塔克拉玛干沙漠腹地自然沙面与人工绿地不同季节局地气候的差异性

Microclimate Variability of Natural Sand and Artificial Green Land in Different Seasons over Taklimakan Desert Hinterland

[目的]开展塔克拉玛干沙漠腹地自然沙面与人工绿地不同季节局地气候差异性研究,通过观测数据的解析,反映出沙漠与绿地区之间小气候变化的互馈机制,为沙漠区域人工绿地的可持续发展提供理论支持。[方法]利用塔克拉玛干沙漠腹地流动沙丘—人工绿地不同下垫面4个气象站的同步加密观测资料,分析自然沙面与人工绿地的小气候特征差异,初步探讨产生这些差异的原因。[结果]沙漠区对气温的升降速率响应快,绿洲区对气温的变化幅度响应显著;四季在增温时段绿洲相对于沙漠属冷岛,降温时段属热岛;夏季比湿最大,冬季最小,绿洲区相对于沙漠区在秋季湿岛效应持续时间最长,强度最大;春、夏、秋季凌晨至日出时段,绿洲上游边界呈现湿岛效应特征,绿洲下游边界四季全天均表现为湿岛效应;沙漠区域风速日变化极值出现时间早于绿洲区,风速变化范围沙漠区最大,绿洲区最小,在春、夏季,绿洲核心区风速递减率大于绿洲上游边界。[结论]下垫面的差异对小气候影响是十分显著的,绿洲区存在较强的"冷岛效应"和"湿岛效应"。

[Objective] Local microclimate variability of natural sand and artificial green land in different sea- sons over Taklimakan desert hinterland was investigated. Mutual feed mechanism of microclimate changing between natural desert and artificial green land was reflected by analysis of the observation data. The research was expected to offer theoretical support for the sustainable development of artificial green area in the desert region. [Methods] Based on the simultaneous observation data from four meteorological stations with different underlying surfaces of natural sand and artificial green land in Taklimakan desert hinterland, the microclimate different characteristics between natural sand and artificial green were analyzed, and the reasons for these differences were explored. [Results] Desert region has fast response to the up-down rate of temper- ature, while the oasis region had significant influences on the temperature variation range. In comparison with desert, oasis has cold island effect during humidification period, and has heat island effect during cooling period in four seasons. The specific humidity levels of oasis showed the maximum valued in summer, and the minimum values in winter. Beside the above mentioned, the moisture island effects of oasis last longest and strongest in the autumn. In spring, summer and autumn, the upper stream boundary was affected by moisture island effect, whereas in all four seasons, moisture island effect always existed for downstream boundary. The biggest daily variation of wind velocity in the desert occurred early and had the biggest percentage variation. Meanwhile, the oasis has the smallest one. In both spring and summer, as compared with desert, wind weaken rate in oasis is higher than that in the upstream boundary. [Conclusion] The effects of underlying surfaces on microclimate are quite conspicuous, which cause obvious ＂cold island＂ and ＂wet island＂.