How Extreme Apparitions of the Volcanic and Anthropogenic South East Asian Aerosol Plume Trigger and Sustain El Niño events using data from the Last Millennium Ensemble, Large Ensemble, MERRA-2 Reanalysis, four Satellites and the Global Volcanism P

2021 ◽  
Author(s):  
Keith Potts
Keyword(s):  
Global Climate ◽  
East Asian ◽  
Walker Circulation ◽  
Last Millennium ◽  
Large Ensemble ◽  
Enso Events ◽  
Se Asia ◽  
Global Volcanism ◽  
Aerosol Plume ◽  
The Walker Circulation

<p>Volcanic aerosols over south east Asia have always been the trigger and sustaining cause of ENSO events. In recent decades this natural plume has been augmented by the anthropogenic plume which has intensified ENSO events especially in SON. Data from the Last Millennium Ensemble (13,872 months), and Large Ensemble (3,012 months) demonstrate this connection with three ENSO indices and aerosol data derived from the same datasets correlating at 1.00 (LME), 0.97 and 0.99 magnitude (segmented and averaged). ENSO events are the dominant mode of variability in the global climate responsible for Australian, Indian and Indonesian droughts, American floods and increased global temperatures. Understanding the mechanism which enables aerosols over SE Asia and only over SE Asia to create ENSO events is crucial to understanding the global climate. I show that the South East Asian aerosol Plume causes ENSO events by: reflecting/absorbing solar radiation which warms the upper troposphere; and reducing surface radiation which cools the surface under the plume. This inversion reduces convection in the region thereby suppressing the Walker Circulation and the Trade Winds which causes the SST to rise in the central Pacific Ocean and creates convection there. This further weakens/reverses the Walker Circulation driving the climate into an ENSO state which is maintained until the aerosols dissipate and the climate system relaxes into a non-ENSO state. Measured aerosol data from four NASA satellites, estimates of volcanic tephra from the Global Volcanism Program (GVP) for over 100 years and the NASA MERRA-2 reanalysis dataset all confirm this analysis.</p>

scholarly journals Last Millennium Drought-inducing Teleconnections of the West Pacific Gradient during ENSO

2021 ◽  
Author(s):  
Jens Zinke ◽  
Stuart A. Browning ◽  
Andrew Hoell ◽  
Ian D. Goodwin
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
20Th Century ◽  
El Nino ◽  
Global Climate ◽  
Walker Circulation ◽  
Sea Surface ◽  
Last Millennium ◽  
The West ◽  
West Pacific

Abstract Conflicting evidence points to either a strengthening or weakening Walker Circulation over the 20th century based on changes in sea surface temperature and sea level pressure gradients between the western and eastern Pacific. Since small changes in Pacific temperature gradients connected with the El Niño Southern Oscillation (ENSO) are related to global climate anomalies, it is of paramount importance to develop robust indices of their past behaviour. Here, we reconstruct the difference in sea surface temperature between the west and central Pacific during ENSO based on the Last Millennium Paleo Hydrodynamics Data Assimilation since 1000 AD. We demonstrate that the strength of the West Pacific Gradient (WPG) is related to stronger atmospheric circulation and remote precipitation anomalies during both historical El Niño and La Niña events and societally relevant drought teleconnections. A strong negative WPG coupled with a strong zonal Pacific temperature gradient is associated with enhanced megadroughts between 1400 AD and the late 16th century. The 20th century stands out as the period with most extreme swings between positive and negative WPG conditions. We conclude that the WPG serves as a powerful index of Pacific Walker Circulation variability and their associated global climate teleconnections.

scholarly journals ENSO Diversity in a Tropical Stochastic Skeleton Model for the MJO, El Niño, and Dynamic Walker Circulation

2021 ◽  
pp. 1-56
Author(s):  
Qiu Yang ◽  
Andrew J. Majda ◽  
Nan Chen
Keyword(s):  
El Niño ◽  
El Nino ◽  
Global Climate ◽  
Walker Circulation ◽  
Skeleton Model ◽  
Enso Events ◽  
Cp El Niño ◽  
Enso Diversity ◽  
Ep El Niño ◽  
Wind Bursts

