scholarly journals Automated classification of the atmospheric circulation patterns that drive regional wave climates

2014 ◽  
Vol 2 (2) ◽  
pp. 1127-1151
Author(s):  
J. Pringle ◽  
D. D. Stretch ◽  
A. Bárdossy
Keyword(s):  
Atmospheric Circulation ◽  
Low Pressure ◽  
Wave Climate ◽  
Automated Classification ◽  
Coastal Vulnerability ◽  
Extreme Wave ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
Wave Heights ◽  
Objective Classification

Abstract. Wave climates are fundamental drivers of coastal vulnerability and changing trends in wave height, period and direction can severely impact coastlines. In a diverse storm environment, the changes in these parameters are difficult to detect and quantify. Since wave climates are linked to atmospheric circulation patterns an automated and objective classification scheme was developed to explore links between synoptic scale circulation patterns and wave climate variables, specifically wave heights. The algorithm uses a set of objective functions based on wave heights to guide the classification. Fuzzy rules define classification types that are used to detect locally high and low pressure anomalies through a process of simulated annealing. The optimized classification focuses on extreme wave events. The east coast of South Africa was used as a case study. The results show that three dominant patterns drive extreme wave events. The circulation patterns exhibit some seasonality with one pattern present throughout the year. Some 50–80% of the extreme wave events are explained by these three patterns. It is evident that strong low pressure anomalies east of the country drive a wind towards the KwaZulu-Natal coastline which results in extreme wave conditions. We conclude that the methodology can be used to link circulation patterns to wave heights within a diverse storm environment. The circulation patterns agree with qualitative observations of wave climate drivers. There are applications to the assessment of coastal vulnerability and the management of coastlines worldwide.

scholarly journals Automated classification of the atmospheric circulation patterns that drive regional wave climates

2014 ◽  
Vol 14 (8) ◽  
pp. 2145-2155 ◽  
Author(s):  
J. Pringle ◽  
D. D. Stretch ◽  
A. Bárdossy
Keyword(s):  
Atmospheric Circulation ◽  
Low Pressure ◽  
Wave Climate ◽  
Automated Classification ◽  
Coastal Vulnerability ◽  
Extreme Wave ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
Spatially Distributed ◽  
Wave Heights

Abstract. Wave climates are fundamental drivers of coastal vulnerability; changing trends in wave heights, periods and directions can severely impact a coastline. In a diverse storm environment, the changes in these parameters are difficult to detect and quantify. Since wave climates are linked to atmospheric circulation patterns, an automated and objective classification scheme was developed to explore links between synoptic-scale circulation patterns and wave climate variables, specifically wave heights. The algorithm uses a set of objective functions based on wave heights to guide the classification and find atmospheric classes with strong links to wave behaviour. Spatially distributed fuzzy numbers define the classes and are used to detect locally high- and low-pressure anomalies. Classes are derived through a process of simulated annealing. The optimized classification focuses on extreme wave events. The east coast of South Africa was used as a case study. The results show that three dominant patterns drive extreme wave events. The circulation patterns exhibit some seasonality with one pattern present throughout the year. Some 50–80% of the extreme wave events are explained by these three patterns. It is evident that strong low-pressure anomalies east of the country drive a wind towards the KwaZulu-Natal coastline which results in extreme wave conditions. We conclude that the methodology can be used to link circulation patterns to wave heights within a diverse storm environment. The circulation patterns agree with qualitative observations of wave climate drivers. There are applications to the assessment of coastal vulnerability and the management of coastlines worldwide.

Relation Between Atmospheric Circulation Patterns in the North Atlantic and the Sea States in the Iberian Peninsula

2021 ◽  
Vol 143 (3) ◽  
Author(s):  
Cláudia Lucas ◽  
Mariana Bernardino ◽  
C. Guedes Soares
Keyword(s):  
Atmospheric Circulation ◽  
Climatic Variability ◽  
Wave Climate ◽  
Ocean Engineering ◽  
Engineering Structures ◽  
Spectral Parameters ◽  
Energy Devices ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
Wave Conditions

