Weathering the Storm: Mitigating Hurricanes with Ground-Based CCN and Lightning

This research introduces a groundbreaking methodology aimed at mitigating storm and hurricane intensity through the application of a ground-based, manually operated Cloud Condensation Nuclei (CCN) Generator. To meet the demand for more comprehensive context and rationale, this study explores the escalating challenges presented by the growing intensity of hurricanes, exemplified by Hurricane IAN (2022). The controlled release of environmentally friendly aerosols into the atmosphere, achieved by combusting selected wood pieces and organic edible materials, is a pivotal response to the escalating threat of extreme weather events. By generating CCN, the novel approach seeks to augment positive lightning in the eyewall, providing a potential solution to the intensification of hurricanes. Results illustrate the successful implementation of the methodology, with released aerosols effectively reaching the clouds for seeding, thus contributing to the modification of convection in the outer wall of Hurricane IAN and consequent intensity reduction. Rigorous experiments, incorporating considerations of various parameters such as wind patterns and the experimental location in Sarasota City, emphasize the scientific rigor applied to weakening Hurricane IAN. This comprehensive approach not only holds promise in mitigating hurricane intensity but also sheds light on the potential impact of cloud seeding in reducing the severity of future hurricanes, addressing a critical need for sustainable solutions to climate-related challenges.

Understanding the Perceptions and Practices of Homeowners in the Event of Hurricane: A Case Study of University Employees in Louisiana

The purpose of this qualitative study is to explore and gain an understanding of Louisiana homeowners’ perceptions and practices in preparing for hurricanes;contribute to academic research and student learning, while guiding the development of future projects. We focused specifically on how homeowners in Louisiana would protect their important documents and possessions. These documents and possessions include but are not limited to photographs, social security cards, birth certificates, and insurance paperwork. We collected the data throughout the fall semester of 2022 at Louisiana State University (LSU) by conducting a focus group and in-depth interviews. We collected a variety of answers, but most participants expressed a strong need to have their important documents and possessions protected and gave different strategies for how this was carried out, such as digitizing or protective storage. Participants also expressed a strong need for more information to be delivered to residents to talk more about ways they can protect their own documents and possessions. Emphases were also made on the need for: leaders of large institutions to be especially concerned with preparedness for vulnerable populations;outreach programs to be put in place to spread awareness of the importance of protecting important documents and possessions during a disaster;news outlets to switch their focus from normal survival tips to discussions on the importance of protecting documents and possessions;government and non-profit agencies to work together to share tips and information through social media and other forms of handouts.

A Wavelet-Based Deep Learning Framework for Predicting Peak Intensity of Hurricanes in the Atlantic Ocean

Every year, hurricanes pose a serious threat to coastal communities, and forecasting their maximum intensities has been a crucial task for scientists. Computational methods have been used to forecast the intensities of hurricanes across varying time horizons. However, as climate change has increased the volatility of the intensities of recent hurricanes, newer and adaptable methods must be devised. In this study, a framework is proposed to estimate the maximum intensity of tropical cyclones (TCs) in the Atlantic Ocean using a multi-input convolutional neural network (CNN). From the Atlantic hurricane seasons of 2000 through 2021, over 100 TCs that reached hurricane-level wind speeds are used. Novel algorithms are used to collect and preprocess both satellite image data and non-image data for these TCs. Namely, Discrete Wavelet Transforms (DWTs) are used to decompose individual bands of satellite image data, eliminating noise and extracting hidden frequency details before training. Validation tests indicate that this framework can estimate the maximum wind speed of TCs with a root mean square error of 15 knots. This framework provides preliminary predictions that can supplement current computational methods that would otherwise not be able to account for climate change. Future work can be done by forecasting with time constraints, and to provide estimations for more metrics such as pressure and precipitation.

