On the Use of Parametric Wind Models for Wind Wave Modeling under Tropical Cyclones

Wave and wind forces from tropical cyclones are one of the main design parameters of coastal and offshore infrastructure in tropical areas. The estimation of ocean waves parameters in the design of structures in tropical areas is difficult due to the complexity of wind fields associated with tropical cyclones. The use of numerical wave models, forced with parametric wind fields, is a common practice within the climatic characterization of extreme events. However, there is currently no consensus on the selection of parametric models for wave prediction due to the lack of a rigorous assessment of different models. In this study, six well-known parametric wind models were tested, compared, and applied in the Gulf of Mexico and the Caribbean Sea. Therefore, the evaluation and comparison of the resulting wind and wave fields are presented, showing that a particular model may best represent a specific event, but, when dealing with a large number of events, the choice of a particular parametric wind model or a combination of them does not guarantee greater accuracy.

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Numerical Modeling of Tropical Cyclone Generated Waves; Case studies of Irma, Maria and Dorian

10.5194/egusphere-egu2020-11200 ◽

2020 ◽

Author(s):

Gozde Guney Dogan ◽

Pamela Probst ◽

Bora Yalciner ◽

Alessandro Annunziato ◽

Narcisse Zahibo ◽

...

Keyword(s):

Numerical Modeling ◽

Numerical Model ◽

Tropical Cyclone ◽

Atlantic Ocean ◽

Tropical Cyclones ◽

Storm Surge ◽

Coastal Areas ◽

Wind Fields ◽

Caribbean Islands ◽

The Caribbean

Tropical cyclones can be considered one type of extreme event, with their destructive winds, torrential rainfall and storm surge. Every year these natural phenomena affect millions of people around the world, leaving a trail of destruction in several countries, especially along the coastal areas. Only in 2017, two devastating major hurricanes (Irma and Maria) moved across the Caribbean and south-eastern USA, causing extensive damage and deaths. Irma formed in the far eastern Atlantic Ocean on 30 August 2017 and moved towards the Caribbean islands during the following week, significantly strengthening, becoming a Category 5 Hurricane. It caused wide-ranging impacts such as significant storm surge (up to 3m according to US National Oceanic and Atmospheric Administration, NOAA report) to several islands in the Caribbean and Florida. On the second half of September, 2017, another strong Category 5 Hurricane named Maria formed over the Atlantic and moved west towards the Caribbean Sea. Maria also caused several impacts and severe damage in Caribbean Islands, Puerto Rico and the U.S. Virgin Islands due to high speed winds, rainfall, flooding and storm surge with a maximum runup of 3.7 m (US NOAA) on the southern tip of Dominica Island. The most recent devastating event for the Atlantic is Hurricane Dorian. It formed on August 24, 2019 over the Atlantic Ocean and it moved towards the Caribbean islands, as getting stronger as moving, becoming a Category 5 before reaching the Bahamas, where it left a trail of destruction after its passage. The major effect of Dorian was on north-western Bahamas with very strong winds, heavy rainfall and a large storm surge.In this context, a rapid and reliable modeling of storm surge generated by such kind of events is essential for many purposes such as early accurate assessment of the situation, forecasting, estimation of potential impact in coastal areas, and operational issues like emergency management.A numerical model, NAMI DANCE GPU T-SS (Tsunami-Storm Surge) is developed building up on tsunami numerical model NAMI DANCE GPU version to solve nonlinear shallow water equations, using the pressure and wind fields as inputs to compute spatial and temporal distribution of water level throughout the study domain and respective inundation related to tropical cyclones, based on the equations used in the HyFlux2 Code developed by the Joint Research Centre of the European Commission. The code provides a rapid calculation since it is structured for Graphical Processing Unit (GPU) using CUDA API.NAMI DANCE GPU T-SS has been applied to many cases as regular shaped basins under circular static and dynamic pressure fields separately and also different wind fields for validation together with combinations of pressure and wind fields. This study has been conducted to investigate the potential of numerical modeling of tropical cyclone generated storm surge based on recent events Irma, Maria and Dorian. The results are presented and discussed based on comparison with the measurements and observations. The study shows promise for developing a cyclone modeling capability based on available measurement and observational data.

