scholarly journals Application of K1/3 weather coefficient to tropical cyclone avoidance

2017 ◽  
Vol 41 (1) ◽  
pp. 189-206
Author(s):  
Maciej Szymański ◽  
Bernard Wiśniewski
Keyword(s):  
Decision Making ◽  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
North Atlantic ◽  
Support Systems ◽  
Route Optimization ◽  
The North ◽  
Avoidance Manoeuvre ◽  
System Operator ◽  
The North Atlantic

Abstract The article presents the results of an application of K1/3 weather coefficient to tropical cyclone avoidance manoeuvre on the example of a tropical cyclones GASTON in the North Atlantic in. Avoidance manoeuvre was planned with the use of the Bon Voyage ORS (Onboard Routing System) of the AWT and also with the use of the programme CYKLON. The routes considered in the Bon Voyage system were generated by the route optimization algorithms of the system and routes programmed manually were generated by the system operator. Weather coefficient K1/3 was utilized as an index of safety of navigation in decision making regarding the ultimate route choice of all route variants generated and programmed in both decision making support systems. Results obtained point at the legitimacy of utilizing several decision support systems in solving the problem of tropical cyclone avoidance manoeuvre.

scholarly journals Multiseason Lead Forecast of the North Atlantic Power Dissipation Index (PDI) and Accumulated Cyclone Energy (ACE)

2013 ◽  
Vol 26 (11) ◽  
pp. 3631-3643 ◽  
Author(s):  
Gabriele Villarini ◽  
Gabriel A. Vecchi
Keyword(s):  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
North Atlantic ◽  
Power Dissipation ◽  
Skill Assessment ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Storm Activity ◽  
The North ◽  
The North Atlantic ◽  
Atlantic Tropical Cyclone

Abstract By considering the intensity, duration, and frequency of tropical cyclones, the power dissipation index (PDI) and accumulated cyclone energy (ACE) are concise metrics routinely used to assess tropical storm activity. This study focuses on the development of a hybrid statistical–dynamical seasonal forecasting system for the North Atlantic Ocean’s PDI and ACE over the period 1982–2011. The statistical model uses only tropical Atlantic and tropical mean sea surface temperatures (SSTs) to describe the variability exhibited by the observational record, reflecting the role of both local and nonlocal effects on the genesis and development of tropical cyclones in the North Atlantic basin. SSTs are predicted using a 10-member ensemble of the Geophysical Fluid Dynamics Laboratory Climate Model, version 2.1 (GFDL CM2.1), an experimental dynamical seasonal-to-interannual prediction system. To assess prediction skill, a set of retrospective predictions is initialized for each month from November to April, over the years 1981–2011. The skill assessment indicates that it is possible to make skillful predictions of ACE and PDI starting from November of the previous year: skillful predictions of the seasonally integrated North Atlantic tropical cyclone activity for the coming season could be made even while the current one is still under way. Probabilistic predictions for the 2012 North Atlantic tropical cyclone season are presented.

Observational Evidence for Oceanic Controls on Hurricane Intensity

2011 ◽  
Vol 24 (4) ◽  
pp. 1138-1153 ◽  
Author(s):  
Ian D. Lloyd ◽  
Gabriel A. Vecchi
Keyword(s):  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
North Atlantic ◽  
Translation Speed ◽  
Ocean Stratification ◽  
Cyclone Intensity ◽  
The North ◽  
Sst Cooling ◽  
The North Atlantic ◽  
The Impact

Abstract The influence of oceanic changes on tropical cyclone activity is investigated using observational estimates of sea surface temperature (SST), air–sea fluxes, and ocean subsurface thermal structure during the period 1998–2007. SST conditions are examined before, during, and after the passage of tropical cyclones, through Lagrangian composites along cyclone tracks across all ocean basins, with particular focus on the North Atlantic. The influence of translation speed is explored by separating tropical cyclones according to the translation speed divided by the Coriolis parameter. On average for tropical cyclones up to category 2, SST cooling becomes larger as cyclone intensity increases, peaking at 1.8 K in the North Atlantic. Beyond category 2 hurricanes, however, the cooling no longer follows an increasing monotonic relationship with intensity. In the North Atlantic, the cooling for stronger hurricanes decreases, while in other ocean basins the cyclone-induced cooling does not significantly differ from category 2 to category 5 tropical cyclones, with the exception of the South Pacific. Since the SST response is nonmonotonic, with stronger cyclones producing more cooling up to category 2, but producing less or approximately equal cooling for categories 3–5, the observations indicate that oceanic feedbacks can inhibit intensification of cyclones. This result implies that large-scale oceanic conditions are a control on tropical cyclone intensity, since they control oceanic sensitivity to atmospheric forcing. Ocean subsurface thermal data provide additional support for this dependence, showing weaker upper-ocean stratification for stronger tropical cyclones. Intensification is suppressed by strong ocean stratification since it favors large SST cooling, but the ability of tropical cyclones to intensify is less inhibited when stratification is weak and cyclone-induced SST cooling is small. Thus, after accounting for tropical cyclone translation speeds and latitudes, it is argued that reduced cooling under extreme tropical cyclones is the manifestation of the impact of oceanic conditions on the ability of tropical cyclones to intensify.

