Derivation of Parametric Tropical Cyclone Models for Storm Surge Modeling

In this paper, the parametric tropical cyclone models for storm surge modeling are further developed. Instead of tangential wind speed via cyclostrophic balance and radial wind speed using a simple formulation of defection angle, the analyrical expressions of tangential and radial wind speed distribution are derived from the governing momentum equations based on the general symmetric pressure distribution of Holland and Fujita. The radius of the maximum wind is estimated by tropical cyclone wind structure which is characterized by the radial extent of special wind speed. The shape parameter in the pressure model is estimated by the data of several tropical cyclones that occurred in the East China Sea. Finally, the Fred cyclone （typhoon 199417） is calculated, and comparisons of the measured and calculated air pressures and wind speed are presented.

Two parametric tropical cyclone models for storm surge modeling

In this paper,the two parametric tropical cyclone models for storm surge modeling are further developed.The analytical expressions of tangential and radial velocity distribution are derived from the governing momentum equations,based on the general symmetric pressure distribution proposed by Holland and Fujita.On the basis of the data of several tropical cyclones that occurred in East China Ocean,the shape parameter in pressure model is estimated.Finally,the Fred cyclone(typhoon 199417)is calculated,and comparisons of measured and calculated air pressures and wind speed are presented.

Historic and Future Perspectives of Storm and Cyclone

In weather sciences,the two specific terms“storm”and“cyclone”frequently appear in literature and usually refer to the violent nature of a number of weather systems characterized by central low pressure,strong winds,large precipitation amounts in the form of rain,freezing rain,or snow,as well as thunder and lightning.But what is the connection between these two specific terms?In this paper,the historic evolutions of the terms“storm”and“cyclone”are reviewed from the perspective of weather science.The earliest recorded storms in world history are also briefly introduced.Then,the origin of the term“meteorological bomb”,which is the nickname of the“explosive cyclone”is introduced.Later,the various definitions of explosive cyclones given by several researchers are discussed.Also,the climatological features of explosive cyclones,as well as the future trends of explosive cyclones under global climate change,are discussed.

Seasonal Prediction of Tropical Cyclones and Storms over the Southwestern Indian Ocean Region Using the Generalized Linear Models

Tropical cyclones (TCs) and storms (TSs) are among the devastating events in the world and southwestern Indian Ocean (SWIO) in particular. The seasonal forecasting TCs and TSs for December to March (DJFM) and November to May (NM) over SWIO were conducted. Dynamic parameters including vertical wind shear, mean zonal steering wind and vorticity at 850 mb were derived from NOAA (NCEP-NCAR) reanalysis 1 wind fields. Thermodynamic parameters including monthly and daily mean Sea Surface Temperature (SST), Outgoing Longwave Radiation (OLR) and equatorial Standard Oscillation Index (SOI) were used. Three types of Poison regression models (i.e. dynamic, thermodynamic and combined models) were developed and validated using the Leave One Out Cross Validation (LOOCV). Moreover, 2 × 2 square matrix contingency tables for model verification were used. The results revealed that, the observed and cross validated DJFM and NM TCs and TSs strongly correlated with each other (p ≤ 0.02) for all model types, with correlations (r) ranging from 0.62 - 0.86 for TCs and 0.52 - 0.87 for TSs, indicating great association between these variables. Assessment of the model skill for all model types of DJFM and NM TCs and TSs frequency revealed high skill scores ranging from 38% - 70% for TCs and 26% - 72% for TSs frequency, respectively. Moreover, results indicated that the dynamic and combined models had higher skill scores than the thermodynamic models. The DJFM and NM selected predictors explained the TCs and TSs variability by the range of 0.45 - 0.65 and 0.37 - 0.66, respectively. However, verification analysis revealed that all models were adequate for predicting the seasonal TCs and TSs, with high bias values ranging from 0.85 - 0.94. Conclusively, the study calls for more studies in TCs and TSs frequency and strengths for enhancing the performance of the March to May (MAM) and December to October (OND) seasonal rainfalls in the East African (EA) and Tanzania in particular.

