Coastal Forecasts and Storm Surge Predictions for Tropical Cyclones: A Timely Partnership Program

Abstract This study examines the implications of recent advances in global climate modelling for simulating storm surges. Following the ERA-Interim (0.75° × 0.75°) global climate reanalysis, in 2018 the European Centre for Medium-range Weather Forecasts released its successor, the ERA5 (0.25° × 0.25°) reanalysis. Using the Global Tide and Surge Model, we analyse eight historical storm surge events driven by tropical—and extra-tropical cyclones. For these events we extract wind fields from the two reanalysis datasets and compare these against satellite-based wind field observations from the Advanced SCATterometer. The root mean squared errors in tropical cyclone wind speed reduce by 58% in ERA5, compared to ERA-Interim, indicating that the mean sea-level pressure and corresponding strong 10-m winds in tropical cyclones greatly improved from ERA-Interim to ERA5. For four of the eight historical events we validate the modelled storm surge heights with tide gauge observations. For Hurricane Irma, the modelled surge height increases from 0.88 m with ERA-Interim to 2.68 m with ERA5, compared to an observed surge height of 2.64 m. We also examine how future advances in climate modelling can potentially further improve global storm surge modelling by comparing the results for ERA-Interim and ERA5 against the operational Integrated Forecasting System (0.125° × 0.125°). We find that a further increase in model resolution results in a better representation of the wind fields and associated storm surges, especially for small size tropical cyclones. Overall, our results show that recent advances in global climate modelling have the potential to increase the accuracy of early-warning systems and coastal flood hazard assessments at the global scale.

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Coastal Resilience Against Storm Surge from Tropical Cyclones

Atmosphere ◽

10.3390/atmos11070725 ◽

2020 ◽

Vol 11 (7) ◽

pp. 725

Author(s):

Robert Mendelsohn ◽

Liang Zheng

Keyword(s):

United States ◽

Probability Distribution ◽

Tropical Cyclones ◽

Storm Surge ◽

Urban Areas ◽

Storm Surges ◽

The United States ◽

Atlantic Seaboard ◽

Order Of Magnitude ◽

Coastal Resilience

It is well known that seawalls are effective at stopping common storm surges in urban areas. This paper examines whether seawalls should be built to withstand the storm surge from a major tropical cyclone. We estimate the extra cost of building the wall tall enough to stop such surges and the extra flood benefit of this additional height. We estimate the surge probability distribution from six tidal stations spread along the Atlantic seaboard of the United States. We then measure how valuable the vulnerable buildings behind a 100 m wall must be to justify such a tall wall at each site. Combining information about the probability distribution of storm surge, the average elevation of protected buildings, and the damage rate at each building, we find that the value of protected buildings behind this 100 m wall must be in the hundreds of millions to justify the wall. We also examine the additional flood benefit and cost of protecting a km2 of land in nearby cities at each site. The density of buildings in coastal cities in the United States are generally more than an order of magnitude too low to justify seawalls this high. Seawalls are effective, but not at stopping the surge damage from major tropical cyclones.

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The Global Long-term Effects of Storm Surge Damages on Human Settlements

10.5194/egusphere-egu2020-21564 ◽

2020 ◽

Author(s):

Sven Kunze

Keyword(s):

Economic Impact ◽

Tropical Cyclones ◽

Storm Surge ◽

Local Population ◽

Developed Countries ◽

Sub Saharan Africa ◽

Positive Trend ◽

Long Term Effects ◽

Human Settlements ◽

Combining Data

The influence of natural conditions on human settlements are immense. While a friendly and calm environment can lead to prosperity and growth, a hostile one with frequent natural disasters can result in stagnation, collapse, and even death. Tropical cyclones, as an unpredictable and recurring disastrous events, pose a considerable threat to prosperous development of human societies. The IPCC estimates that globally around 250 million people are vulnerable to storm surge events every year. If the threat is too large, a natural adaptation strategy would seem to move away to less dangerous places. It thus can be considered puzzling that there is a positive trend of moving to coastal flooding zones in Sub-Saharan Africa, North America and Asia, and this is projected to continue in the future. Additionally, climate change may increase the local exposure to storm surge by rising sea levels and changing intensity of tropical cyclones.Given this worrisome development, a systematic analysis of the relationship between settlement structures and tropical cyclones is called for. In this paper we analyze whether people relocate from hazardous areas impacted by tropical cyclones. Importantly, the greatest threat from a tropical cyclone is generally due to the accompanying storm surge. But, because storm surge levels are hard to model, as of date no global (economic) impact study has attempted to model or used historic storm surge data to estimate the economic impact of tropical storms. Rather most studies only focus on wind damages, while other also include rain damages. Within this paper, we are closing this gap by explicitly modeling historic storm surge data worldwide from 1850-2015 and linking this to local population settlement.&#160;By combining data on bathymetry, tidal cycles, weather conditions, and &#160;pressure drop models for the tropical cyclones we are able to estimate spatial storm surge data at a resolution of 5 arc minutes. This data then allows us, in a first step, to analyze its systematic impact on historical geo-referenced population and settlement structure data at a spatial scale of 5 arc minutes. We are able to show some interesting population patterns in response to tropical cyclones. Contrary to many empirical studies, we find that people do settle away from hazardous areas. This effect is especially large for low elevation coastal zones, while for non low elevation coastal areas we find no effect. The same pattern can be found for developing and developed countries, but the shrinking of the population is 39 percent larger in developing countries.&#160;

