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1.
The complex siliciclastic aquifer system underneath the Baton Rouge area, Louisiana (USA), is fluvial in origin and is characterized by strongly binary heterogeneity of sand units and mudstones as pervious and impervious hydrofacies. The east–west trending Baton Rouge fault and Denham Springs-Scotlandville fault cut across East Baton Rouge Parish and play an important role in groundwater flow and aquifer salinization. This study reconstructs the Baton Rouge aquifer-fault system architecture for a Miocene-Pliocene depth interval that consists of the 1,200-foot sand to the 2,000-foot sand. The results show the spatial extent of sand units, their interconnections, and flow paths within each sand unit. The regional-scale formation dip, the sand unit offset on the faults, and the volumetric spatial extent of individual sand units are quantified. The study reveals the complexity of the Baton Rouge aquifer-fault system where the sand deposition is non-uniform, different sand units are interconnected, the sand unit displacement on the faults is significant, and the spatial distribution of flow pathways through the faults is sporadic. The identified locations of flow pathways through the Baton Rouge fault provide useful information on possible windows for saltwater intrusion from the south. 相似文献
2.
The rapid intensification of Hurricane Charley (2004) near landfall is studied using the fifth-generation Pennsylvania State
University/National Center for Atmospheric Research (PSU/NCAR) Mesoscale Model (MM5) and its adjoint system for both vortex
initialization and forecasts. A significant improvement in both track and intensity forecasts is achieved after an ill-defined
storm vortex, derived from large-scale analysis, in the initial condition is replaced by the vortex generated by a four-dimensional
data variational (4D-Var) hurricane initialization scheme. Results from numerical experiments suggest that both the inclusion
of the upper-level trough and the use of high horizontal resolution (6 km) are important for numerical simulations to capture
the observed rapid intensification as well as the size reduction during the rapid intensification of Hurricane Charley. The
approach of the upper-level trough significantly enhanced the upper-level divergence and vertical motion within simulated
hurricanes. Small-scale features that are not resolvable at 18 km resolution are important to the rapid intensification and
shrinking of Hurricane Charley (2004). Numerical results from this study further confirm that the theoretical relationship
between the intensification and shrinking of tropical cyclones based on the angular momentum conservation and the cyclostrophic
approximation can be applied to the azimuthal mean flows. 相似文献
3.
One hundred school districts were surveyed along the Atlantic and Gulf of Mexico coasts from North Carolina to Texas. Nearly all had recent experience with a tropical storm or hurricane and had hurricane plans in place. About half teach hurricane preparedness to students and 85 % train staff members in hurricane preparedness. Sources of information about cyclone threats were the National Hurricane Center (91 %), local television news (74 %), The Weather Channel (67 %), and the internet (67 %). Only 36 % would cancel classes for a hurricane warning but 89 % would cancel classes for a mandatory evacuation. Most districts (75 %) would use schools as storm shelters, and 92 % would use school busses to assist in community evacuations. Districts with a higher percentage of Hispanic population provided hurricane information in Spanish. Larger school districts were less likely to cancel classes in the middle of the day for a storm threat. Districts with higher home values were less likely to use school busses for evacuations, and smaller school districts were less likely to provide schools as storm shelters. There were no other significant associations between hurricane preparedness of the districts and district demographic variables of poverty, percent black, percent Hispanic, population, district size, or median home values. 相似文献
4.
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
5.
The paper presents comprehensive statistical analyses of winds and water levels in Mobile Bay, Alabama, based on long-term meteorological and tidal observations at several locations. A procedure has been developed to select the most probable parent distribution function from a list of candidate distributions. The theoretical functions that fit the data best enable us to predict the extreme values of winds and water levels at different return periods. We have demonstrated the importance of dividing the winds into hurricane and nonhurricane seasons and separating astronomical tides from weather-driven water level changes. The statistical analysis suggests that the wind speed averaged over 8 min at Dauphin Island, Alabama, at the 100-year return period would be 48.9 m/s, which is equivalent to a sustained 1-min wind of 205 km/h, a very strong category 3 hurricane on the Saffir-Simpson scale. The probability distribution models predict that the 100-year maximum water level would be 3.23 m above the mean lower low water (MLLW) level at the bay entrance and 3.41 m above the MLLW level near the head of the bay, respectively. Extremely low water levels important to navigation are also found. Application of the predicted extreme winds and surges is illustrated through the development of a storm wave atlas in the estuary. It is expected that the methodology and results presented in this paper will benefit the management and preservation of the ecosystems and habitats in Mobile Bay. 相似文献
6.
