An experimental study is carried out for waves passing an isolated reef terrain in a wave tank. A three-dimensional model of a representative and isolated reef terrain in the West Pacific is built. Random wave trains ...An experimental study is carried out for waves passing an isolated reef terrain in a wave tank. A three-dimensional model of a representative and isolated reef terrain in the West Pacific is built. Random wave trains with various periods and wave heights are generated by a wave maker using the improved JONSWAP spectrum. It is observed that there are different kinds of generation processes and waveforms of freak waves. The freak wave factor Hm/Hs (where Hm is the maximum wave height of wave series, and Hs is significant wave height) is analyzed in detail, in terms of the skewness, kurtosis and water depth, as well as the relationship between freak wave height H& and skewness. The freak wave factor Hm/Hs is found to be in positive correlation with the kurtosis, while larger H[x tends to be related with bigger skewness. The rapid variation of water depth, such as slope and seamount, contributes to the occurrence probability of freak waves.展开更多
There is no doubt that the UHI （urban heat island） is a mounting problem in built-up environments, due to the energy retention by surface dense building materials, leading to increased temperatures, air pollution, a...There is no doubt that the UHI （urban heat island） is a mounting problem in built-up environments, due to the energy retention by surface dense building materials, leading to increased temperatures, air pollution, and energy consumption. Much of the earlier research on the UHI has used two-dimensional （2-D） information, such as land uses and the distribution of vegetation. In the case of homogeneous land uses, it is possible to predict surface temperatures with reasonable accuracy with 2-D information. However, three-dimensional （3-D） information is necessary to analyze more complex sites, including dense building clusters. In this research, 3-D building geometry information is combined with 2-D urban surface information to examine the relationship between urban characteristics and temperature. The research includes the following stages： （1） estimating urban temperature; （2） developing a 3-D city model; （3） generating geometric parameters; and （4） conducting statistical analyses using both linear and non-linear regression models. The implications of the results are discussed, providing guidelines for policies aiming to reduce the UHI.展开更多
本文利用中尺度模式WRF-ARW(Weather Research and Forecasting Model-Advanced Research WRF)(Version 4.0)对海南岛不同天气条件下的典型海风锋个例进行了高分辨率数值模拟,通过设计局地城镇化的敏感性试验,重点分析了海南岛沿海城镇...本文利用中尺度模式WRF-ARW(Weather Research and Forecasting Model-Advanced Research WRF)(Version 4.0)对海南岛不同天气条件下的典型海风锋个例进行了高分辨率数值模拟,通过设计局地城镇化的敏感性试验,重点分析了海南岛沿海城镇化对海风锋推进的影响及其可能机制。研究结果表明:海南岛沿海城镇化造成的海风锋结构差异是热力作用和动力作用共同影响的结果;城镇下垫面的摩擦效应与城市热岛的增强阻碍海风向内陆推进,减弱了海风锋途经地区的降温增湿效应,造成海风锋位置相对滞后;而城镇化所引起的高海陆热力差异增强了海风风速及海风辐合,同时导致海风锋前的垂直上升气流和海风环流厚度也明显增强。海风锋发展不同时期,城镇化对海风锋的推进影响有所不同。海风锋发展初期,海陆热力差异引起的推动作用与摩擦效应的阻碍作用相抵消,导致海风锋的推进无明显影响;海风锋发展强盛阶段,城镇化条件下内陆城市与非城市之间的热力差异有所增强,阻碍了海风锋向内陆推进,导致海风锋内陆渗透距离减小。不同天气条件下城市化对海风锋推进的影响有所不同,相比于晴空天气,多云天气下城市与非城市的热力差异稍强,加强了城市热岛效应对海风推进的阻碍作用,导致海风锋滞后距离稍远。此外,当土地利用类型更换为城镇后,净辐射与陆气间交换能量减少,导致其潜热通量显著减小,感热通量值变大,从而升高了下垫面温度,增强了海风的垂直上升运动,进而造成边界层高度的升高。展开更多
An improved topographic database for King George Island,one of the most frequently visited regions in Antarctica,is presented.A first step consisted in combining data from differential GPS surveys gained during the au...An improved topographic database for King George Island,one of the most frequently visited regions in Antarctica,is presented.A first step consisted in combining data from differential GPS surveys gained during the austral summers 1997～1998 and 1999～2000,with the current coastline from a SPOT satellite image mosaic,topographic information from existing maps and from the Antarctic Digital Database.From this data sets,a digital terrain model (DTM) was generated using Arc/Info GIS.In a second step,a satellite image map at the scale 1∶100 000 was assembled from contour lines derived from the DTM and the satellite mosaic.A lack of accurate topographic information in the eastern part of the island was identified.Additional topographic surveying or SAR interferometry should be used to improve the data quality in that area.The GIS integrated database will be indispensable for glaciological and climatological studies and administrative and scientific purposes.In future,the application of GIS techniques will be mandatory for environmental impact studies and environmental monitoring as well as for management plans on King George Island.展开更多
interest is to make clear the occurring mechanism of the init(?) (?)ion on the limestone terrain I have been investigating (?) (?)ssions on several islands over the Ryukyu islands under the hum(?) (?) zone.The Ryukyus...interest is to make clear the occurring mechanism of the init(?) (?)ion on the limestone terrain I have been investigating (?) (?)ssions on several islands over the Ryukyu islands under the hum(?) (?) zone.The Ryukyus are composod of more than 70 isiands with (?) (?) reef limestone There are geomor(?)hological feature of var karstic initial depressions on each isiand affeeted by diff(?) crustal movement with (?)eated aplifted dro(?)ed展开更多
基金The Qingdao National Laboratory for Marine Science and Technology under contract No.QNLM20160RP0402the National Natural Science Foundation of China under contract Nos 51522902 and 51579040+1 种基金the Fundamental Research Funds for the Central Universities under contract No.DUT17ZD233the Ministry of Industry and Information Technology of China under contract No.[2016]22
文摘An experimental study is carried out for waves passing an isolated reef terrain in a wave tank. A three-dimensional model of a representative and isolated reef terrain in the West Pacific is built. Random wave trains with various periods and wave heights are generated by a wave maker using the improved JONSWAP spectrum. It is observed that there are different kinds of generation processes and waveforms of freak waves. The freak wave factor Hm/Hs (where Hm is the maximum wave height of wave series, and Hs is significant wave height) is analyzed in detail, in terms of the skewness, kurtosis and water depth, as well as the relationship between freak wave height H& and skewness. The freak wave factor Hm/Hs is found to be in positive correlation with the kurtosis, while larger H[x tends to be related with bigger skewness. The rapid variation of water depth, such as slope and seamount, contributes to the occurrence probability of freak waves.
