未来土地利用类型对珠江三角洲气象场的影响

Impacts of future land use on meteorological conditions over the Pearl River Delta Region

利用WRF/Noah/UCM开展未来下垫面变更的对比试验,分别对珠江三角洲区域冬季(1月)和夏季(7月)的气象场特征进行数值模拟,以探讨未来城镇化建设对区域气象条件的影响.WRF模式中控制试验使用GLC2009下垫面资料,敏感性试验使用变更后的下垫面资料.对比试验的结果表明:由于城市扩张,受下垫面类型变化的影响,地表能量平衡会发生显著变化;珠江三角洲建成区的气温将升高0.75℃(1月)及1.20℃(7月),相对湿度将下降2.61%(1月)与6.88%(7月);城市热岛效应将增强,城乡温差将升高0.21℃(1月)及0.41℃(7月);局地热力环流与背景流场叠加,将使得1月风速降低0.11m/s,而7月风速升高0.11m/s.近地面的变化可以传递到整个边界层内,并使得边界层高度抬升.

A coupled WRF/Noah/UCM model was employed to investigate the change of the underlying surface and simulate the impacts of urban expansion in the Pearl River Delta(PRD)on regional meteorological conditions in winter(January)and summer(July)in the future.The land use types were updated in the WRF model based on“the full scale strategic planning of the Pearl River Delta for the period of2014~2020”.In WRF model simulation,the GlobCover2009(GLC2009)underlying surface data were used in the control experiment,while the updated one was employed in the sensitivity experiment.Several conclusions can be drawn from this study:significant changes of surface energy balance were observed due to the change of the underlying surface types that are caused by urban expansion;urban temperatures in the PRD region increase by0.75℃and1.20℃respectively in January and in July;relative humidity decrease by2.61%and by6.88%respectively in January and in July;urban heat island effect will be strengthened;the temperature difference between urban areas and rural areas increased by0.21℃and by0.41℃respectively in January and in July;the superimposing effect of thermal circulation and the large-scale circulation resultd in decrease of the wind speed by0.11m/s in January and increase by0.11m/s in July.In addition,changes near the surface can influence the whole boundary layer and increase the boundary layer height.