scholarly journals Increased threat of tropical cyclones and coastal flooding to New York City during the anthropogenic era

2015 ◽  
Vol 112 (41) ◽  
pp. 12610-12615 ◽  
Author(s):  
Andra J. Reed ◽  
Michael E. Mann ◽  
Kerry A. Emanuel ◽  
Ning Lin ◽  
Benjamin P. Horton ◽  
...  
Keyword(s):  
New York ◽  
New York City ◽  
Tropical Cyclone ◽  
Sea Level ◽  
Tropical Cyclones ◽  
North Atlantic ◽  
York City ◽  
Storm Surges ◽  
The North ◽  
The North Atlantic

In a changing climate, future inundation of the United States’ Atlantic coast will depend on both storm surges during tropical cyclones and the rising relative sea levels on which those surges occur. However, the observational record of tropical cyclones in the North Atlantic basin is too short (A.D. 1851 to present) to accurately assess long-term trends in storm activity. To overcome this limitation, we use proxy sea level records, and downscale three CMIP5 models to generate large synthetic tropical cyclone data sets for the North Atlantic basin; driving climate conditions span from A.D. 850 to A.D. 2005. We compare pre-anthropogenic era (A.D. 850–1800) and anthropogenic era (A.D.1970–2005) storm surge model results for New York City, exposing links between increased rates of sea level rise and storm flood heights. We find that mean flood heights increased by ∼1.24 m (due mainly to sea level rise) from ∼A.D. 850 to the anthropogenic era, a result that is significant at the 99% confidence level. Additionally, changes in tropical cyclone characteristics have led to increases in the extremes of the types of storms that create the largest storm surges for New York City. As a result, flood risk has greatly increased for the region; for example, the 500-y return period for a ∼2.25-m flood height during the pre-anthropogenic era has decreased to ∼24.4 y in the anthropogenic era. Our results indicate the impacts of climate change on coastal inundation, and call for advanced risk management strategies.

scholarly journals Objective Identification of Annular Hurricanes

2008 ◽  
Vol 23 (1) ◽  
pp. 17-28 ◽  
Author(s):  
John A. Knaff ◽  
Thomas A. Cram ◽  
Andrea B. Schumacher ◽  
James P. Kossin ◽  
Mark DeMaria
Keyword(s):  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
North Atlantic ◽  
North Pacific ◽  
Probability Of Detection ◽  
Linear Discriminant ◽  
The North ◽  
The North Atlantic ◽  
Special Algorithm ◽  
Central North Pacific

Abstract Annular hurricanes are a subset of intense tropical cyclones that have been shown in previous work to be significantly stronger, to maintain their peak intensities longer, and to weaken more slowly than average tropical cyclones. Because of these characteristics, they represent a significant forecasting challenge. This paper updates the list of annular hurricanes to encompass the years 1995–2006 in both the North Atlantic and eastern–central North Pacific tropical cyclone basins. Because annular hurricanes have a unique appearance in infrared satellite imagery, and form in a specific set of environmental conditions, an objective real-time method of identifying these hurricanes is developed. However, since the occurrence of annular hurricanes is rare (∼4% of all hurricanes), a special algorithm to detect annular hurricanes is developed that employs two steps to identify the candidates: 1) prescreening the data and 2) applying a linear discriminant analysis. This algorithm is trained using a dependent dataset (1995–2003) that includes 11 annular hurricanes. The resulting algorithm is then independently tested using datasets from the years 2004–06, which contained an additional three annular hurricanes. Results indicate that the algorithm is able to discriminate annular hurricanes from tropical cyclones with intensities greater than 84 kt (43.2 m s−1). The probability of detection or hit rate produced by this scheme is shown to be ∼96% with a false alarm rate of ∼6%, based on 1363 six-hour time periods with a tropical cyclone with an intensity greater than 84 kt (1995–2006).