文摘There is no doubt that the UHI （urban heat island） is a mounting problem in built-up environments, due to the energy retention by surface dense building materials, leading to increased temperatures, air pollution, and energy consumption. Much of the earlier research on the UHI has used two-dimensional （2-D） information, such as land uses and the distribution of vegetation. In the case of homogeneous land uses, it is possible to predict surface temperatures with reasonable accuracy with 2-D information. However, three-dimensional （3-D） information is necessary to analyze more complex sites, including dense building clusters. In this research, 3-D building geometry information is combined with 2-D urban surface information to examine the relationship between urban characteristics and temperature. The research includes the following stages： （1） estimating urban temperature; （2） developing a 3-D city model; （3） generating geometric parameters; and （4） conducting statistical analyses using both linear and non-linear regression models. The implications of the results are discussed, providing guidelines for policies aiming to reduce the UHI.
文摘本文利用中尺度模式WRF-ARW(Weather Research and Forecasting Model-Advanced Research WRF)(Version 4.0)对海南岛不同天气条件下的典型海风锋个例进行了高分辨率数值模拟,通过设计局地城镇化的敏感性试验,重点分析了海南岛沿海城镇化对海风锋推进的影响及其可能机制。研究结果表明:海南岛沿海城镇化造成的海风锋结构差异是热力作用和动力作用共同影响的结果;城镇下垫面的摩擦效应与城市热岛的增强阻碍海风向内陆推进,减弱了海风锋途经地区的降温增湿效应,造成海风锋位置相对滞后;而城镇化所引起的高海陆热力差异增强了海风风速及海风辐合,同时导致海风锋前的垂直上升气流和海风环流厚度也明显增强。海风锋发展不同时期,城镇化对海风锋的推进影响有所不同。海风锋发展初期,海陆热力差异引起的推动作用与摩擦效应的阻碍作用相抵消,导致海风锋的推进无明显影响;海风锋发展强盛阶段,城镇化条件下内陆城市与非城市之间的热力差异有所增强,阻碍了海风锋向内陆推进,导致海风锋内陆渗透距离减小。不同天气条件下城市化对海风锋推进的影响有所不同,相比于晴空天气,多云天气下城市与非城市的热力差异稍强,加强了城市热岛效应对海风推进的阻碍作用,导致海风锋滞后距离稍远。此外,当土地利用类型更换为城镇后,净辐射与陆气间交换能量减少,导致其潜热通量显著减小,感热通量值变大,从而升高了下垫面温度,增强了海风的垂直上升运动,进而造成边界层高度的升高。
文摘An improved topographic database for King George Island,one of the most frequently visited regions in Antarctica,is presented.A first step consisted in combining data from differential GPS surveys gained during the austral summers 1997～1998 and 1999～2000,with the current coastline from a SPOT satellite image mosaic,topographic information from existing maps and from the Antarctic Digital Database.From this data sets,a digital terrain model (DTM) was generated using Arc/Info GIS.In a second step,a satellite image map at the scale 1∶100 000 was assembled from contour lines derived from the DTM and the satellite mosaic.A lack of accurate topographic information in the eastern part of the island was identified.Additional topographic surveying or SAR interferometry should be used to improve the data quality in that area.The GIS integrated database will be indispensable for glaciological and climatological studies and administrative and scientific purposes.In future,the application of GIS techniques will be mandatory for environmental impact studies and environmental monitoring as well as for management plans on King George Island.
文摘interest is to make clear the occurring mechanism of the init(?) (?)ion on the limestone terrain I have been investigating (?) (?)ssions on several islands over the Ryukyu islands under the hum(?) (?) zone.The Ryukyus are composod of more than 70 isiands with (?) (?) reef limestone There are geomor(?)hological feature of var karstic initial depressions on each isiand affeeted by diff(?) crustal movement with (?)eated aplifted dro(?)ed