AbstractThe El Niño-Southern Oscillation (ENSO) diversity has a significant impact on global climate and seasonal prediction. However, it is still a challenging problem for present-day global climate models to simulate different types of ENSO events with realistic features simultaneously. In this paper, a tropical stochastic skeleton model for the interactions among wind bursts and the Madden-Julian Oscillation (MJO), the El Niño, and the Walker circulation is developed to reproduce both dynamical and statistical features of the ENSO diversity. In this model, the intraseasonal component with state-dependent noise captures general features of wind bursts and the MJO, both of which play important roles in triggering the El Niño. The thermocline feedback is the dominant mechanism for generating the eastern Pacific (EP) El Niño, while a nonlinear zonal advection is incorporated into the model that contributes to the central Pacific (CP) El Niño. Besides, a simple but effective stochastic process describing the multidecadal variation of the background Walker circulation modulates the spatial patterns and occurrence frequency of the EP and CP El Niño. This model succeeds in simulating the quasi-regular moderate EP El Niño, the super El Niño, and the CP El Niño as well as the La Niña simultaneously. It also captures the observed non-Gaussian characteristics of sea surface temperature anomalies in different Niño regions. Individual case studies highlight the outstanding skill of the model in reproducing the observed El Niño episodes and their underlying mechanisms.

scholarly journals Recent Increased Covariability of Tropical Cyclogenesis Latitude and Longitude over the Western North Pacific during the Extended Boreal Summer

2019 ◽  
Vol 32 (23) ◽  
pp. 8167-8179 ◽  
Author(s):  
Haikun Zhao ◽  
Jie Zhang ◽  
Philip J. Klotzbach ◽  
Shaohua Chen
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Regime Shift ◽  
Hadley Circulation ◽  
Walker Circulation ◽  
Boreal Summer ◽  
Tropical Cyclogenesis ◽  
Central Pacific ◽  
Enso Events ◽  
The Walker Circulation

Abstract This study examines interdecadal changes in the interannual relationship between the extended boreal summer (May–November) tropical cyclogenesis (TCG) latitude and longitude over the western North Pacific Ocean (WNP) during 1979–2016. Increasing covariability of WNP TCG latitude and longitude is observed since 1998, which is found to be closely linked to shifting ENSO conditions and a tropical Pacific climate regime shift. Accompanied by an increasing occurrence in central Pacific (CP) ENSO events during recent decades, there has been a more consistent northwestward or southeastward shift of WNP TCG location since 1998. These coherent latitude and longitude shifts were generally not evident during 1979–97, a period characterized by a more conventional eastern Pacific (EP) ENSO pattern. Our statistical results show a robust relationship between TCG latitude and the Hadley circulation and between longitude and the Walker circulation during the period prior to and since the regime shift, and a possible physical explanation for the recent increased covariability of TCG latitude and longitude is given. During 1998–2016, there is a significant association of CP ENSO events with the intensity of both the Hadley and Walker circulations that likely caused the recent increase in the covariability of TCG latitude and longitude. However, the strong association of EP ENSO events with the intensity of the Hadley circulation but not with the Walker circulation during 1979–97 weakened the covariability of TCG latitude and longitude. In addition, changes in tropical Indian Ocean sea surface temperatures appear to also importantly contribute to the recent increased covariability of WNP TCG location.

Oscillating Relationship between the East Asian Winter Monsoon and ENSO

2013 ◽  
Vol 26 (24) ◽  
pp. 9819-9838 ◽  
Author(s):  
Shengping He ◽  
Huijun Wang
Keyword(s):  
East Asian Winter Monsoon ◽  
East Asian ◽  
Low Frequency ◽  
Walker Circulation ◽  
Winter Monsoon ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation ◽  
Asian Winter Monsoon ◽  
The Pacific ◽  
The Walker Circulation

