scholarly journals Historic Yangtze flooding of 2020 tied to extreme Indian Ocean conditions

2021 ◽  
Vol 118 (12) ◽  
pp. e2022255118
Author(s):  
Zhen-Qiang Zhou ◽  
Shang-Ping Xie ◽  
Renhe Zhang
Keyword(s):  
Indian Ocean ◽  
East Asia ◽  
El Niño ◽  
El Nino ◽  
Summer Rainfall ◽  
Ocean Warming ◽  
Northwest Pacific ◽  
Indian Ocean Warming ◽  
Yangtze Basin ◽  
The Indian Ocean

Heavy monsoon rainfall ravaged a large swath of East Asia in summer 2020. Severe flooding of the Yangtze River displaced millions of residents in the midst of a historic public health crisis. This extreme rainy season was not anticipated from El Niño conditions. Using observations and model experiments, we show that the record strong Indian Ocean Dipole event in 2019 is an important contributor to the extreme Yangtze flooding of 2020. This Indian Ocean mode and a weak El Niño in the Pacific excite downwelling oceanic Rossby waves that propagate slowly westward south of the equator. At a mooring in the Southwest Indian Ocean, the thermocline deepens by a record 70 m in late 2019. The deepened thermocline helps sustain the Indian Ocean warming through the 2020 summer. The Indian Ocean warming forces an anomalous anticyclone in the lower troposphere over the Indo-Northwest Pacific region and intensifies the upper-level westerly jet over East Asia, leading to heavy summer rainfall in the Yangtze Basin. These coupled ocean-atmosphere processes beyond the equatorial Pacific provide predictability. Indeed, dynamic models initialized with observed ocean state predicted the heavy summer rainfall in the Yangtze Basin as early as April 2020.

scholarly journals Mechanisms for the Indian Ocean warming during the 1997-98 El Niño

1999 ◽  
Vol 26 (6) ◽  
pp. 735-738 ◽  
Author(s):  
Lisan Yu ◽  
Michele M. Rienecker
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Ocean Warming ◽  
Indian Ocean Warming ◽  
The Indian Ocean

Remote forcing of Indian Ocean warming on Northwest Pacific during El Niño decaying years: a FOAM model approach

2013 ◽  
Vol 31 (6) ◽  
pp. 1375-1383 ◽  
Author(s):  
Haibo Hu ◽  
Xiaoyuan Hong ◽  
Yuan Zhang ◽  
Xiuqun Yang ◽  
Wei Liu ◽  
...  
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Ocean Warming ◽  
Northwest Pacific ◽  
Remote Forcing ◽  
Foam Model ◽  
Indian Ocean Warming ◽  
Model Approach

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

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

Response of the Indian Ocean Basin Mode and Its Capacitor Effect to Global Warming*

2011 ◽  
Vol 24 (23) ◽  
pp. 6146-6164 ◽  
Author(s):  
Xiao-Tong Zheng ◽  
Shang-Ping Xie ◽  
Qinyu Liu
Keyword(s):  
Global Warming ◽  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Ocean Basin ◽  
Northwest Pacific ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Indian Ocean Basin Mode ◽  
Easterly Wind ◽  
The Indian Ocean

Abstract The development of the Indian Ocean basin (IOB) mode and its change under global warming are investigated using a pair of integrations with the Geophysical Fluid Dynamics Laboratory Climate Model version 2.1 (CM2.1). In the simulation under constant climate forcing, the El Niño–induced warming over the tropical Indian Ocean (TIO) and its capacitor effect on summer northwest Pacific climate are reproduced realistically. In the simulation forced by increased greenhouse gas concentrations, the IOB mode and its summer capacitor effect are enhanced in persistence following El Niño, even though the ENSO itself weakens in response to global warming. In the prior spring, an antisymmetric pattern of rainfall–wind anomalies and the meridional SST gradient across the equator strengthen via increased wind–evaporation–sea surface temperature (WES) feedback. ENSO decays slightly faster in global warming. During the summer following El Niño decay, the resultant decrease in equatorial Pacific SST strengthens the SST contrast with the enhanced TIO warming, increasing the sea level pressure gradient and intensifying the anomalous anticyclone over the northwest Pacific. The easterly wind anomalies associated with the northwest Pacific anticyclone in turn sustain the SST warming over the north Indian Ocean and South China Sea. Thus, the increased TIO capacitor effect is due to enhanced air–sea interaction over the TIO and with the western Pacific. The implications for the observed intensification of the IOB mode and its capacitor effect after the 1970s are discussed.