J. C. Senkbeil D. M. Brommer P. G. Dixon M. E. Brown K. Sherman-Morris 《Natural Hazards》2010,54(1):141-158
Hurricane evacuations in the United States are costly, chaotic, and sometimes unnecessary. Many coastal residents consider
evacuation after viewing a forecasted graphic of where the storm is anticipated to make landfall. During the evacuation process,
hurricane tracks commonly deviate from the forecasted landfall track and many evacuees may not pay attention to these track
deviations after evacuating. Frequently, a disconnect may occur between the actual landfall track, the official forecasted
track, and the perceived track of each individual as they made their evacuation decision. Specifically for evacuees, a shift
in track may decrease the hazards associated with a landfalling hurricane since evacuees perceive their threat level to be
high at the time of evacuation. Using survey data gathered during the evacuation from Hurricane Gustav (2008) in coastal Louisiana
(USA), we calculated a type of Z-score to measure the distance error between each evacuee’s perceived landfall location and the actual landfall location from
each evacuee’s home zip code. Results indicate a personal landfall bias in the direction of home zip code for evacuees of
three metropolitan regions. Evacuees from the greater New Orleans area displayed the highest error, followed by evacuees from
greater Lafayette. Furthermore, we validate the authenticity of the previous results by employing two additional methods of
error assessment. A large regional error score might possibly be a predictor of evacuation complacency for a future hurricane
of similar magnitude, although there are many other variables that must be considered. 相似文献
7.
Ensemble prediction methodology based on variations in physical process parameterizations in tropical cyclone track prediction has been assessed. Advanced Research Weather Research and Forecasting model with 30-km resolution was used to make 5-day simulation of the movement of Orissa super cyclone (1999), one of the most intense tropical cyclones over the North Indian Ocean. Altogether 36 ensemble members with all possible combinations of three cumulus convection, two planetary boundary layer and six cloud microphysics parameterization schemes were produced. A comparison of individual members indicated that Kain–Fritsch cumulus convection scheme, Mellor–Yamada–Janjic planetary boundary layer scheme and Purdue Lin cloud microphysics scheme showed better performance. The best possible ensemble formulation is identified based on SPREAD and root mean square error (RMSE). While the individual members had track errors ranging from 96–240 km at 24 h to 50–803 km at 120 h, most of the ensemble predictions show significant betterment with mean errors less than 130 km up to 120 h. The convection ensembles had large spread of the cluster, and boundary layer ensembles had significant error disparity, indicating their important roles in the movement of tropical cyclones. Six-member ensemble predictions with cloud microphysics schemes of LIN, WSM5, and WSM6 produce the best predictions with least of RMSE, and large SPREAD indicates the need for inclusion of all possible hydrometeors in the simulation and that six-member ensemble is sufficient to produce the best ensemble prediction of tropical cyclone tracks over Bay of Bengal. 相似文献
8.
Gary L. Taghon Patricia A. Ramey Charlotte M. Fuller Rosemarie F. Petrecca Judith P. Grassle 《Estuaries and Coasts》2017,40(1):160-172
Hurricane Sandy was an extraordinarily large storm that affected most of the eastern coast of the USA in October 2012. To assess this storm’s impact, the benthic invertebrate community structure and sediment properties were compared in samples collected 3.5 months prior to (July 2012) and 8 months after (July 2013) the hurricane at 97 locations in Barnegat Bay, New Jersey, USA. Barnegat Bay is a shallow back-barrier estuary just north of where Sandy made landfall. For all locations taken together, sediment total nitrogen concentration was lower afterwards, while total organic carbon and total phosphorus concentrations were similar. Sediment median particle size was the same before and after, but the sediment was better sorted after the storm. There were no differences in total abundance of invertebrates, species richness, species diversity, or the abundance of polychaetes, bivalves, or gastropods. Malacostracan crustaceans were more abundant after Sandy (average 82 (0.04 m2)?1) than they were before (average 64), due almost entirely to increased abundance of ampeliscid amphipods, which showed a shift toward smaller sizes in 2013. Annelids in the order Clitellata were on average less abundant after the hurricane (17) than before (53). The apparent minimal effect of Sandy on the benthic community in Barnegat Bay was probably because the passage of the hurricane had no detectable effects on salinity or dissolved oxygen concentrations throughout the bay. 相似文献
9.
