scholarly journals Different Pacific Ocean Warming Decaying Types and Northwest Pacific Tropical Cyclone Activity

2013 ◽  
Vol 26 (22) ◽  
pp. 8979-8994 ◽  
Author(s):  
Yao Ha ◽  
Zhong Zhong ◽  
Xiuqun Yang ◽  
Yuan Sun
Keyword(s):  
Tropical Cyclone ◽  
East Asian ◽  
The Philippines ◽  
La Niña ◽  
Eastern Pacific ◽  
Northwest Pacific ◽  
Central Pacific ◽  
East Indian ◽  
La Nina ◽  
Central Pacific Warming

Abstract This study focuses on statistical analysis of anomalous tropical cyclone (TC) activities and the physical mechanisms behind these anomalies. Different patterns of decaying of the warm sea surface temperature anomaly (SSTA) over the equatorial central-eastern Pacific are categorized into three types: eastern Pacific warming decaying to La Niña (EPWDL), eastern Pacific warming decaying to a neutral phase (EPWDN), and a central Pacific warming decaying year (CPWD). Differences in TC activity over the western North Pacific (WNP) corresponding to the above three types are discussed, and possible mechanisms are proposed. For EPWDL, TC genesis shows a significant positive (negative) anomaly over the northwestern (southeastern) WNP and more TCs move westward and make landfall over the southern East Asian coast. This is attributed primarily to the combined modulation of La Niña and the warm equatorial east Indian Ocean SSTA. For EPWDN, enhanced TC genesis is observed over the northeastern WNP, and suppressed TC activity is located mainly in the zonal region extending from the Philippine Sea to the eastern WNP, close to 160°E. Most of the TCs formed over the eastern WNP experience early recurvature east of 140°E, then move northeastward; hence, fewer TCs move northwestward to make landfall over the East Asian coast. For CPWD, the enhanced TC activity appears over the western WNP. This is due to the weak anomalous cyclonic circulation over the Philippines, primarily caused by the weaker, more westward-shifting warm SSTA compared to that in the previous warming year over the central Pacific.

scholarly journals ENSO Effect on East Asian Tropical Cyclone Landfall via Changes in Tracks and Genesis in a Statistical Model

2014 ◽  
Vol 53 (2) ◽  
pp. 406-420 ◽  
Author(s):  
Emmi Yonekura ◽  
Timothy M. Hall
Keyword(s):  
Tropical Cyclone ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
North Pacific Ocean ◽  
East Asian ◽  
The Philippines ◽  
La Niña ◽  
Local Regression ◽  
La Nina

AbstractImprovements on a statistical tropical cyclone (TC) track model in the western North Pacific Ocean are described. The goal of the model is to study the effect of El Niño–Southern Oscillation (ENSO) on East Asian TC landfall. The model is based on the International Best-Track Archive for Climate Stewardship (IBTrACS) database of TC observations for 1945–2007 and employs local regression of TC formation rates and track increments on the Niño-3.4 index and seasonally varying climate parameters. The main improvements are the inclusion of ENSO dependence in the track propagation and accounting for seasonality in both genesis and tracks. A comparison of simulations of the 1945–2007 period with observations concludes that the model updates improve the skill of this model in simulating TCs. Changes in TC genesis and tracks are analyzed separately and cumulatively in simulations of stationary extreme ENSO states. ENSO effects on regional (100-km scale) landfall are attributed to changes in genesis and tracks. The effect of ENSO on genesis is predominantly a shift in genesis location from the southeast in El Niño years to the northwest in La Niña years, resulting in higher landfall rates for the East Asian coast during La Niña. The effect of ENSO on track propagation varies seasonally and spatially. In the peak activity season (July–October), there are significant changes in mean tracks with ENSO. Landfall-rate changes from genesis– and track–ENSO effects in the Philippines cancel out, while coastal segments of Vietnam, China, the Korean Peninsula, and Japan show enhanced La Niña–year increases.

scholarly journals Different El Niño Types and Tropical Cyclone Landfall in East Asia

