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 The Relationship between the Interannual Variation of the North Indian Ocean SST Induced by Surface Wind and ENSO during Boreal Summer

2005 ◽  
Vol 18 (12) ◽  
pp. 1942-1956 ◽  
Author(s):  
Motoki Nagura ◽  
Masanori Konda
Keyword(s):  
Indian Ocean ◽  
Interannual Variation ◽  
Temporal Change ◽  
Surface Wind ◽  
North Indian Ocean ◽  
Boreal Summer ◽  
The North ◽  
Second Mode ◽  
Sst Anomaly ◽  
The Relationship

Abstract The relationship between the interannual variation of the surface wind in the north Indian Ocean (0°–30°N, 30°–100°E) and El Niño–Southern Oscillation (ENSO) during boreal summer is investigated. The association of the surface wind with the sea surface temperature (SST) in the north Indian Ocean is evaluated. The NCEP–NCAR reanalysis, NOAA outgoing longwave radiation (OLR), and Reynolds SST data are used. The June–August mean of the surface wind anomaly over the north Indian Ocean is decomposed by EOF analysis, and two dominant modes are extracted. The first (second) mode shows the corresponding variation with the ENSO events maturing in the subsequent (previous) winter. The first mode has a large amplitude during the 1990s, while the amplitude of the second mode is large mainly during the 1980s. Such contrast of the amplitude of the two modes results in the temporal change of the surface wind–ENSO relationships between the two decades. The temporal characteristics of the first and second modes are consistent with those of convective variability in the eastern Indian Ocean and the Philippine Sea, respectively. The local thermal forcings associated with these two contrastive modes are compared with the time change of the SST anomaly. The thermal forcings are evaluated in terms of the latent heat flux and the Ekman heat transport. The thermal forcing of the first mode is consistent with a meridionally antisymmetric pattern of the SST anomaly during the 1990s, while that of the second mode is correlated with the basinwide SST anomaly during the 1980s. This result suggests that the temporal change is also found in the north Indian Ocean SST anomaly.

Tropical Indian Ocean Basin Warming and East Asian Summer Monsoon: A Multiple AGCM Study

2008 ◽  
Vol 21 (22) ◽  
pp. 6080-6088 ◽  
Author(s):  
Shuanglin Li ◽  
Jian Lu ◽  
Gang Huang ◽  
Kaiming Hu
Keyword(s):  
Indian Ocean ◽  
Time Scales ◽  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Tropical Indian Ocean ◽  
Ocean Warming ◽  
Indian Ocean Warming ◽  
Asian Summer

Abstract A basin-scale warming is the leading mode of tropical Indian Ocean sea surface temperature (SST) variability on interannual time scales, and it is also the prominent feature of the interdecadal SST trend in recent decades. The influence of the warming on the East Asian summer monsoon (EASM) is investigated through ensemble experiments of several atmospheric general circulation models (AGCMs). The results from five AGCMs consistently suggest that near the surface, the Indian Ocean warming forces an anticyclonic anomaly over the subtropical western Pacific, intensifying the southwesterly winds to East China; and in the upper troposphere, it forces a Gill-type response with the intensified South Asian high, both favoring the enhancement of the EASM. These processes are argued to contribute to the stronger EASM during the summer following the peak of El Niño than monsoons in other years. These model results also suggest that tropical Indian Ocean warming may not have a causal relationship to the synchronous weakening of EASM on interdecadal time scales.

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.

scholarly journals North Indian Ocean warming and sea level rise in an OGCM

2008 ◽  
Vol 117 (2) ◽  
pp. 169-178 ◽  
Author(s):  
Bijoy Thompson ◽  
C. Gnanaseelan ◽  
Anant Parekh ◽  
P. S. Salvekar
Keyword(s):  
Indian Ocean ◽  
Sea Level Rise ◽  
Sea Level ◽  
North Indian Ocean ◽  
Ocean Warming ◽  
Indian Ocean Warming ◽  
And Sea Level

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.

Variations of the Indian Ocean Walker circulation since the Last Glacial Maximum revealed by reconstructed and simulated zonal wind intensity

2021 ◽  
Author(s):  
Xinquan Zhou ◽  
Stéphanie Duchamp-Alphonse ◽  
Masa Kageyama ◽  
Franck Bassinot ◽  
Xiaoxu Shi ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Surface Temperature ◽  
Equatorial Indian Ocean ◽  
Walker Circulation ◽  
Sea Surface ◽  
The Indian Ocean ◽  
Sst Anomaly ◽  
Mean Circulation ◽  
The Last Glacial Maximum ◽  
The Last Glacial

<p>Today, precipitation and wind patterns over the equatorial Indian Ocean and surrounding lands are paced by monsoon and Walker circulations that are controlled by the seasonal land-sea temperature contrast and the inter-annual convection over the Indo-Pacific Warm Pool, respectively. The annual mean surface westerly winds are particularly tied to the Walker circulation, showing interannual variability coupled with the gradient of Sea Surface Temperature (SST) anomaly between the tropical western and southeastern Indian Ocean, namely, the Indian Ocean Dipole (IOD). While the Indian monsoon pattern has been widely studied in the past, few works deal with the evolution of Walker circulation despite its crucial impacts on modern and future tropical climate systems. Here, we reconstruct the long-term westerly (summer) and easterly (winter) wind dynamics of the equatorial Indian Ocean (10°S−10°N), since the Last Glacial Maximum (LGM) based on i) primary productivity (PP) records derived from coccolith analyses of sedimentary cores MD77-191 and BAR94-24, retrieved off the southern tip of India and off the northwestern tip of Sumatra, respectively and ii) the calculation of a sea surface temperature (SST) anomaly gradient off (south) western Sumatra based on published SST data. We compare these reconstructions with atmospheric circulation simulations obtained with the general coupled model AWI-ESM-1-1-LR (Alfred Wegener Institute Earth System Model).</p><p>Our results show that the Indian Ocean Walker circulation was weaker during the LGM and the early/middle Holocene than present. Model simulations suggest that this is due to anomalous easterlies over the eastern Indian Ocean. The LGM mean circulation state may have been comparable to the year 1997 with a positive IOD, when anomalously strong equatorial easterlies prevailed in winter. The early/mid Holocene mean circulation state may have been equivalent to the year 2006 with a positive IOD, when anomalously strong southeasterlies prevailed over Java-Sumatra in summer. The deglaciation can be seen as a transient period between these two positive IOD-like mean states.</p>

scholarly journals Step Increase in Eastern U.S. Precipitation Linked to Indian Ocean Warming

2020 ◽  
Vol 47 (17) ◽  
Author(s):  
Courtenay Strong ◽  
Gregory J. McCabe ◽  
Alexander Weech
Keyword(s):  
Indian Ocean ◽  
Ocean Warming ◽  
Indian Ocean Warming
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