Intensity Estimation of Tropical Cyclones over the Western North Pacific with AMSU-A Temperature Data

Abstract The role of scale interactions in the maintenance of eddy kinetic energy (EKE) during the extreme phases of the intraseasonal oscillation (ISO) is examined through the construction of a new eddy energetics diagnostic tool that separates the effects of ISO and a low-frequency background state (LFBS; with periods longer than 90 days). The LFBS always contributes positively toward the EKE in the boreal summer, regardless of the ISO phases. The synoptic eddies extract energy from the ISO during the ISO active phase. This positive barotropic energy conversion occurs when the synoptic eddies interact with low-level cyclonic and convergent–confluent ISO flows. This contrasts with the ISO suppressed phase during which the synoptic eddies lose kinetic energy to the ISO flow. The anticyclonic and divergent–diffluent ISO flows during the suppressed phase are responsible for the negative barotropic energy conversion. A positive (negative) EKE tendency occurs during the ISO suppressed-to-active (active-to-suppressed) transitional phase. The cause of this asymmetric EKE tendency is attributed to the spatial phase relation among the ISO vorticity, eddy structure, and EKE. The southwest–northeast-tilted synoptic disturbances interacting with cyclonic (anticyclonic) vorticity of ISO lead to a positive (negative) EKE tendency in the northwest region of the maximum EKE center. The genesis number and location and intensification rate of tropical cyclones in the western North Pacific are closely related to the barotropic energy conversion. The enhanced barotropic energy conversion favors the generation and development of synoptic seed disturbances, some of which eventually grow into tropical cyclones.

Download Full-text

Occurrences of Wintertime Tropical Cyclones in the Western North Pacific under the Background of Global Warming

Atmospheric and Oceanic Science Letters ◽

10.1080/16742834.2009.11446825 ◽

2009 ◽

Vol 2 (6) ◽

pp. 333-338

Author(s):

He Jie-Lin ◽

Guan Zhao-Yong ◽

Qian Dai-Li ◽

Wan Qi-Lin ◽

Wang Li-Juan

Keyword(s):

Global Warming ◽

Tropical Cyclones ◽

North Pacific ◽

Western North Pacific

Download Full-text

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

Weather and Forecasting ◽

10.1175/waf-d-13-00133.1 ◽

2014 ◽

Vol 29 (3) ◽

pp. 505-516 ◽

Cited By ~ 25

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.

Download Full-text

Imprints of Tropical Cyclones on Structural Characteristics of Mesoscale Oceanic Eddies over the Western North Pacific

Geophysical Research Letters ◽

10.1029/2021gl092601 ◽

2021 ◽

Author(s):

Zhanhong Ma ◽

Zheliang Zhang ◽

Jianfang Fei ◽

Huizan Wang

Keyword(s):

Tropical Cyclones ◽

North Pacific ◽

Western North Pacific ◽

Structural Characteristics ◽

Oceanic Eddies

Download Full-text

High-Resolution Seeded Simulations of Western North Pacific Ocean Tropical Cyclones in Two Future Extreme Climates

Journal of Climate ◽

10.1175/jcli-d-18-0353.1 ◽

2018 ◽

Vol 32 (2) ◽

pp. 309-334

Author(s):

J. G. McLay ◽

E. A. Hendricks ◽

J. Moskaitis

Keyword(s):

High Resolution ◽

Pacific Ocean ◽

Tropical Cyclones ◽

North Pacific ◽

Western North Pacific ◽

North Pacific Ocean ◽

Weather Prediction ◽

Bootstrap Analysis ◽

Western North Pacific Ocean ◽

The Future

ABSTRACT A variant of downscaling is devised to explore the properties of tropical cyclones (TCs) that originate in the open ocean of the western North Pacific Ocean (WestPac) region under extreme climates. This variant applies a seeding strategy in large-scale environments simulated by phase 5 of the Coupled Model Intercomparison Project (CMIP5) climate-model integrations together with embedded integrations of Coupled Ocean–Atmosphere Mesoscale Prediction System for Tropical Cyclones (COAMPS-TC), an operational, high-resolution, nonhydrostatic, convection-permitting numerical weather prediction (NWP) model. Test periods for the present day and late twenty-first century are sampled from two different integrations for the representative concentration pathway (RCP) 8.5 forcing scenario. Then seeded simulations for the present-day period are contrasted with similar seeded simulations for the future period. Reinforcing other downscaling studies, the seeding results suggest that the future environments are notably more conducive to high-intensity TC activity in the WestPac. Specifically, the future simulations yield considerably more TCs that exceed 96-kt (1 kt ≈ 0.5144 m s−1) intensity, and these TCs exhibit notably greater average life cycle maximum intensity and tend to spend more time above the 96-kt intensity threshold. Also, the future simulations yield more TCs that make landfall at >64-kt intensity, and the average landfall intensity of these storms is appreciably greater. These findings are supported by statistical bootstrap analysis as well as by a supplemental sensitivity analysis. Accounting for COAMPS-TC intensity forecast bias using a quantile-matching approach, the seeded simulations suggest that the potential maximum western North Pacific TC intensities in the future extreme climate may be approximately 190 kt.

Download Full-text