This research project proposed a unique solution to make use of these base stations to keep all subscribers alerted with warning of possible disaster should that be required. As the current, network does not provide a provision for such a noble approach, a new network model has been developed and simulated to interface a sensor (weather station, WeS), with WiMAX weather station. The weather station is based on DSP processor to receive a digitised sensor values, process these values, analyse them and if they fall within the alert zones, packet them according to WiMAX protocol and send them to subscribers. The developed standard bypasses any commercial network to offer free transmission to subscribers. This setup is also able to extract information on weather condition or react on uncertainty, i.e. disaster scenarios. Natural disasters, such as torrent, tornado/ hurricane, volcano eruption, earthquake, Tsunamis or landslide are increasing. Unfortunately they bring with them human tragedies, environment catastrophes, villages, cities and counties are subject to endless devastation during and after the destructive forces. Water, electricity and gas supply are most disrupted and difficult to restore in short time. However, communication is another item that can be affected adversely but WLAN with specific considerations, should be excluded from the effect. This project presents a solution, albeit minor relative to the maximum effect of the disaster, but will keep the telecommunication/communication in operation. Our novel technique, a “Clone Wireless Wide Area Network (CloneWAN)” is a clone wireless network to the wired Network. In the event of natural calamities, it gives continuity of network operation. It is based on WiMAX. The realization of CloneWAN has been formed and simulated to set the national network of the UAE at its correct form. CloneWAN model has been simulated with Opnet platform. All results revealed that the model is complete. The interface to Alerting System is discussed. Results show that the dynamic behavior of the parameters delay and Throughput of CloneWAN model is stable over various and different load scenarios. WiMAX is a de-facto standard in the current and future network requirement standards. Its main component is the Base Station which is normally stationed in the air, high enough to couple signals from other base stations. It is purpose is merely focused on networking signals for commercial purposes. The suggested hardware interface for the Weather Station is based on DSP SHARC processor. The model has been written in C and simulated under Opnet package. A number of scenarios have been set to represent different disasters worldwide. All results are listed and discussed later in the thesis.

Approved for public release; distribution is unlimited. / The Tropical Cyclone Vorticity Tracking Program is used to identify vortices in the western North Pacific from the Navy Operational Global Atmospheric Prediction System (NOGAPS) analyses and forecasts during May- October 2002 and 2003. Based on the NOGAPS analyses, several parameters are different between the 23vortices that developed into storms during 2002 according to the Joint Typhoon Warning Center (JTWC) and the231 vortices that did not develop. After eliminating 127 vortices that did not persist at least 24 h, this left 104 nondevelopingcases. For the developing circulations, the average 850-mb relative vorticity value at the first JTWCwarningtime was 5.0 x 10-5 s-1, with an easterly deep layer wind shear of -1.8 m s-1. The average 850-mb relativevorticity maximum for the non-developing cases was 3.3 x 10-5 s-1, with a westerly vertical shear of 4.1 m s-1. TheNOGAPS model tends to over-forecast relative vorticity prior to formation time for both developers and nondevelopers.Especially for the 72-h and 96-h forecasts, the over-forecasting tendency leads to non-developingvortices meeting the threshold vorticity value of the developing vortices. The tendency for NOGAPS to forecastthe non-developing deep layer wind shear to become increasingly easterly with time is considered to be a majorfactor in these over-forecasts of formation. Some adjustments in the cumulus parameterization heating andmoistening plus convective momentum transport may improve these forecasts of tropical cyclone formation. / Captain, United States Air Force

Since an extratropical transition (ET) of a decaying tropical cyclone (TC) often results in a fast-moving, rapidly developing extratropical cyclone and amplification of synoptic-scale systems far downstream, proper forecasting of ET events is critical to forecast accuracy over large ocean regions. Past studies have linked forecast accuracy to the phasing of a decaying TC with favorable midlatitudes conditions. Because ET events are sensitive to the analyzed initial conditions, this phasing is examined using 11 member ensemble predictions available four times daily from the National Centers for Environmental Prediction, which were combined into a single 44 member ensemble based on a common forecast verification time. Recurring ET patterns within the 44 member ensemble were objectively identified using a combination of EOF and cluster analysis. Ensemble spread first appears near the point where the TC moves into the midlatitudes and then propagates downstream. Although ensemble spread in the forecast fields was large at extended forecast intervals, the ensemble spread, and the number of ET patterns identified in successive EPS predictions, decreased as the ET process became better defined. Within 48 hours of the ET event, the ensemble prediction system properly identified the ET pattern with a minimum ensemble spread. Similar to Klein et al. (2002), the shifts in the initial position of the TC and the subsequent dynamical coupling can explain differences between weak and strong ET reintensifications.