台风灾害下考虑脆弱线路加固的新型电力系统弹性提升方法

随着双碳目标的提出,传统电力系统将不断向新型电力系统转变。在此背景下,有效应对台风等小概率高损失的极端自然灾害事件是新型电力系统建设中的巨大挑战。线路加固在提升新型电力系统弹性方面有重要作用,但现有加固措施方案制定过程中对新型电力系统内输电网侧脆弱线路关注较少,忽略了灾害下脆弱线路开断引发的多重故障风险,可能导致加固方案适用性减弱。文中聚焦台风灾害,将灾害下负荷损失和脆弱线路存护比例作为弹性量化指标,提出一种考虑脆弱线路加固的新型电力系统弹性提升模型。根据弹性指标特性,分别将灾害下负荷损失和脆弱线路存护比例作为目标函数和约束条件,该模型以线路加固成本、台风灾害下切负荷成本之和最小为目标,考虑了脆弱线路存护比例约束。通过IEEE RTS 24系统算例分析表明所提方法能够有效满足弹性指标要求。

台风“艾克”(2008)的海面风场模型研究

台风风场模拟的准确性对台风风场后报工作具有重要意义,目前通过参数模型构建台风边界层的海面风场是较快速且常用的方法之一。以2008年侵入墨西哥湾的大西洋第8号台风“艾克”为例,选取多种参数模型对比研究台风风场模拟的效果。实验结果表明,台风风场模型的选择对台风风场模拟效果具有显著影响。采用Jelesnianski-1风廓线模型即可较好地再现“艾克”台风风场的时空特征;此外,具有可变系数的Holland等气压模型风场和Miller等风廓线模型风场则具有较好的适用性,通过调整可变系数使得参数风场的风廓线贴合实际台风案例。整体而言,基于理想模型的参数风场能基本反映台风核心区域的海面风场特征,但对外围背景风场模拟效果不甚理想,而分析及再分析风场数据则能较好地反映台风外围的背景风场,因此采用参数风场与分析及再分析风场融合的方式构建台风风场,可显著提高台风“艾克”风场的数值模拟效果。

ESA理论在Face to Face with Hurricane Camille课堂教学中的应用

Jeremy Harmer的ESA理论中提出了英语教学中的三要素,且阐释了三要素下的三种课型模式。该文是在ESA理论的杂拼模式(patchwork sequence)的指导下,结合《高级英语》中的课文Face to Face with Hurricane Camille,在教学中进行了一次尝试,进一步发现了ESA在课堂教学中的积极作用。

Observation of ocean current response to 1998 Hurricane Georges in the Gulf of Mexico

The ocean current response to a hurricane on the shelf-break is examined. The study area is the DeSoto Canyon in the northeast Gulf of Mexico, and the event is the passage of 1998 Hurricane Georges with a maximum wind speed of 49 m/s. The data sets used for analysis consist of the mooring data taken by the Field Program of the DeSoto Canyon Eddy Intrusion Study, and simultaneous winds observed by NOAA （National Oceanic and Atmospheric Administration） Moored Buoy 42040. Time-depth ocean current energy density images derived from the observed data show that the ocean currents respond almost immediately to the hurricane with important differences on and offthe shelf. On the shelf, in the shallow water of 100 m, the disturbance penetrates rapidly downward to the bottom and forms two energy peaks, the major peak is located in the mixed layer and the secondary one in the lower layer. The response dissipates quickly after external forcing disappears. Offthe shelf, in the deep water, the major disturbance energy seems to be trapped in the mixed layer with a trailing oscillation; although the disturbance signals may still be observed at the depths of 500 and 1 290 m. Vertical dispersion analysis reveals that the near-initial wave packet generated offthe shelf consists of two modes. One is a barotropic wave mode characterized by a fast decay rate of velocity amplitude of 0.020 s^-, and the other is baroclinic wave mode characterized by a slow decay rate of 0.006 9 s^-1. The band-pass-filtering and empirical function techniques are employed to the frequency analysis. The results indicate that ialf frequencies shift above the local inertial frequency. On the shelf, the average frequency is 1.04fin the mixed layer, close to the diagnosed frequency of the first baroclinic mode, and the average frequency increases to 1.07fin the thermocline. Offthe shelf, all frequencies are a little smaller than the diagnosed frequency of the first mode. The average frequency decreases from 1.035fin the mixed layer to 1.02fin the thermocline, implying a trend for the shift in frequency of the oscillations towards f with the depth.