In this study, evacuees from the path of Hurricane Gustav were surveyed to determine which meteorological hazards most influenced
their decision to leave. Surveys were conducted along two major evacuation routes on August 30 and 31, 2008, to collect time-sensitive
data on individual evacuation decisions related to the meteorological hazards from Hurricane Gustav. The regions of New Orleans,
Houma, and Lafayette were represented most frequently, as determined by zip code data collected from the surveys. Responses
were evaluated first by meteorological hazard for the entire dataset and then by three-digit zip code region. Overall, storm
surge was the most important meteorological variable, followed by the size of the storm, wind, rain, and tornadoes. When separated
into three-digit zip code regions, analyses revealed evacuees from in and around New Orleans were driven to evacuate as a
result of the perceived threat from storm surge and storm size; residents in the Houma, Louisiana region were motivated to
leave due to the threat from storm surge; and Lafayette and the surrounding areas were most-concerned with the threats posed
by hurricane-force winds. Given the forecast track and intensity, survey respondents understood the meteorological hazards
from Gustav and were motivated to leave based on personal evaluations of risk associated with the storm. 相似文献
10.
Paul A. Zandbergen 《Natural Hazards》2009,48(1):83-99
Exposure of counties in the continental United States to tropical storm and hurricane conditions was determined using the
historic record of storm tracks for the period 1851–2003. Two approaches were used to determine exposure: (1) cumulative number
of hits, with a hit occurring when the storm’s path crosses a county and (2) cumulative exposure factor, which describes how
much of the county has been exposed to tropical storm, hurricane, and intense hurricane-force winds. In both approaches the
top 10 counties in terms of cumulative exposure are in coastal Florida, North Carolina, and Louisiana. An explanatory model
was developed to describe the patterns in the documented exposure, which included distance to coast, latitude, longitude,
size, and shape of the counties. Multivariate linear regression confirmed that much of the spatial variability in exposure
to storm conditions can be explained with these simple parameters. 相似文献
11.
Over the past 100 years, the Isles Dernieres, a low lying barrier island chain along the coast of central Louisiana, Usa , has undergone more than 1 km of northward beach face retreat with the loss of 70% of its surface area. The erosion results from a long term relative sea level rise coupled with day to day wind and wave action that ultimately favours erosion over deposition. At a site in the central Isles Dernieres, 8 days of wind and beach profile measurements during the passage of one winter cold front documented aeolian erosion and deposition patterns under both onshore and offshore winds. For offshore winds, the theoretical erosion rate, based on wind shear velocity, closely matched the measured erosion rate; for onshore winds, the theoretical rate matched the measured rate only after being corrected by a factor that accounted for beach face morphology. In late February 1989, a strong cold front moved into coastal Louisiana. That cold front stalled over the Gulf of Mexico, resulting in 4 days of strong northerly winds at a study site on the Isles Dernieres. During those 4 days, the wind moved sand from the backshore to the upper beach face. When the cold front finally moved out of the area, the wind shifted to the south and decreased in strength. The onshore wind then restored some of the upper beach face sand to the backshore while increased wave activity moved the rest into the nearshore. The theoretical estimate of 1·28 m3 m?1 for the rate of sand transport by the northerly wind compares well with the measured backshore erosion rate of 1·26 m3 m?1, which was determined by comparing beach profiles from the start and end of the period of northerly winds. The theoretical estimate of 0·04 m3 m?1 for the rate of sand transport by the southerly wind, however, is notably less than the measured rate of 0·45 m3 m?1. The large discrepancy between the two rates can be explained by a difference in the shear velocity of the wind between the beach face, where the erosion occurred, and the backshore, where the wind stress was measured. Using an empirical relationship for the wind shear drag coefficient as a function of coastal environment, the theoretical estimate for the rate of sand transport by the southerly wind becomes 0·44 m3 m?1 相似文献
12.
