A Strengthened Influence of ENSO on August High Temperature Extremes over the Southern Yangtze River Valley since the Late 1980s

2013 ◽  
Vol 26 (7) ◽  
pp. 2205-2221 ◽  
Author(s):  
Kaiming Hu ◽  
Gang Huang ◽  
Renguang Wu
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Yangtze River ◽  
El Nino ◽  
North Indian Ocean ◽  
Yangtze River Valley ◽  
Indian Ocean Warming ◽  
Upper Level ◽  
The Relationship ◽  
High Temperature Extremes

Abstract The present study investigates the decadal change in the relationship between China high temperature extremes (HTEs) and El Niño–Southern Oscillation (ENSO). It is found that the relationship between the August HTEs in the southern Yangtze River valley (SYRV) and ENSO has strengthened since the late 1980s. Before the late 1980s, the relationship is weak, whereas, after the late 1980s, the August hot-day numbers in the SYRV region tend to be more than normal during El Niño decaying years. During 1988–2008, El Niño–induced August warm SST anomalies are mainly located in the eastern tropical and north Indian Ocean. As a response to the north Indian Ocean warming, the South Asia high extends eastward, and the SYRV is overlain by upper-level easterly anomalies. The cold horizontal temperature advection induced by upper-level easterly anomalies leads to anomalous descent, which is conducive to the occurrence of HTEs through adiabatic warming. During 1966–86, El Niño–induced August warm SST anomalies are mainly distributed in the equatorial central and southwest tropical Indian Ocean. Corresponding to the equatorial Indian Ocean warming, the ascending motion over the Arabian Sea is enhanced, which leads to an anomalous anticyclone over the Middle East through a Rossby wave–type response and in turn an anomalous cyclone over China through a midlatitude wave pattern. The SYRV is controlled by upper-level westerly anomalies, which is not conducive to the occurrence of HTEs since the corresponding horizontal temperature advection and anomalous vertical motion are weak. As such, the impact of ENSO on August SYRV HTEs is weak before the late 1980s.

Indo-Pacific climate during the decaying phase of the 2015/16 El Niño: role of southeast tropical Indian Ocean warming

2017 ◽  
Vol 50 (11-12) ◽  
pp. 4707-4719 ◽  
Author(s):  
Zesheng Chen ◽  
Yan Du ◽  
Zhiping Wen ◽  
Renguang Wu ◽  
Chunzai Wang
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Tropical Indian Ocean ◽  
Ocean Warming ◽  
Indian Ocean Warming

Delayed impact of Indian Ocean warming on the East Asian surface temperature variation in boreal summer

2021 ◽  
pp. 1-40
Author(s):  
Sunyong Kim ◽  
Jong-Seong Kug
Keyword(s):  
Indian Ocean ◽  
Surface Temperature ◽  
East Asian ◽  
Negative Relationship ◽  
North Indian Ocean ◽  
Ocean Warming ◽  
Boreal Summer ◽  
Indian Ocean Warming ◽  
Sst Anomaly ◽  
The Relationship

AbstractA significant negative relationship is found between the summer mean North Indian Ocean sea surface temperature (SST) and East Asian surface temperature anomalies. However, the relationship is distinctively different for each month and shows a time-lagged relation rather than a simultaneous one. The North Indian Ocean warming in June is responsible for significant cold anomalies over the Korea-Japan region that peak in July, exhibiting a 1-month leading role. The SST increase is closely associated with enhanced convective activity in the region in June, but the relationship between SST and resultant precipitation is substantially weakened afterward. This dependency of the precipitation sensitivity to SST anomaly is related to the climatological evolution of SST. The relatively low background SST due to the strengthening of southwesterly monsoons in the late summer can weaken the sensitivity of the precipitation to SST anomaly, yet the background SST in June is strong enough to maintain an increased sensitivity of precipitation. Thus, the Indian Ocean warming in June effectively drives atmospheric Kelvin waves that propagate into the equatorial western Pacific. In the western North Pacific (WNP), the resultant Kelvin wave-induced Ekman divergence triggers suppressed convection and anticyclonic anomalies. The WNP suppressed convection and anticyclonic anomalies move slowly northeastward until they are located near 20°N through the local air-sea interaction, and act as a source of the Pacific-Japan teleconnection. This teleconnection pathway brings clod surface anomalies to the Korea-Japan region due to the cyclonic circulation that causes the radiative and horizontal advection.