Disaster prevention design criteria for the estuarine cities:New Orleans and Shanghai The lesson from Hurricane Katrina

The accurate prediction of the typhoon （hurricane） induced extreme sea environments is very important for the coastal structure design in areas influenced by typhoon （hurricane）. In 2005 Hurricane Katrina brought a severe catastrophe in New Orleans by combined effects of hurricane induced extreme sea environments and upper flood of the Mississippi River. Like the New Orleans City, Shanghai is located at the estuarine area of the Changjiang River and the combined effect of typhoon induced extreme sea en- vironments, flood peak runoff from the Changjiang River coupled with the spring tide is the dominate factor for disaster prevention design criteria. The Poisson-nested logistic trivariate compound extreme value distribution （PNLTCEYD） is a new type of joint probability model which is proposed by compounding a discrete distribution （typhoon occurring frequency） into a continuous multivariate joint distribution （ typhoon induced extreme events）. The new model gives more reasonable predicted results for New Orleans and Shanghai disaster prevention design criteria.

The Impact of the Storm-Induced SST Cooling on Hurricane Intensity

The effects of storm-induced sea surface temperature （SST） cooling on hurricane intensity are investigated using a 5-day cloud-resolving simulation of Hurricane Bonnie （1998）. Two sensitivity simulations are performed in which the storm-induced cooling is either ignored or shifted close to the modeled storm track. Results show marked sensitivity of the model-simulated storm intensity to the magnitude and relative position with respect to the hurricane track. It is shown that incorporation of the storm-induced cooling, with an average value of 1.3℃, causes a 25-hPa weakening of the hurricane, which is about 20 hPa per 1℃ change in SST. Shifting the SST cooling close to the storm track generates the weakest storm, accounting for about 47% reduction in the storm intensity. It is found that the storm intensity changes are well correlated with the air-sea temperature difference. The results have important implications for the use of coupled hurricane-ocean models for numerical prediction of tropical cyclones.

Dependence of Hurricane Intensity and Structures on Vertical Resolution and Time-Step Size

In view of the growing interests in the explicit modeling of clouds and precipitation, the effects of varying vertical resolution and time-step sizes on the 72-h explicit simulation of Hurricane Andrew (1992) are studied using the Pennsylvania State University/National Center for Atmospheric Research (PSU/NCAR) mesoscale model (i.e., MM5) with the finest grid size of 6 km. It is shown that changing vertical resolution and time-step size has significant effects on hurricane intensity and inner-core cloud/precipitation, but little impact on the hurricane track. In general, increasing vertical resolution tends to produce a deeper storm with lower central pressure and stronger three-dimensional winds, and more precipitation. Similar effects, but to a less extent, occur when the time-step size is reduced. It is found that increasing the low-level vertical resolution is more efficient in intensifying a hurricane, whereas changing the upper-level vertical resolution has little impact on the hurricane intensity. Moreover, the use of a thicker surface layer tends to produce higher maximum surface winds. It is concluded that the use of higher vertical resolution, a thin surface layer, and smaller time-step sizes, along with higher horizontal resolution, is desirable to model more realistically the intensity and inner-core structures and evolution of tropical storms as well as the other convectively driven weather systems.

