[PDF] The Navys Next Generation Tropical Cyclone Model eBook

Author :
Publisher :
Page : 11 pages
File Size : 41,34 MB
Release : 2008
Category :
ISBN :

GET BOOK

The long-term goal of this project is to develop a robust and hardened high-resolution air-ocean coupled tropical cyclone (TC) data assimilation and prediction system that is able to assimilate the wide variety of available in-situ and remotely-sensed observations in order to analyze and predict TC structure and intensity changes in an operational environment. Significant gains have been made in TC track prediction over the past three decades. This considerable achievement is due, in large part, to the steady improvement of numerical models, especially the global scale prediction systems, and the judicial utilization of multi-model ensemble results. In contrast, the TC intensity forecast by numerical models has shown very little improvement during the same time period, and remains a formidable forecast problem. Advanced statistical prediction models nowadays are able to predict the trend for intensification, but as statistical tools, they inherently cannot predict the rapid intensity changes, as evident in Katrina and Rita of 2005, and other tropical cyclones. It is generally accepted now that while advancements in data assimilation and modeling have resulted in better analyses and predictions of steering flows, the processes that affect the structure and intensity of tropical cyclones are much more difficult for current numerical models to capture and reproduce. Physical processes in tropical cyclones that can affect their structure and intensity include enthalpy and mechanical interchanges with the underlying ocean and land surfaces, shallow and deep atmospheric convection in the convectively unstable tropical atmosphere with vertical and horizontal wind shears, and internal multiscale non-linear dynamic interactions. Current prediction systems have been shown to be able to reproduce rapid intensification in case studies involving complex upper tropospheric and oceanic conditions in a carefully conducted simulation mode (e.g. Hong et al. 2000).

Author : Russell L. Elsberry
Publisher :
Page : 151 pages
File Size : 42,71 MB
Release : 1985
Category :
ISBN :

GET BOOK

A project planning meeting on dynamical tropical cyclone models was held january 3-4 1985 at NAVENVPREDRSCHFAC to guide development of a next-generation forecast model, or Advanced Tropical Cyclone Model (ATCM). The meeting was structured in three groups: an Operational group (OP) to provide forecaster needs and real world constraints; a Numerical Aspects group (NUM) with expertise in the numerical modeling issues; and a Data Analysis and Initialization group (DAI) to guide the development of the data analysis and initialization component of ATCM. Contents: Operational Considerations; Data Analysis and Initialization Issues; Numerical Issues; Research Plan Framework; Operational Considerations for the Design of an Advanced Tropical Cyclone Model; Summary of Fleet Numerical Oceanography Center Operational Considerations; A Brief Description of the Navy Tropical Analysis and the NOGAPS Analysis; A Review of the Dynamic Tropical Cyclone Forecast Models Developed by the U.S.; Strawman Proposal for an Advanced Tropical Cyclone Model.

Author : National Academies of Sciences, Engineering, and Medicine
Publisher : National Academies Press
Page : 351 pages
File Size : 18,93 MB
Release : 2016-08-22
Category : Science
ISBN : 0309388805

GET BOOK

As the nation's economic activities, security concerns, and stewardship of natural resources become increasingly complex and globally interrelated, they become ever more sensitive to adverse impacts from weather, climate, and other natural phenomena. For several decades, forecasts with lead times of a few days for weather and other environmental phenomena have yielded valuable information to improve decision-making across all sectors of society. Developing the capability to forecast environmental conditions and disruptive events several weeks and months in advance could dramatically increase the value and benefit of environmental predictions, saving lives, protecting property, increasing economic vitality, protecting the environment, and informing policy choices. Over the past decade, the ability to forecast weather and climate conditions on subseasonal to seasonal (S2S) timescales, i.e., two to fifty-two weeks in advance, has improved substantially. Although significant progress has been made, much work remains to make S2S predictions skillful enough, as well as optimally tailored and communicated, to enable widespread use. Next Generation Earth System Predictions presents a ten-year U.S. research agenda that increases the nation's S2S research and modeling capability, advances S2S forecasting, and aids in decision making at medium and extended lead times.

Author : James E. Peak
Publisher :
Page : 0 pages
File Size : 13,64 MB
Release : 1981
Category : Cyclone forecasting
ISBN :

GET BOOK

A statistical technique proposed by Elsberry and Frill (1980) for adjusting dynamical tropical cyclone motion forecasts is extended to the Two-Way Interactive Nested Tropical Cyclone Model (NTCM) and the operational One-Way Interactive Tropical Cyclone Model (TCMO). The technique utilizes linear regression equations to reduce systemic errors. Backward extrapolation positions are presented as a less expensive, but inferior, alternative to the backward integration positions required by the original technique. A scheme is developed for applying the technique in storm-motion coordinates as well as zonal-meridional coordinates. Tests with 186 NTCM cases indicate moderate improvement in forecast errors by the zonal-meridional regression technique, and slight improvement by the storm-coordinate scheme. In TCMO tests with 212 cases, the zonal-meridional regression equations reduced the forecast errors, but the storm-coordinate equations did not. The technique failed to improve forecast errors in independent tests with NTCM 1981 data, presumably due to differences in error biases, which indicates a need for a larger sample size. Alternatively backward integration positions may be necessary to achieve consistent improvements from this statistical technique. The technique was able to improve 60h-72h forecast errors in TCMO 1981 cases. (Author).