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The Mesoamerican mid-summer drought: the impact of its definition on occurrences and recent changes

10.5194/hess-2021-543 ◽

2021 ◽

Author(s):

Edwin P. Maurer ◽

Iris T. Stewart ◽

Kenneth Joseph ◽

Hugo G. Hidalgo

Keyword(s):

Historical Record ◽

Climate Projections ◽

Summer Drought ◽

Seasonal Forecasts ◽

Drought Pattern ◽

The Caribbean ◽

The Impact ◽

Minimum Intensity ◽

Selection Of

Abstract. The mid-summer drought, veranillo or canícula, is a phenomenon experienced in many areas, including Mexico, Central America, and the Caribbean. It generally is experienced as reduced rainfall in July–August, in the middle of the typical rainy season (May–September). Many past studies have attempted to quantify changes in mid-summer drought characteristics during the recent past or for future climate projections. To do this, objective definitions of a mid-summer drought’s occurrence, strength and duration have been developed by many researchers. In this effort we adopt a recent set of definitions and examine the impact of varying these on the characterization of mid-summer droughts and the detected changes over the past four decades. We find the selection of a minimum intensity threshold has a dramatic effect on the results of both the area considered as experiencing a mid-summer drought and the changes detected in the recent historical record. The intensity chosen can affect both the magnitude and direction of changes reported in the recent observed record. Further, we find that the typical mid-summer drought pattern may not be occurring during the time it has historically; whether examining past or future changes or developing improved seasonal forecasts, the non-stationarity of its timing should be accommodated.

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Improving Parametric Cyclonic Wind Fields Using Recent Satellite Remote Sensing Data

10.20944/preprints201803.0095.v1 ◽

2018 ◽

Author(s):

Yann Krien ◽

Gaël Arnaud ◽

Raphaël Cécé ◽

Jamal Khan ◽

Ali Bel Madani ◽

...

Keyword(s):

Remote Sensing ◽

Tropical Cyclones ◽

Satellite Remote Sensing ◽

Wind Waves ◽

Surface Wind ◽

Coupled Model ◽

Remote Sensing Data ◽

Parametric Models ◽

Substantial Part ◽

Wind Fields

Parametric cyclonic wind fields are widely used worldwide for insurance risk underwriting, coastal planning, or storm surge forecasts. They support high-stakes financial, development, and emergency decisions. Yet, there is still no consensus on the best parametric approach, or relevant guidance to choose among the great variety of published models. The aim of this paper is first and foremost to demonstrate that recent progresses on estimating extreme surface wind speeds from satellite remote sensing now makes it possible to select the best option with greater objectivity. In particular, we show that the Cyclone Global Navigation Satellite System (CYGNSS) mission of NASA is able to capture a substantial part of the tropical cyclones structure, and allows identifying systematic biases in a number of parametric models. Our results also suggest that none of the traditional empirical approaches can be considered as the best option in all cases. Rather, the choice of a parametric model depends on several criteria such as cyclone intensity and/or availability of wind radii information. The benefit of our approach is demonstrated by comparing traditional models with an improved vortex for hurricane Maria in the Caribbean. The wave heights computed by a wave-current hydrodynamic coupled model are found to be much better reproduced, with a significant reduction of the model biases. The results and approach presented in this study should shed new light on how to handle parametric cyclonic wind models. This will help the scientific community to conduct better wind, waves and surge analysis for tropical cyclones.

