scholarly journals Extremely Active Tropical Cyclone Activities over the Western North Pacific and South China Sea in Summer 2018: Joint Effects of Decaying La Niña and Intraseasonal Oscillation

2019 ◽  
Vol 33 (4) ◽  
pp. 609-626 ◽  
Author(s):  
Lijuan Chen ◽  
Zhensong Gong ◽  
Jie Wu ◽  
Weijing Li
Keyword(s):  
Tropical Cyclone ◽  
South China Sea ◽  
South China ◽  
North Pacific ◽  
Western North Pacific ◽  
Intraseasonal Oscillation ◽  
La Niña ◽  
Joint Effects ◽  
China Sea ◽  
La Nina

Comparison of Madden–Julian Oscillation Modulation on tropical-cyclone genesis over the South China Sea and Western North Pacific under different El Niño Southern Oscillation conditions

2020 ◽  
Author(s):  
Chengyao Ye ◽  
Liping Deng ◽  
Wan-Ru Huang ◽  
Jinghua Chen
Keyword(s):  
Tropical Cyclone ◽  
South China Sea ◽  
South China ◽  
North Pacific ◽  
Western North Pacific ◽  
Southern Oscillation ◽  
The South China Sea ◽  
Dominant Factor ◽  
The South ◽  
China Sea

<p>This paper explores the modulation by Madden–Julian Oscillation (MJO) on tropical-cyclone (TC; hereafter, MJO TC) genesis over the Western North Pacific (WNP) and the South China Sea (SCS) under different El Niño Southern Oscillation (ENSO) conditions. Analyses used Joint Typhoon Warning Center (JTWC) Best Track data, the Real-Time Multivariate MJO (RMM) index, and European Center for Medium-Range Weather Forecasts (ECMWF) Interim (ERA-Interim) reanalysis data. Results showed that MJO has significant modulation on both SCS and WNP TC genesis in neutral years, with more (fewer) TCs forming during active (inactive) MJO phases. However, during El Niño and La Niña years, modulation over the two regions differs. Over the SCS, the modulation of TC genesis is strong in La Niña years, while it becomes weak in El Niño years. Over the WNP, MJO has stronger influence on TC genesis in El Niño years compared to that in La Niña years. Related Genesis Potential Index (GPI) analysis suggests that midlevel moisture is the primary factor for MJO modulation on SCS TC genesis in La Niña years, and vorticity is the secondary factor. Over the WNP, midlevel moisture is the dominant factor for MJO TC genesis modulation during El Niño years. The main reason is increased water-vapor transport from the Bay of Bengal associated with the active MJO phase related westerly wind anomalies; these features are a significant presence over the SCS during La Niña years, and over the WNP during El Niño years.</p>

scholarly journals Comparison of the Madden–Julian Oscillation-Related Tropical Cyclone Genesis over the South China Sea and Western North Pacific under Different El Niño-Southern Oscillation Conditions

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 183
Author(s):  
Chengyao Ye ◽  
Liping Deng ◽  
Wan-Ru Huang ◽  
Jinghua Chen
Keyword(s):  
Tropical Cyclone ◽  
South China Sea ◽  
El Niño ◽  
North Pacific ◽  
Western North Pacific ◽  
El Nino ◽  
Southern Oscillation ◽  
La Niña ◽  
Madden Julian Oscillation ◽  
La Nina

This paper explores the Madden–Julian Oscillation (MJO) modulation of tropical cyclone (TC; hereafter, MJO-TC) genesis over the South China Sea (SCS) and Western North Pacific (WNP) under different El Niño-Southern Oscillation (ENSO) conditions. Analyses used Joint Typhoon Warning Center (JTWC) best-track data, the Real-Time Multivariate MJO (RMM) index, and European Center for Medium-Range Weather Forecasts (ECMWF) Interim (ERA-Interim) reanalysis data. The results showed that the MJO has significant modulation on both the SCS and WNP TC genesis in neutral years, with more (fewer) TCs forming during the active (inactive) MJO phases. However, during the El Niño and La Niña years, the MJO-TC genesis modulation over the two regions differs from each other. Over the SCS, the MJO modulation of TC genesis is stronger in the La Niña years, while it becomes weaker in the El Niño years. Over the WNP, the MJO has a stronger influence on TC genesis in the El Niño years compared to that in the La Niña years. Related Genesis Potential Index (GPI) analysis suggests that midlevel moisture is the primary factor and vorticity is the secondary factor, for the MJO-TC genesis modulation over the SCS in the La Niña years. Over the WNP, midlevel moisture is the dominant factor for the MJO-TC genesis modulation during the El Niño years. These results can be explained by increased water vapor transport from the Bay of Bengal, associated with enhanced westerly wind anomalies, during the active phases relative to the inactive MJO phases; these conditions prevail over the SCS during the La Niña years, and over the WNP during the El Niño years.

scholarly journals Climatological analysis of passage-type tropical cyclones from the Western North Pacific into the South China Sea

2017 ◽  
Vol 28 (3) ◽  
pp. 327-343 ◽  
Author(s):  
Jau-Ming Chen ◽  
Pei-Hua Tan ◽  
Liang Wu ◽  
Jin-Shuen Liu ◽  
Hui-Shan Chen
Keyword(s):  
South China Sea ◽  
Tropical Cyclones ◽  
South China ◽  
North Pacific ◽  
Western North Pacific ◽  
The South China Sea ◽  
The South ◽  
China Sea

scholarly journals Improved Simulation of Tropical Cyclone Responses to ENSO in the Western North Pacific in the High-Resolution GFDL HiFLOR Coupled Climate Model*