A Modified Algorithm for Identifying and Tracking Extratropical Cyclones

In this study, a modified identification and tracking algorithm for extratropical cyclones is developed. This identification scheme is based on triangular-mesh contouring techniques combined with a connected-component labeling method in order to detect the outer boundaries and spatial domain characteristics of individual cyclones. A new tracking method allowing for the identification of cyclone merging and splitting events, as well as short-lived windstorms, is developed to reduce the uncertainty in the tracking of extratropical cyclones. I also show that this method excludes the tracks of open systems that would have been unnecessarily detected using conventional NCP methods. The climatological features of the distribution of cyclone frequencies are substantially larger over the traditional storm track regions compared to those seen in previous studies. Interestingly, a significant increase in the cyclone density in the Arctic occurs during all four seasons（up to 19%in summer） compared to that seen with a latitude-longitude gridded mesh analysis. I develop two new regional intensity indices（depth and vorticity） based on the cyclonic domain to better quantify the cyclonic activity in the Arctic region, and find that the interannual variabilities in these two indices are highly consistent. The results of this analysis may shed light on high-latitude cyclonic behavior studies via the newly detected 2D cyclone atlas derived from this cyclonic-domain-based algorithm.

Cyclone and Tsunami Hazards in the Arabian Sea-A Numerical Modelling Case Study by Royal HaskoningDHV

Significant loss of life and damage to properties, ecosystems and marine facilities occur due to various natural hazards such as cyclones and tsunamis. Royal HaskoningDHV has developed regional hydrodynamic and wave models covering the Northern Arabian Sea to address these issues. Cyclone modelling was carried out on 11 major cyclones since 1945 and the tsunami modelling on an earthquake along the Makran Fault Line in 1945. Sample results from these modelling studies are presented in this paper. The methodology described in this article for modelling cyclones and tsunamis in the Arabian Sea could be applied to simulate these natural hazards at other sites around the world.

A METHOD FOR DETERMINATION OF GALE REGION OVER OCEANSURFACE BY TROPICAL CYCLONE USING T_(BB)

With black-body temperature (TBB) from GMS infrared cloud imagery for 16 tropical cyclones in 1996 -- 1997 and domestic and overseas reports of gale by tropical cyclones as well as some conventional andshipboard wind reports, a number of conceptual charts are statistically summarized to determine ranges of galesOn near gale and 10 of the storm. A method by which the radius of gale is operationally useful has beed tested.

Study of Weak Intensity Cyclones over Bay of Bengal Using WRF Model

Numerical simulations of four weak cyclonic storms [two cases of pre-monsoon cyclones: Laila (2010), Aila (2009) and two cases of post-monsoon cyclones: Jal (2010), SCS (2003)] are carried out using WRF-ARW mesoscale model. Betts-Miller-Janjic (BMJ) as cumulus parameterization (CP) scheme, Yonsei University(YSU) planetary boundary layer (PBL) scheme and WRF single moment 6 class (WSM6) microphysics (MP) scheme is kept same for all the cyclone cases. Three two-way interactive nested domains [60 km,20 kmand6.6 km] are used with initial and boundary conditions from NCEP Final Analysis data. The model integration is performed to evaluate the track, landfall time and position as well as intensity in terms of Central Sea Level Pressure (CSLP) and Maximum Surface Wind speed (MSW) of the storm. The track and landfall (time and position) of almost all cyclones are well predicted by the model (except for SCS cyclone case) which may be because of the accurate presentation of the steering flow by CP scheme. Irrespective of season, the intensity is overestimated in all the cases of cyclone, mainly because of the lower tropospheric and mid-tropospheric parameters are overestimated. YSU PBL scheme used here is responsible for the deep convection in and above PBL. Concentration of frozen hydrometeors at the mid-tropospheric levels and thus the latent heat released during auto conversion of hydrometeors is also responsible for overestimation of intensity.