Waves in the North Atlantic are strongly seasonal, and peak in the winter season. The west coast of Portugal is exposed to winter swell, generated by wind associated with North Atlantic extratropical cyclones. The track of these storms, generated near the North America east coast, is strongly influenced by the North Atlantic Oscillation (NAO). When the NAO is in its positive phase they normally track northeast and reach Western Europe well north of the Iberian Peninsula, in the British Islands or Scandinavia. However, in the negative NAO situation,the track of the storms is more zonal and south than usual, due to a weakened NAO. The characteristics of wave regime in Portugal are shown to be strongly related to the NAO phase and corresponding storm tracking. Positive NAO storms, tracking northeast towards the north of Europe, drive longer period swell from the northwest, whereas negative NAO storms have associated shorter period swell arriving to Portugal from a more westerly direction. The relation between the NAO phase and the storm tracks and the characteristics of the wave regime is investigated with ten year observations from four directional waverider coastal buoys, located off the coast of Portugal.

During July 2005, Typhoon Banyan recurved and underwent tropical transition over the western North Pacific. Coincident with the extratropical transition of Banyan, a large mid-tropospheric anticyclone developed immediately east of the recurving typhoon. The anticyclone was associated with a high-amplitude Rossby wave-like pattern that developed downstream of the anticyclone and extended across the North Pacific. Development of the anticyclone is examined with respect of the interaction between the outflow from Banyan and the midlatitude jet streak. During the poleward movement of TY Banyan, an anticyclonically-curved jet streak was forced by the merger of the upper-level outflow from Banyan and a jet streak associated with an upstream trough. The anticyclonic curvature was accentuated by the presence of a mid-tropospheric cyclone east of Banyan. The anticyclonic curvature increased as Banyan moved poleward and the mid-tropospheric cyclone moved equatorward. Thermodynamic forcing of the mid-tropospheric anticyclone is examined with respect to the poleward movement of warm moist air that ascends as it is advected around the eastern side of the decaying typhoon. The combination of dynamic and thermodynamic factors is examined in a potential vorticity framework to identify the development of the anticyclone east of Banyan and the transformation of Banyan into a midlatitude cyclone.

The increase in skill of numerical model guidance and the use of consensus forecast techniques have led to significant improvements in the accuracy of tropical cyclone track forecasts at ranges beyond 72 h. Identification of instances when the forecast track from an individual numerical model may be in error could lead to additional improvement in the accuracy of tropical cyclone track forecasts. An objective methodology is tested to characterize the spread among the three primary global numerical model forecast tracks used as guidance by the Joint Typhoon Warning Center. Statistically-significant principal components derived from empirical orthogonal functions of mid-tropospheric height and vorticity forecast fields identify cases of large spread among model forecasts. Cases in which the three-model average forecast track resulted in a large error were characterized by a distribution of principal components such that one component was significantly different from the other two. Removal of the forecast track associated with the outlying principal component resulted in a reduced forecast error. Therefore, the objective methodology may be utilized to define a selective consensus by removing forecast tracks from consideration based on the projection of forecast fields onto empirical orthogonal functions and inspecting the distribution of the resulting principal components.

