scholarly journals A new approach for location-specific seasonal outlooks of typhoon and super typhoon frequency across the Western North Pacific region

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Andrew D. Magee ◽  
Anthony S. Kiem ◽  
Johnny C. L. Chan
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Selection Procedure ◽  
The Philippines ◽  
Atmospheric Variability ◽  
Teleconnection Patterns ◽  
Super Typhoon ◽  
The North ◽  
Predictor Model ◽  
Typhoon Season

AbstractWith an average of 26 tropical cyclones (TCs) per year, the western North Pacific (WNP) is the most active TC basin in the world. Considerable exposure lies in the coastal regions of the WNP, which extends from Japan in the north to the Philippines in the south, amplifying TC related impacts, including loss of life and damage to property, infrastructure and environment. This study presents a new location-specific typhoon (TY) and super typhoon (STY) outlook for the WNP basin and subregions, including China, Hong Kong, Japan, Korea, Philippines, Thailand, and Vietnam. Using multivariate Poisson regression and considering up to nine modes of ocean-atmospheric variability and teleconnection patterns that influence WNP TC behaviour, thousands of possible predictor model combinations are compared using an automated variable selection procedure. For each location, skillful TY and STY outlooks are generated up to 6 months before the start of the typhoon season, with rolling monthly updates enabling refinement of predicted TY and STY frequency. This unparalleled lead time allows end-users to make more informed decisions before and during the typhoon season.

A Global View of Equatorial Waves and Tropical Cyclogenesis

2012 ◽  
Vol 140 (3) ◽  
pp. 774-788 ◽  
Author(s):  
Carl J. Schreck ◽  
John Molinari ◽  
Anantha Aiyyer
Keyword(s):  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
North Pacific ◽  
Western North Pacific ◽  
The Philippines ◽  
Tropical Cyclogenesis ◽  
Equatorial Waves ◽  
Wave Type ◽  
The North ◽  
Equatorial Wave

Abstract This study investigates the number of tropical cyclone formations that can be attributed to the enhanced convection from equatorial waves within each basin. Tropical depression (TD)-type disturbances (i.e., easterly waves) were the primary tropical cyclone precursors over the Northern Hemisphere basins, particularly the eastern North Pacific and the Atlantic. In the Southern Hemisphere, however, the number of storms attributed to TD-type disturbances and equatorial Rossby waves were roughly equivalent. Equatorward of 20°N, tropical cyclones formed without any equatorial wave precursor most often over the eastern North Pacific and least often over the western North Pacific. The Madden–Julian oscillation (MJO) was an important tropical cyclone precursor over the north Indian, south Indian, and western North Pacific basins. The MJO also affected tropical cyclogenesis by modulating the amplitudes of higher-frequency waves. Each wave type reached the attribution threshold 1.5 times more often, and tropical cyclogenesis was 3 times more likely, within positive MJO-filtered rainfall anomalies than within negative anomalies. The greatest MJO modulation was observed for storms attributed to Kelvin waves over the north Indian Ocean. The large rainfall rates associated with tropical cyclones can alter equatorial wave–filtered anomalies. This study quantifies the contamination over each basin. Tropical cyclones contributed more than 20% of the filtered variance for each wave type over large potions of every basin except the South Pacific. The largest contamination, exceeding 60%, occurred for the TD band near the Philippines. To mitigate the contamination, the tropical cyclone–related anomalies were removed before filtering in this study.

scholarly journals 2010 Western North Pacific Typhoon Season: Seasonal Overview and Forecast Using a Track-Pattern-Based Model

2012 ◽  
Vol 27 (3) ◽  
pp. 730-743 ◽  
Author(s):  
Joo-Hong Kim ◽  
Chang-Hoi Ho ◽  
Hyeong-Seog Kim ◽  
Woosuk Choi
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Track Density ◽  
Contributing Factors ◽  
Forecast System ◽  
The North ◽  
Rapid Transition ◽  
Typhoon Season ◽  
Track Pattern ◽  
Low Activity

