An Exploratory Analysis of the Relationship between Tropical Storm Formation in the Western North Pacific and ENSO

1994 ◽  
Vol 122 (4) ◽  
pp. 636-651 ◽  
Author(s):  
Mark A. Lander
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Tropical Storm ◽  
Exploratory Analysis ◽  
The Relationship

scholarly journals A Survey on the Relationship between Ocean Subsurface Temperature and Tropical Cyclone over the Western North Pacific

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Difu Sun ◽  
Junqiang Song ◽  
Kaijun Ren ◽  
Xiaoyong Li ◽  
Guangjie Wang
Keyword(s):  
Tropical Cyclone ◽  
Water Temperature ◽  
Negative Correlation ◽  
North Pacific ◽  
Western North Pacific ◽  
Vertical Wind Shear ◽  
Longwave Radiation ◽  
Subsurface Water ◽  
Subsurface Temperature ◽  
The Relationship

The relationship between ocean subsurface temperature and tropical cyclone (TC) over the western North Pacific (WNP) is studied based on the TC best-track data and global reanalysis data during the period of 1948–2012. Here the TC frequency (TCF), lifespan, and genesis position of TCs are analysed. A distinctive negative correlation between subsurface water temperature and TCF is observed, especially the TCF in the southeastern quadrant of the WNP (0–15°N, 150–180°E). According to the detrended subsurface temperature anomalies of the 125 m depth layer in the main TC genesis area (0–30°N, 100–180°E), we selected the subsurface cold and warm years. During the subsurface cold years, TCs tend to have a longer mean lifespan and a more southeastern genesis position than the subsurface warm years in general. To further investigate the causes of this characteristic, the TC genesis potential indexes (GPI) are used to analyse the contributions of environmental factors to TC activities. The results indicate that the negative correlation between subsurface water temperature and TCF is mainly caused by the variation of TCF in the southeastern quadrant of the WNP, where the oceanic and atmospheric environments are related to ocean subsurface conditions. Specifically, compared with the subsurface warm years, there are larger relative vorticity, higher relative humidity, smaller vertical wind shear, weaker net longwave radiation, and higher ocean mixed layer temperature in the southeastern quadrant during cold years, which are all favorable for genesis and development of TC.

scholarly journals Seasonality and El Niño Diversity in the Relationship between ENSO and Western North Pacific Tropical Cyclone Activity

2019 ◽  
Vol 32 (23) ◽  
pp. 8021-8045 ◽  
Author(s):  
Yumi Choi ◽  
Kyung-Ja Ha ◽  
Fei-Fei Jin
Keyword(s):  
Tropical Cyclone ◽  
Seasonal Change ◽  
El Niño ◽  
North Pacific ◽  
Western North Pacific ◽  
El Nino ◽  
Southern Oscillation ◽  
Central Pacific ◽  
Southeastern Part ◽  
The Relationship

Abstract Both the impacts of two types of El Niño on the western North Pacific (WNP) tropical cyclone (TC) activity and the seasonality in the relationship between genesis potential index (GPI) and El Niño–Southern Oscillation (ENSO) are investigated. The ENSO-induced GPI change over the northwestern (southeastern) part of the WNP is mostly attributed to the relative humidity (absolute vorticity) term, revealing a distinct meridional and zonal asymmetry in summer and fall, respectively. The seasonal change in ENSO (background states) from summer to fall is responsible for the seasonal change in GPI anomalies south of 20°N (over the northeastern part of the WNP). The downdraft induced by the strong upper-level convergence in the eastern Pacific (EP)-type El Niño and both the northwestward-shifted relative vorticity and northward-extended convection over the southeastern part of the WNP in the central Pacific (CP)-type El Niño lead to distinct TC impacts over East Asia (EA). The southward movement of genesis location of TCs and increased westward-moving TCs account for the enhanced strong typhoon activity for the EP-type El Niño in summer. In fall the downdraft and anomalous anticyclonic steering flows over the western part of the WNP remarkably decrease TC impacts over EA. The enhanced moist static energy and midlevel upward motion over the eastern part of the WNP under the northern off-equatorial sea surface temperature warming as well as longer passage of TCs toward EA are responsible for the enhanced typhoon activity for the CP-type El Niño. It is thus important to consider the seasonality and El Niño pattern diversity to explore the El Niño–induced TC impacts over EA.

scholarly journals Implications of the Observed Relationship between Tropical Cyclone Size and Intensity over the Western North Pacific

2015 ◽  
Vol 28 (24) ◽  
pp. 9501-9506 ◽  
Author(s):  
Liguang Wu ◽  
Wei Tian ◽  
Qingyuan Liu ◽  
Jian Cao ◽  
John A. Knaff
Keyword(s):  
Numerical Simulation ◽  
Tropical Cyclone ◽  
Numerical Simulations ◽  
North Pacific ◽  
Western North Pacific ◽  
Horizontal Resolution ◽  
Wind Damage ◽  
Nonlinear Relationship ◽  
Rainfall Distribution ◽  
The Relationship