2012 ◽  
Vol 25 (19) ◽  
pp. 6510-6523 ◽  
Author(s):  
Wei Zhang ◽  
H.-F. Graf ◽  
Yee Leung ◽  
Michael Herzog
Keyword(s):  
Tropical Cyclone ◽  
East Asia ◽  
El Niño ◽  
El Nino ◽  
The Philippines ◽  
La Niña ◽  
Malay Peninsula ◽  
Cp El Niño ◽  
La Nina ◽  
Ep El Niño

Abstract This study examines whether there exist significant differences in tropical cyclone (TC) landfall between central Pacific (CP) El Niño, eastern Pacific (EP) El Niño, and La Niña during the peak TC season (June–October) and how and to what extent CP El Niño influences TC landfall over East Asia for the period 1961–2009. The peak TC season is subdivided into summer [June–August (JJA)] and autumn [September–October (SO)]. The results are summarized as follows: (i) during the summer of CP El Niño years, TCs are more likely to make landfall over East Asia because of a strong easterly steering flow anomaly induced by the westward shift of the subtropical high and northward-shifted TC genesis. In particular, TCs have a greater probability of making landfall over Japan and Korea during the summer of CP El Niño years. (ii) In the autumn of CP El Niño years, TC landfall in most areas of East Asia, especially Indochina, the Malay Peninsula, and the Philippines, is likely to be suppressed because the large-scale circulation resembles that of EP El Niño years. (iii) During the whole peak TC season [June–October (JJASO)] of CP El Niño years, TCs are more likely to make landfall over Japan and Korea. TC landfall in East Asia as a whole has an insignificant association with CP El Niño during the peak TC season. In addition, more (less) TCs are likely to make landfall in China, Indochina, the Malay Peninsula, and the Philippines during the peak TC season of La Niña (EP El Niño) years.

scholarly journals Impacts of ENSO on Philippine Tropical Cyclone Activity

2016 ◽  
Vol 29 (5) ◽  
pp. 1877-1897 ◽  
Author(s):  
Irenea L. Corporal-Lodangco ◽  
Lance M. Leslie ◽  
Peter J. Lamb
Keyword(s):  
Tropical Cyclone ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
The Philippines ◽  
Life Cycles ◽  
La Niña ◽  
Cyclone Activity ◽  
La Nina ◽  
The Mean

Abstract This study investigates the El Niño–Southern Oscillation (ENSO) contribution to Philippine tropical cyclone (TC) variability, for a range of quarterly TC metrics. Philippine TC activity is found to depend on both ENSO quarter and phase. TC counts during El Niño phases differ significantly from neutral phases in all quarters, whereas neutral and La Niña phases differ only in January–March and July–September. Differences in landfalls between neutral and El Niño phases are significant in January–March and October–December and in January–March for neutral and La Niña phases. El Niño and La Niña landfalls are significantly different in April–June and October–December. Philippine neutral and El Niño TC genesis cover broader longitude–latitude ranges with similar long tracks, originating farther east in the western North Pacific. In El Niño phases, the mean eastward displacement of genesis locations and more recurving TCs reduce Philippine TC frequencies. Proximity of La Niña TC genesis to the Philippines and straight-moving tracks in April–June and October–December increase TC frequencies and landfalls. Neutral and El Niño accumulated cyclone energy (ACE) values are above average, except in April–June of El Niño phases. Above-average quarterly ACE in neutral years is due to increased TC frequencies, days, and intensities, whereas above-average El Niño ACE in July–September is due to increased TC days and intensities. Below-average La Niña ACE results from fewer TCs and shorter life cycles. Longer TC durations produce slightly above-average TC days in July–September El Niño phases. Fewer TCs than neutral years, as well as shorter TC durations, imply less TC days in La Niña phases. However, above-average TC days occur in October–December as a result of higher TC frequencies.

scholarly journals Changes in Spread and Predictability Associated with ENSO in an Ensemble Coupled GCM

2006 ◽  
Vol 19 (17) ◽  
pp. 4378-4396 ◽  
Author(s):  
Renguang Wu ◽  
Ben P. Kirtman
Keyword(s):  
Surface Pressure ◽  
El Niño ◽  
El Nino ◽  
Tropical Pacific ◽  
La Niña ◽  
Boreal Summer ◽  
Boreal Winter ◽  
Central Pacific ◽  
La Nina ◽  
Signal Change