After a Decade Are Atlantic Tropical Cyclone Gale Force Wind Radii Forecasts Now Skillful?

2015 ◽  
Vol 30 (3) ◽  
pp. 702-709 ◽  
Author(s):  
John A. Knaff ◽  
Charles R. Sampson
Keyword(s):  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
North Atlantic ◽  
The Public ◽  
The North ◽  
Radial Extent ◽  
History Of ◽  
The North Atlantic ◽  
National Hurricane Center ◽  
Atlantic Tropical Cyclone

Abstract The National Hurricane Center (NHC) has a long history of forecasting the radial extent of gale force or 34-knot (kt; where 1 kt = 0.51 m s−1) winds for tropical cyclones in their area of responsibility. These are referred to collectively as gale force wind radii forecasts. These forecasts are generated as part of the 6-hourly advisory messages made available to the public. In 2004, NHC began a routine of postanalysis or “best tracking” of gale force wind radii that continues to this day. At approximately the same time, a statistical wind radii forecast, based solely on climatology and persistence, was implemented so that NHC all-wind radii forecasts could be evaluated for skill. This statistical wind radii baseline forecast is also currently used in several applications as a substitute for or to augment NHC wind radii forecasts. This investigation examines the performance of NHC gale force wind radii forecasts in the North Atlantic over the last decade. Results presented within indicate that NHC’s gale force wind radii forecasts have increased in skill relative to the best tracks by several measures, and now significantly outperform statistical wind radii baseline forecasts. These results indicate that it may be time to reinvestigate whether applications that depend on wind radii forecast information can be improved through better use of NHC wind radii forecast information.

scholarly journals Extreme Translation Events of Atlantic Tropical Cyclones

Atmosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1032
Author(s):  
Wei Zhang
Keyword(s):  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
North Atlantic ◽  
Large Scale ◽  
Spatial And Temporal Variability ◽  
Pressure System ◽  
The North ◽  
The North Atlantic ◽  
Moving Groups ◽  
Translational Speed

Changes in the translational speed of tropical cyclones (e.g., sluggish tropical cyclones) are associated with extreme precipitation and flash flooding. However, it is still unclear regarding the spatial and temporal variability of extreme tropical cyclone translation events in the North Atlantic and underlying large-scale drivers. This work finds that the frequencies of extreme fast- and slow-translation events of Atlantic tropical cyclones exhibited a significant rising trend during 1980–2019. The extreme fast-translation events of Atlantic tropical cyclones are primarily located in the northern part of the North Atlantic, while the extreme slow-translation events are located more equatorward. There is a significant rising trend in the frequency of extreme slow-translation events over ocean with no trend over land. However, there is a significant rising trend in the frequency of extreme fast-translation events over ocean and over land. The extreme slow-translation events are associated with a strong high-pressure system in the continental United States (U.S.). By contrast, the extreme fast-translation events are related to a low-pressure system across most of the continental U.S. that leads to westerly steering flow that enhances tropical cyclone movement. This study suggests that it might be useful to separate tropical cyclone events into fast-moving and slow-moving groups when examining the translational speed of North Atlantic tropical cyclones, instead of examining regional or global mean translational speed.

scholarly journals On tropical cyclone frequency and the warm pool area

2009 ◽  
Vol 9 (2) ◽  
pp. 635-645 ◽  
Author(s):  
R. E. Benestad
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
Tropical Cyclones ◽  
North Atlantic ◽  
Warm Pool ◽  
North Indian Ocean ◽  
North West ◽  
The North ◽  
The North Atlantic ◽  
Pool Area

Abstract. The proposition that the rate of tropical cyclogenesis increases with the size of the "warm pool" is tested by comparing the seasonal variation of the warm pool area with the seasonality of the number of tropical cyclones. An analysis based on empirical data from the Northern Hemisphere is presented, where the warm pool associated with tropical cyclone activity is defined as the area, A, enclosed by the 26.5°C SST isotherm. Similar analysis was applied to the temperature weighted area AT with similar results. An intriguing non-linear relationship of high statistical significance was found between the temperature weighted area in the North Atlantic and the North-West Pacific on the one hand and the number of cyclones, N, in the same ocean basin on the other, but this pattern was not found over the North Indian Ocean. A simple statistical model was developed, based on the historical relationship between N and A. The simple model was then validated against independent inter-annual variations in the seasonal cyclone counts in the North Atlantic, but the correlation was not statistically significant in the North-West Pacific. No correlation, however, was found between N and A in the North Indian Ocean. A non-linear relationship between the cyclone number and temperature weighted area may in some ocean basins explain both why there has not been any linear trend in the number of cyclones over time as well as the recent upturn in the number of Atlantic hurricanes. The results also suggest that the notion of the number of tropical cyclones being insensitive to the area A is a misconception.

