21世纪初中国北方半干旱区土地利用变化对地表温度的影响

Impact of Land Use and Cover Change in the Semi-arid Regions of China on the Temperature in the Early 21st Century

利用区域模式WRF（Weather Research and Forecasting）模拟分析了21世纪初期2001~2010年中国北方半干旱区土地利用变化对地表温度影响,通过给出区域尺度的人类活动影响气候变化的定量表达,有助于我们理解中国北方半干旱区气候变化的归因,也将对我国科学规划土地利用、合理开展有序人类活动具有一定的参考价值。研究结果表明：农田扩张、植树造林和草地恢复3类土地利用与覆盖变化（land use and cover change,LUCC）现象对格点尺度多年平均温度的影响均呈现负效应。农田扩张导致当地多年平均温度降低0.11°C,夏季和冬季分别降温0.39°C和0.06°C。植树造林格点的多年平均温度降低0.33°C,冬季强于夏季,冬季平均温度减小0.24°C,夏季减小0.15°C。草地恢复使得格点年平均温度降低0.41°C,夏季降低0.58°C,冬季减小0.51°C。LUCC对最低温度的影响强于最高温度,并且由于最低温度减小使得大部分地区日较差显著增大。LUCC导致的局地温度变化与同期背景温度的变幅相当,但对区域平均温度的影响很小。一方面由于LUCC格点占区域的面积很小,另一方面由于正、负温度效应在区域平均的过程中相互抵消,使得LUCC对区域温度变化的影响微乎其微,21世纪初期现实LUCC对地表温度的影响主要限于局地。

The impacts of land use and cover change（LUCC） in the early 21 st century on the temperature in the semi-arid regions of China were simulated using the WRF model. Determining the contribution rate of regional-scale LUCC on climate warming can improve and deepen our understanding of climate change attribution, which can in turn provide an important scientific basis for climate warming mitigation through the regulation of human activity. The simulated results show that the three main types of LUCC phenomena in the semi-arid regions, including farmland expansion, afforestation, and grassland restoration, all appear to have had negative effects on local-scale surface air temperature. Farmland expansion resulted in a decrease in local annual mean temperature by 0.11°C, with the summer and winter values being 0.39 °C and 0.06 °C, respectively. Afforestation reduced local annual mean temperature by 0.33 °C, with winter witnessing stronger cooling than summer（0.24 °C and 0.15 °C, respectively）. Grassland restoration resulted in a decrease in local annual mean temperature by 0.41 °C, with the values for summer and winter being 0.58 °C and 0.51 °C, respectively. The influence of LUCC on the minimum temperature was more than the maximum temperature; moreover, the diurnal temperature range increased, mainly due to the decrease in minimum temperature. The local temperature changes caused by LUCC were comparable with the grid-scale background temperature changes, while the impact of LUCC on the regional average temperature was negligible. On the one hand, the share of LUCC grids was small; while on the other hand, the positive and negative effects in the process of regional averaging offset each other. Therefore, the influence of actual LUCC on temperature was mainly limited to the local scale.