Abstract This work investigates the interdecadal variations of the relationship between the El Niño–Southern Oscillation (ENSO) and the East Asian winter monsoon (EAWM), further explores possible mechanisms, and finally considers a recent switch in the ENSO–EAWM relationship. The 23-yr sliding correlation between the Niño-3.4 index and the EAWM index reveals an obvious low-frequency oscillation with a period of about 50 yr in the ENSO–EAWM relationship. Warm ENSO events during high-correlation periods are associated with an unusually weak East Asian trough, a positive phase of the North Pacific Oscillation (NPO), significant southerly wind anomalies along coastal East Asia, and warmer East Asian continent and adjacent oceans. However, there are no robust and significant anomalies in the EAWM-related circulation during low-correlation periods. Because of the southeastward shift of the Walker circulation, the area of anomalously high pressure in the western Pacific retreats south of 25°N, confining it to the region of the Philippine Sea. In this sense, the Pacific–East Asian teleconnection is not well established. Consequently, ENSO’s impact on the EAWM is suppressed. Additionally, the low-frequency oscillation of the ENSO–EAWM relationship might be attributable to the combined effect of the Pacific decadal oscillation (PDO) and the Atlantic multidecadal oscillation owing to their modulation on the establishment of the NPO teleconnection. The observation of two full cycles of the ENSO–EAWM relationship, a transition to negative PDO in the early 2000s and an enhancement of the Walker circulation in the late 1990s, suggests a recovery of the ENSO–EAWM relationship.

Orchestrating the nation

2018 ◽  
Author(s):  
Barley Norton
Keyword(s):  
Climate Change ◽  
Global Climate Change ◽  
Global Climate ◽  
East Asian ◽  
Ancestor Worship ◽  
National Heritage ◽  
The City ◽  
Historical Periods ◽  
Party State

This chapter addresses the cultural politics, history and revival of Vietnamese court orchestras, which were first established at the beginning of the Nguyễn dynasty (1802–1945). Based on fieldwork in the city of Hue, it considers the decolonizing processes that have enabled Vietnamese court orchestras to take their place alongside other East Asian court orchestras as a display of national identity in the global community of nations. The metaphor of ‘orchestrating the nation’ is used to refer to the ways in which Vietnamese orchestras have been harnessed for sociopolitical ends in several historical periods. Court orchestras as heritage have recourse to a generic, precolonial past, yet they are not entirely uncoupled from local roots. Through a case-study of the revival of the Nam Giao Sacrifice, a ritual for ‘venerating heaven’, the chapter addresses the dynamics of interaction and exchange between staged performances of national heritage and local Buddhist and ancestor worship rituals. It argues that with growing concern about global climate change, the spiritual and ecological resonances of the Nam Giao Sacrifice have provided opportunities for the Party-state to reassert its position as the supreme guardian of the nation and its people.

scholarly journals Linking Holocene East Asian monsoon variability to solar forcing and ENSO activity: Multi-proxy evidence from a peatland in Northeastern China

The Holocene ◽  
2021 ◽  
pp. 095968362199466
Author(s):  
Nannan Li ◽  
Arash Sharifi ◽  
Frank M Chambers ◽  
Yong Ge ◽  
Nathalie Dubois ◽  
...  
Keyword(s):  
Asian Monsoon ◽  
East Asian Monsoon ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Northeastern China ◽  
Solar Irradiation ◽  
Enso Events ◽  
Monsoon Area ◽  
Wavelet Coherency ◽  
Cross Wavelet

High-resolution proxy-based paleoenvironmental records derived from peatlands provide important insights into climate changes over centennial to millennial timescales. In this study, we present a composite climatic index (CCI) for the Hani peatland from northeastern China, based on an innovative combination of pollen-spore, phytolith, and grain size data. We use the CCI to reconstruct variations of the East Asian summer monsoon (EASM) intensity during the Holocene. This is accomplished with complete ensemble empirical mode decomposition (CEEMD), REDFIT, and cross-wavelet coherency analysis to reveal the periodicities (frequencies) of the multi-proxy derived CCI sequences and to assess potential external forcing of the EASM. The results showed that periodicities of ca. 300–350, 475, 600, 1075, and 1875 years were present in the Hani CCI sequence. Those periodicities are consistent with previously published periodicities in East Asia, indicating they are a product of external climate controls over an extensive region, rather than random variations caused by peatland-specific factors. Cross-wavelet coherency analysis between the decomposed CCI components and past solar activity reconstructions suggests that variations of solar irradiation are most likely responsible for the cyclic characteristics at 500-year frequency. We propose a conceptual model to interpret how the sun regulates the monsoon climate via coupling with oceanic and atmospheric circulations. It seems that slight solar irradiation changes can be amplified by coupling with ENSO events, which result in a significant impact on the regional climate in the East Asian monsoon area.

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