我国干旱半干旱区气候变化特征及其对干湿波动的影响

Characteristics of climate change in arid and semi-arid areas of China and its influence on climatic dry-wet fluctuation

气候干湿状况是表征区域气候特征的重要指标,是在全球气候变暖背景下,水循环与陆面蒸散发作用的综合结果。本文从湿润度指数入手,结合降水与潜在蒸散的时空变化,分析了我国干旱半干旱区气候特点与干湿变化特征及对土壤湿度的影响。分析发现:近50年来,我国干旱与半干旱区均呈变湿趋势。干旱区与半干旱区潜在蒸散与降水月差值在年内出现时间上存在不一致,且干旱区明显大于半干旱区;3~9月为干旱气候区潜在蒸散与降水差值大值期,3~6月半干旱区潜在蒸散明显大于降水,7月起差值明显减小。作用分析表明,在干旱区,降水对湿润度指数的影响更大,而对于半干旱区,降水与潜在蒸散作用相当。长期以来,我国整个干旱与半干旱区大部分土壤湿度在逐渐变干,尤其是农业耕作层的浅层土壤,几乎全区域一致呈现变干趋势,说明我国干旱半干旱区农牧业生产存在较大的潜在干旱风险。

Climate wetness and dryness are important indicators of regional climate characteristics,which are the comprehensive results of the water cycle and land surface evapotranspiration in the context of global warming.Based on the wbtness index and the spatiotemporal variation of precipitation and potential evapotranspiration(PET),this paper analyzes the characteristics of climate change and climatic dry-wet variation and its effects on soil moisture in arid and semi-arid areas in China.The analysis reveals that China’s arid and semi-arid areas have become wet in the past 50 years.The monthly difference in PET and precipitation between arid and semi-arid areas is inconsistent over the year,and the arid area is obviously larger than the semi-arid area.From March to September,the PET is greater than the precipitation in the arid areas,and from March to June,the PET is greater than the precipitation in the semi-arid areas of China.Since July,the difference has decreased significantly.The wetness index is analyzed using the difference method,and the results show that precipitation has more influence on the wetness index than PET in the arid region,while precipitation and PET have similar influences in the semi-arid region.For a long time,the majority of soil moisture in arid and semi-arid areas in China has gradually become drier,especially the plough layer,which has shown a trend of becoming drier throughout the entire region,indicating that there are great potential drought risks in northern agricultural and animal husbandry production.