Abstract Fourteen named tropical cyclones (TCs) formed in the western North Pacific (WNP) in 2010, representing the lowest count since 1951. Both low activity during the typhoon season (June–October) and quiescence during the pre- and posttyphoon seasons were major contributing factors. Despite overall low activity, TC activity along land boundaries was enhanced because the overall genesis locations of TCs shifted to the north and west and a majority of them affected the coastal countries in the WNP. These features are attributed to the expansion of the subtropical high and weakening of the monsoon trough associated with the rapid transition of the 2009/10 El Niño to the 2010/11 La Niña. The National Typhoon Center (NTC) in South Korea utilizes the recently developed track-pattern-based model of the hybrid statistical–dynamical type as the operational long-range TC forecast system. This model fairly forecast the anomalous spatial distribution of TC track density for the 2010 typhoon season. A higher-than-normal track density was successfully forecast near Korea and Japan. This is attributed to the overall skillful forecast of TC count for each pattern by the NTC model, though some deficiencies in forecasting extremes for some patterns are evident. The total seasonal genesis frequency integrated over the seven patterns is well below normal (about 16.4) close to the observations. The fair predictability in 2010 using the NTC model is attributed to the skillful forecast of the ENSO transition by the National Centers for Environmental Prediction’s Climate Forecast System, in addition to the validity of the NTC model itself.

Quasi-biweekly oscillation over the western North Pacific in boreal winter and its influence on the central North American air temperature

2021 ◽  
pp. 1-43
Keyword(s):  
North America ◽  
North American ◽  
North Pacific ◽  
Western North Pacific ◽  
Wave Train ◽  
The Philippines ◽  
Climate Impacts ◽  
Boreal Winter ◽  
The North ◽  
North American Climate

Abstract This study investigates the characteristics and climate impacts of the quasi-biweekly oscillation (QBWO) over the western North Pacific (WNP) in boreal winter based on observational and reanalysis data and numerical experiments with a simplified model. The wintertime convection over the WNP is dominated by significant biweekly variability with a 10–20-day period, which explains about 66% of the intraseasonal variability. Its leading mode on the biweekly timescale is a northwestward-propagating convection dipole over the WNP, which oscillates over a period of about 12 days. When the convection-active center of this QBWO is located to the east of the Philippines, it can generate an anticyclonic vorticity source to the south of Japan via inducing upper-tropospheric divergence and excite a Rossby wave train propagating towards North America along the Pacific rim. The resultant lower-tropospheric circulation facilitates cold advection and leads to cold anomalies over central North America in the following week. This result highlights a cause-effect relationship between the WNP convection and the North American climate on the quasi-biweekly timescale and may provide some prediction potential for the North American climate.

scholarly journals On the Relationship between Synoptic Wintertime Atmospheric Variability and Path Shifts in the Gulf Stream and the Kuroshio Extension

2009 ◽  
Vol 22 (12) ◽  
pp. 3177-3192 ◽  
Author(s):  
Terrence M. Joyce ◽  
Young-Oh Kwon ◽  
Lisan Yu
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
Gulf Stream ◽  
Kuroshio Extension ◽  
Storm Track ◽  
Western Boundary ◽  
Atmospheric Variability ◽  
The North ◽  
The Kuroshio ◽  
The North Pacific

Abstract Coherent, large-scale shifts in the paths of the Gulf Stream (GS) and the Kuroshio Extension (KE) occur on interannual to decadal time scales. Attention has usually been drawn to causes for these shifts in the overlying atmosphere, with some built-in delay of up to a few years resulting from propagation of wind-forced variability within the ocean. However, these shifts in the latitudes of separated western boundary currents can cause substantial changes in SST, which may influence the synoptic atmospheric variability with little or no time delay. Various measures of wintertime atmospheric variability in the synoptic band (2–8 days) are examined using a relatively new dataset for air–sea exchange [Objectively Analyzed Air–Sea Fluxes (OAFlux)] and subsurface temperature indices of the Gulf Stream and Kuroshio path that are insulated from direct air–sea exchange, and therefore are preferable to SST. Significant changes are found in the atmospheric variability following changes in the paths of these currents, sometimes in a local fashion such as meridional shifts in measures of local storm tracks, and sometimes in nonlocal, broad regions coincident with and downstream of the oceanic forcing. Differences between the North Pacific (KE) and North Atlantic (GS) may be partly related to the more zonal orientation of the KE and the stronger SST signals of the GS, but could also be due to differences in mean storm-track characteristics over the North Pacific and North Atlantic.