Epidemiology of Biopsy Proven Glomerular Disorders and Effect of Severe Cyclone on Its Incidence in Central Queensland Region of Australia

Aim: The objectives of this study are to determine the epidemiology of biopsy-proven glomerular disease (GD) in Central Queensland and the effect of a severe cyclone on its incidence and clinical phenotype. Background: Central Queensland (CQ) has a relatively high incidence of kidney disease. Since its biopsy service commenced in 2005, there have been no data on biopsy-proven GD. It has been suggested that GD incidence changes around times of natural disasters. In February 2015, the CQ region was affected by a category 5 Cyclone Marcia. This provides an opportunity to explore possible environmental triggers of GD. Methods: This was a single-centre retrospective observational study on biopsy-proven kidney disease in CQ. All kidney biopsies performed between January 2005 and December 2019 were included. Patients with biopsy-proven GD during 3 years before and after Cyclone Marcia (from 2012 to 2018) were analysed. Results: 170 native kidney biopsies occurred during the 15 years. The number of annual biopsies steadily increased from 7 to 16. The most common biopsy-proven kidney disease was IgA Nephropathy (27%) followed by diabetic nephropathy (20%). GD comprised 64% of biopsies. Unlike other GD, the incidence of ANCA-associated vasculitis (AAV) significantly increased after cyclone (one pre- and eight post-cyclone, P value = 0.039). The majority of AAV cases occurred in the first year after the cyclone. Conclusion: Kidney biopsies in CQ provide important epidemiological data on biopsy-proven kidney disease. Cyclones have a possible effect on the incidence and clinical phenotype of ANCA associated vasculitis.

Numerical Modelling of Waves and Surge from Cyclone Mekunu (May 2018) in the Arabian Sea

Cyclone Mekunu developed in the Arabian Sea on 22 May 2018 and made landfall near the Port of Salalah(Oman)on 25 May.Wide spread damages to properties and coastal facilities and human casualties were reported in Yemen and Oman.Less information on numerical modelling of waves and surge is publicly available on this cyclone.Therefore,numerical modelling of Cyclone Mekunu was carried out in the present study to derive waves and storm surge.The MIKE21 Spectral Wave Model and the Flow Model were used in coupled mode to simulate the waves and surge from the cyclone.Model results of waves and surge are presented in this paper for illustration purposes.The methodology of the present study can be used to simulate any cyclone around the world.

A Case Study of Ocean-Atmosphere Interactions during the Passage of an Extra-Tropical Cyclone in the Vicinity of Cape Hatteras, North Carolina

The authors document the interaction of the atmosphere and ocean during the formation and passage of an Extra-Tropical Cyclone, which is a Nor-Easter, winter storm that formed in the southern apex of the Middle Atlantic Bight near Cape Hatteras North Carolina, between February 15 and 18, 1996. While Nor-Easters per se, which have formed along the Atlantic Eastern Seaboard of the United States have been studied for decades, the actual atmospheric-oceanic mechanics and thermodynamics in the formation of a Nor-Easter has never been documented. We report on having done so with in-situ observations and data-based calculations and a numerical model. The in-situ observations were made via a Control Volume consisting of an array of Eulerian Oceanic-Atmospheric Moorings with current meters, temperature and salinity sensors and meteorological towers. We find that Gulf Stream waters were located surrounding the mooring array, and that with the invasion of cold dry atmospheric air, there was a rapid loss of heat from the ocean to the atmosphere via latent and sensible surface heat flux during the cyclogenesis onset of the storm. A unique feature of this storm was that neither satellite nor buoy data showed significant sea surface cooling in the control volume. The findings indicate that storm winds drove warm saline waters from the Gulf Stream across the continental shelf into the control volume, accounting for a 51 cm rise in water level along the coast. This lateral heat advection provided heat to the control volume of 3.4e+18 Joules. On average, the heat loss at the surface of the control volume, via sensible and latent heat fluxes and radiation, was 0.7e+18 Joules, corresponding to a surface heat flux of -600 Watts per Meter2 (W/m2). However, the heat lost by the control volume as latent and sensible heat fluxes was less than the heat it received via lateral heat advection, resulting in the lack of an often-observed sea surface cooling during other winter storms. The serendipitous and detailed observations and calculations reveal a climatological flywheel in this region, documenting the role of ETCs in the global heat balance.