Epochal changes in the seasonal evolution of tropical Indian Ocean warming associated with El Niño

2013 ◽  
Vol 42 (3-4) ◽  
pp. 805-822 ◽  
Author(s):  
Soumi Chakravorty ◽  
J. S. Chowdary ◽  
C. Gnanaseelan
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Tropical Indian Ocean ◽  
Ocean Warming ◽  
Seasonal Evolution ◽  
Indian Ocean Warming

scholarly journals Different Influences of Southeastern Indian Ocean and Western Indian Ocean SST Anomalies on Eastern China Rainfall during the Decaying Summer of the 2015/16 Extreme El Niño

2020 ◽  
Vol 33 (13) ◽  
pp. 5427-5443
Author(s):  
Jiepeng Chen ◽  
Jin-Yi Yu ◽  
Xin Wang ◽  
Tao Lian
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Eastern China ◽  
Surface Wind ◽  
Tropical Indian Ocean ◽  
Northern China ◽  
Ocean Warming ◽  
Indian Ocean Warming ◽  
Extreme El Niño

ABSTRACTPrevious studies linked the increase of the middle and low reaches of the Yangtze River (MLRYR) rainfall to tropical Indian Ocean warming during extreme El Niños’ (e.g., 1982/83 and 1997/98 extreme El Niños) decaying summer. This study finds the linkage to be different for the recent 2015/16 extreme El Niño’s decaying summer, during which the above-normal rainfalls over MLRYR and northern China are respectively linked to southeastern Indian Ocean warming and western tropical Indian Ocean cooling in sea surface temperatures (SSTs). The southeastern Indian Ocean warming helps to maintain the El Niño–induced anomalous lower-level anticyclone over the western North Pacific Ocean and southern China, which enhances moisture transport to increase rainfall over MLRYR. The western tropical Indian Ocean cooling first enhances the rainfall over central-northern India through a regional atmospheric circulation, the latent heating of which further excites a midlatitude Asian teleconnection pattern (part of circumglobal teleconnection) that results in an above-normal rainfall over northern China. The western tropical Indian Ocean cooling during the 2015/16 extreme El Niño is contributed by the increased upward latent heat flux anomalies associated with enhanced surface wind speeds, opposite to the earlier two extreme El Niños.

scholarly journals Indian Ocean impact on ENSO evolution 2014–2016 in a set of seasonal forecasting experiments

2021 ◽  
Author(s):  
Michael Mayer ◽  
Magdalena Alonso Balmaseda
Keyword(s):  
Pacific Ocean ◽  
Indian Ocean ◽  
El Niño ◽  
Initial Conditions ◽  
El Nino ◽  
Southern Oscillation ◽  
Heat Content ◽  
Tropical Pacific ◽  
Decadal Variations ◽  
The Indian Ocean

AbstractThis study investigates the influence of the anomalously warm Indian Ocean state on the unprecedentedly weak Indonesian Throughflow (ITF) and the unexpected evolution of El Niño-Southern Oscillation (ENSO) during 2014–2016. It uses 25-month-long coupled twin forecast experiments with modified Indian Ocean initial conditions sampling observed decadal variations. An unperturbed experiment initialized in Feb 2014 forecasts moderately warm ENSO conditions in year 1 and year 2 and an anomalously weak ITF throughout, which acts to keep tropical Pacific ocean heat content (OHC) anomalously high. Changing only the Indian Ocean to cooler 1997 conditions substantially alters the 2-year forecast of Tropical Pacific conditions. Differences include (i) increased probability of strong El Niño in 2014 and La Niña in 2015, (ii) significantly increased ITF transports and (iii), as a consequence, stronger Pacific ocean heat divergence and thus a reduction of Pacific OHC over the two years. The Indian Ocean’s impact in year 1 is via the atmospheric bridge arising from altered Indian Ocean Dipole conditions. Effects of altered ITF and associated ocean heat divergence (oceanic tunnel) become apparent by year 2, including modified ENSO probabilities and Tropical Pacific OHC. A mirrored twin experiment starting from unperturbed 1997 conditions and several sensitivity experiments corroborate these findings. This work demonstrates the importance of the Indian Ocean’s decadal variations on ENSO and highlights the previously underappreciated role of the oceanic tunnel. Results also indicate that, given the physical links between year-to-year ENSO variations, 2-year-long forecasts can provide additional guidance for interpretation of forecasted year-1 ENSO probabilities.

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