An effort to improve track and intensity prediction of tropical cyclones through vortex initialization in NCUM-global model

Abstract A highly configurable vortex initialization methodology has been constructed in order to permit manipulation of the initial vortex structure in numerical models of tropical cyclones. By using distinct specifications of the flow in the boundary layer and free atmosphere, an array of parameters is available to modify the structure. A nonlinear similarity model that solves the steady-state, height-dependent equations for a neutrally stratified, axisymmetric vortex is solved for the boundary layer flow. Above the boundary layer, a steady-state, moist-neutral, hydrostatic and gradient wind balanced model is used to generate the angular momentum distribution in the free atmosphere. In addition, an unbalanced mass-conserving secondary circulation is generated through the assumption of conservation of mass and angular momentum above the boundary layer. Numerical simulations are conducted using a full-physics mesoscale model to explore the sensitivity of the vortex evolution to different prescriptions of the initial vortex. Dynamical adjustment is found to be dominant in the early evolution of the simulations, thereby masking any sensitivity to initial changes in the secondary circulation and boundary layer structure. The adjustment time can be significantly reduced by arbitrarily enhancing the moisture in the eyewall region.

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Further Improvements to the Statistical Hurricane Intensity Prediction Scheme (SHIPS)

Weather and Forecasting ◽

10.1175/waf862.1 ◽

2005 ◽

Vol 20 (4) ◽

pp. 531-543 ◽

Cited By ~ 350

Author(s):

Mark DeMaria ◽

Michelle Mainelli ◽

Lynn K. Shay ◽

John A. Knaff ◽

John Kaplan

Keyword(s):

Brightness Temperature ◽

Satellite Altimetry ◽

Heat Content ◽

Satellite Observations ◽

Global Model ◽

Hurricane Intensity ◽

East Pacific ◽

Intensity Prediction ◽

Time Period ◽

Prediction Scheme

Abstract Modifications to the Atlantic and east Pacific versions of the operational Statistical Hurricane Intensity Prediction Scheme (SHIPS) for each year from 1997 to 2003 are described. Major changes include the addition of a method to account for the storm decay over land in 2000, the extension of the forecasts from 3 to 5 days in 2001, and the use of an operational global model for the evaluation of the atmospheric predictors instead of a simple dry-adiabatic model beginning in 2001. A verification of the SHIPS operational intensity forecasts is presented. Results show that the 1997–2003 SHIPS forecasts had statistically significant skill (relative to climatology and persistence) out to 72 h in the Atlantic, and at 48 and 72 h in the east Pacific. The inclusion of the land effects reduced the intensity errors by up to 15% in the Atlantic, and up to 3% in the east Pacific, primarily for the shorter-range forecasts. The inclusion of land effects did not significantly degrade the forecasts at any time period. Results also showed that the 4–5-day forecasts that began in 2001 did not have skill in the Atlantic, but had some skill in the east Pacific. An experimental version of SHIPS that included satellite observations was tested during the 2002 and 2003 seasons. New predictors included brightness temperature information from Geostationary Operational Environmental Satellite (GOES) channel 4 (10.7 μm) imagery, and oceanic heat content (OHC) estimates inferred from satellite altimetry observations. The OHC estimates were only available for the Atlantic basin. The GOES data significantly improved the east Pacific forecasts by up to 7% at 12–72 h. The combination of GOES and satellite altimetry improved the Atlantic forecasts by up to 3.5% through 72 h for those storms west of 50°W.

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Evaluation of different versions of NCUM global model for simulation of track and intensity of tropical cyclones over Bay of Bengal

Dynamics of Atmospheres and Oceans ◽

10.1016/j.dynatmoce.2017.04.001 ◽

2017 ◽

Vol 78 ◽

pp. 71-88 ◽

Cited By ~ 8

Author(s):

A. Routray ◽

Vivek Singh ◽

Harvir Singh ◽

Devajyoti Dutta ◽

John P. George ◽

...

Keyword(s):

Tropical Cyclones ◽

Bay Of Bengal ◽

Global Model

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Ending Storm Version of the 7-day Weighted Analog Intensity Prediction Technique for Western North Pacific Tropical Cyclones

Weather and Forecasting ◽

10.1175/waf-d-17-0151.1 ◽

2017 ◽

Vol 32 (6) ◽

pp. 2229-2235 ◽

Cited By ~ 3

Author(s):

Hsiao-Chung Tsai ◽

Russell L. Elsberry

Keyword(s):

Tropical Cyclones ◽

North Pacific ◽

Western North Pacific ◽

Storm Events ◽

Training Set ◽

Intensity Prediction ◽

Prediction Technique ◽

The Mean ◽

Forecast Interval ◽

Intensity Spread

Abstract The weighted analog intensity prediction technique for western North Pacific (WAIP) tropical cyclones (TCs) was the first guidance product for 7-day intensity forecasts, which is skillful in the sense that the 7-day errors are about the same as the 5-day errors. Independent tests of this WAIP version revealed an increasingly large intensity overforecast bias as the forecast interval was extended from 5 to 7 days, which was associated with “ending storms” due to landfall, extratropical transition, or to delayed development. Thus, the 7-day WAIP has been modified to separately forecast ending and nonending storms within the 7-day forecast interval. The additional ending storm constraint in the selection of the 10 best historical analogs is that the intensity at the last matching point with the target TC track cannot exceed 50 kt (where 1 kt = 0.51 m s−1). A separate intensity bias correction calculated for the ending storm training set reduces the mean biases to near-zero values and thereby improves the mean absolute errors in the 5–7-day forecast interval for the independent set. A separate calibration of the intensity spreads for the training set to ensure that 68% of the verifying intensities will be within the 12-h WAIP intensity spread values results in smaller spreads (or higher confidence) for ending storms in the 5–7-day forecast intervals. Thus, some extra effort by the forecasters to identify ending storm events within 7 days will allow improved intensity and intensity spread forecast guidance.

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