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Optimal Characterization of 28 GHz Bowtie Antenna for 5G Applications

10.21203/rs.3.rs-1092202/v1 ◽

2021 ◽

Author(s):

AHMET ULUSLU

Keyword(s):

Design Optimization ◽

Antenna Design ◽

Microwave Antenna ◽

Design Parameters ◽

Design Problems ◽

Bowtie Antenna ◽

5G Technologies ◽

Reliable Solution ◽

Selection Of

Abstract Here, the selection of the design parameters of the bowtie patch antenna (BPA) for 5G applications is presented as a multidimensional, multi-purpose design optimization problem. The operating frequency of the proposed antenna is 28 GHz, which is the standard for millimeter waveband and 5G technologies. In order to overcome this difficult design optimization, a new, fast and powerful optimization algorithm was used by modified the non-dominant sorting genetic algorithm (NSGA)-III and optimal characterization of the microwave antenna design was obtained. It is assumed that the optimal characterization gives the best solution for the determined cost function, among the possible solutions within the specified range. The superiority of the proposed method has been proven by comparing it with similar types of algorithm. The antennas in the results found have good performance operating at 28 GHz, with a return loss of up to –49 dB, a gain of around 1.96 dB, good directivity, and the radiation pattern of the proposed antenna has a good match over the required frequency. Therefore, the proposed design can be used in 5G devices. As a whole, the proposed design optimization process is an efficient, fast and reliable solution for all antenna design problems.

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Improving Parametric Cyclonic Wind Fields Using Recent Satellite Remote Sensing Data

10.20944/preprints201803.0095.v2 ◽

2018 ◽

Author(s):

Yann Krien ◽

Gaël Arnaud ◽

Raphaël Cécé ◽

Jamal Khan ◽

Ali Bel Madani ◽

...

Keyword(s):

Remote Sensing ◽

Tropical Cyclones ◽

Satellite Remote Sensing ◽

Wind Waves ◽

Surface Wind ◽

Remote Sensing Data ◽

Parametric Model ◽

Parametric Models ◽

Wind Fields ◽

Sensing Data

Parametric cyclonic wind fields are widely used worldwide for insurance risk underwriting, coastal planning, or storm surge forecasts. They support high-stakes financial, development, and emergency decisions. Yet, there is still no consensus on the best parametric approach, or relevant guidance to choose among the great variety of published models. The aim of this paper is first and foremost to demonstrate that recent progresses on estimating extreme surface wind speeds from satellite remote sensing now makes it possible to select the best option with greater objectivity. In particular, we show that the Cyclone Global Navigation Satellite System (CYGNSS) mission of NASA is able to capture a substantial part of the tropical cyclones structure, and allows identifying systematic biases in a number of parametric models. Our results also suggest that none of the traditional empirical approaches can be considered as the best option in all cases. Rather, the choice of a parametric model depends on several criteria such as cyclone intensity and/or availability of wind radii information. The benefit of using satellite remote sensing data to better select a parametric model for a specific case study is tested here by simulating hurricane Maria (2017). The significant wave heights computed by a wave-current hydrodynamic coupled model are found to be in good accordance with the predictions given by the remote sensing data in terms of bias. The results and approach presented in this study should shed new light on how to handle parametric cyclonic wind models, and help the scientific community to conduct better wind, waves and surge analysis for tropical cyclones.

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Applications of Transmission Electron Microscopy in the Characterization of Metal Machinability

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101967 ◽

1968 ◽

Vol 26 ◽

pp. 442-443 ◽

Cited By ~ 1

Author(s):

L.E. Murr ◽

A.B. Draper

Keyword(s):

Electron Microscopy ◽

State Physics ◽

Test Material ◽

Milling Machine ◽

Rotary Table ◽

Solid State Physics ◽

Materials Properties ◽

Transmission Electron ◽

Selection Of

The industrial characterization of the machinability of metals and alloys has always been a very arbitrarily defined property, subject to the selection of various reference or test materials; and the adoption of rather naive and misleading interpretations and standards. However, it seems reasonable to assume that with the present state of knowledge of materials properties, and the current theories of solid state physics, more basic guidelines for machinability characterization might be established on the basis of the residual machined microstructures. This approach was originally pursued by Draper; and our presentation here will simply reflect an exposition and extension of this research.The technique consists initially in the production of machined chips of a desired test material on a horizontal milling machine with the workpiece (specimen) mounted on a rotary table vice. A single cut of a specified depth is taken from the workpiece (0.25 in. wide) each at a new tool location.

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