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1.
Storm surge induced by hurricane is a major threat to the Gulf Coasts of the United States. A numerical modeling study was conducted to simulate the storm surge during Hurricane Michael, a category 5 hurricane that landed on the Florida Panhandle in 2018. A high-resolution model mesh was used in the ADCIRC hydrodynamic model to simulate storm surge and tides during the hurricane. Two parametric wind models, Holland 1980 model and Holland 2010 model, have been evaluated for their effects on the accuracy of storm surge modeling by comparing simulated and observed maximum water levels along the coast. The wind model parameters are determined by observed hurricane wind and pressure data. Results indicate that both Holland 1980 and Holland 2010 wind models produce reasonable accuracy in predicting maximum water level in Mexico Beach, with errors between 1 and 3.7%. Comparing to the observed peak water level of 4.74 m in Mexico Beach, Holland 1980 wind model with radius of 64-knot wind speed for parameter estimation results in the lowest error of 1%. For a given wind model, the wind profiles are also affected by the wind data used for parameter estimation. Away from hurricane eye wall, using radius of 64-knot wind speed for parameter estimation generally produces weaker wind than those using radius of 34-knot wind speed for parameter estimation. Comparing model simulated storm tides with 17 water marks observed along the coast, Holland 2010 wind model using radius of 34-knot wind speed for parameter estimation leads to the minimum mean absolute error. The results will provide a good reference for researchers to improve storm surge modeling. The validated model can be used to support coastal hazard mitigation planning.
相似文献2.
Probability-based assessment of hurricane damage costs for coastal communities is vital for policy-makers and insurers. The uncertainties associated with hurricane damage costs include both the inherent uncertainty due to the random nature of hurricane process and the model uncertainty of the mathematical representation of hurricane damage (vulnerability model). The hurricane vulnerability model has traditionally been modeled as a deterministic function of hurricane wind speed in the literature, without considering the effect of vulnerability model uncertainty on hurricane damage assessment. This paper develops two methods to assess the hurricane damage costs in the presence of vulnerability model uncertainty. To account for the non-stationarity in hurricane actions due to the potential impact of climate change, the hurricane occurrence process is modeled as a non-stationary Poisson process and the hurricane intensity is assumed to vary in time with time-variant statistical parameters of hurricane wind speed. A case study of Miami-Dade County, Florida, is conducted to illustrate the proposed methods and to investigate the impact of vulnerability model uncertainty on hurricane damage costs. 相似文献
3.
Ping Zhu 《Natural Hazards》2008,47(3):577-591
Hurricane wind damage constitutes the largest percentage of catastrophic insured losses in the US. Yet the complicated wind
structures and their changes are not fully understood and, thus, have not been considered in current risk catastrophic models.
To obtain realistic landfall hurricane surface winds, a large eddy simulation (LES) framework in a weather forecasting mode
has been developed from a multiple nested Weather Research & Forecasting (WRF) model to explicitly simulate a spectrum of
scales from large-scale background flow, hurricane vortex, mesoscale organizations, down to fine-scale turbulent eddies in
a unified system. The unique WRF-LES enables the high resolution data to be generated in a realistic environment as a hurricane
evolves. In this paper, a simulation of the landfalling Hurricane Katrina is presented to demonstrate various features of
the WRF-LES. It shows that the localized damaging winds are caused by the large eddy circulations generated in the hurricane
boundary layer. With a sufficient computational power, WRF-LES has the potential to be developed into the next generation
operational public wind-field model for hurricane wind damage mitigation. 相似文献
4.
A minimal three-dimensional hurricane model formulated on an \(f\) -plane is used to investigate the asymmetries that develop when a model storm is subjected to ambient vertical wind shear. The asymmetries that form in the moist version of the model have a different structure to those that form in a dry version. In the moist case, there are two competing factors that influence the inner-core asymmetries: vertical wind shear and frictional convergence in the boundary layer. We show that the relative importance of these factors is different in the different stages of vortex evolution and different also in the core region compared with the outer region of the vortex. In the developing stage, the patterns of vertical velocity and temperature deviation above the boundary layer are primarily determined by the shear. When saturation occurs in the core region, the vortex rapidly intensifies and the upper and lower portions of the vortex become strongly coupled so that there is little tilt of the core region. In the mature stage, ascent associated with frictional convergence in the core tends to dominate the vertical motion field induced by the shear, but there are individual times when the patterns of ascent at the top of the boundary layer and at the upper level differ significantly. These times coincide mostly with fluctuations in the vortex track, which, in turn, must be influenced by asymmetries in the horizontal flow in the vortex. Even though the inner core of the vortex becomes upright with the onset of deep moist convection, the outer regions continue to have a significant tilt. Outside the core region, the asymmetries in the pattern of vertical motion above the boundary layer are associated primarily with the tilt of the outer vortex. 相似文献
5.