Abstract Tropical cyclone (TC) size, usually measured with the radius of gale force wind (34 kt or 17 m s−1), is an important parameter for estimating TC risks such as wind damage, rainfall distribution, and storm surge. Previous studies have reported that there is a very weak relationship between TC size and TC intensity. A close examination presented here using satellite-based wind analyses suggests that the relationship between TC size and intensity is nonlinear. TC size generally increases with increasing TC maximum sustained wind before a maximum of 2.50° latitude at an intensity of 103 kt or 53.0 m s−1 and then slowly decreases as the TC intensity further increases. The observed relationship between TC size and intensity is compared to the relationships produced by an 11-yr seasonal numerical simulation of TC activity. The numerical simulations were able to produce neither the observed maximum sustained winds nor the observed nonlinear relationship between TC size and intensity. This finding suggests that TC size cannot reasonably be simulated with 9-km horizontal resolution and increased resolution is needed to study TC size variations using numerical simulations.

scholarly journals Interchange and movements of humpback whales (Megaptera novaeangliae) between western North Pacific winter breeding grounds in northern Luzon, Philippines and Okinawa, Japan

2021 ◽  
Vol 22 (1) ◽  
pp. 39-53
Author(s):  
Jo Marie Acebes ◽  
Haruna Okabe ◽  
Nozomi Kobayashi ◽  
Shotaro Nakagun ◽  
Naoto Higashi ◽  
...  
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
The Philippines ◽  
Humpback Whales ◽  
Distinct Population Segment ◽  
Breeding Grounds ◽  
Different Seasons ◽  
The Relationship ◽  
Population Segment ◽  
Winter Breeding

Humpback whales wintering in the northern Philippines and Okinawa, Japan, belong to the western North Pacific subpopulation, now recognised as a distinct population segment. The numbers for this subpopulation are low hence it is being proposed to be listed as endangered. Although previous research revealed movements between breeding grounds, the relationship between these areas remain little understood. Recent survey efforts in the Philippines resulted in a total of 234 photo-identified individuals from 1999-2016 while Okinawa had 1,445 from 1991-2014. Within the seasons a total of 100 matches were found between the two breeding grounds including 38 males and 24 females while the rest were unknown. Within these matches, eight individuals were recorded moving within seasons, including two individuals moving across seasons multiple times. The two whales were both males, where one was recorded in both breeding grounds in three different seasons (2005, 2008 and 2012). The shortest duration of recorded sightings between grounds was one whale seen in the Philippines in late March 2012 and in Okinawa 13 days later. More females with calves were sighted in the Philippines than in Okinawa and this may indicate the Philippines as a preferred nursing ground.

scholarly journals Sub-seasonal variations of the tropical storm track in the western north Pacific

MAUSAM ◽  
2021 ◽  
Vol 48 (2) ◽  
pp. 189-194
Author(s):  
BIN WANG ◽  
LIGUANG WU
Keyword(s):  
Summer Monsoon ◽  
Seasonal Variations ◽  
North Pacific ◽  
Time Scale ◽  
Western North Pacific ◽  
Storm Track ◽  
Tropical Storm ◽  
Climatological Data ◽  
Seasonal Oscillation ◽  
The Western Pacific

 With 20-year (1975-94) climatological data, we demonstrate that the tropical storm track over the western North Pacific (0° - 40°N, 100 - 180°E) exhibits prominent sub-seasonal variations on a time scale of about 40 days from May to November. The storm track variability is regulated by the conspicuous Climatological Intra Seasonal Oscillation (CISO) in the strength of the western North Pacific summer monsoon and the associated position of the western Pacific Sub-tropical High. The CISO cycle regulates the number of tropical storm formation during the Pre-Onset and Withdraw Cycles but not during the Onset and Peak Monsoon Cycles (from mid-June to mid-September).    

scholarly journals A Physical Basis for the Probabilistic Prediction of the Accumulated Tropical Cyclone Kinetic Energy in the Western North Pacific

2013 ◽  
Vol 26 (20) ◽  
pp. 7981-7991 ◽  
Author(s):  
Hye-Mi Kim ◽  
Myong-In Lee ◽  
Peter J. Webster ◽  
Dongmin Kim ◽  
Jin Ho Yoo
Keyword(s):  
Tropical Cyclone ◽  
Kinetic Energy ◽  
El Niño ◽  
North Pacific ◽  
Wind Shear ◽  
Western North Pacific ◽  
El Nino ◽  
Vertical Wind Shear ◽  
Tropical Storm ◽  
Probabilistic Prediction

Abstract The relationship between El Niño–Southern Oscillation (ENSO) and tropical storm (TS) activity over the western North Pacific Ocean is examined for the period from 1981 to 2010. In El Niño years, TS genesis locations are generally shifted to the southeast relative to normal years and the passages of TSs tend to recurve to the northeast. TSs of greater duration and more intensity during an El Niño summer induce an increase of the accumulated tropical cyclone kinetic energy (ACE). Based on the strong relationship between the TS properties and ENSO, a probabilistic prediction for seasonal ACE is investigated using a hybrid dynamical–statistical model. A statistical relationship is developed between the observed ACE and large-scale variables taken from the ECMWF seasonal forecast system 4 hindcasts. The ACE correlates positively with the SST anomaly over the central to eastern Pacific and negatively with the vertical wind shear near the date line. The vertical wind shear anomalies over the central and western Pacific are selected as predictors based on sensitivity tests of ACE predictive skill. The hybrid model performs quite well in forecasting seasonal ACE with a correlation coefficient between the observed and predicted ACE at 0.80 over the 30-yr period. A relative operating characteristic analysis also indicates that the ensembles have significant probabilistic skill for both the above-normal and below-normal categories. By comparing the ACE prediction over the period from 2003 to 2011, the hybrid model appears more skillful than the forecast from the Tropical Storm Risk consortium.

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