The Impact of AIRS Atmospheric Temperature and Moisture Profiles on Hurricane Forecasts: Ike(2008) and Irene(2011)

Atmospheric InfraRed Sounder （AIRS） measurements are a valuable supplement to current observational data,especially over the oceans where conventional data are sparse.In this study,two types of AIRS-retrieved temperature and moisture profiles,the AIRS Science Team product （SciSup） and the single field-of-view （SFOV） research product,were evaluated with European Centre for Medium-Range Weather Forecasts （ECMWF） analysis data over the Atlantic Ocean during Hurricane Ike （2008） and Hurricane Irene （2011）.The evaluation results showed that both types of AIRS profiles agreed well with the ECMWF analysis,especially between 200 hPa and 700 hPa.The average standard deviation of both temperature profiles was approximately 1 K under 200 hPa,where the mean AIRS temperature profile from the AIRS SciSup retrievals was slightly colder than that from the AIRS SFOV retrievals.The mean SciSup moisture profile was slightly drier than that from the SFOV in the mid troposphere.A series of data assimilation and forecast experiments was then conducted with the Advanced Research version of the Weather Research and Forecasting （WRF） model and its three-dimensional variational （3DVAR） data assimilation system for hurricanes Ike and Irene.The results showed an improvement in the hurricane track due to the assimilation of AIRS clear-sky temperature profiles in the hurricane environment.In terms of total precipitable water and rainfall forecasts,the hurricane moisture environment was found to be affected by the AIRS sounding assimilation.Meanwhile,improving hurricane intensity forecasts through assimilating AIRS profiles remains a challenge for further study.

Retrieval of sea surface winds under hurricane conditions from GNSS-R observations

Reflected signals from global navigation satellite systems（GNSSs） have been widely acknowledged as an important remote sensing tool for retrieving sea surface wind speeds.The power of GNSS reflectometry（GNSS-R）signals can be mapped in delay chips and Doppler frequency space to generate delay Doppler power maps（DDMs）,whose characteristics are related to sea surface roughness and can be used to retrieve wind speeds.However,the bistatic radar cross section（BRCS）,which is strongly related to the sea surface roughness,is extensively used in radar.Therefore,a bistatic radar cross section（BRCS） map with a modified BRCS equation in a GNSS-R application is introduced.On the BRCS map,three observables are proposed to represent the sea surface roughness to establish a relationship with the sea surface wind speed.Airborne Hurricane Dennis（2005） GNSS-R data are then used.More than 16 000 BRCS maps are generated to establish GMFs of the three observables.Finally,the proposed model and classic one-dimensional delay waveform（DW） matching methods are compared,and the proposed model demonstrates a better performance for the high wind speed retrievals.

Effect of stratification on current hydrodynamics over Louisiana shelf during Hurricane Katrina

Numerical experiments were conducted using the finite volume community ocean model(FVCOM) to study the impact of the initial density stratification on simulated currents over the Louisiana shelf during Hurricane Katrina. Model results for two simulation scenarios, including an initially stratified shelf and an initially non-stratified shelf, were examined. Comparison of two simulations for two-dimensional(2D) currents,the time series of current speed, and variations of cross-shore currents across different sections showed that the smallest differences between simulated currents for these two scenarios occurred over highly mixed regions within 1 radius of maximum wind(RMW) under the hurricane.For areas farther from the mixed zone, differences increased, reaching the maximum values off Terrebonne Bay. These large discrepancies correspond to significant differences between calculated vertical eddy viscosities for the two scenarios. The differences were addressed based on the contradictory behavior of turbulence in a stratified fluid, as compared to a non-stratified fluid. Incorporation of this behavior in the MellorYamada turbulent closure model established a Richardson number-based stability function that was used for estimation of the vertical eddy viscosity from the turbulent energy and macroscale. The results of this study demonstrate the necessity for inclusion of shelf stratification when circulation modeling is conducted using three-dimensional(3D) baroclinic models. To achieve high-accuracy currents, the parameters associated with the turbulence closures should be calibrated with field measurements of currents at different depths.