2016 ◽  
Vol 29 (4) ◽  
pp. 1391-1415 ◽  
Author(s):  
Wei Zhang ◽  
Gabriel A. Vecchi ◽  
Hiroyuki Murakami ◽  
Thomas Delworth ◽  
Andrew T. Wittenberg ◽  
...  
Keyword(s):  
High Resolution ◽  
Tropical Cyclone ◽  
El Niño ◽  
North Pacific ◽  
Western North Pacific ◽  
El Nino ◽  
Walker Circulation ◽  
La Niña ◽  
Sea Surface ◽  
La Nina

Abstract This study aims to assess whether, and the extent to which, an increase in atmospheric resolution of the Geophysical Fluid Dynamics Laboratory (GFDL) Forecast-Oriented Low Ocean Resolution version of CM2.5 (FLOR) with 50-km resolution and the High-Resolution FLOR (HiFLOR) with 25-km resolution improves the simulation of the El Niño–Southern Oscillation (ENSO)–tropical cyclone (TC) connections in the western North Pacific (WNP). HiFLOR simulates better ENSO–TC connections in the WNP including TC track density, genesis, and landfall than FLOR in both long-term control experiments and sea surface temperature (SST)- and sea surface salinity (SSS)-restoring historical runs (1971–2012). Restoring experiments are performed with SSS and SST restored to observational estimates of climatological SSS and interannually varying monthly SST. In the control experiments of HiFLOR, an improved simulation of the Walker circulation arising from more realistic SST and precipitation is largely responsible for its better performance in simulating ENSO–TC connections in the WNP. In the SST-restoring experiments of HiFLOR, more realistic Walker circulation and steering flow during El Niño and La Niña are responsible for the improved simulation of ENSO–TC connections in the WNP. The improved simulation of ENSO–TC connections with HiFLOR arises from a better representation of SST and better responses of environmental large-scale circulation to SST anomalies associated with El Niño or La Niña. A better representation of ENSO–TC connections in HiFLOR can benefit the seasonal forecasting of TC genesis, track, and landfall; improve understanding of the interannual variation of TC activity; and provide better projection of TC activity under climate change.

scholarly journals Two Distinctive Processes for Abnormal Spring to Summer Transition over the South China Sea

2017 ◽  
Vol 30 (23) ◽  
pp. 9665-9678 ◽  
Author(s):  
Renguang Wu ◽  
Zhuoqi He
Keyword(s):  
South China Sea ◽  
South China ◽  
North Pacific ◽  
Western North Pacific ◽  
The South China Sea ◽  
The South ◽  
Maritime Continent ◽  
China Sea ◽  
Tropical Western North Pacific ◽  
Sst Anomalies

The period from April to June signifies the transition from spring to summer over the South China Sea (SCS). The present study documents two distinct processes for abnormal spring to summer transition over the SCS. One process is related to large-scale sea surface temperature (SST) anomalies in the tropical Indo-Pacific region. During spring of La Niña decaying years, negative SST anomalies in the equatorial central Pacific (ECP) and the southwestern tropical Indian Ocean (TIO) coexist with positive SST anomalies in the tropical western North Pacific. Negative ECP SST anomalies force an anomalous Walker circulation, negative southwestern TIO SST anomalies induce anomalous cross-equatorial flows from there, and positive tropical western North Pacific SST anomalies produce a Rossby wave–type response to the west. Together, they contribute to enhanced convection and an anomalous lower-level cyclone over the SCS, leading to an advanced transition to summer there. The other process is related to regional air–sea interactions around the Maritime Continent. Preceding positive ECP SST anomalies induce anomalous descent around the Maritime Continent, leading to SST increase in the SCS and southeast TIO. An enhanced convection region moves eastward over the south TIO during spring and reaches the area northwest of Australia in May. This enhances descent over the SCS via an anomalous cross-equatorial overturning circulation and contributes to further warming in the SCS. The SST warming in turn induces convection over the SCS, leading to an accelerated transition to summer. Analysis shows that the above two processes are equally important during 1979–2015.

scholarly journals Climate shift of the South China Sea summer monsoon onset in 1993/1994 and its physical causes

2019 ◽  
Vol 54 (3-4) ◽  
pp. 1819-1827
Author(s):  
Ailan Lin ◽  
Renhe Zhang
Keyword(s):  
South China Sea ◽  
South China ◽  
North Pacific ◽  
Early Onset ◽  
Western North Pacific ◽  
The South China Sea ◽  
The South ◽  
Climate Shift ◽  
China Sea ◽  
Zonal Winds

AbstractThe characteristics of anomalous circulations during spring associated with the climate shift of the South China Sea summer monsoon (SCSSM) onset in 1993/1994 and its physical causes are investigated. It is found that the interdecadal shift of SCSSM onset happened in 1993/1994 is related closely to the 850 hPa zonal wind anomalies over the area around Kalimantan Island. Easterly (westerly) anomalies over Kalimantan Island enhance (weaken) subtropical high over the western North Pacific, leading to the late (early) onset of SCSSM in 1979–1993 (1994–2013). The sea surface temperature anomalies (SSTAs) in the key region 140°–150° E, 5° S–2.5° N influence the interdecadal change of zonal winds over Kalimantan Island. The positive SSTAs over this key region in 1994–2013 force convergence toward the region at low-level and form significant westerly anomalies near Kalimantan Island located to the west of the key region. The negative anomalies of meridional gradient of zonal winds over the South China Sea region increase the atmospheric vorticity over there significantly and result in the weakening and retreating eastward of the subtropical high over the western North Pacific, which is conducive to the early onset of SCSSM.

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