› › A Statistical Dynamical Approach To Intraseasonal Prediction Of Tropical Cyclogenesis In The Western North Pacific

A Statistical-dynamical Approach to Intraseasonal Prediction of Tropical Cyclogenesis in the Western North Pacific

Author : Bryan D. Mundhenk

Publisher :

Page : 107 pages

File Size : 38,40 MB

Release : 2009

Category : Cyclones

ISBN :

Get eBook

Book Description

We have developed a combined statistical-dynamical prediction scheme to predict the probability of tropical cyclone (TC) formation at daily, 2.5° horizontal resolution across the western North Pacific at intraseasonal lead times. Through examination of previous research and our own analysis, we chose five variables to represent the favorability of the climate system to support tropical cyclogenesis. These so-called large-scale environmental factors (LSEFs) include: low-level relative vorticity, sea surface temperature, vertical wind shear, Coriolis, and upper-level divergence. Logistic regression was employed to generate a statistical model representing the probability of TC formation at every grid point based on these LSEFs. Thorough verification of zero-lead hindcasts reveals this model displays skill and potential value for risk adverse customers. In particular, these hindcasts had a positive Brier skill score of 0.03 and a skillful relative operating characteristic skill score of 0.68. The fully coupled, one-tier NCEP Climate Forecast System was used as the dynamical model with which to forecast the LSEFs and, in turn, force the regression model. A series of individual TC case studies were conducted to demonstrate the predictive potential, at intraseasonal leads, of our statistical-dynamical method. Lastly, we investigated the applicability of intraseasonal forecasts to military planning.



Statistical-dynamical Forecasting of Tropical Cyclogenesis in the North Atlantic at Intraseasonal Lead Times

Author : Chad S. Raynak

Publisher :

Page : 71 pages

File Size : 46,97 MB

Release : 2009

Category : Cyclones

ISBN :

Get eBook

Book Description

We have created a combined statistical-dynamical model to predict the probability of tropical cyclone (TC) formation at daily, 2.5°̊ horizontal resolution in the North Atlantic (NA) at intraseasonal lead times. Based on prior research and our own analyses, we chose five large scale environmental factors (LSEFs) to represent favorable environments for TC formation. The LSEFs include: 850 mb relative vorticity, sea surface temperature, vertical wind shear, Coriolis, and 200 mb divergence. We used logistic regression to create a statistical model that depicts the probability for TC formation based on these LSEFs. Through verification of zero lead hindcasts, we determined that our regression model performs better than climatology. For example, these hindcasts had a Brier skill score of 0.04 and a relative operating characteristic skill score of 0.72. We then forced our regression model with LSEF fields from the NCEP Climate Forecast System to produce non-zero lead hindcasts and forecasts. We conducted a series of case studies to evaluate and study the predictive skill of our regression model, with the results showing that our model produces promising results at intraseasonal lead times.





Sub-seasonal to Seasonal Prediction

Author : Andrew Robertson

Publisher : Elsevier

Page : 588 pages

File Size : 18,6 MB

Release : 2018-10-19

Category : Science

ISBN : 012811715X

Get eBook

Book Description

The Gap Between Weather and Climate Forecasting: Sub-seasonal to Seasonal Prediction is an ideal reference for researchers and practitioners across the range of disciplines involved in the science, modeling, forecasting and application of this new frontier in sub-seasonal to seasonal (S2S) prediction. It provides an accessible, yet rigorous, introduction to the scientific principles and sources of predictability through the unique challenges of numerical simulation and forecasting with state-of-science modeling codes and supercomputers. Additional coverage includes the prospects for developing applications to trigger early action decisions to lessen weather catastrophes, minimize costly damage, and optimize operator decisions. The book consists of a set of contributed chapters solicited from experts and leaders in the fields of S2S predictability science, numerical modeling, operational forecasting, and developing application sectors. The introduction and conclusion, written by the co-editors, provides historical perspective, unique synthesis and prospects, and emerging opportunities in this exciting, complex and interdisciplinary field. - Contains contributed chapters from leaders and experts in sub-seasonal to seasonal science, forecasting and applications - Provides a one-stop shop for graduate students, academic and applied researchers, and practitioners in an emerging and interdisciplinary field - Offers a synthesis of the state of S2S science through the use of concrete examples, enabling potential users of S2S forecasts to quickly grasp the potential for application in their own decision-making - Includes a broad set of topics, illustrated with graphic examples, that highlight interdisciplinary linkages