Design Code Calibration of Offshore Platform Against Typhoon/Hurricane Attacks

Hurricanes Katrina and Rita resulted in the largest number of platforms destroyed and damaged in the history of Gulf of Mexico operations. With the trend of global warming, sea level rising and the frequency and intensity of typhoon increase. How to determine a reasonable deck elevation against the largest hurricane waves has become a key issue in offshore platforms design and construction for the unification of economy and safety. In this paper, the multivariate compound extreme value distribution （MCEVD） model is used to predict the deck elevation with different combination of tide, surge height, and crest height. Compared with practice recommended by American Petroleum Institute （API）, the prediction by MCEVD has probabilistic meaning and universality.

Effects of silviculture treatments in a hurricane-damaged forest on carbon storage and emissions in central Hokkaido, Japan

Hurricanes cause abrupt carbon reduction in forests, but silviculture treatment can be an effective means of quickly regenerating and restoring hurricane-damaged sites. This study assessed how silviculture treatments affect carbon balance after hurricane damage in central Hokkaido, Japan. We examined carbon storage in trees and underground vegetation as well as carbon emissions from silviculture operations in 25-year-old stands, where scarification and plantation occurred just after hurricane damage. The amount of carbon stored varied according to silviculture treatment. Among three scarification treatments, a scarified depth of 0 cm （understory vegetation removal） led to the largest amount of carbon stored （64.7 t·ha^-1 C）. Among four plantation treatments, the largest amount of carbon was stored in a Larix hybrid （L. gmelinii var. japonica × L. kaempferi） plantation （80.3 t·ha^-1 C）. The plantation of Abies sachalinensis was not successful at accumulating carbon （40.5·ha^-1 C）. The amount of carbon emitted from silviculture operations was 0.05-0.14 t·ha^-1 C, and it marginally affected the net carbon balance of the silviculture project. Results indicate that silviculture treatments should beperformed in an appropriate way to effectively recover the ability of carbon sequestration in hurricane-damaged forests.

The observed analysis on the wave spectra of Hurricane Juan (2003)

Hurricane Juan provides an excellent opportunity to probe into the detailed wave spectral patterns and spectral parameters of a hurricane system, with enough wave spectral observations around Juan＇s track in the deep ocean and shallow coastal water. In this study, Hurricane Juan and wave observation stations around Juan＇s track are introduced. Variations of wave composition are discussed and analyzed based on time series of one-dimensional frequency spectra, as well as wave steepness around Juan＇s track： before, during, and after Juan＇s passing. Wave spectral involvement is studied based on the observed one-dimensional spectra and two-dimensional spectra during the hurricane. The standardization method of the observed wave spectra during Hurricane Juan is discussed, and the standardized spectra show relatively conservative behavior, in spite of the huge variation in wave spectral energy, spectral peak, and peak frequency during this hurricane. Spectral widths＇ variation during Hurricane Juan are calculated and analyzed. A two-layer nesting WW3 model simulation is applied to simulate the one-dimensional and two-dimensional wave spectra, in order to examine WW3＇s ability in simulating detailed wave structure during Hurricane Juan.

Numerical Simulation of the Rapid Intensification of Hurricane Katrina(2005):Sensitivity to Boundary Layer Parameterization Schemes

Accurate forecasting of the intensity changes of hurricanes is an important yet challenging problem in numerical weather prediction. The rapid intensification of Hurricane Katrina（2005） before its landfall in the southern US is studied with the Advanced Research version of the WRF（Weather Research and Forecasting） model. The sensitivity of numerical simulations to two popular planetary boundary layer（PBL） schemes, the Mellor–Yamada–Janjic（MYJ） and the Yonsei University（YSU） schemes, is investigated. It is found that, compared with the YSU simulation, the simulation with the MYJ scheme produces better track and intensity evolution, better vortex structure, and more accurate landfall time and location. Large discrepancies（e.g.,over 10 hPa in simulated minimum sea level pressure） are found between the two simulations during the rapid intensification period. Further diagnosis indicates that stronger surface fluxes and vertical mixing in the PBL from the simulation with the MYJ scheme lead to enhanced air–sea interaction, which helps generate more realistic simulations of the rapid intensification process. Overall, the results from this study suggest that improved representation of surface fluxes and vertical mixing in the PBL is essential for accurate prediction of hurricane intensity changes.