Trend of Storm Surge Induced by Typical Landfall Super Typhoons During 1975–2021 in the Eastern China Sea

Climate change affects the activity of global and regional tropical cyclones(TCs).Among all TCs,typical super typhoons(STYs)are particularly devastating because they maintain their intensity when landing on the coast and thus cause casualties,economic losses,and environmental damage.Using a 3D tidal model,we reconstructed the typhoon(TY)wind field to simulate the storm surge induced by typical STYs.The TY activity was then analyzed using historical data.Results showed a downtrend of varying degrees in the annual frequency of STYs and TCs in the Western North Pacific(WNP)Basin,with a significant trend change observed for TCs from 1949 to 2021.A large difference in the interannual change in frequency was found between STYs and TCs in the WNP and Eastern China Sea(ECS).Along the coast of EC,the frequency of landfall TCs showed a weak downtrend,and the typical STYs showed reverse micro growth with peak activity in August.Zhejiang,Fujian,and Taiwan were highly vulnerable to the frontal hits of typical STYs.Affected by climate change,the average lifetime maximum intensity(LMI)locations and landfall locations of typical STYs in the ECS basin showed a significant poleward migration trend.In addition,the annual average LMI and accumulated cyclone energy showed an uptrend,indicating the increasing severity of the disaster risk.Affected by the typical STY activity in the ECS,the maximum storm surge area also showed poleward migration,and the coast of North China faced potential growth in high storm surge risks.

Moored Ship Motions due to Tropical Cyclone Linda

Severe wind-wave due to tropical cyclone Linda can cause port downtime which affects port operations such as berthing, mooting and （un）loading of the ship. The ship motions are criteria for limiting the port operations, human safety and preventing the damage of port equipment and furniture. Therefore, this study discusses moored ship motions due to severe wind-wave during the tropical cyclone Linda which entered the Gulf of Thailand in November 1997. The ship motions are represented in the moored ship analysis at SRH （Sriracha Harbour Port） and BLCP （BLCP Coal-Fired Power Plant Port）, and are subject to the static environmental load on the ship in accordance with Spanish Standard （ROM 0.2-1990） [1]. The environment in numerical model is derived from the wave model and hydrodynamics model using the application of Delft3D-WAVE and Delft3D-FLOW. The model location includes Ao Udom Bay and Rayong Sea. The model results represent the environment at Rayong Sea which is more severe than Ao Udom Bay. The ship motions at BLCP are mostly larger than SRH.

中国沿海地区热带气旋危险性分析

基于1980—2016年的西北太平洋热带气旋尺度资料,采用2种方法分析了热带气旋灾害的危险性。第一种方法根据热带气旋的风圈半径,用GIS生成了每个气旋的影响范围,对于登陆中国沿海的227个热带气旋,用叠加法得到了其影响范围与频次。第二种方法侧重热带气旋引发的风暴潮灾害,用潮位模型估算了热带气旋登陆时的潮位数据,提出了H3指标,该指标用潮位、风速和中心气压3个因子计算潮位点的风暴潮危险性,并根据H3指标得到了海岸线的危险性综合指标。分析结果表明,福建、广东两省受热带气旋的影响最为严重。37 a间,福建省有80%的面积(约9.8万km^(2))受热带气旋影响的频次超过20次;广东省则有70%的面积(约12.6万km2)受热带气旋影响的频次超过20次。受风暴潮危害大的海岸线主要位于广东、广西、福建、浙江四省,危险性指标在30以上的有广东的湛江市、茂名市、江门市、阳江市和珠海市;广西的北海市、防城港市和钦州市;福建的福州市以及浙江的台州市和温州市。

Changes of tropical cyclone size in three oceanic basins of the northern hemisphere from 2001 to 2021