Extratropical cyclones (ETCs) are a common feature of mid- and high-latitudes which, on a large scale, are a primary mechanism by which heat and moisture are transported from equator to pole. ETCs also exert a major impact at smaller scales. Communities along the western coast of Alaska face many types of impacts generated by the winds associated with ETCs, including storm surges, sea water intrusion into fresh water stores, and coastal erosion. Such “strong wind events”, which can occur independent of an ETC, can also generate hazardous sea states and associated impacts on shipping. With no roads, coastal Alaska relies heavily on marine and air transportation. Hazards posed to marine and air travel are often related to two main types of weather: wind and fog. Consultations with stakeholders in the marine transportation community have indicated more precisely specific aspects of poor weather, such as high wind events, that are problematic, including the idea that the periods between strong wind events, defined as lull periods, represent an important metric when planning travel between points of safe harbour. Three separate studies of storminess metrics in the North Pacific and Alaskan regions are presented. The first study presents both a comparison of two storm identification and tracking algorithms and an evaluation of the general characteristics of extratropical cyclones for the North Pacific as portrayed in two reanalyses. The second study applies a modified wind event identification algorithm to reanalysis data to evaluate the spatial climatological patterns of wind events in the circum-Arctic. The third study tests the statistical relationships and predictability of two measures of storm activity - cyclone track density (TDEN) and wind event frequency - in the North Pacific using teleconnection indices exhibiting local influence. The first study showed that the general patterns and trends of cyclone characteristics are similar between the two methods, though with increased values of cyclogenesis density, cyclolysis density, and track density when using the relative vorticity based method. A comparison between storm tracks for NCEP1 and the 56-member ensemble of the Twentieth Century Reanalysis v2 (20CR) shows distinct differences between the 20CR and NCEP1 mean climatology for main storminess indicators. The second study evaluated the spatial and temporal characteristics of wind events and introduced a novel indicator that characterizes periods of favorable weather between strong wind events that last 48-hours or longer, termed lull events. Lull periods were found to be an important consideration for northern marine operations – both economic and subsistence. Additionally, combinations of lull and wind event indicators, termed lull/storm winds (LSW), were analyzed and showed that preferred areas of wind events and lull events are not always spatially coherent. The third study tested the statistical relationships and predictability of two measures of storm activity - cyclone track density (TDEN) and wind event frequency - in the North Pacific using teleconnection indices with local influence for the winter period of 1950 - 2012. Two statistical modeling techniques are applied to evaluate linear and non-linear methods of prediction for the region. For both measures of storm activity, the North Pacific index, Niño 3.4 index, and the AO index were found to be the best predictors. Using a 23-year hindcast period (1980 – 2012), the region of highest wind event anomaly prediction skill is located in the western Bering Sea, with hindcast correlation values as high as +0.5 and root mean squared skill scores (RMSESS) 25% higher than climatology. Highest TDEN predictive skill from the 23-year hindcast is found in the southeast region of the North Pacific, near the California coastline, with correlation and RMSESS as high as +0.7 and 25 - 30%, respectively. / Graduate