Randhir Singh P. K. Pal C. M. Kishtawal P. C. Joshi 《Journal of Earth System Science》2005,114(4):427-436
The initialization scheme designed to improve the representation of a tropical cyclone in the initial condition is tested
during Orissa super cyclone (1999) over Bay of Bengal using the fifth-generation Pennsylvania State University — National
Center for Atmospheric Research (Penn State — NCAR) Mesoscale Model (MM5). A series of numerical experiments are conducted
to generate initial vortices by assimilating the bogus wind information into MM5. Wind speed and location of the tropical
cyclone obtained from best track data are used to define maximum wind speed, and centre of the storm respectively, in the
initial vortex. The initialization scheme produced an initial vortex that was well adapted to the forecast model and was much
more realistic in size and intensity than the storm structure obtained from the NCEP analysis. Using this scheme, the 24-h,
48-h, and 72-h forecast errors for this case was 63, 58, and 46 km, respectively, compared with 120, 335, and 550 km for the
non-vortex initialized case starting from the NCEP global analysis. When bogus vortices are introduced into initial conditions,
the significant improvements in the storm intensity predictions are also seen.
The impact of the vortex size on the structure of the initial vortex is also evaluated. We found that when the radius of maximum
wind (RMW) of the specified vortex is smaller than that of which can be resolved by the model, the specified vortex is not
well adapted by the model. In contrast, when the vortex is sufficiently large for it to be resolved on horizontal grid, but
not so large to be unrealistic, more accurate storm structure is obtained. 相似文献
6.
Bin Pei Weichiang Pang Firat Y. Testik Nadarajah Ravichandran Fangqian Liu 《Natural Hazards》2014,74(2):375-403
Combined effects of hurricane wind and surge can pose significant threats to coastal cities. Although current design codes consider the joint occurrence of wind and surge, information on site-specific joint distributions of hurricane wind and surge along the US Coast is still sparse and limited. In this study, joint hazard maps for combined hurricane wind and surge for Charleston, South Carolina (SC), were developed. A stochastic Markov chain hurricane simulation program was utilized to generate 50,000 years of full-track hurricane events. The surface wind speeds and surge heights from individual hurricanes were computed using the Georgiou’s wind field model and the Sea, Lake and Overland Surges from Hurricanes (SLOSH) model, respectively. To validate the accuracy of the SLOSH model, the simulated surge levels were compared to the surge levels calculated by another state-of-the-art storm surge model, ADCIRC (Advanced Circulation), and the actual observed water elevations from historical hurricane events. Good agreements were found between the simulated and observed water elevations. The model surface wind speeds were also compared with the design wind speeds in ASCE 7-10 and were found to agree well with the design values. Using the peak wind speeds and maximum surge heights, the joint hazard surfaces and the joint hazard maps for Charleston, SC, were developed. As part of this study, an interactive computer program, which can be used to obtain the joint wind speed and surge height distributions for any location in terms of latitude and longitude in Charleston area, was created. These joint hazard surfaces and hazard maps can be used in a multi-hazard design or risk assessment framework to consider the combined effects of hurricane wind and surge. 相似文献
7.
Anthropogenic effects and climate change threats on the flood diversion of Erchung Floodway in Tanshui River,northern Taiwan 总被引：1，自引：0，他引：1
Hurricanes pose serious threats to people and infrastructure along the United States Gulf and Atlantic coasts. The risk of the strongest hurricane winds over the North Atlantic basin is analyzed using a statistical model from extreme value theory and a tessellation of the domain. The spatial variation in model parameters is shown, and an estimate of the limiting strength of hurricanes at locations across the basin is provided. Quantitative analysis of the variation is done using a geographically weighted regression with regional sea surface temperature as a covariate. It is found that as sea surface temperatures increase, the expected hurricane wind speed for a given return period also increases. 相似文献
8.
Numerical simulation of sea breeze characteristics observed at tropical coastal site,Kalpakkam 总被引：1，自引：0，他引：1
Sea breeze characteristics around Kalpakkam tropical coastal site are studied using an Advanced Regional Prediction System
(ARPS) mesoscale model, which is non-hydrostatic, compressible atmospheric prediction model following the terrain coordinate
system. Various options such as surface physics, atmospheric radiation physics, Coriolis force, microphysics, cumulus parameterization
and 1.5 level TKE closure scheme for diffusion are included in the model.
