Author: Peter M. Klein
Publisher:
ISBN: 9781423564164
Category :
Languages : en
Pages : 101
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Book Description
Extratropical transition (ET) of a tropical cyclone (TC) often results in a mid-latitude storm that threatens maritime and coastal interests. Cases of ET between 1 July through 31 October during 1994-1996 are reviewed using Navy Operational Global Atmospheric Prediction System (NOGAPS) analyses and hourly geostationary satellite imagery. Current conceptual models are found to be inadequate to explain the physical processes in ET. ET is redefined to have two stages: transformation, where the TC is transformed from a warm-core vortex into a baroclinic, cold-core extratropical cyclone, and re- intensification, where the transformed TC either deepens or dissipates, depending on the existence of upper4ropospheric support for extratropical cyclogenesis. ET is further defined in terms of two characteristic mid-latitude synoptic patterns: meridional, in which the cyclones have meridional tracks and tend to re-intensify less vigorously than zonal, which have zonal tracks and may deepen explosively. Review of NOGAPS 5OO-mb anomaly correlation scores in 1996 demonstrated that ET may be associated with significant NOGAPS errors. Sea-level pressure forecasts during ET events involving a merger tend to be too deep. In ET cases of rapidly deepening storms, NOGAPS tends to overforecast their intensity during transformation, and then underforecast during re- intensification. Rules of thumb are provided to assist forecasters in improving predictions of the track and intensity of storms undergoing ET.
Author: Peter M. Klein
Publisher:
ISBN: 9781423531807
Category :
Languages : en
Pages : 262
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Book Description
This study of extratropical transition (ET) of tropical cyclones (TCs) in the western North Pacific examines 30 cases during 1 June through 31 October 1994-98 using Navy analyses, plus geostationary satellite visible, infrared, water vapor, and microwave imagery. Based on the similarity of all 30 ET cases in satellite imagery, a three-dimensional conceptual model of the transformation stage of ET is proposed to describe how these ET cases evolve into an incipient, baroclinic cyclone. A climatology of ET during the period studied is presented, and three levels of re-intensification (little, moderate, and deep) are defined based on storm intensity at the end of ET. The re- intensification stage in nine cases is studied via Navy Coupled Ocean-Atmosphere Mesoscale Prediction System (COAMPS) control forecasts, simulations with the initial TC vortex removed, and simulations in which the initial TC vortex is displaced. These COAMPS simulations demonstrate that deep or moderate re- intensification depends on phasing of the poleward translating TC remnants with a critical region in which cyclogenesis is favored in the mid-latitude circulation. The mid-latitude circulation and TC contributions to the re- intensification stage are identified via superposition with the critical region and modification of its location and diagnostic values, respectively, and the combination of these contributions determines the final storm intensity at the end of ET.
Author:
Publisher:
ISBN:
Category : Cyclones
Languages : en
Pages : 101
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Book Description
Analysis of the eddy kinetic energy budget for four cases of extratropical transition (ET) with North Pacific tropical cyclones (TCs) is conducted. The cases compare varying ET and midlatitude flow characteristics. Each case was examined to determine the impacts of eddy kinetic energy generation and/or transfer on downstream development in the midlatitude circulation. Typhoon Tokage (October 2004) was a large TC that moved into a high-amplitude midlatitude circulation. Energetics analysis revealed that the ET of Tokage influenced the development of a deep trough over the central North Pacific before Tokage moved poleward and weakened transfer. Typhoon Banyan (July 2005) was a mid-summer case that influenced downstream development ultimately over the Aleutian Islands. Typhoon Guchol (August 2005) was a small TC that was dominated by midlatitude flow. However, the merger of Guchol with a midlatitude trough enabled development downstream of a separate trough. Typhoon Nabi was an intense TC that injected significant EKE into the midlatitude circulation during ET. Through downstream development, Nabi changed a zonal pattern over the North Pacific into an amplified pattern. These cases indicate that the ET process over the western North Pacific impacts the midlatitude circulation across the entire North Pacific basin.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 9
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Book Description
The long-term goal of this project is to develop a better understanding of mesoscale and synoptic-scale processes associated with the entire life cycle of tropical cyclones in the western North Pacific. The inability to correctly identify tropical cyclone formation over the period of 24-48 hours poses a threat to shore and afloat assets across the western North Pacific. Furthermore, once a tropical cyclone has formed, the predictability of structure changes during intensification of the cyclone is very low, which is due to complex physical processes that vary over a wide range of space and time scales. Periods of reduced predictability occur throughout the tropical cyclone life cycle, which includes the decaying stage. Because decaying tropical cyclones often transition to a fast-moving and rapidly-developing extratropical cyclone that may contain gale-, storm-, or hurricane-force winds, there is a need to improve understanding and prediction of the extratropical transition phase of a decaying tropical cyclone. The structural evolution of the transition from a tropical to extratropical circulation involves rapid changes to the wind, cloud, and precipitation patterns that potentially impact maritime and shore-based facilities. The research being conducted on the comprehensive data sets gathered during the TCS-08 field program will result in increased accuracy associated with the prediction of tropical cyclone formation, intensification, and structural changes.