A Península Antártica (PA) é uma das regiões no planeta que apresentam as mais adversas condições do tempo devido à constante passagem de ciclones. O conhecimento das condições meteorológicas futuras é fundamental para o desenvolvimento de atividades operacionais e de pesquisa na região. Nos últimos anos a implantação e melhoramento dos modelos numéricos, que tem como foco a previsão do tempo na Antártica, têm sido alvo de diversos estudos pela comunidade acadêmica. O objetivo principal deste trabalho foi avaliar o desempenho do modelo BRAMS na simulação de parâmetros meteorológicos durante a passagem de ciclones na Península Antártica. Diversas simulações, que envolveram diferentes configurações estruturais e físicas do modelo foram realizadas para dois casos de passagem de ciclones na PA, um que ocorreu em fevereiro e outro em julho de 2009. A avaliação do desempenho do modelo BRAMS foi feita através de duas análises, uma qualitativa, analisado o comportamento de cada variável simulada pelo modelo em comparação com os dados de estações meteorológicas, e a outra uma análise de sensibilidade baseada em índices estatísticos. O desempenho do modelo BRAMS se mostrou altamente dependente das condições iniciais adotadas. A pressão ao nível médio do mar foi a variável melhor representada, mas o modelo não conseguiu prever adequadamente os aumentos de pressão que ocorrem após a passagem do ciclone pela PA, o que ficou evidente no evento de julho. Por outro lado, o BRAMS se mostrou ineficiente em representar as variações de temperatura que ocorrem durante o período de simulação, principalmente no evento de fevereiro. As temperaturas simuladas pelo BRAMS foram mais elevadas que aquelas observadas nas estações meteorológicas para os dois casos (fevereiro e julho). Além disso, o modelo não conseguiu prever as quedas abruptas de temperatura, observadas durante o avanço do ciclone no mês de julho, devido em grande parte à ausência de gelo marinho nas regiões onde, de fato, as observações mostravam que ele estava presente. O modelo BRAMS, de forma geral, não obteve bom desempenho na simulação do vento, principalmente em relação às variações de direção. O modelo capta as principais variações da componente zonal do vento no caso de verão, porém em algumas estações, quando o escoamento tornou-se meridional, o BRAMS simulou um vento de leste, demonstrando uma forte dependência das condições iniciais. Já no caso de inverno, após o ciclone cruzar a PA, os experimentos simulam um vento de oeste que não condiz com o observado nas estações meteorológicas. Já em se tratando do vento meridional notou-se que o BRAMS intensifica os fluxos de sul, principalmente após a passagem do ciclone pela PA. / The Antarctic Peninsula is one of the regions of the earth, which have the most adverse weather conditions due to the constant movement of cyclones. The knowledge of future meteorological conditions is essential for the operational activities and research developments on the region. In the last years, implantation and improvement of the numeric models, which focus is the weather forecasting on Antarctic, has been the subject of several studies of academic community. The main objective of this study is evaluating the model BRAMS performance, on the simulation of meteorological parameters in events of cyclones on Antarctic Peninsula. Several simulations with different structural and physics configurations on the model were performed in two events of cyclones on AP. One of them occurred in February e the other one in July of 2009. The evaluation of BRAMS model was performed by means of two analyses. The first analysis was qualitative, which analyzed the behavior of each variable simulated by the model in compared to weather stations data. The second analysis was related with the sensibility based on statistical indexes. The BRAMS model performance seems to be dependent on the initial conditions. The pressure at mean sea level was a well represented variable, however the model did not forecasted properly the pressure increase, which occurred after the cyclone event on the AP and it was more evident on event of July. Otherwise, the BRAMS seems to be inefficient for variations on temperatures during the simulation period, especially on February event. Temperatures simulated by BRAMS were higher than that observed on weather station for both cases (February and July). Furthermore, the model did not predicted the abrupt decrease in temperature, observed during the cyclone in July, due to the absence of ice sea in regions where, in fact, the observations showed that he was present. In general, the BRAMS model did not achieved good performance simulating winds, especially on changes of direction. The model captures the major variations of zonal wind during summer, however, in some stations, when the flow direction was changed to meridional, the BRAMS simulated an easterly wind, showing a strong dependence on initial conditions. During winter events, after the cyclone cross the AP, the experiments simulated a west wind, which is not consistent with that observed at meteorological stations. In the case of meridional wind, BRAMS intensified the south flows, especially after the cyclone on AP.

