,发生突变年份前后2个时段PE均表现为在冬季略有下降,从全年尺度来看突变前后2个时段PE均表现为增加趋势,且发生突变后增加速率高于发生突变前。气温日较差减小是近34 a济源PE下降的主要原因。蒸发的能量供给(温度条件)是济源蒸发主要的限制性因素,在冬春季节水汽输送条件(饱和差、风速、日照时间等)也对蒸发有协同影响。

[Background]Pan evaporation(PE)is an important parameter for estimating land evaporation and agricultural water resources management.The southern foot of Taihang Mountain is an important component of the key ecological area along the Yellow River.Study on the variation characteristics and influencing factors of PE in this area is of great significance to maintain the ecological security of the Yellow River Basin in China.[Methods]This study took Jiyuan city in the southern foot of Taihang Mountain as the research area.Based on the meteorological data from 1980 to 2013,the variation characteristics of meteorological factors and pan evaporation in different seasons in this area were analyzed.Mann-Kendall trend test was used to test the reliability of climate tendency rate.The influencing factors of PE in different seasons were analyzed by multiple regression.[Results]1)The change rate of temperature was 0.041℃/a.The warming rate in spring and summer was higher than that in autumn and winter.The interannual fluctuation of precipitation is large.Precipitation showed a slight increasing trend,with a change rate of 6.72 mm/10 a.Precipitation decreased in spring and autumn and increased in summer and winter.2)The overall change of PE showed a downward trend,and the change rate was-1.966 mm/a)PE in spring showed an increasing trend,with a change rate of 1.732 mm/a,and the other three seasons showed a downward trend.The evaporation in autumn decreases the most significantly,followed by winter.The change rates of PE in autumn and winter were-2.173 mm/a and-1.029 mm/a respectively.PE had an abrupt change around 2003.In the two periods before and after abrupt change year,PE declined slightly in winter,and showed an increasing trend on a yearly scale.The increase rate after the abrupt change was higher than that before the abrupt change.4)The main influencing factors of PE were diurnal temperature range(DTR)and vapor pressure deficit(D)in spring,the DTR and average temperature in summer,DTR in autumn,DTR and D in winter.DTR had an obvious effect on PE in all seasons.Wind speed and sunshine duration only had effects on PE in winter.[Conclusions]The climate change in Jiyuan tends to be warmer and wetter over the past 34 years.There is an obvious phenomenon of“evaporation paradox”in Jiyuam.PE shows a downward trend.The decrease of diurnal temperature range is the main reason for the decline of PE.The energy supply of evaporation is the main limiting factor of evaporation,and the water vapor transmission conditions also have a synergistic effect on evaporation in winter and spring.