Extreme storm tide usually causes flooding of low-lying land in a coastal city. Hence, developing an efficient and accurate forecasting model for issuing a timely warning is important. In this study, an adaptive Kalma...Extreme storm tide usually causes flooding of low-lying land in a coastal city. Hence, developing an efficient and accurate forecasting model for issuing a timely warning is important. In this study, an adaptive Kalman filter-based storm tide forecasting model was proposed and applied to the inner Harbor of Macau. The model is a dynamic linear regression model with the harmonic tidal prediction, wind speed, wind direction and atmospheric pressure as its input parameters. With persistence forecast of weather assumed during the prediction period, the model was tested with 40 cases of storm tide induced by tropical cyclones in Macau between 2005 and 2012. Success was found for forecasts with lead times up to 3 hours. The proposed adaptive model is considered a practical tool for storm tide forecast in small coastal cities.展开更多
This review summarizes the rapporteur report on advances in monitoring and forecasting of rainfall associated with tropical cyclones(TCs)and its impact during 2014–18,as presented to the 10th International Workshop o...This review summarizes the rapporteur report on advances in monitoring and forecasting of rainfall associated with tropical cyclones(TCs)and its impact during 2014–18,as presented to the 10th International Workshop on TCs(IWTC-10)held in Bali,Indonesia during 5th–9th December 2022.Major physical processes that can modulate TC rainfall distribution,including topography,storm motion,vertical wind shear,and intensity,along with the fundamental physics of rain bands and clouds as simulated by numerical models,diurnal variation of rainfall,and various synoptic and mesoscale features controlling the rainfall distribution are briefly discussed.Improvements to the dynamic core and physical processes in global models are providing useable forecasts nearly up to 7 days.This report also summarizes,some tools that have been developed to predict TC rainfall.Lately there is a tendency for operational forecasting centers to utilize multi-model ensemble systems for rainfall forecasting that demonstrate superior performance than individual models,ensemble members,or even single model ensembles.Major impacts include pluvial and fluvial floods,and landslides.The techniques developed by various forecasting centers to assist in predicting and communicating the impacts associated with these events are also presented in this report.展开更多
泛洪被作为实现广播通信的最简单的技术,广泛应用于车联网VANET(vehicular Ad Hoc network)路由。然而,由于VANET中节点的快速移动以及网络拓扑动态变化,简单的泛洪容易导致大量的冗余数据包,并引发广播风暴。为此,以典型的按需式距离...泛洪被作为实现广播通信的最简单的技术,广泛应用于车联网VANET(vehicular Ad Hoc network)路由。然而,由于VANET中节点的快速移动以及网络拓扑动态变化,简单的泛洪容易导致大量的冗余数据包,并引发广播风暴。为此,以典型的按需式距离矢量路由协议AODV(Ad Hoc on-demand distance vector)为基础,提出基于概率转发的AODV路由协议,记为AODV_P。AODV_P协议利用概率转发机制替代AODV中的泛洪。节点利用距离、密度信息计算转发概率,并依据转发概率设置计时器。计时器时间越短,成为下一跳转发节点的可能性越大。仿真结果表明,提出的AODV_P能够有效降低冗余数据包,缓解广播风暴问题。与AODV协议相比,AODV_P在传输时延、数据包传输率方面得到了有效提高。展开更多
A numerical model for simulating storm surge with nested grid system has been applied to hindcast the coastal flooding on both sides of Taiwan Strait. The simulation results can be used to understand the transport var...A numerical model for simulating storm surge with nested grid system has been applied to hindcast the coastal flooding on both sides of Taiwan Strait. The simulation results can be used to understand the transport variation and the inundation distribution induced by the storm surge on the interested area during typhoon invades. The case in this study is Typhoon SEPAT, which passed through central Taiwan in 2007. The transport characteristics through Taiwan Strait under the influence of Typhoon SEPAT were discussed by comparing the field observations and numerical simulations during the typhoon period. The results indicate that the surge height of Typhoon SEPAT did not respond to the peak of wind waves accompanied with 15 hrs time lag. According to the influence of dynamical forces on the storm surge in Taiwan Strait, the onshore wind is the dominant role of coastal inundation during this typhoon event in Taiwan Strait. By observing the inundation map through the typhoon period, the coasts of Yulin County are verified to be the most serious affected area in the vicinity of Taiwan Strait.展开更多
The southern coast of the Gulf of Maine in the United States is prone to flooding caused by nor＇easters. A state-of-the-art fully-coupled model, the Simulating WAves Nearshore （SWAN） model with unstructured grids a...The southern coast of the Gulf of Maine in the United States is prone to flooding caused by nor＇easters. A state-of-the-art fully-coupled model, the Simulating WAves Nearshore （SWAN） model with unstructured grids and the ADvanced CIRCulation （ADCIRC） model, was used to study the hydrodynamic response in the Gulf of Maine during the Patriot＇s Day storm of 2007, a notable example of nor＇easters in this area. The model predictions agree well with the observed tide-surges and waves during this storm event. Waves and circulation in the Gulf of Maine were analyzed. The Georges Bank plays an important role in dissipating wave energy through the bottom friction when waves propagate over the bank from offshore to the inner gulf due to its shallow bathymetry. Wave energy dissipation results in decreasing significant wave height （SWH） in the cross-bank direction and wave radiation stress gradient, which in turn induces changes in currents. While the tidal currents are dominant over the Georges Bank and in the Bay of Fundy, the residual currents generated by the meteorological forcing and waves are significant over the Georges Bank and in the coastal area and can reach 0.3 m/s and 0.2 m/s, respectively. In the vicinity of the coast, the longshore current generated by the surface wind stress and wave radiation stress acting parallel to the coastline is inversely proportional to the water depth and will eventually be limited by the bottom friction. The storm surge level reaches 0.8 m along the western periphery of the Gulf of Maine while the wave set-up due to radiation stress variation reaches 0.2 m. Therefore, it is significant to coastal flooding.展开更多
基金supported by the Research Committee (Grant No. MYRG2014-00038-FST) of the University of Macaothe Science and Technology Development Fund (Grant No. 079/2013/A3) of the Macao SAR Government
文摘Extreme storm tide usually causes flooding of low-lying land in a coastal city. Hence, developing an efficient and accurate forecasting model for issuing a timely warning is important. In this study, an adaptive Kalman filter-based storm tide forecasting model was proposed and applied to the inner Harbor of Macau. The model is a dynamic linear regression model with the harmonic tidal prediction, wind speed, wind direction and atmospheric pressure as its input parameters. With persistence forecast of weather assumed during the prediction period, the model was tested with 40 cases of storm tide induced by tropical cyclones in Macau between 2005 and 2012. Success was found for forecasts with lead times up to 3 hours. The proposed adaptive model is considered a practical tool for storm tide forecast in small coastal cities.