A joint meteorological field experiment was carried out by IITM-Pune and IGCAR at Kalpakkam by deploying state-of-the-art
sensors and tether balloon systems for observing the height profiles of meteorological parameters. The data obtained from
the field experiment are used here to compare the results from numerical simulations. From the simulated results, it is seen
that duration of the sea breeze is 6 hours which agrees well with the observations. The height of the Thermal Internal Boundary
Layer (TIBL) is also simulated from the vertical profiles of potential temperature. Simulated wind speed and wind directions
are compared with the 50 m tower data and potential temperature profiles are compared with the kytoon data. Results are in
good agreement with the observed values except during night time wherein a small difference is seen in the wind speed. 相似文献
9.
风流场对于局地条件下地-气能量交换过程与强度影响显著,同时也是多年冻土区对流调控类冷却路基的关键环境边界。结合现场监测与数值模拟,对高海拔冻土路基周边风流场进行特征区划研究并考察路基高度的影响。结果表明：坡前扰动区为低风速区,3 m路基高度条件下迎风坡坡脚0.5~2.0 m高度范围内风速约为环境风速的30%。路基上部为高风速区,迎风坡路肩风速明显大于环境、路面中部及背风坡风速。背风坡坡后扰动区为低风速区,靠近坡脚区域受气流辐散效应作用形成涡旋区,整体风速仅为环境风速的30%。涡旋区水平范围随路基高度增加呈线性增加,3 m路基高度条件下涡旋区水平范围约为12 m。分离式路基即两幅路基并行条件下,受前幅路基影响后幅路基坡前风速下降明显,以两幅路基坡前风速差值不超过环境风速的10%（0.35 m·s-1）为标准,3 m路基高度条件下两幅路基最小间距为60 m。因此,在路基工程的修建过程中为减少路基间的遮挡所造成的两幅路基间的对流换热强度差异,分离式对流换热类冷却路基的现场修建间距应不低于60 m。 相似文献
10.
选取国内外常用的水动力学模型(EFDC)和典型的浅水湖泊(太湖),采用拉丁超立方取样(LHS),研究湖泊水动力模块中常用的5个重要参数(风拖曳系数、床面粗糙高度、涡粘性系数、紊流扩散系数以及风遮挡系数)对湖体水位和流速的影响。结果表明:针对大型浅水湖泊,湖泊岸线形状和湖底地形、湖泊周围地形、湖泊水面风场对模拟结果产生决定性影响。尤其是在湖湾区和周边地形比较复杂的地区,风场参数对水动力模拟结果不确定性的贡献率最大。在垂向上,表层流速受到参数不确定性的影响最大,底层次之,中层最小。床面粗糙高度对水动力模拟结果不确定性贡献率较风场参数要小,水体涡粘滞系数和扩散系数影响则更小。故在选择大型浅水湖泊水动力模型参数时,要充分考虑湖泊岸线和周围地形,着重率定风场参数以及床面粗糙高度。 相似文献
11.
A mathematical model has been developed to forecast or hindcast wind, waves, and longshore currents during the passage of a coastal storm. Storm intensity is a function of the barometric pressure gradient which is modeled by rotating an inverted normal curve around the center of an ellipse. The length and orientation of the major and minor axes of the ellipse control the size and shape of the storm. The path of the storm is determined by a sequence of storm positions for the hindcast mode, and by interpolated positions assuming constant speed and direction for the forecast mode. The site location, shoreline orientation, and nearshore bottom slope provide input data for the shore position. The geostrophic wind speed and direction at the shore site are computed from the latitude and barometric pressure gradient. The geostrophic wind is converted into surface wind speed and direction by applying corrections for frictional effects over land and sea. The surface wind speed and direction, effective fetch, and wind duration are used to compute wave period, breaker height, and breaker angle at the shore site. The longshore current velocity is computed as a function of wave period, breaker height and angle, and nearshore slope. The model was tested by comparing observed data for several coastal locations with predicted values for wind speed, wave period and height, and longshore current velocity. Forecasts were made for actual storms and for hypothetical circular and elliptical storms. 相似文献
12.