Abstract The present study documents the influence of El Niño and La Niña events on the spread and predictability of rainfall, surface pressure, and 500-hPa geopotential height, and contrasts the relative contribution of signal and noise changes to the predictability change based on a long-term integration of an interactive ensemble coupled general circulation model. It is found that the pattern of the El Niño–Southern Oscillation (ENSO)-induced noise change for rainfall follows closely that of the corresponding signal change in most of the tropical regions. The noise for tropical Pacific surface pressure is larger (smaller) in regions of lower (higher) mean pressure. The ENSO-induced noise change for 500-hPa height displays smaller spatial scales compared to and has no systematic relationship with the signal change. The predictability for tropical rainfall and surface pressure displays obvious contrasts between the summer and winter over the Bay of Bengal, the western North Pacific, and the tropical southwestern Indian Ocean. The predictability for tropical 500-hPa height is higher in boreal summer than in boreal winter. In the equatorial central Pacific, the predictability for rainfall is much higher in La Niña years than in El Niño years. This occurs because of a larger percent reduction in the amplitude of noise compared to the percent decrease in the magnitude of signal from El Niño to La Niña years. A consistent change is seen in the predictability for surface pressure near the date line. In the western North and South Pacific, the predictability for boreal winter rainfall is higher in El Niño years than in La Niña years. This is mainly due to a stronger signal in El Niño years compared to La Niña years. The predictability for 500-hPa height increases over most of the Tropics in El Niño years. Over western tropical Pacific–Australia and East Asia, the predictability for boreal winter surface pressure and 500-hPa height is higher in El Niño years than in La Niña years. The predictability change for 500-hPa height is primarily due to the signal change.

scholarly journals Indo-Pacific Variability on Seasonal to Multidecadal Time Scales. Part II: Multiscale Atmosphere–Ocean Linkages

2018 ◽  
Vol 31 (2) ◽  
pp. 693-725 ◽  
Author(s):  
Dimitrios Giannakis ◽  
Joanna Slawinska
Keyword(s):  
Time Scales ◽  
El Niño ◽  
El Nino ◽  
Walker Circulation ◽  
La Niña ◽  
Central Pacific ◽  
Australian Monsoon ◽  
La Nina ◽  
Combination Modes ◽  
Sst Anomalies

The coupled atmosphere–ocean variability of the Indo-Pacific domain on seasonal to multidecadal time scales is investigated in CCSM4 and in observations through nonlinear Laplacian spectral analysis (NLSA). It is found that ENSO modes and combination modes of ENSO with the annual cycle exhibit a seasonally synchronized southward shift of equatorial surface zonal winds and thermocline adjustment consistent with terminating El Niño and La Niña events. The surface winds associated with these modes also generate teleconnections between the Pacific and Indian Oceans, leading to SST anomalies characteristic of the Indian Ocean dipole. The family of NLSA ENSO modes is used to study El Niño–La Niña asymmetries, and it is found that a group of secondary ENSO modes with more rapidly decorrelating temporal patterns contributes significantly to positively skewed SST and zonal wind statistics. Besides ENSO, fundamental and combination modes representing the tropospheric biennial oscillation (TBO) are found to be consistent with mechanisms for seasonally synchronized biennial variability of the Asian–Australian monsoon and Walker circulation. On longer time scales, a multidecadal pattern referred to as the west Pacific multidecadal mode (WPMM) is established to significantly modulate ENSO and TBO activity, with periods of negative SST anomalies in the western tropical Pacific favoring stronger ENSO and TBO variability. This behavior is attributed to the fact that cold WPMM phases feature anomalous decadal westerlies in the tropical central Pacific, as well as an anomalously flat zonal thermocline profile in the equatorial Pacific. Moreover, the WPMM is found to correlate significantly with decadal precipitation over Australia.