文摘This review summarizes the rapporteur report on advances in monitoring and forecasting of rainfall associated with tropical cyclones(TCs)and its impact during 2014–18,as presented to the 10th International Workshop on TCs(IWTC-10)held in Bali,Indonesia during 5th–9th December 2022.Major physical processes that can modulate TC rainfall distribution,including topography,storm motion,vertical wind shear,and intensity,along with the fundamental physics of rain bands and clouds as simulated by numerical models,diurnal variation of rainfall,and various synoptic and mesoscale features controlling the rainfall distribution are briefly discussed.Improvements to the dynamic core and physical processes in global models are providing useable forecasts nearly up to 7 days.This report also summarizes,some tools that have been developed to predict TC rainfall.Lately there is a tendency for operational forecasting centers to utilize multi-model ensemble systems for rainfall forecasting that demonstrate superior performance than individual models,ensemble members,or even single model ensembles.Major impacts include pluvial and fluvial floods,and landslides.The techniques developed by various forecasting centers to assist in predicting and communicating the impacts associated with these events are also presented in this report.
文摘泛洪被作为实现广播通信的最简单的技术,广泛应用于车联网VANET(vehicular Ad Hoc network)路由。然而,由于VANET中节点的快速移动以及网络拓扑动态变化,简单的泛洪容易导致大量的冗余数据包,并引发广播风暴。为此,以典型的按需式距离矢量路由协议AODV(Ad Hoc on-demand distance vector)为基础,提出基于概率转发的AODV路由协议,记为AODV_P。AODV_P协议利用概率转发机制替代AODV中的泛洪。节点利用距离、密度信息计算转发概率,并依据转发概率设置计时器。计时器时间越短,成为下一跳转发节点的可能性越大。仿真结果表明,提出的AODV_P能够有效降低冗余数据包,缓解广播风暴问题。与AODV协议相比,AODV_P在传输时延、数据包传输率方面得到了有效提高。
文摘A numerical model for simulating storm surge with nested grid system has been applied to hindcast the coastal flooding on both sides of Taiwan Strait. The simulation results can be used to understand the transport variation and the inundation distribution induced by the storm surge on the interested area during typhoon invades. The case in this study is Typhoon SEPAT, which passed through central Taiwan in 2007. The transport characteristics through Taiwan Strait under the influence of Typhoon SEPAT were discussed by comparing the field observations and numerical simulations during the typhoon period. The results indicate that the surge height of Typhoon SEPAT did not respond to the peak of wind waves accompanied with 15 hrs time lag. According to the influence of dynamical forces on the storm surge in Taiwan Strait, the onshore wind is the dominant role of coastal inundation during this typhoon event in Taiwan Strait. By observing the inundation map through the typhoon period, the coasts of Yulin County are verified to be the most serious affected area in the vicinity of Taiwan Strait.
基金supported by the project funded by the Maine Sea Grant and National Oceanic and Atmospheric Administration(Grant No.NA10OAR4170072)the Ensemble Estimation of Flood Risk in a Changing Climate(EFRa CC)project funded by the British Council under its Global Innovation Initiative
文摘The southern coast of the Gulf of Maine in the United States is prone to flooding caused by nor＇easters. A state-of-the-art fully-coupled model, the Simulating WAves Nearshore （SWAN） model with unstructured grids and the ADvanced CIRCulation （ADCIRC） model, was used to study the hydrodynamic response in the Gulf of Maine during the Patriot＇s Day storm of 2007, a notable example of nor＇easters in this area. The model predictions agree well with the observed tide-surges and waves during this storm event. Waves and circulation in the Gulf of Maine were analyzed. The Georges Bank plays an important role in dissipating wave energy through the bottom friction when waves propagate over the bank from offshore to the inner gulf due to its shallow bathymetry. Wave energy dissipation results in decreasing significant wave height （SWH） in the cross-bank direction and wave radiation stress gradient, which in turn induces changes in currents. While the tidal currents are dominant over the Georges Bank and in the Bay of Fundy, the residual currents generated by the meteorological forcing and waves are significant over the Georges Bank and in the coastal area and can reach 0.3 m/s and 0.2 m/s, respectively. In the vicinity of the coast, the longshore current generated by the surface wind stress and wave radiation stress acting parallel to the coastline is inversely proportional to the water depth and will eventually be limited by the bottom friction. The storm surge level reaches 0.8 m along the western periphery of the Gulf of Maine while the wave set-up due to radiation stress variation reaches 0.2 m. Therefore, it is significant to coastal flooding.