This thesis addresses the extratropical transition (ET) of tropical cyclones. ET is the process by which a tropical cyclone, upon encountering a baroclinic environment at higher latitudes, loses its tropical characteristics and transforms into an extratropical cyclone. The three main goals of the thesis are to develop a historical climatology of global ET occurrence, to examine future projections of ET using a global climate model, and to advance the predictive understanding of ET. A global climatology of ET from 1979-2017 is presented, which explores frequency of occurrence, geographical and seasonal patterns, climate variability, and environmental settings associated with different types of ET in global ocean basins. ET is defined objectively by means of tropical cyclones' trajectories through the Cyclone Phase Space (CPS), which is calculated using storm tracks from best track data and geopotential height fields from reanalysis datasets. Two reanalysis datasets are used and compared for this purpose, the Japanese 55-year Reanalysis (JRA-55) and the ECMWF Interim Reanalysis (ERA-Interim). Results show that ET is most common in the western North Pacific and the North Atlantic, where about half of the tropical cyclones transition into extratropical cyclones. Coastal regions in these basins also face the highest rates of landfalling ET storms. In the Southern Hemisphere basins, ET percentages range from about 20% to 40%. Different "ET pathways" through the CPS are linked to different geographical trajectories and environmental settings: A majority of ETs start with the tropical cyclone becoming thermally asymmetric and end with the formation of a cold core. This pathway typically occurs over warmer sea surface temperatures and takes longer than the reverse pathway, in which a tropical cyclone undergoes ET by developing a cold core before becoming asymmetric. The classifications of tropical cyclones into "ET storms" (tropical cyclones that undergo at some point in their lifetimes) and "non-ET storms" (tropical cyclones that do not undergo ET) obtained from JRA-55 and ERA-Interim are evaluated against the classification obtained from the best track records. In contrast to the CPS definition of ET, which is automated and objective, the best track definition of ET is given by the subjective judgment of human forecasters who take into account a wider range of data. According to the F1 score and the Matthews correlation coefficient, two performance metrics that balance classification sensitivity and specificity, the CPS classification agrees most with the best track classification in the western North Pacific and the North Atlantic, and least in the eastern North Pacific. The JRA-55 classification achieves higher performance scores than does the ERA-Interim classification, mostly because ERA-Interim has a bias toward cold-core structures in the representation of tropical cyclones. Future projections of ET are examined using a five-member ensemble of a coupled global climate model, the Flux-Adjusted Forecast-oriented Low Ocean Resolution (FLOR-FA) version of CM2.5 developed at the Geophysical Fluid Dynamics Laboratory. First, CPS is applied to 1979-2005 FLOR-FA output to develop a historical ET climatology, which is compared to the 1979-2005 ET climatology obtained from JRA-55. This comparison shows that FLOR-FA simulates many unrealistic low-latitude ET events, due to strong local maxima in the geopotential height fields used as input to calculate the CPS parameters. These local maxima, which arguably result from strong grid-scale convective updrafts, mislead the CPS to detect an upper-level cold core where one is not present. Three solutions to this problem are examined: changing the algorithm to compute the CPS parameters such that it uses 95th percentile values of geopotential instead of the maxima, a temporal smoothing of the CPS parameters, and a combination of the previous two. All three modifications largely correct the misdiagnosed cases. Future (2071-2100) projections of ET activity under the Representative Concentration Pathway 4.5 are then explored. A number of changes between the future and historical simulations are robust with respect to the different modifications to the CPS described above, though few are statistically significant. A statistical model that predicts ET in the western North Pacific and the North Atlantic is introduced. The model, a logistic regression with elastic net regularization, was developed with a focus on predictive performance as well as physical interpretability and thus resides at the interface between machine learning and traditional statistics. It uses eight predictors that characterize the storm and its environment, the most important ones being latitude and sea surface temperature. The model is shown to have skill in forecasting ET at lead times up to two days, and it can predict the phase evolution of storms that undergo ET as well as of storms that remain tropical throughout their lifetimes. When used as an instantaneous diagnostic of a storm's tropical/extratropical status, the model performs about as well as the CPS in the western North Pacific and better than the CPS in the North Atlantic, and it predicts the timings of the transitions better than the CPS in both basins. The model can be integrated into statistical tropical cyclone risk models, or may be applied to provide baseline guidance for operational forecasts.

Myanmar remained largely closed to the world through political instability for several years, when it continued to suffer terribly at the hands of nature that remained largely unknown. Of note is the period between 2008 and 2013, during which the country suffered at least eight major natural calamities that killed more than 141,000 people and affected 3.2 million. The worst of these was Cyclone Nargis in May 2008 that killed more than 130,000. With an estimated $4 billion in damages, Nargis remains the deadliest and most destructive named cyclone ever to have occurred in the North Indian Ocean. Recent studies have shown that, due to increased greenhouse gases and aerosol loading in the atmosphere, more and stronger tropical cyclones (TCs) in the last three decades are tracking eastwards toward the Indochina peninsula. Unfortunately, the Burmese lack the capacity to deal with the impacts of such storms. Myanmar was left behind as the world made significant technological and industrial advancement; but agriculture, which employs at least 65% of the active labor force, has remained the backbone of the Myanmar economy – an industry that is heavily reliant on monsoon rainfall. The pre-monsoon TC season in the Bay of Bengal (BoB) precedes the onset of the Myanmar monsoon but sometimes the two (i.e.TC formation and the monsoon onset) occur in unison. This work studied the mechanism by which the Madden Julian Oscillation (MJO) modulates the Myanmar monsoon onset and TC activity collectively (i.e. ISO-Onset-TC connection). Avoiding TC destruction at the beginning of the planting season is crucial, so is the monsoon onset date critical for planning. Additional understanding of the aforementioned ISO-Onset-TC connection could provide further insight into predicting the Myanmar monsoon onset and aid in disaster planning for TC impact. This research is part of a two-year NASA funded project to study extreme climate and weather events.