scholarly journals Decadal Shift in El Niño Influences on Indo–Western Pacific and East Asian Climate in the 1970s*

2010 ◽  
Vol 23 (12) ◽  
pp. 3352-3368 ◽  
Author(s):  
Shang-Ping Xie ◽  
Yan Du ◽  
Gang Huang ◽  
Xiao-Tong Zheng ◽  
Hiroki Tokinaga ◽  
...  
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Rossby Waves ◽  
El Nino ◽  
East Asian ◽  
North Indian Ocean ◽  
Ocean Warming ◽  
Interdecadal Change ◽  
Wind Pattern ◽  
The North

Abstract El Niño’s influence on the subtropical northwest (NW) Pacific climate increased after the climate regime shift of the 1970s. This is manifested in well-organized atmospheric anomalies of suppressed convection and a surface anticyclone during the summer (June–August) of the El Niño decay year [JJA(1)], a season when equatorial Pacific sea surface temperature (SST) anomalies have dissipated. In situ observations and ocean–atmospheric reanalyses are used to investigate mechanisms for the interdecadal change. During JJA(1), the influence of the El Niño–Southern Oscillation (ENSO) on the NW Pacific is indirect, being mediated by SST conditions over the tropical Indian Ocean (TIO). The results here show that interdecadal change in this influence is due to changes in the TIO response to ENSO. During the postregime shift epoch, the El Niño teleconnection excites downwelling Rossby waves in the south TIO by anticyclonic wind curls. These Rossby waves propagate slowly westward, causing persistent SST warming over the thermocline ridge in the southwest TIO. The ocean warming induces an antisymmetric wind pattern across the equator, and the anomalous northeasterlies cause the north Indian Ocean to warm through JJA(1) by reducing the southwesterly monsoon winds. The TIO warming excites a warm Kelvin wave in tropospheric temperature, resulting in robust atmospheric anomalies over the NW Pacific that include the surface anticyclone. During the preregime shift epoch, ENSO is significantly weaker in variance and decays earlier than during the recent epoch. Compared to the epoch after the mid-1970s, SST and wind anomalies over the TIO are similar during the developing and mature phases of ENSO but are very weak during the decay phase. Specifically, the southern TIO Rossby waves are weaker, so are the antisymmetric wind pattern and the North Indian Ocean warming during JJA(1). Without the anchor in the TIO warming, atmospheric anomalies over the NW Pacific fail to develop during JJA(1) prior to the mid-1970s. The relationship of the interdecadal change to global warming and implications for the East Asian summer monsoon are discussed.

Indian Ocean warming during peak El Niño cools surrounding land masses

2017 ◽  
Vol 51 (5-6) ◽  
pp. 2097-2112 ◽  
Author(s):  
N. Herold ◽  
A. Santoso
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Ocean Warming ◽  
Indian Ocean Warming

scholarly journals Indian Ocean Variability in the CMIP5 Multimodel Ensemble: The Basin Mode

2013 ◽  
Vol 26 (18) ◽  
pp. 7240-7266 ◽  
Author(s):  
Yan Du ◽  
Shang-Ping Xie ◽  
Ya-Li Yang ◽  
Xiao-Tong Zheng ◽  
Lin Liu ◽  
...  
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Tropical Indian Ocean ◽  
Ocean Basin ◽  
North Indian Ocean ◽  
Cmip5 Models ◽  
Northwest Pacific ◽  
Kelvin Wave