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

2014 ◽  
Vol 29 (3) ◽  
pp. 505-516 ◽  
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.

scholarly journals Variability of Tropical Cyclone Frequency Over the Western North Pacific in 2018–2020

2021 ◽  
Vol 3 ◽  
Author(s):  
Tomomichi Ogata ◽  
Yuya Baba
Keyword(s):  
Tropical Cyclone ◽  
North Pacific ◽  
General Circulation ◽  
Western North Pacific ◽  
Circulation Model ◽  
Atmospheric Variability ◽  
Convection Scheme ◽  
Planetary Scale ◽  
Ensemble Simulations ◽  
Potential Index

In this study, we examine the tropical cyclone (TC) activity over the western North Pacific (WNP) in 2018–2020 and its relationship with planetary scale convection and circulation anomalies, which play an important role for TC genesis. To determine the sea surface temperature (SST)-forced atmospheric variability, atmospheric general circulation model (AGCM) ensemble simulations are executed along with the observed SST. For AGCM experiments, we use two different convection schemes to examine uncertainty in convective parameterization and robustness of simulated atmospheric response. The observed TC activity and genesis potential demonstrated consistent features. In our AGCM ensemble simulations, the updated convection scheme improves the simulation ability of observed genesis potential as well as planetary scale convection and circulation features, e.g., in September–October–November (SON), a considerable increase in the genesis potential index over the WNP in SON 2018, WNP in SON 2019, and South China Sea (SCS) in SON 2020, which were not captured in the Emanuel scheme, have been simulated in the updated convection scheme.

scholarly journals Report on hydrozoans (Cnidaria), excluding Stylasteridae, from the Emperor Seamounts, western North Pacific Ocean

Zootaxa ◽  
2021 ◽  
Vol 4950 (2) ◽  
pp. 201-247
Author(s):  
DALE R. CALDER ◽  
LES WATLING
Keyword(s):  
Pacific Ocean ◽  
North Pacific ◽  
Western North Pacific ◽  
Cold Water ◽  
North Pacific Ocean ◽  
First Record ◽  
Western North Pacific Ocean ◽  
The North ◽  
Seamount Chain ◽  
The North Pacific

Fourteen species of hydroids, collected during August 2019 by ROV SuBastian of the Schmidt Ocean Institute, are reported from the Emperor Seamount chain in the western North Pacific Ocean. Two others, Candelabrum sp. and Eudendrium sp., were observed only on videos taken by the ROV. From collections and video observations, eight species of hydroids were found at Jingū Seamount, three at Yomei, Nintoku, and Annei seamounts, and one at Koko Seamount and Hess Rise. At Suiko and Godaigo seamounts, hydroids were seen in videos but they could not be identified. Latebrahydra schulzei, an endobiotic associate of the hexactinellid sponge Walteria flemmingii Schulze, 1886 from Annei Seamount and Hess Rise, is described as a new genus and species tentatively attributed to Hydractiniidae L. Agassiz, 1862. Another new species, Hydractinia galeai, is described from Jingū Seamount. Among its distinctive characters is a zooid termed a sellectozooid, likely serving in both food capture and defence. Hydroids examined from Yomei, Nintoku, and Jingū seamounts are elements of a cold-water fauna occurring in the North Pacific Boreal Bathyal province, while those of Annei and Koko seamounts, and Hess Rise, are part of the biota of the Central North Pacific Bathyal province. Hydroids identified as Bouillonia sp., from Nintoku Seamount, represent the first record of this predominantly deep water tubulariid genus in the North Pacific Ocean. Bonneviella superba Nutting, 1915, from Jingū Seamount, is reported for the first time outside the Aleutian Islands. Bonneviella cf. gracilis Fraser, 1939, known elsewhere only from Dease Strait in the western Canadian Arctic, was also collected on Jingū. In addition to hydroids, medusae of Ptychogastria polaris Allman, 1878 were observed on videos from Nintoku, Jingū, Annei, and Koko seamounts at depths between 2423–1422 m. An unidentified siphonophore was observed near bottom at 2282 m on Nintoku Seamount. 