Alen Alexanderian Justin Winokur Ihab Sraj Ashwanth Srinivasan Mohamed Iskandarani William C. Thacker Omar M. Knio 《Computational Geosciences》2012,16(3):757-778
Polynomial chaos (PC) expansions are used to propagate parametric uncertainties in ocean global circulation model. The computations
focus on short-time, high-resolution simulations of the Gulf of Mexico, using the hybrid coordinate ocean model, with wind
stresses corresponding to hurricane Ivan. A sparse quadrature approach is used to determine the PC coefficients which provides
a detailed representation of the stochastic model response. The quality of the PC representation is first examined through
a systematic refinement of the number of resolution levels. The PC representation of the stochastic model response is then
utilized to compute distributions of quantities of interest (QoIs) and to analyze the local and global sensitivity of these
QoIs to uncertain parameters. Conclusions are finally drawn regarding limitations of local perturbations and variance-based
assessment and concerning potential application of the present methodology to inverse problems and to uncertainty management. 相似文献
13.
Makarand A. Kulkarni Sunil Patil G. V. Rama P. N. Sen 《Journal of Earth System Science》2008,117(4):457-463
Prediction of wind speed in the atmospheric boundary layer is important for wind energy assessment, satellite launching and
aviation, etc. There are a few techniques available for wind speed prediction, which require a minimum number of input parameters.
Four different statistical techniques, viz., curve fitting, Auto Regressive Integrated Moving Average Model (ARIMA), extrapolation
with periodic function and Artificial Neural Networks (ANN) are employed to predict wind speed. These methods require wind
speeds of previous hours as input. It has been found that wind speed can be predicted with a reasonable degree of accuracy
using two methods, viz., extrapolation using periodic curve fitting and ANN and the other two methods are not very useful. 相似文献
14.
Most tropical cyclones have very few observations in their vicinity. Hence either they go undetected in standard analyses
or are analyzed very poorly, with ill defined centres and locations. Such initial errors obviously have major impact on the
forecast of cyclone tracks using numerical models. One way of overcoming the above difficulty is to remove the weak initial
vortex and replace it with a synthetic vortex (with the correct size, intensity and location) in the initial analysis. The
objective of this study is to investigate the impact of introducing NCAR–AFWA synthetic vortex scheme in the regional model
MM5 on the simulation of a tropical cyclone formed over the Arabian Sea during November 2003. Two sets of numerical experiments
are conducted in this study. While the first set utilizes the NCEP reanalysis as the initial and lateral boundary conditions,
the second set utilizes the NCAR–AFWA synthetic vortex scheme. The results of the two sets of MM5 simulations are compared
with one another as well as with the observations and the NCEP reanalysis. It is found that inclusion of the synthetic vortex
has resulted in improvements in the simulation of wind asymmetries, warm temperature anomalies, stronger vertical velocity
fields and consequently in the overall structure of the tropical cyclone. The time series of the minimum sea level pressure
and maximum wind speed reveal that the model simulations are closer to observations when synthetic vortex was introduced in
the model. The central minimum pressure reduces by 17 hPa while the maximum wind speed associated with the tropical cyclone
enhances by 17 m s −1 with the introduction of the synthetic vortex. While the lowest central pressure estimated from the satellite image is 988 hPa,
the corresponding value in the synthetic vortex simulated cyclone is 993 hPa. Improvements in the overall structure and initial
location of the center of the system have contributed to considerable reduction in the vector track prediction errors ie.
642 km in 24 h, 788 km in 48 h and 1145 km in 72 h. Further, simulation with the synthetic vortex shows realistic spatial
distribution of the precipitation associated with the tropical cyclone. 相似文献
15.
为了研究透壁式通风管-块石复合气冷路基的降温效果,针对年均气温约-3.5℃,平均风速2.5 m·s-1,主导风向为西北方向的高原环境条件开展室内模型试验,分析了单一块石气冷路基和透壁式通风管-块石复合气冷路基的孔隙空气对流速度、特征点地温变化过程以及模型整体温度场变化过程.结果表明：在透壁式通风管的疏导作用下,透壁式通风管与块石层的复合结构能够起到强化路基体对流的效果,复合路基块石孔隙中的空气流速比单一块石路基提高约20%,由此导致复合路基模型底部的降温幅度是单一块石路基模型的2.2倍.模型整体温度场表明,复合路基能够起到储存冷量、降低下伏多年冻土地温的作用. 相似文献
16.
A number of sensitivity experiments have been conducted to investigate the influence of using synthetic data on cyclone forecasts
by a global spectral model. Some well known vortices have been used and the generated wind and pressure profiles are compared.
It is found that the Rankine vortex and Holland’s vortex show the best representation of cyclonic circulation. Hence these
two vortices are used in the sensitivity studies to simulate two cyclones, one of May 1979 and the other of August 1979. For
this purpose the FGGE level-III b data set, produced at ECM WF, UK is used. Synthetic temperature and humidity data are also
introduced to make the cyclones more realistic.