Effects of hurricane forward speed and approach angle on storm surges: an idealized numerical experiment

The effects of hurricane forward speed(V)and approach angle(θ)on storm surge are important and a systematic investigation covering possible and continuous ranges of these parameters has not been done before.Here we present such a study with a numerical experiment using the Finite Volume Community Ocean Model(FVCOM).The hurricane track is simplified as a straight line,such that V andθfully define the motion of the hurricane.The maximum surge is contributed by both free waves and a forced storm surge wave moving with the hurricane.Among the free waves,Kelvin-type waves can only propagate in the down-coast direction.Simulations show that those waves can only have a significant positive storm surge when the hurricane velocity has a down-coast component.The optimal values of V andθthat maximize the storm surge in an idealized semi-circular ocean basin are functions of the bathymetry.For a constant bathymetry,the maximum surge occurs when the hurricane approaches the coast from the normal direction when the free wave generation is minimal;for a stepped bathymetry,the maximum surge occurs at a certain acute approach angle which maximizes the duration of persistent wind forcing;a step-like bathymetry with a sloped shelf is similar to the stepped bathymetry,with the added possibility of landfall resonance when the free and forced waves are moving at about the same velocity.For other cases,the storm surge is smaller,given other parameters(hurricane size,maximum wind speed,etc.)unchanged.

Quantifying the Contribution of Track Changes to Interannual Variations of North Atlantic Intense Hurricanes

Previous studies have linked interannual variability of tropical cyclone(TC)intensity in the North Atlantic basin(NA)to Sahelian rainfall,vertical shear of the environmental flow,and relative sea surface temperature(SST).In this study,the contribution of TC track changes to the interannual variations of intense hurricane activity in the North Atlantic basin is evaluated through numerical experiments.It is found that that observed interannual variations of the frequency of intense hurricanes during the period 1958–2017 are dynamically consistent with changes in the large-scale ocean/atmosphere environment.Track changes can account for~50%of the interannual variability of intense hurricanes,while no significant difference is found for individual environmental parameters between active and inactive years.The only significant difference between active and inactive years is in the duration of TC intensification in the region east of 60°W.The duration increase is not due to the slow-down of TC translation.In active years,a southeastward shift of the formation location in the region east of 60°W causes TCs to take a westward prevailing track,which allows TCs to have a longer opportunity for intensification.On the other hand,most TCs in inactive years take a recurving track,leading to a shorter duration of intensification.This study suggests that the influence of track changes should be considered to understand the basin-wide intensity changes in the North Atlantic basin on the interannual time scale.

Resilience in a Mexican Pacific Mangrove after Hurricanes: Implications for Conservation Restoration

High resilience is a mangrove trait that is compatible with life in a dynamic environment, however, catastrophic disturbance can lead to the entire forest structure being re-defined. In the Pochutla district of Oaxaca, two hurricanes made landfall in 1997 and one more in 2012. Following the 1997 hurricanes, extensive mangrove restoration was carried out in the study area. A cohort of Rhizophora mangle saplings planted in 2007 showed 10% mortality during the first year after transplantation, an average growth of 39 cm, and a positive association between growth rate and the level of water in the lagoon. Following Hurricane Carlotta of 2012, measurements of structural impact and tree mortality were taken in restored R. mangle stands and in naturally regenerated patches of Laguncularia racemosa. The role of tree girth in R. mangle susceptibility to wind damage was also investigated. The stands of R. mangle suffered 80% reduction in stem density and 86% loss of basal area, whereas the corresponding values for L. racemosa were 26% and 15%, respectively. Within stands of R. mangle, mortality conserved a positive relationship with structural impact categories and the frequency of snapped stems was segregated across girth classes. The results suggest that L. racemosa has greater resilience to hurricane damage, which has some consistency with previous research and implications for conservation restoration protocols. In order to promote a system with higher resilience, we recommend an on-going restoration effort with mixed mangrove species.