Much progress has been made in the area of tropical cyclone prediction using high-resolution mesoscale models based on community models developed at National Centers for Environmental Predication (NCEP) and National Center for Atmospheric Research (NCAR). While most of these model research and development activities are focused on predicting hurricanes in the Atlantic and Eastern Pacific domains, there has been much interest in using these models for tropical cyclone prediction in the North Indian Ocean region, particularly for Bay of Bengal storms that are known historically causing severe damage to life and property. In this study, the advanced operational hurricane modeling system developed at NCEP, known as the Hurricane Weather Research and Forecast (HWRF) model, is used to simulate two recent Bay of Bengal tropical cyclones??Nargis of November 2007 and Sidr of April 2008. The advanced NCEP operational vortex initialization procedure is adapted for simulating these Bay of Bengal tropical cyclones. Two additional regional models, the NCAR Advanced Research WRF and NCAR/Penn State University Mesoscale Model version 5 (MM5) are also used in simulating these storms. Results from these experiments highlight the superior performance of HWRF model over other models in predicting the Bay of Bengal cyclones. These results also suggest the need for a sophisticated vortex initialization procedure in conjunction with a model designed exclusively for tropical cyclone prediction for operational considerations. 相似文献
13.
Donglian Sun Menas Kafatos Guido Cervone Zafer Boybeyi Ruixin Yang 《Natural Hazards》2007,43(2):273-284
Sea surface temperature (SST) from the remotely sensed infrared measurements, like the GOES, AVHRR, and MODIS, etc., show
missing values of SST over the cloudy regions associated with hurricanes. While satellite microwave measurements, like the
Tropical Rainfall Measuring Mission (TRMM) microwave imager (TMI), can provide SST even under cloudy conditions. Both satellite
microwave measurements and buoy observations show SST increase in advance of significant hurricane intensification. Moreover,
hurricane intensification may also be related to the location of high SST. Our results indicate pre-existing high SST anomaly
(SSTA) located at the right side of the storm track for Hurricane Katrina. Numerical simulations also confirm the important
impacts of SSTA location on hurricane intensification. Similar situations are also found for Hurricanes Rita and Wilma. In
contrast, if there is no high SSTA at the right location, hurricane may not undergo further intensification. This may explain
why not all tropical cyclones associated with warm waters can attain peak intensity (categories 4 and 5) during their life
cycle, and partially explains why hurricanes do not reach the maximum potential intensity as calculated only according to
the magnitude of SST. 相似文献
14.
Asbury H. Sallenger Hilary F. Stockdon Laura Fauver Mark Hansen David Thompson C. Wayne Wright Jeff Lillycrop 《Estuaries and Coasts》2006,29(6):880-888
Four hurricanes battered the state of Florida during 2004, the most affecting any state since Texas endured four in 1884.
Each of the storms changed the coast differently. Average shoreline change within the right front quadrant of hurricane force
winds varied from 1 m of shoreline advance to 20 m of retreat, whereas average sand volume change varied from 11 to 66 m3 m−1 of net loss (erosion). These changes did not scale simply with hurricane intensity as described by the Saffir-Simpson Hurricane
Scale. The strongest storm of the season, category 4 Hurricane Charley, had the least shoreline retreat. This was likely because
of other factors like the storm's rapid forward speed and small size that generated a lower storm surge than expected. Two
of the storms, Hurricanes Frances and Jeanne, affected nearly the same area on the Florida east coast just 3 wk apart. The
first storm, Frances, although weaker than the second, caused greater shoreline retreat and sand volume erosion. As a consequence,
Hurricane Frances may have stripped away protective beach and exposed dunes to direct wave attack during Jeanne, although
there was significant dune erosion during both storms. The maximum shoreline change for all four hurricanes occurred during
Ivan on the coasts of eastern Alabama and the Florida Panhandle. The net volume change across a barrier island within the
Ivan impact zone approached zero because of massive overwash that approximately balanced erosion of the beach. These data
from the 2004 hurricane season will prove useful in developing new ways to scale and predict coastal-change effects during
hurricanes. 相似文献
15.