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Storm Surge, Blocking, and Cyclones: A Compound Hazards Analysis for the Northeast United States

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-21-0062.1 ◽

2021 ◽

Author(s):

James F. Booth ◽

Veeshan Narinesingh ◽

Katherine L. Towey ◽

Jeyavinoth Jeyaratnam

Keyword(s):

United States ◽

Tropical Cyclones ◽

Storm Surge ◽

Short Duration ◽

Extratropical Cyclones ◽

Northeast United States ◽

Long Duration ◽

Medium Range ◽

Slow Moving ◽

The Relationship

AbstractStorm surge is a weather hazard that can generate dangerous flooding and is not fully understood in terms of timing and atmospheric forcing. Using observations along the Northeast United States, surge is sorted based on duration and intensity to reveal distinct time-evolving behavior. Long-duration surge events slowly recede, while strong, short-duration events often involve negative surge in quick succession after the maximum. Using Lagrangian track information, the tropical and extratropical cyclones and atmospheric blocks that generate the surge events are identified. There is a linear correlation between surge duration and surge maximum, and the relationship is stronger for surge caused by extratropical cyclones as compared to those events caused by tropical cyclones. For the extremes based on duration, the shortest-duration strong surge events are caused by tropical cyclones, while the longest-duration events are most often caused by extratropical cyclones. At least half of long-duration surge events involve anomalously strong atmospheric blocking poleward of the cyclone, while strong, short-duration events are most often caused by cyclones in the absence of blocking. The dynamical influence of the blocks leads to slow-moving cyclones that take meandering paths. In contrast, for strong, short-duration events, cyclones travel faster and take a more meridional path. These unique dynamical scenarios provide better insight for interpreting the threat of surge in medium-range forecasts.

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Achieving Residential Coastal Communities Resilient to Tropical Cyclones and Climate Change

Frontiers in Built Environment ◽

10.3389/fbuil.2020.576403 ◽

2021 ◽

Vol 6 ◽

Author(s):

Pramodit Adhikari ◽

Mohamed A. Abdelhafez ◽

Yue Dong ◽

Yanlin Guo ◽

Hussam N. Mahmoud ◽

...

Keyword(s):

Climate Change ◽

Tropical Cyclones ◽

Storm Surge ◽

Residential Buildings ◽

The United States ◽

Performance Criteria ◽

Climate Change Scenarios ◽

Hurricane Wind ◽

Increased Risk ◽

The Impact

Coastal cities in the Southeast and Gulf Coast of the United States are at an increased risk of tropical cyclones (hurricanes) due to the combined effects of urbanization, rapid economic development, and climate change. Current building codes and standards focus on minimum performance criteria for individual buildings exposed to severe hazard events to ensure occupant safety. However, they do not consider the resilience of buildings and building portfolios, which are key factors in determining whether a community can respond to and recover from a severe natural hazard event. Light-frame wood residential buildings dominate the residential market in the US, represent a significant percentage of the investment in the built environment, and are especially vulnerable to hurricane winds and storm surge in coastal areas. Our study of the impact of various hurricane and climate change scenarios on the performance of coastal residential communities reveals that decision-making at the community level is needed to develop rational engineering and urban planning policies, to mitigate the impact of hurricane wind and storm surge, and to adapt to climate change. The results suggest that fundamental changes in the current building regulatory process may be necessary.

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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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Compound impact of rainfall, tidal level and storm surge on flood risk from tropical cyclones in the coastal area of shanghai

10.5194/egusphere-egu2020-6518 ◽

2020 ◽

Author(s):

Hanqing Xu

Keyword(s):

Tropical Cyclone ◽

Tropical Cyclones ◽

Storm Surge ◽

Extreme Events ◽

Joint Probability ◽

Storm Surges ◽

Heavy Precipitation ◽

Tidal Level ◽

Sea Levels ◽

The Impact

Catastrophic flooding resulting from extreme tropical cyclones has occurred more frequently and drawn great attention in recent years in China. Coastal cities are particularly vulnerable to flood under multivariable conditions, such as heavy precipitation, high sea levels, and storms surge. In coastal areas, floods caused by rainstorms and storm surges have been one of the most costly and devastating natural hazards in coastal regions. Extreme precipitation and storm tide are both inducing factors of flooding and therefore their joint probability would be critical to determine the flooding risk. Usually, extreme events such as tidal level, storm surges, precipitation occur jointly, leading to compound flood events with significantly higher hazards compared to the sum of the single extreme events. The purpose of this study is to improve our understanding of multiple drivers to compound flooding in shanghai. The Wind Enhance Scheme (WES) model characterized by Holland model is devised to generate wind "spiderweb" both for historical (1949-2018) and future (2031-2060, 2069-2098) tropical cyclones. The tidal level and storm surge model based on Delft3D-FLOW is employed with an unstructured grid to simulate the change of water level. For precipitation, maximum value between tropical cyclone events is selected. Following this, multivariate Copula model would be employed to compare the change of joint probability between tidal level, storm surge and heavy precipitation under climate change, taking into account sea-level rise and land subsidence. Finally, the impact of tropical cyclone on the joint risk of tidal, storm surge and heavy precipitation is investigated.&#160;

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