In this study the changes of tropical cyclone(TC)size from 2001 to 2021 are analyzed based on linear and quadratic curve fittings of the National Hurricane Center(NHC)/Joint Typhoon Warning Center(JTWC)best track data,based on the radius of maximum wind(RMW)and the average radius of 34-kt wind(AR34),in three oceanic basins of the North Atlantic(NATL),the Western North Pacific(WPAC)and the Eastern North Pacific(EPAC).The computations are done separately for two categories of tropical cyclones:tropical storms(TS)and hurricanes(HT).Size changes of landfalling and non-landfalling TCs are also discussed.Results show that there is a great inter-basin variability among the changes in TC sizes.Major conclusions include:1)overall,the inner cores of TSs have become larger in all three basins,with the increasing tendencies being significant in the NATL and WAPC,while those of HTs mostly get smaller or remain similar;2)meanwhile,comparatively large inter-basin differences are observed for the TC outer core sizes,and the sizes of landfalling TCs;3)particularly,a significant decrease in landfalling HT outer core size is observed over the EPAC;4)in contrast,significant increases in landfalling TS inner core size are found over the NATL and WPAC.The presented analysis results could benefit future research about TC forecasts,storm surge studies,and the cyclone climate and its changes.

Comparative analysis of the rapid intensification of two super cyclonic storms in the Arabian Sea

A comparative analysis of the rapid intensification(RI)of super cyclonic storms Chapala(2015)and Kyarr(2019)in the Arabian Sea is conducted using the North Indian Ocean tropical cyclone data,microwave sounding images,the NOAA OISST data and the ERA5 reanalysis data.Results show that the subtropical westerly jet stream and the Southern Hemisphere anticyclonic circulation led to the formation of an obvious double-channel outflow from the northern and southern sides of the two storm centers,and the substantial inflow appeared at the eastern boundary layer of both storms.These promoted the vertical ascent motion and release of the latent heat of condensation.A warm sea surface is a necessary but not dominant factor for the RI of cyclonic storms in the Arabian Sea.During the RI of Chapala and Kyarr,the deep vertical wind shear was less than 10 m s-1;moreover,the mid-level humidity conditions favored the RI of the two cyclonic storms.Chapala had a single warm core,whereas Kyarr had double warm cores in the vertical direction.The impacts of the latent heat of fusion is more obvious for Chapala,and the potential vorticity in its inner core increases from 4.4 PVU to 8.8 PVU,whereas the potential vorticity and vorticity in the inner core of Kyarr do not change significantly.Microwave detection images show that both Chapala and Kyarr were accompanied by the formation of eyewalls during the RI phase,and the radius of maximum wind decreased and the maximum wind speed increased during the eyewall-thinning process.Both Chapala and Kyarr passed through a positive anomaly region of maximum potential intensity during the RI phase,which increases the possibility to develop to higher intensity after genesis.

强龙卷超级单体风暴特征分析与预警研究

利用多普勒雷达资料,对发生在安徽的3次强烈龙卷过程进行了分析。重点研究了导致F2~F3级强龙卷的3次超级单体风暴多普勒雷达回波特征及其与强冰雹超级单体风暴的差异。另外,利用安徽省、市、县气象报表、历年气候评价灾情资料（部分来自民政部门的灾情报告）,对1960年至今的龙卷天气的时空分布及变化趋势、产生龙卷的环流形势特征进行了分析,结果表明：（1）龙卷主要出现在淮北东部和江淮之间东部地势平坦地区,7月份出现龙卷的概率最高。（2）超级单体龙卷产生在中等大小的对流有效位能和强垂直风切变条件下,同时抬升凝结高度较低。（3）3次F2~F3级龙卷在发生前、发生时在多普勒雷达上都探测到强中气旋和龙卷涡旋特征TVS。与非龙卷超级单体风暴相比,导致强龙卷的中气旋底高明显偏低,基本在1 km以下。同时风暴结构也有所不同,造成龙卷天气的超级单体风暴最大反射率因子与风暴质心高度接近,基本在3 km左右,反射率因子在50~60 dBz。造成强冰雹的超级单体风暴在冰雹产生前,风暴最大反射率因子高于风暴质心的高度;当风暴开始降雹时,最大反射率因子高度开始降低,而风暴质心的高度变化不大,高于最大反射率因子高度,基本保持在5km左右,反射率因子在60~70 dBz。