The quality of the surface wind analysis at the National Centre for Medium Range Weather Forecasts (NCMRWF), New Delhi over
the tropical Indian Ocean and its improvement in 2001 are examined by comparing it within situ buoy measurements and satellite derived surface winds from NASA QuikSCAT satellite (QSCT) during 1999, 2000 and 2001. The
NCMRWF surface winds suffered from easterly bias of 1.0–1.5 ms-1 in the equatorial Indian Ocean (IO) and northerly bias of 2.0–3.0 ms-1 in the south equatorial IO during 1999 and 2000 compared to QSCT winds. The amplitude of daily variability was also underestimated
compared to that in QSCT. In particular, the amplitude of daily variability of NCMRWF winds in the eastern equatorial IO was
only about 60% of that of QSCT during 1999 and 2000. The NCMRWF surface winds during 2001 have significantly improved with
the bias of the mean analyzed winds considerably reduced everywhere bringing it to within 0.5 ms-1 of QSCT winds in the equatorial IO. The amplitude and phase of daily and intraseasonal variability are very close to that
in QSCT almost everywhere during 2001. It is shown that the weakness in the surface wind analysis during 1999 and 2000 and
its improvement in 2001 are related to the weakness in simulation of precipitation by the forecast model in the equatorial
IO and its improvement in 2001. 相似文献
16.
Domain configuration and several physical parameterization settings such as planetary boundary layer, cumulus convection, and ocean–atmosphere surface flux parameterizations can play significant roles in numerical prediction of tropical cyclones. The present study focuses to improve the prediction of the TC Gonu by investigating the sensitivity of simulations to mentioned configurations with the Advanced Hurricane WRF model. The experiments for domain design sensitivity with 27 km resolution has been shown moving the domains towards the east improve the results, due to better account for the large-scale process. The fixed and movable nests on a 9-km grid were considered separately within the coarse domain and their results showed that despite salient improvement in simulated intensity, an accuracy reduction in simulated track was observed. Increasing horizontal resolution to 3 km incredibly reduced the simulated intensity accuracy when compared to 27 km resolution. Thereafter, different initial conditions were experimented and the results have shown that the cyclone of 1000 hPa sea level pressure is the best simulation initial condition in predicting the track and intensity for cyclone Gonu. The sensitivity of simulations to ocean–atmosphere surface-flux parameterizations on a 9-km grid showed the combination of ‘Donelan scheme’ for momentum exchanges along with ‘Large and Pond scheme’ for heat and moisture exchanges provide the best prediction for cyclone Gonu intensity. The combination of YSU and MYJ PBL scheme with KF convection for prediction of track and the combination of YSU PBL scheme with KF convection for prediction of intensity are found to have better performance than the other combinations. These 22 sensitivity experiments also implicitly lead us to the conclusion that each particular forecast aspect of TC (e.g., track, intensity, etc.) will require its own special design. 相似文献
17.
In recent years, tropical cyclones on the Pacific Northwest have decreased. We cannot infer that tropical cyclones impact China have reduced, because the Pacific Northwest is not homogeneous, and the variation characteristics of tropical cyclones in different sea areas are not clear. This paper uses gray relational density clustering algorithm to cluster tropical cyclone data sets between 1949 and 2008, according to the generated position of tropical cyclones, generated density and the possibility of landing. The Pacific Northwest is divided into different sea areas. Then, we analyze the risk of tropical cyclones generated in these sea areas. The results show that the probability of tropical cyclones landing generated in some sea areas is very high, reached 74 %, but the probability of tropical cyclones landing generated in other sea areas is only 2 %. Tropical cyclones generated in some sea areas are more likely to develop into typhoons, strong typhoons and so on, but the intensity of tropical cyclones generated in other sea areas is lower, there is little risk for China. Finally, according to the climate change stage trends, we divide the period 1949–2008 into three stages and analyze the tropical cyclone risk of each sea areas. 相似文献
18.
