利用2012~2013年北京中央商务区(Central Business District,CBD)加密观测资料,分析CBD区域城市热岛(Urban Heat Island,UHI)强度日变化和空间变化特征及其影响因子。研究发现,CBD区域气温高于周边自动站气温,平均偏高0.64°C;CBD...利用2012~2013年北京中央商务区(Central Business District,CBD)加密观测资料,分析CBD区域城市热岛(Urban Heat Island,UHI)强度日变化和空间变化特征及其影响因子。研究发现,CBD区域气温高于周边自动站气温,平均偏高0.64°C;CBD区域城市热岛强度呈现夜间强、白天弱的现象,中午甚至存在"城市冷岛"现象。季节平均UHI日变化表现为:在夜间,秋季最强,冬季次之,春季和夏季较弱;在白天,夏季最强,冬季次之,春季和秋季较弱。相对于晴朗无风天气,雾、雨、大风等天气对城市热岛有抑制作用,并结合小波分析结果发现,秋季城市热岛强度强于冬季是由于冬季雾、雨、大风等天气过程发生比例较高的缘故。CBD区域城市热岛空间变化特征研究发现,花园、学校等绿地有助于缓解城市热岛效应。雾日、雨日和大风日的CBD区域城市热岛强度空间变化标准差比晴朗无风日小。展开更多
The 1-year（2009-2010） measurements are analyzed of the urban surface energy balance（SEB） obtained from the sensors located at three vertical layers of a 325-m tower in downtown Beijing.Results show that：（1） The...The 1-year（2009-2010） measurements are analyzed of the urban surface energy balance（SEB） obtained from the sensors located at three vertical layers of a 325-m tower in downtown Beijing.Results show that：（1） The measurements from the 325-m tower represent the SEB characteristics of the cities located in semi-humid warm-temperate continental monsoon climate zone.In a typical hot and rainy summer,cold and dry winter,the measured Bowen ratio is minimum in summer and maximum in winter.The Bowen ratio measured at 140 m for spring,summer,autumn,and winter are 2.86,0.82,1.17,and 4.16 respectively.（2） At the height of 140-m（in the constant flux layer）,the noontime albedo is ~0.10 for summer,~0.12 for spring and autumn,and ~0.14 for winter.The ratios of daytime sensible heat flux,latent heat flux,and storage heat flux to net radiation are 0.25,0.16,and 0.59 for clear-sky days,and 0.33,0.19,and 0.48 for cloudy days respectively.（3） Under clear-sky days,the nighttime sensible heat flux is almost zero,but the latent heat flux is greater than zero.For cloudy days,the nighttime sensible heat flux is slightly greater than the latent heat flux in winter.The nighttime upward heat flux is presumably due to the anthropogenic release（mainly latent heat for summer,while latent and sensible heat for winter）.展开更多
In order to discuss the values and daily variation characteristics of heat storage fluxes in a tropical seasonal rain forest in Xishuangbanna,the sensible and latent heat storage flux within air column,canopy heat sto...In order to discuss the values and daily variation characteristics of heat storage fluxes in a tropical seasonal rain forest in Xishuangbanna,the sensible and latent heat storage flux within air column,canopy heat storage flux,energy storage by photosynthesis and ground heat storage above the soil heat flux plate,as well as the ratios of these heat storage fluxes to the net radiation in the cool-dry,hot-dry and rainy season were compared and analyzed based on the observation data of carbon fluxes,meteorological factors and biomass within this tropical seasonal rain forest from January 2003 to December 2004.The findings showed that heat storage terms ranged significantly in the daytime and weakly in the nighttime,and the absolute values of sensible and latent heat storage fluxes were obviously greater than other heat storage terms in all seasons.In addition,the absolute values of total heat storage fluxes reached the peak in the hot-dry season,then were higher in the rainy season,and reached the minimum in the cool-dry season.The ratios of heat storage fluxes to net radiation generally decreased with time in the daytime,moreover,the sensible and latent heat storage dominated a considerable fraction of net radiation,while other heat storage contents occupied a smaller fraction of the net radiation and the peak value was not above 3.5%.In the daytime,the ratios of the total heat storage to net radiation were greater and differences in these ratios were distinct among seasons before 12:00,and then they became lower and differences were small among seasons after 12:00.The energy closure was improved when the storage terms were considered in the energy balance,which indicated that heat storage terms should not been neglected.The energy closure of tropical seasonal rain forest was not very well due to effects of many factors.The results would help us to further understand energy transfer and mass exchange between tropical forest and atmosphere.Moreover,they would supply a research basis for studying energy closure at other places.展开更多