Intraseasonal Variability in the Atmosphere-Ocean Climate System

Author : William K.-M. Lau

Publisher : Springer Science & Business Media

Page : 642 pages

File Size : 29,83 MB

Release : 2011-10-25

Category : Science

ISBN : 3642139140

Get eBook

Book Description

Improving the reliability of long-range forecasts of natural disasters, such as severe weather, droughts and floods, in North America, South America, Africa and the Asian/Australasian monsoon regions is of vital importance to the livelihood of millions of people who are affected by these events. In recent years the significance of major short-term climatic variability, and events such as the El Nino/Southern Oscillation in the Pacific, with its worldwide effect on rainfall patterns, has been all to clearly demonstrated. Understanding and predicting the intra-seasonal variability (ISV) of the ocean and atmosphere is crucial to improving long range environmental forecasts and the reliability of climate change projects through climate models. In the second edition of this classic book on the subject, the authors have updated the original chapters, where appropriate, and added a new chapter that includes short subjects representing substantial new development in ISV research since the publication of the first edition.



Climate Variability and Tropical Cyclone Activity

Author : Pao-Shin Chu

Publisher : Cambridge University Press

Page : 321 pages

File Size : 35,86 MB

Release : 2022-03-10

Category : Science

ISBN : 1108754392

Get eBook

Book Description

This book presents a comprehensive summary of research on tropical cyclone variability at various time scales, from intraseasonal and interannual to interdecadal and centennial. It covers the fundamental theory, statistics and numerical modelling techniques used when considering climate variability in relation to tropical cyclone activity. Major climate oscillations including the Madden-Julian, El Niño, Atlantic Meridional Mode, and Pacific Decadal oscillations are covered, and their impacts on tropical cyclone activity in the Pacific and Atlantic oceans are discussed. Hurricane landfalls in the United States, Caribbean and East Asia are also considered. Climate models and numerical simulations are used to show how prediction models of tropical cyclones are developed, while looking to the future, particular attention is paid to predicting how tropical cyclones will change in response to increased concentrations of greenhouse gases. This book ideal for researchers and practitioners in atmospheric science, climatology, oceanography and civil and environmental engineering.



Accuracy of Western North Pacific Tropical Cyclone Intensity Guidance

Author :

Publisher :

Page : 107 pages

File Size : 47,42 MB

Release : 2005

Category : Cyclone forecasting

ISBN :

Get eBook

Book Description

Consensus methods require that the techniques have no bias and have skill. The accuracy of six statistical and dynamical model tropical cyclone intensity guidance techniques was examined for western North Pacific tropical cyclones during the 2003 and 2004 seasons using the climatology and persistence technique called ST5D as a measure of skill. A framework of three phases: (i) initial intensification; (ii) maximum intensity with possible decay/reintensification cycles; and (iii) decay was used to examine the skill. During both the formation and intensification stages, only about 60% of the 24-36 h forecasts were within +/- 10 kt, and the predominant tendency was to under-forecast the intensity. None of the guidance techniques predicted rapid intensification well. All of the techniques tended to under-forecast maximum intensity and miss decay/reintensification cycles. A few of the techniques provided useful guidance on the magnitude of the decay, although the timing of the decay was often missed. Whereas about 60-70% of the 12-h to 72-h forecasts by the various techniques during the decay phase were within +/- 10 kt, the strong bias was to not decay the cyclone rapidly enough. In general the techniques predict too narrow a range of intensity changes for both intensification and decay.





Evaluation of Dynamical Track Predictions for Tropical Cyclones in the Atlantic During 1997-98

Author : David S. Brown

Publisher :

Page : 92 pages

File Size : 39,78 MB

Release : 2000

Category :

ISBN :

Get eBook

Book Description

Carr and Elsberry (1999; NPS Tech Report) have described eight conceptual models that explain most cases of large (> 300 n mi at 72 h) western North Pacific tropical cyclone (TC) track errors by the Navy Operational Global Atmospheric Prediction System (NOGAPS) and the Geophysical Fluid Dynamics Lab (Navy version - GFDN) models. This study is for TCs in the Atlantic basin and includes the European Centre for Medium-range Weather Forecasting (ECMWF) and the United Kingdom Meteorological Office global models, whereas the GFDL model is eliminated. A detailed examination is made of large (> 250 n mi at 72 h) errors made by the three dynamical models for two seasons of Atlantic TC tracks (1997-98). The percentages of> 250 n mi 72-h errors for the NOGAPS, UKMO, and ECMWF models were 23%, 26%, and 19%, respectively. The same error mechanisms found to apply in other basins also affect the dynamical models in the Atlantic. The NOGAPS and UKMO models have a tendency to over-represent TCs and other circulations, which leads to a cyclonic rotation, or even merger, via the Excessive Direct Cyclone Interaction (E-DCI) process, just as was found in the western North Pacific. The primary ECMWF error source was Excessive Midlatitude CycloGenesis (MCG).