Abstract This study evaluates the simulation of the Indian Ocean Basin (IOB) mode and relevant physical processes in models from phase 5 of the Coupled Model Intercomparison Project (CMIP5). Historical runs from 20 CMIP5 models are available for the analysis. They reproduce the IOB mode and its close relationship to El Niño–Southern Oscillation (ENSO). Half of the models capture key IOB processes: a downwelling oceanic Rossby wave in the southern tropical Indian Ocean (TIO) precedes the IOB development in boreal fall and triggers an antisymmetric wind anomaly pattern across the equator in the following spring. The anomalous wind pattern induces a second warming in the north Indian Ocean (NIO) through summer and sustains anticyclonic wind anomalies in the northwest Pacific by radiating a warm tropospheric Kelvin wave. The second warming in the NIO is indicative of ocean–atmosphere interaction in the interior TIO. More than half of the models display a double peak in NIO warming, as observed following El Niño, while the rest show only one winter peak. The intermodel diversity in the characteristics of the IOB mode seems related to the thermocline adjustment in the south TIO to ENSO-induced wind variations. Almost all the models show multidecadal variations in IOB variance, possibly modulated by ENSO.

Changing impact of ENSO events on the following summer rainfall in eastern China since the 1950s

2021 ◽  
pp. 1-55
Author(s):  
Linyuan Sun ◽  
Xiu-Qun Yang ◽  
Lingfeng Tao ◽  
Jiabei Fang ◽  
Xuguang Sun
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
North Pacific ◽  
Yangtze River ◽  
El Nino ◽  
East Asian ◽  
Eastern China ◽  
Summer Rainfall ◽  
The Yangtze River ◽  
Enso Events

AbstractThe El Niño-Southern Oscillation (ENSO) events which generally mature in winter profoundly affect the following summer rainfall in eastern China (ECSR), but such an impact can change significantly with decadal background. This study examines how the impact changes since the 1950s by running correlation and regression analyses. It is found that the ENSO’s impact on ECSR has undergone two decadal shifts in the late 1970s and 1990s, respectively. Sequentially, three distinct ENSO-induced ECSR anomaly patterns are categorized, which exhibit both robust and changeable sides. The robust side manifests generally more precipitation in the Yangtze River basin affected by the anomalous tropical western North Pacific anticyclone (WNPAC) in the post-El Niño summer. The changeable side is reflected in the more variable ENSO-induced rainfall anomalies north of the Yangtze River, due to the ENSO-induced different East Asian midlatitude circulation anomalies. Meanwhile, the El Niño-induced drought in South China is enhanced since the late 1970s with the intensification of the anomalous WNPAC. The ENSO’s changing impact on the ECSR stems from the changes of ENSO-induced tropical and midlatitude circulation anomalies over East Asia, which are associated with different zonal (from tropical Pacific to Indian Ocean) and meridional (from tropical Pacific to Midlatitude North Pacific) teleconnections of ENSO-induced SST anomalies. The former affects the intensity and location of the anomalous WNPAC by affecting Indian Ocean capacitor effect and convection anomalies over the tropical Indo-western Pacific. The latter modulates the ocean-to-atmosphere feedback in the midlatitude North Pacific, contributes to different local geopotential anomaly sources, and then directly or indirectly through Rossby wavetrain affects the East Asian midlatitude circulation.

scholarly journals The Indian Ocean Dipole: A Missing Link between El Niño Modokiand Tropical Cyclone Intensity in the North Indian Ocean

Climate ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 38 ◽  
Author(s):  
Kopal Arora ◽  
Prasanjit Dash
Keyword(s):  
Tropical Cyclone ◽  
Indian Ocean ◽  
El Niño ◽  
Indian Ocean Dipole ◽  
El Nino ◽  
North Indian Ocean ◽  
Missing Link ◽  
El Niño Modoki ◽  
The North ◽  
The Indian Ocean

This study is set out to understand the impact of El Niño Modoki and the Tropical Cyclone Potential Intensity (TCPI) in the North Indian Ocean. We also hypothesized and tested if the Indian Ocean Dipole (IOD) reveals a likely connection between the two phenomena. An advanced mathematical tool namely the Empirical Mode Decomposition (EMD) is employed for the analysis. A major advantage of using EMD is its adaptability approach to deal with the non-linear and non-stationary signals which are similar to the signals used in this study and are also common in both atmospheric and oceanic sciences. This study has identified IOD as a likely missing link to explain the connection between El Niño Modoki and TCPI. This lays the groundwork for future research into this connection and its possible applications in meteorology.

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