Frequent central Pacific La Niña events may accelerate Arctic warming since the 1980s

2021 ◽  
Vol 40 (11) ◽  
pp. 62-69
Author(s):  
Jing Li ◽  
Lin Mu ◽  
Linhao Zhong
Keyword(s):  
La Niña ◽  
Central Pacific ◽  
Arctic Warming ◽  
La Nina

scholarly journals Simulation of Asymmetric ENSO Transition in WCRP CMIP3 Multimodel Experiments

2010 ◽  
Vol 23 (22) ◽  
pp. 6051-6067 ◽  
Author(s):  
Masamichi Ohba ◽  
Daisuke Nohara ◽  
Hiroaki Ueda
Keyword(s):  
El Niño ◽  
El Nino ◽  
Transition Process ◽  
La Niña ◽  
Western Boundary ◽  
Central Pacific ◽  
Cold Event ◽  
Transition Processes ◽  
La Nina ◽  
Rapid Transition

Abstract Based on the Coupled Model Intercomparison Project phase 3 (CMIP3) multimodel dataset, the relationships between the climatological states and transition processes of simulated ENSO are investigated. The air–sea coupled system of the observed ENSO can remain in the weak cold event for up to 2 yr, whereas those of the warm events tend to turn rapidly into a cold phase. Therefore, the authors separately investigate the simulated transition process of a warm-phase and a cold-phase ENSO in the CMIP3 models. Some of the models reproduce the features of the observed transition process of El Niño/La Niña, whereas most models fail to concurrently reproduce the process during both phases. In the CMIP3 models, four climate models simulate well the rapid transition from El Niño to La Niña. The intensity of a rapid transition of El Niño is mainly related to the intensity of the simulated climatological precipitation over the western–central Pacific (WCP). The models that have strong WCP precipitation can simulate the rapid termination of the equatorial zonal wind in the WCP, which tends to result in the termination of El Niño phase. This relationship is not applicable for the La Niña transition phase. The simulation of La Niña persistency is related to the reflection of off-equatorial Rossby waves at the western boundary of the Pacific and the seasonal evolution of the climatological precipitation in the WCP. Differences in the transition processes between El Niño and La Niña events are fundamentally due to the nonlinear atmospheric (convective) response to SST, which originates from the distribution of climatological SST and its seasonal changes. The results of the present study indicate that a realistic simulation of the climatological state and its seasonality in the WCP are important to be able to simulate the observed transition process of the ENSO.

scholarly journals Tropical Cyclone Activity in the Fiji Region: Spatial Patterns and Relationship to Large-Scale Circulation

2009 ◽  
Vol 22 (14) ◽  
pp. 3877-3893 ◽  
Author(s):  
Savin S. Chand ◽  
Kevin J. E. Walsh
Keyword(s):  
Tropical Cyclone ◽  
El Niño ◽  
Large Scale ◽  
El Nino ◽  
Southern Oscillation ◽  
Vertical Wind Shear ◽  
Relative Vorticity ◽  
La Niña ◽  
Factors Affecting ◽  
La Nina

Abstract This study examines the variations in tropical cyclone (TC) genesis positions and their subsequent tracks for different phases of the El Niño–Southern Oscillation (ENSO) phenomenon in the Fiji, Samoa, and Tonga region (FST region) using Joint Typhoon Warning Center best-track data. Over the 36-yr period from 1970/71 to 2005/06, 122 cyclones are observed in the FST region. A large spread in the genesis positions is noted. During El Niño years, genesis is enhanced east of the date line, extending from north of Fiji to over Samoa, with the highest density centered around 10°S, 180°. During neutral years, maximum genesis occurs immediately north of Fiji with enhanced genesis south of Samoa. In La Niña years, there are fewer cyclones forming in the region than during El Niño and neutral years. During La Niña years, the genesis positions are displaced poleward of 12°S, with maximum density centered around 15°S, 170°E and south of Fiji. The cyclone tracks over the FST region are also investigated using cluster analysis. Tracks during the period 1970/71–2005/06 are conveniently described using three separate clusters, with distinct characteristics associated with different ENSO phases. Finally, the role of large-scale environmental factors affecting interannual variability of TC genesis positions and their subsequent tracks in the FST region are investigated. Favorable genesis positions are observed where large-scale environments have the following seasonal average thresholds: (i) 850-hPa cyclonic relative vorticity between −16 and −4 (×10−6 s−1), (ii) 200-hPa divergence between 2 and 8 (×10−6 s−1), and (iii) environmental vertical wind shear between 0 and 8 m s−1. The subsequent TC tracks are observed to be steered by mean 700–500-hPa winds.

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