中国黄土高原近地面气候环境演变趋势

The Evolvement Trend of Ground Climate in China Loess Plateau

为了较为全面地揭示中国黄土高原气候系统年代际演变特征,寻找近地面气候因子演变规律,利用近50年来黄土高原地区地面气象观测资料,分析该区域气候演变的主要趋势。结果表明,中国黄土高原地区气温上升以对称性变化为主,气温要素逐因子月变幅格局差别较大,其中最高气温变化复杂程度最高,最低气温复杂程度最低。降水的量和日数在上、下半年存在相反的变化趋势,6月增多明显,9月减少明显;秋季连阴雨天气时段缩短、连续无雨时段增长、过程雨量减少,春季与秋季相反;降水日数变化复杂程度最高,最大日降水量最低。地面风速明显减小,水汽上升,日照总量下降。云量、相对湿度年均量增减倾向不明显,上半年增加,下半年明显减少,春秋季反差较大。蒸发量下降幅度较大,上半年尤为明显,与众多气候因子显著相关。地温升高,夏半年表现最明显。

In order to more fully reveal decadal change characteristics of climate system in loess plateau of China, look for near-surface climate evolution, the author investigated the loess plateau area 33 climate items, with weather datum of 51 stations during 1960 to 2009 in China loess plateau, by applying weighted average and fractal dimension analysis to make clear the characters of ground climate system trend characteristic of China loess plateau. The results showed that： the temperature increased with symmetry evolvement. The trend of kinds of month temperature factor had different patter. The maximum temperature change was the most complex, so the minimum temperature was contrary. The rainfall and rain day had reverse directed trend in front a half year and behind a half year; that had obviously increased in June, so contrary in September. The continuum overcast and rainy reduced in autumn, ascended in spring; on the contrary in the connect un-rain period. In the rain climate factor, rain-day change was the most complex; the heaviest rainfall was simple. The wind speed became slow and the air vapor ascended in the loess plateau during 1960 to 2009. The sunlight time was decreased; mainly did in the spring, on the contrary in autumn. The trend of cloud and relative humidity was not inclining in the plateau; the cloud and relative humidity had increased in the front a half year, but one decreased in the behind a half year; specially different in spring and autumn. That the evaporating descended large extent particularly did in the front a half year; the evaporating had marketable correlation between other climate factors.