文摘利用2012~2013年北京中央商务区(Central Business District,CBD)加密观测资料,分析CBD区域城市热岛(Urban Heat Island,UHI)强度日变化和空间变化特征及其影响因子。研究发现,CBD区域气温高于周边自动站气温,平均偏高0.64°C;CBD区域城市热岛强度呈现夜间强、白天弱的现象,中午甚至存在"城市冷岛"现象。季节平均UHI日变化表现为:在夜间,秋季最强,冬季次之,春季和夏季较弱;在白天,夏季最强,冬季次之,春季和秋季较弱。相对于晴朗无风天气,雾、雨、大风等天气对城市热岛有抑制作用,并结合小波分析结果发现,秋季城市热岛强度强于冬季是由于冬季雾、雨、大风等天气过程发生比例较高的缘故。CBD区域城市热岛空间变化特征研究发现,花园、学校等绿地有助于缓解城市热岛效应。雾日、雨日和大风日的CBD区域城市热岛强度空间变化标准差比晴朗无风日小。
基金supported by National Natural Science Foundation of China (Grant No. 41175015)the Ministry of Science and Technology of China (Grant Nos. GYHY200906026,GYHY201106050,2008BAC37B04,and 2006BAJ02A01)
文摘The 1-year（2009-2010） measurements are analyzed of the urban surface energy balance（SEB） obtained from the sensors located at three vertical layers of a 325-m tower in downtown Beijing.Results show that：（1） The measurements from the 325-m tower represent the SEB characteristics of the cities located in semi-humid warm-temperate continental monsoon climate zone.In a typical hot and rainy summer,cold and dry winter,the measured Bowen ratio is minimum in summer and maximum in winter.The Bowen ratio measured at 140 m for spring,summer,autumn,and winter are 2.86,0.82,1.17,and 4.16 respectively.（2） At the height of 140-m（in the constant flux layer）,the noontime albedo is ~0.10 for summer,~0.12 for spring and autumn,and ~0.14 for winter.The ratios of daytime sensible heat flux,latent heat flux,and storage heat flux to net radiation are 0.25,0.16,and 0.59 for clear-sky days,and 0.33,0.19,and 0.48 for cloudy days respectively.（3） Under clear-sky days,the nighttime sensible heat flux is almost zero,but the latent heat flux is greater than zero.For cloudy days,the nighttime sensible heat flux is slightly greater than the latent heat flux in winter.The nighttime upward heat flux is presumably due to the anthropogenic release（mainly latent heat for summer,while latent and sensible heat for winter）.
基金This research was supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KZCX1-SW-01-01)the National Basic Research Program of China(Grant No.2002CB412501)+1 种基金the Natural Science Foundation of Yunnan Province,China(Grant No.98C098M)We give thanks to Xishuang-banna Tropical Rainforest Ecosystem Station,the Chinese Academy of Sciences for help in this project.We offer spe-cial thanks to Associate Professor Sha Liqing for assistance with the paper.
文摘In order to discuss the values and daily variation characteristics of heat storage fluxes in a tropical seasonal rain forest in Xishuangbanna,the sensible and latent heat storage flux within air column,canopy heat storage flux,energy storage by photosynthesis and ground heat storage above the soil heat flux plate,as well as the ratios of these heat storage fluxes to the net radiation in the cool-dry,hot-dry and rainy season were compared and analyzed based on the observation data of carbon fluxes,meteorological factors and biomass within this tropical seasonal rain forest from January 2003 to December 2004.The findings showed that heat storage terms ranged significantly in the daytime and weakly in the nighttime,and the absolute values of sensible and latent heat storage fluxes were obviously greater than other heat storage terms in all seasons.In addition,the absolute values of total heat storage fluxes reached the peak in the hot-dry season,then were higher in the rainy season,and reached the minimum in the cool-dry season.The ratios of heat storage fluxes to net radiation generally decreased with time in the daytime,moreover,the sensible and latent heat storage dominated a considerable fraction of net radiation,while other heat storage contents occupied a smaller fraction of the net radiation and the peak value was not above 3.5%.In the daytime,the ratios of the total heat storage to net radiation were greater and differences in these ratios were distinct among seasons before 12:00,and then they became lower and differences were small among seasons after 12:00.The energy closure was improved when the storage terms were considered in the energy balance,which indicated that heat storage terms should not been neglected.The energy closure of tropical seasonal rain forest was not very well due to effects of many factors.The results would help us to further understand energy transfer and mass exchange between tropical forest and atmosphere.Moreover,they would supply a research basis for studying energy closure at other places.