Beyond Hurricane Sandy: What Might the Future Hold for Tropical Cyclones in the North Atlantic?

2014 ◽  
Vol 01 (01) ◽  
pp. 1450007 ◽  
Author(s):  
Radley M. Horton ◽  
Jiping Liu
Keyword(s):  
Tropical Cyclone ◽  
Sea Level Rise ◽  
Sea Level ◽  
Tropical Cyclones ◽  
North Atlantic ◽  
Hurricane Sandy ◽  
Economic Losses ◽  
The North ◽  
The Future ◽  
The North Atlantic

Coastal communities are beginning to understand that sea level rise is projected to dramatically increase the frequency of coastal flooding. However, deep uncertainty remains about how tropical cyclones may change in the future. The North Atlantic has historically been responsible for the majority of global tropical cyclone economic losses, with Hurricane Sandy's approximately USD$70 billion price tag providing a recent example. The North Atlantic has experienced an upward trend in both total tropical cyclones (maximum sustained winds > 18 m/s) and major hurricanes (maximum sustained winds > 50 m/s) in recent decades. While it remains unclear how much of this trend is related to anthropogenic warming, and how tropical cyclone risk may change in the future, the balance of evidence suggests that the strongest hurricanes may become more frequent and intense in the future, and that rainfall associated with tropical cyclones may increase as well. These projections, along with sea level rise and demographic trends, suggest vulnerability to tropical cyclones will increase in the future, thus requiring major coastal adaptation initiatives.

Satellite-Derived Tropical Cyclone Intensity in the North Pacific Ocean Using the Deviation-Angle Variance Technique

2014 ◽  
Vol 29 (3) ◽  
pp. 505-516 ◽  
Author(s):  
Elizabeth A. Ritchie ◽  
Kimberly M. Wood ◽  
Oscar G. Rodríguez-Herrera ◽  
Miguel F. Piñeros ◽  
J. Scott Tyo
Keyword(s):  
Tropical Cyclone ◽  
North Atlantic ◽  
North Pacific ◽  
Western North Pacific ◽  
North Pacific Ocean ◽  
Deviation Angle ◽  
Intensity Estimation ◽  
The North ◽  
The North Atlantic ◽  
The North Pacific

Abstract The deviation-angle variance technique (DAV-T), which was introduced in the North Atlantic basin for tropical cyclone (TC) intensity estimation, is adapted for use in the North Pacific Ocean using the “best-track center” application of the DAV. The adaptations include changes in preprocessing for different data sources [Geostationary Operational Environmental Satellite-East (GOES-E) in the Atlantic, stitched GOES-E–Geostationary Operational Environmental Satellite-West (GOES-W) in the eastern North Pacific, and the Multifunctional Transport Satellite (MTSAT) in the western North Pacific], and retraining the algorithm parameters for different basins. Over the 2007–11 period, DAV-T intensity estimation in the western North Pacific results in a root-mean-square intensity error (RMSE, as measured by the maximum sustained surface winds) of 14.3 kt (1 kt ≈ 0.51 m s−1) when compared to the Joint Typhoon Warning Center best track, utilizing all TCs to train and test the algorithm. The RMSE obtained when testing on an individual year and training with the remaining set lies between 12.9 and 15.1 kt. In the eastern North Pacific the DAV-T produces an RMSE of 13.4 kt utilizing all TCs in 2005–11 when compared with the National Hurricane Center best track. The RMSE for individual years lies between 9.4 and 16.9 kt. The complex environment in the western North Pacific led to an extension to the DAV-T that includes two different radii of computation, producing a parametric surface that relates TC axisymmetry to intensity. The overall RMSE is reduced by an average of 1.3 kt in the western North Pacific and 0.8 kt in the eastern North Pacific. These results for the North Pacific are comparable with previously reported results using the DAV for the North Atlantic basin.

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