Author : James E. Peak
Publisher :
Page : 48 pages
File Size : 15,56 MB
Release : 1982
Category : Cyclones
ISBN :

GET BOOK

The Navy Nested Tropical Cyclone model is evaluated for performance on southern hemisphere storms in the Australian region. East of 135 E the model exhibits mean forecast errors of 246, 467 and 694 km at 24, 48 and 72 h, respectively. West of 135 E the mean forecast errors are 214, 511 and 745 km at 24, 48 and 72 h. The NTCM tends to have a poleward directional bias in the predicted tracks. This bias may be attributed to the lack of current data, which causes the analysis scheme to revert to climatological values. The NTCM also did not forecast storm tracks well near the Australia coast, especially in the western cases, presumably due to lack of consideration of land/sea effects. In a homogeneous sample comparison with TYAN78, the NTCM performed worse in terms of forecast error at early forecast times and better at late forecast times east of 135 E. West of 135 E, the model performance is generally poorer than the analog scheme at all forecast times. The regression post-processing technique of Peak and Elsberry (1981) when applied to the NTCM forecasts results in a reduction of the eastern region sample forecast errors by as much as 150 km at 72 h. The western region forecast improvement is even greater, such that the regression modified NTCM forecasts are superior to TYAN78 in both test regions. (Author).

Author :
Publisher :
Page : 16 pages
File Size : 20,2 MB
Release : 2010
Category :
ISBN :

GET BOOK

A new algorithm to generate wave heights consistent with tropical cyclone official forecasts from the Joint Typhoon Warning Center (JTWC) has been developed. The process involves generating synthetic observations from the forecast track and the 34-, 50-, and 64-kt wind radii. The JTWC estimate of the radius of maximum winds is used in the algorithm to generate observations for the forecast intensity (wind), and the JTWC-estimated radius of the outermost closed isobar is used to assign observations at the outermost extent of the tropical cyclone circulation. These observations are then interpolated to a high-resolution latitude-longitude grid covering the entire extent of the circulation. Finally, numerical weather prediction (NWP) model fields are obtained for each forecast time, the NWP model forecast tropical cyclone is removed from these fields, and the new JTWC vortex is inserted without blending zones between the vortex and the background. These modified fields are then used as input into a wave model to generate waves consistent with the JTWC forecasts. The algorithm is applied to Typhoon Yagi (2006), in anticipation of which U.S. Navy ships were moved from Tokyo Bay to an area off the southeastern coast of Kyushu. The decision to move (sortie) the ships was based on NWP model-driven long-range wave forecasts that indicated high seas impacting the coast in the vicinity of Tokyo Bay. The sortie decision was made approximately 84 h in advance of the high seas in order to give ships time to steam the approximately 500 n mi to safety. Results from the new algorithm indicate that the high seas would not affect the coast near Tokyo Bay within 84 h. This specific forecast verifies, but altimeter observations show that it does not outperform, the NWP model-driven wave analysis and forecasts for this particular case.

Author : Caroline A. Bower
Publisher :
Page : 139 pages
File Size : 10,2 MB
Release : 2004-03-01
Category : Cyclone forecasting
ISBN : 9781423514978

GET BOOK

The Tropical Cyclone Vortex Tracking Program is used to identify vortices in the western North Pacific from the Navy Operational Global Atmospheric Prediction System (NOGAPS) analyses and forecasts during May - October 2002 and 2003. Based on the NOGAPS analyses, several parameters are different between the 23 vortices that developed into storms% during 2002 according to the Joint Typhoon Warning Center (JTWC) and the 231 vortices that did not develop. After eliminating 127 vortices that did not persist at least 24 h, this left 104 non developing cases. For the developing circulations, the average 850- mb relative vorticity value at the first JTWC-warning time was 5.0 x 10(-5) s(-1), with an easterly deep layer wind shear of-1.8 m s(-1).

Author : David Longshore
Publisher : Infobase Publishing
Page : 481 pages
File Size : 49,41 MB
Release : 2010-05-12
Category : Nature
ISBN : 1438118791

GET BOOK

Presents a detailed encyclopedia of named hurricanes, typhoons and cyclones, descriptions of storm activity, definitions of meteorological terms, and more.