黄土高原地区土地覆盖变化对气候的反馈作用数值模拟

Numerical simulation of the feedback of land-cover change on regional climate in the Loess Plateau

区域尺度土地覆盖变化是自然变化和人类活动共同驱动的结果,同时又对区域气候环境产生反馈。利用欧洲中值数值预报中心(ECMWF)ERA-Interim再分析资料,驱动RegCM4.5区域气候模式,进行了两个时间段(1980-2014、2005-2014)的数值模拟试验。以1∶250 000土地利用图为基础,结合植被图、土壤图制作具有高精度、极强现势性的土地覆盖资料,区域模式中陆面过程模式采用BATS,模拟了现实的土地覆盖改变对气候要素的影响,分析了黄土高原地区土地覆盖变化对气候的反馈作用。结果表明:(1)RegCM4.5不但能够较好描述黄土高原气温、降水的时间空间分布特征,也能够模拟土地覆盖变化对黄土高原局地气候变化的反馈。(2)不同土地覆盖变化特征对气候反馈作用不同,荒漠化会引起局部地区气温升高和降水减少,并通过正反馈机制,致使自然植被生长发育受阻;水域旱化会导致夏季气温升高和降水增加,从而加剧干旱洪涝灾害风险;草地覆盖增加会导致春夏季降水量与气温的降低,秋冬季降水量与气温升高。(3)土地覆盖变化对气温与降水的影响在夏季较强。该研究可促进对黄土高原生态治理环境效应的理解,也能深化对土地利用-气候变化之间互馈作用的过程认识,并为区域生态建设对策选择提供参考。

Land-cover change is driven by the natural climate change and human activities,in turn,the land-cover change also has impact on regional climate.The processes of land-cover change affected the regional climate through exchanges of materials （e.g.,water） and energy across the land-atmosphere interface,and the processes play an important role in regional ecological construction.In this paper,we conducted two numerical simulations （1980-2014,2005-2014） using Regional Climate model （RegCM） version 4.5,which are driven by ERA-Interim reanalysis data produced by the European Centre for Medium-Range Weather Forecasts （ECMWF）.A set of land-cover data with high spatial resolution and timeliness had been built based on the 1：250 000 land-use data,the map of vegetation and the map of soil.Then the changes in temperature and precipitation that influenced by the actual land-cover changes were simulated with the land surface process model Biosphere-Atmosphere Transfer Scheme （BATS） in the Loess Plateau.The feedback of land-cover change and the surface energy budget were analyzed on regional climate.The implications are follows：（1） RegCM4.5 can reproduce the observed annual cycle of mean temperature and precipitation well,as well as the feedback of water-heat conditions under the land-cover change on the Loess Plateau.（2） Land-cover change has stronger impact on precipitation and temperature in summer.The feedback is different under different types of land-cover change.（3） Desertification can lead to increase of temperature and decrease of precipitation,which would hinder the natural vegetation recovery.（4） Reclamation will lead to increase of temperatures and precipitation in summer,which may cause more drought and flood events.（5） Grassland amplification will lead to decrease of temperature and precipitation in spring and summer and increase of temperatures and precipitation in autumn and winter.The conclusion can deepen the understanding of the effects of ecological environment change in loess plateau,and the process of reciprocal effects between land-use and climate change.The conclusion provides a reference for selection of regional ecological construction policy.