A parametric hurricane wind model has been developed based on the asymmetric Holland-type vortex model. The model creates
a two-dimensional surface wind field based on the National Hurricane Center forecast (or observed) hurricane wind and track
data. Three improvements have been made to retain consistency between the input parameters and the model output and to better
resolve the asymmetric structure of the hurricane. First, in determination of the shape parameter B, the Coriolis effect is included and the range restriction is removed. It is found that ignoring the Coriolis effect can
lead to an error greater than 20% in the maximum wind speed for weak but large tropical cyclones. Second, the effect of the
translational velocity of a hurricane is excluded from the input of specified wind speeds before applying the Holland-type
vortex to avoid exaggeration of the wind asymmetry. The translational velocity is added back in at the very end of the procedure.
Third, a new method has been introduced to develop a weighted composite wind field that makes full use of all wind parameters,
not just the largest available specified wind speed and its 4-quadrant radii. An idealized hurricane and two historical Gulf
of Mexico hurricanes have been used to test the model. It is found that the modified parametric model leads to better agreement
with field observation compared with the results from the unmodified model. This will result in better predictions of hurricane
waves and storm surges. 相似文献
19.
Sultan Al-Yahyai Abeer Aulad Thani Noura Al-kaabi Khalifa Al-Sudairi Badriya Al-Mawali Issa Al Amri 《Arabian Journal of Geosciences》2017,10(4):76
An accurate tropical cyclone track and intensity forecast is very important for disaster management. Specialized numerical prediction models have been recently used to provide high-resolution temporal and special forecasts. Hurricane Weather Research and Forecast (HWRF) model is one of the emerging numerical models for tropical cyclone forecasting. This study evaluates the performance of HWRF model during the post monsoon tropical cyclone Nilofar on the north Indian Ocean basin. The evaluation uses the best track data provided by the Indian Meteorological Department (IMD) and the Joint Typhoon Warning Centre (JTWC). Cyclone track, central pressure, and wind speed are covered on this evaluation. Generally, HWRF was able to predict the Nilofar track with track error less than 230 km within the first 66 h of forecast time span. HWRF predicted more intense tropical cyclone. It predicted the lowest central pressure to be 922 hPa while it reached 950 hPa according to IMD and 937 hPa according to JTWC. Wind forecast was better as it predicted maximum wind speed of 122 kt while it reached 110 and 115 kt according to IMD and JTWC, respectively. 相似文献
20.
A tropical cyclone was formed over central northern Africa near Egypt, Libya and Crete, and it moved and deepened toward the north–northeast; meanwhile, the storm destroyed many regions in the west, southwest and central of Turkey. The cyclone carried huge dust from the north of Africa to Turkey and reduced the visibility to less than 1 km and raised the wind speed. As a result of severe storm, some meteorological stations have new extreme values that the strongest wind speed measured was 81 knots in the central region of Turkey. Medicane with wind speed 81 knots especially over Turkey is a rare event. This devastating cyclone carried exceptionally very strong winds (>80 kts) with favorable conditions to follow windstorm conceptual model. The cyclone caused adverse conditions such as excessive injuries, fatal incidents and forest fires. Mesoscale vortex formed and affected particularly the middle and western regions of Turkey. The vertical thermodynamic structure of storm is compared with April values of 40 years of datasets over Istanbul. Moreover, four different winds {measurement masts} of Istanbul Atatürk Airport are used for the microscale analysis of different meteorological parameters during deepened pressure level. In addition, divergence and vorticity of stormy weather are discussed in details during the effective time period of storm by solving equations and validated using ERA-40 reanalysis. We obtained many monitoring data sources such as ground base, radar, radiosonde and satellite display the values of the intensity of wind speed caused by cyclones of tropics have revealed similarities. 相似文献