Abstract A statistical analysis of significant wave height (Hs) in a location offshore Portugal continental coast, Leixões, is performed. The spectral and parametric information of sea states at this point used in this analysis was obtained from a 21-year hindcast simulation using the spectral wave model simulating wave nearshore (SWAN) forced by wind fields produced by the Weather Research and Forecasting (WRF) model forced by the ERA-Interim reanalysis. The modeling of the climatic variability of directional spectra provides information of the shape of the expected directional spectra in the various sea states at these locations, i.e., how the spectral parameters and their probability of occurrence change in the regions studied. The occurrences of spectral classes are estimated, and for each class, the variability of the spectral parameters is described by means of joint distributions. The classification of the different sea states provides important information about the wave conditions present in the target areas. A relation between the sea states and the Lamb weather types (WTs) as well as a methodology for classifying atmospheric circulation patterns is presented in this study. The results of this study provide a description of the wave climate through demonstration of the interaction between sea states and weather patterns and relating different circulation patterns to different sea states. This study provides useful information on the wave conditions that can be utilized in the design of ocean engineering structures as well as in the assessment of the operability and safety of shipping and renewable energy devices.

Relation Between Atmospheric Circulation Patterns in the North Atlantic and the Sea States in the Iberian Peninsula

2020 ◽  
Author(s):  
C. Lucas ◽  
M. Bernardino ◽  
C. Guedes Soares
Keyword(s):  
Atmospheric Circulation ◽  
Climatic Variability ◽  
Wave Climate ◽  
Ocean Engineering ◽  
Engineering Structures ◽  
Spectral Parameters ◽  
Energy Devices ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
Wave Conditions

Abstract A statistical analysis of significant wave height (Hs) in eight locations offshore Portugal continental coast is performed. Specifically, locations at different water depths at Aguçadoura, Leixões, Nazaré, Peniche, Sines and Faro were chosen. The spectral and parametric information from these points used in this analysis was obtained from 21-year hindcast simulations using the spectral wave model SWAN. The modelling of the climatic variability of directional spectra provides reliable information of the most relevant parameters at these locations, i.e., how the spectral parameters and their probability of occurrence change in the regions studied. The occurrences of spectral classes are estimated, and for each class, the variability of the spectral parameters is described by means of joint distributions. The classification of the different sea states provides important information about the wave conditions present in the target areas. A relation between the sea states and the Lamb weather types (WTs), a methodology for classifying atmospheric circulation patterns, is presented in this study. The results of this study provide a description of the wave climate, through the interaction between the sea states and weather patterns, relating different circulation patterns to different sea states. This study provides useful information on the wave conditions that can be used in the design of ocean engineering structures, in the assessment of the operability and safety of shipping and renewable energy devices.

scholarly journals Spectral Ocean Wave Climate Variability Based on Atmospheric Circulation Patterns

2014 ◽  
Vol 44 (8) ◽  
pp. 2139-2152 ◽  
Author(s):  
Antonio Espejo ◽  
Paula Camus ◽  
Iñigo J. Losada ◽  
Fernando J. Méndez
Keyword(s):  
Climate Variability ◽  
Atmospheric Circulation ◽  
Wave Energy ◽  
Ocean Waves ◽  
Wave Climate ◽  
Future Climate Change ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
Basin Scale

Abstract Traditional approaches for assessing wave climate variability have been broadly focused on aggregated or statistical parameters such as significant wave height, wave energy flux, or mean wave direction. These studies, although revealing the major general modes of wave climate variability and trends, do not take into consideration the complexity of the wind-wave fields. Because ocean waves are the response to both local and remote winds, analyzing the directional full spectra can shed light on atmospheric circulation not only over the immediate ocean region, but also over a broad basin scale. In this work, the authors use a pattern classification approach to explore wave climate variability in the frequency–direction domain. This approach identifies atmospheric circulation patterns of the sea level pressure from the 31-yr long Climate Forecast System Reanalysis (CFSR) and wave spectral patterns of two selected buoys in the North Atlantic, finding one-to-one relations between each synoptic pattern (circulation type) and each spectral wave energy distribution (spectral type). Even in the absence of long-wave records, this method allows for the reconstruction of long-term wave spectra to cover variability at several temporal scales: daily, monthly, seasonal, interannual, decadal, long-term trends, and future climate change projections.

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