一次多种强对流天气过程的雷达回波特征分析

利用桂林的CINRAD-SB雷达资料和NCEP资料对2004年11月9—11日桂林市中北部连续性暴雨、大暴雨,南部连续局地冰雹龙卷过程进行了分析。结果表明:一强降水超级单体演变成弓形回波导致了10日桂林市短时暴洪;一系列线型波动(LEWP)的列车效应造成了9—11日桂林北部的暴雨。弓形回波和线形波动前侧都有V型缺口,表明有强的西南气流进入上升气流,同时都有后侧V型缺口,表明具有强的下沉气流和后侧偏北气流。可用弓形回波提前20～33分钟预警短时暴洪。而造成南部恭城附近连续两日的冰雹和龙卷风天气都是由孤立的右移型γ尺度超级单体造成,有三体散射长钉(TBSS)回波特征,可用于提前15～22分钟预警大冰雹。对流单体发展成为龙卷单体伴随有下击暴流的气旋性辐散特征,非常临近地面大风出现时间。

“2012.4.11”两个强降雹超级单体特征分析

利用常规气象资料、自动站资料、新一代天气雷达和风廓线雷达等资料,对一次强对流天气过程中两个强风暴单体的形势背景、强对流发生条件、强风暴单体演变及结构特征、风暴异同点进行了详细分析。结果表明:(1)本次强对流过程是发生在强的垂直风切变条件下;高层冷平流降温减湿、低层暖平流增温增湿的对流不稳定层结,高CAPE值为强对流发生发展提供了必要的能量条件;上干下湿的水汽分布有利于冰雹、雷暴大风的产生;适宜的0℃、-20℃层高度使此次过程地面以降雹为主;地面倒槽低压、辐合线及低层锋区的南压是这次强对流天气的触发因子。(2)两个强降雹单体雷达回波共同特征是降大雹前均出现了三体散射长钉回波,弱回波区,回波强度强,VIL密度均大于4 kg·m^(-3),成熟阶段均右偏高空风约30°。(3)长生命史超级单体风暴Ⅱ的中气旋维持2个多小时,它保证了一支强上升气流支撑空中大冰雹的增长,维持了雷暴的持续发展,使其生命史长达近6 h,同时也存在前侧、后侧入流缺口,反映了上升气流与下沉气流共存的风暴动力特征,其高层辐散更强,移动路径东略偏南且移向稳定,平均右偏高空风约28°,移速均匀为14 m·s^(-1);超级单体风暴Ⅰ的中气旋维持时间仅十几分钟,且处于弱中气旋的下限,其高层辐散和上升气流更弱,风暴生命史更短,移动路径东略偏北,除成熟阶段外右偏高空风10°~20°。这些差异与产生风暴的环境条件如垂直风切变、垂直涡度等存在差异有密切关系。

热带气旋影响福建沿海风暴潮特征分析

文中利用1990-2008年气象要素资料、热带气旋路径资料和福建沿海9个验潮站资料，从热带气旋登陆、路径以及福建沿海地理特征等方面，分析研究福建沿海热带气旋风暴潮特征。结果表明：每年平均约有5.58个热带气旋登陆或影响福建，风暴潮发生率为81.1%，福建沿海风暴潮主要出现在5-10月，风暴潮过程最多的是8-9月，平均每年有4.53次风暴潮过程。正面登陆福建的热带气旋和登陆浙南的影响热带气旋，最容易引发福建省沿海热带气旋风暴潮过程，且风暴增水最强，最大增水可达200cm以上，其次是登陆广东的影响热带气旋。由于闽江口的喇叭口地形作用，位于闽江入海处的闽江口岸段在全省4个岸段中风暴增水最强。