Intraseasonal Teleconnection between North American and Western North Pacific Monsoons with 20-Day Time Scale

2008 ◽  
Vol 21 (11) ◽  
pp. 2664-2679 ◽  
Author(s):  
Xianan Jiang ◽  
Ngar-Cheung Lau
Keyword(s):  
United States ◽  
North American ◽  
North Pacific ◽  
Time Scale ◽  
Western North Pacific ◽  
Wave Train ◽  
Eastern Pacific ◽  
Southwestern United States ◽  
Low Level ◽  
The North

Abstract Based on a recently released, high-resolution reanalysis dataset for the North American region, the intraseasonal variability (ISV; with a time scale of about 20 days) of the North American monsoon (NAM) is examined. The rainfall signals associated with this phenomenon first emerge near the Gulf of Mexico and eastern Pacific at about 20°N. They subsequently migrate to the southwestern United States along the slope of the Sierra Madre Occidental. The rainfall quickly dissipates upon arrival at the desert region of Arizona and New Mexico (AZNM). The enhanced rainfall over AZNM is accompanied by strong southeasterly low-level flow along the Gulf of California. This pattern bears strong resemblance to the circulation related to “gulf surge” events, as documented by many studies. The southeasterly flow is associated with an anomalous low vortex over the subtropical eastern Pacific Ocean off California, and a midlatitude anticyclone over the central United States in the lower troposphere. This flow pattern is in broad agreement with that favoring the “wet surges” over the southwestern United States. It is further demonstrated that the aforementioned low-level circulations associated with ISV of the NAM are part of a prominent trans-Pacific wave train extending from the western North Pacific (WNP) to the Eastern Pacific/North America along a “great circle” path. The circulation anomalies along the axis of this wave train exhibit a barotropic vertical structure over most regions outside of the WNP, and a baroclinic structure over the WNP, thus suggesting the important role of convective activities over the WNP in sustaining this wave train. This inference is further substantiated by an analysis of the pattern of wave-activity–flux vectors. Variations in the WNP convection are correlated with the ISV of the monsoons in both North American and East Asian (EA)/WNP sectors. These relationships lead to notable teleconnections between NAM and the EA/WNP monsoon on 20-day time scales.

Developing versus Nondeveloping Disturbances for Tropical Cyclone Formation. Part II: Western North Pacific

2012 ◽  
Vol 140 (4) ◽  
pp. 1067-1080 ◽  
Author(s):  
Bing Fu ◽  
Melinda S. Peng ◽  
Tim Li ◽  
Duane E. Stevens
Keyword(s):  
Tropical Cyclone ◽  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
Relative Vorticity ◽  
Tropical Cyclone Genesis ◽  
Horizontal Shear ◽  
The North ◽  
Thermodynamic Variables ◽  
Cyclone Genesis

Global daily reanalysis fields from the Navy Operational Global Atmospheric Prediction System (NOGAPS) are used to analyze Northern Hemisphere summertime (June–September) developing and nondeveloping disturbances for tropical cyclone (TC) formation from 2003 to 2008. This is Part II of the study focusing on the western North Pacific (WNP), following Part I for the North Atlantic (NATL) basin. Tropical cyclone genesis in the WNP shows different characteristics from that in the NATL in both large-scale environmental conditions and prestorm disturbances. A box difference index (BDI) is used to identify parameters in differentiating between the developing and nondeveloping disturbances. In order of importance, they are 1) 800-hPa maximum relative vorticity, 2) rain rate, 3) vertically averaged horizontal shear, 4) vertically averaged divergence, 5) 925–400-hPa water vapor content, 6) SST, and 7) translational speed. The study indicates that dynamic variables are more important in TC genesis in the WNP, while in Part I of the study the thermodynamic variables are identified as more important in the NATL. The characteristic differences between the WNP and the NATL are compared.

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