With the use of Holland’s vortex the system is found to move faster than with the Rankine vortex. Also, the tracks of the
cyclones simulated with Rankine vortex are found to be on the left side of the observed track while that of Holland’s vortex
is on the right side of the observed track. However, substantial filling up of the systems are noticed with introduction of
diabatic initialization of the mass and velocity fields and the forecasts of both the vortices behave differently. It is suggested
that proper selection of synthetic vortex, initialization scheme and resolution of the model are very important for better
forecast of cyclones. 相似文献
17.
通过水槽试验研究浅水非线性波作用下沙纹床面底层流动特性,利用CCD图像技术观测分析非对称沙纹的形成和演化规律。利用声学多普勒测速仪(ADV)测量非对称沙纹底床上的流场,得到了不同波高、周期、水深条件下的沙纹峰顶和谷底断面的瞬时速度。试验结果分析表明,浅水非线性波作用下床面上形成非对称沙纹,其近底流速具有较强紊动特性,随着距床面距离的增大紊动强度逐渐减弱。在水流方向改变时,沙纹背部具有明显漩涡运动。沙纹背后形成的漩涡能起到维持沙纹的作用。浅水非线性波作用下,沙纹的形成原因主要是床面泥沙颗粒在非对称流动和床面近壁粘性底层中漩涡结构动力作用下,作受迫摆动、推移所致。 相似文献
18.
Sand transport model of barchan dune equilibrium 总被引：9，自引：0，他引：9
Erosion and deposition over a barchan dune near the Salton Sea, California, is modelled by book-keeping the quantity of sand in saltation following streamlines of transport. Field observations of near-surface wind velocity and direction plus supplemental measurements of the velocity distribution over a scale model of the dune are combined as input to Bagnold-type sand-transport formulae corrected for slope effects. A unidirectional wind is assumed. The resulting patterns of erosion and deposition compare closely with those observed in the field and those predicted by the assumption of equilibrium (downwind translation of the dune without change in size or geometry). Discrepancies between the simulated results and the observed or predicted erosional patterns appear to be largely due to natural fluctuation in the wind direction. Although the model includes a provision for a lag in response of the transport rate to downwind changes in applied shear stress, the best results are obtained when no delay is assumed. The shape of barchan dunes is a function of grain size, velocity, degree of saturation of the oncoming flow, and the variability in the direction of the oncoming wind. Smaller grain size or higher wind speed produce a steeper and more blunt stoss-side. Low saturation of the inter-dune sandflow produces open crescent-moon-shaped dunes, whereas high saturation produces a whaleback form with a small slip face. Dunes subject to winds of variable direction are blunter than those under unidirectional winds. The size of barchans could be proportional to natural atmospheric scales, to the age of the dune, or to the upwind roughness. The upwind roughness can be controlled by fixed elements or by the sand is saltation. In the latter case, dune scale may be proportional to wind velocity and inversely proportional to grain size. However, because the effective velocity for transport increases with grain size, dune scale may increase with grain size as observed by Wilson (1972). 相似文献
19.
Sergey A. Arsen’yev 《地学前缘(英文版)》2011,2(2):215-221
Recent advances in modeling of tornadoes and twisters consist of significant achievements in mathematical calculation of occurrence and evolution of a violent F5-class tornado on the Fujita scale, and four-dimensional mathematical modeling of a tornado with the fourth coordinate time multiplied by its characteristic velocity.Such a tornado can arise in a thunderstorm supercell filled with turbulent whirlwinds.A theory of the squall storms is proposed.The squall storm is modeled by running perturbation of... 相似文献
20.
The present study aims to investigate the relationships between several soil parameters (texture, organic matter and CaCO3 content) and the threshold wind velocity and erodibility of different soil types. Our aim was to determine the role of these soil parameters play in soil loss due to wind erosion and also to statistically evaluate these correlations. The erodibility studies were carried out in wind tunnel experiments, and the resulting data were analysed with multiple regression analysis and the Kruskal-Wallis test. We found that both the threshold wind speed and the erodibility of soils were mostly determined by silt fraction (0.05–0.02 mm), while sand fractions had a lesser effect on it. Our experiences with organic matter and CaCO3 similar, i.e. in spite of their correlation with the erosion, their contribution was not significant in the multivariate regression model. Consequently, based on mechanical composition of soils, one can predict threshold wind velocity and erodibility of soils. 相似文献