Author: Melanie Bieli
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
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.
Author: Johnny C. L. Chan
Publisher: World Scientific
ISBN: 9814293482
Category : Science
Languages : en
Pages : 445
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Book Description
Pt. I. Theory of tropical cyclones. ch. 1. Tropical cyclone structure and dynamics / Jeffrey D. Kepert. ch. 2. Tropical cyclone formation / Kevin J. Tory and William M. Frank. ch. 3. Air-sea interactions in tropical cyclones / Lynn K. Shay. ch. 4. Movement of tropical cyclones / Johnny C.L. Chan. ch. 5. The extratropical transition of tropical cyclones : structural characteristics, downstream impacts, and forecast challenges / Patrick A. Harr -- pt. II. Observations of tropical cyclones. ch. 6. Observing and analyzing the near-surface wind field in tropical cyclones / Mark D. Powell. ch. 7. Satellite observations of tropical cyclones / Christopher Velden and Jeffrey Hawkins. ch. 8. Aircraft observations of tropical cyclones / Sim D. Aberson [und weitere] -- pt. III. Climate variations of tropical cyclone activity. ch. 9. Tropical cyclones and climate change : a review / Thomas Knutson, Chris Landsea and Kerry Emanuel -- pt. IV. Forecasting of tropical cyclones. ch. 10. Track and structure forecasts of tropical cyclones / Julian Heming and Jim Goerss. ch. 11. The influence of natural climate variability on tropical cyclones, and seasonal forecasts of tropical cyclone activity / Suzana J. Camargo [und weitere] -- pt. V. Hydrological aspects of tropical cyclones. ch. 12. Storm surge modeling and applications in coastal areas / Shishir K. Dube [und weitere] -- pt. VI. Societal impacts of tropical cyclones. ch. 13. Disaster mitigation and societal impacts / David King, Jim Davidson and Linda Anderson-Berry
Author: Gregory D. Fox
Publisher:
ISBN: 9781423517115
Category : Cyclones
Languages : en
Pages : 99
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Book Description
The primary purpose of this research is to provide guidance to forecasters from the Joint (Air Force/Navy) Typhoon Warning Center (JTWC) in Pearl Harbor to use in differentiating between the stages of extratropical transition (ET) of tropical cyclones (TCs). Not only is ET relevant to the Department of Defense, since JTWC stops providing TC warnings once they have undergone ET, but it is also applicable to the meteorological community since there currently "is no commonly accepted definition of ET" (Jones et al 2003). This research compares the results of a conceptual model of ET using subjective satellite analysis with the results of objective indicators based on Navy Operational Global Atmospheric Prediction System (NOGAPS) model analyses. The ultimate goal is to find a way to reduce the negative impact of incorrect TC forecasting by providing tools which are more objective in defining stages of ET. This work discusses the birth, growth, and death of TCs by describing what energy sources are necessary for their growth and dissipation. Recent studies provide a conceptual model of ET with definitions of two stages and ways to use satellite analysis to identify them (Klein et al. 2000). While this conceptual model was being analyzed with data from the western North Pacific Ocean, TCs were also being analyzed using data from the Atlantic Ocean (Hart and Evans 2001). The research from the Atlantic led to the exploitation of objective indicators in a hodograph-like display (Evans and Hart 2003).
Author: Peter M. Klein
Publisher:
ISBN:
Category :
Languages : en
Pages : 261
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Book Description
Author: Samson Brand
Publisher:
ISBN:
Category : Cyclones
Languages : en
Pages : 20
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Book Description
This study examines 16 recurving tropical storms and typhoons that occurred in the western North Pacific Ocean in 1971, to determine the characteristics of the storms after they became extratropical. Many of the extratropical storms that evolved from tropical cyclones maintained destructive seas and winds as long as 5 days after the point of recurvature. Six of the 16 extratropical storms crossed the North Pacific and affected the Aleutians or western North America. Some of the physical processes associated with the evolution of extratropical storms from tropical cyclones are also discussed. (Author).
Author: Heather M. Archambault
Publisher:
ISBN:
Category : Cyclones
Languages : en
Pages : 212
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