Different Impacts of Northern, Tropical, and Southern Volcanic Eruptions on the Tropical Pacific SST in the Last Millennium

2018 ◽  
Vol 31 (17) ◽  
pp. 6729-6744 ◽  
Author(s):  
Meng Zuo ◽  
Wenmin Man ◽  
Tianjun Zhou ◽  
Zhun Guo
Keyword(s):  
El Niño ◽  
El Nino ◽  
Volcanic Eruptions ◽  
Enso Cycle ◽  
Last Millennium ◽  
Westerly Wind ◽  
Central Pacific ◽  
The Pacific ◽  
Sst Anomaly ◽  
The Impact

The impact of northern, tropical, and southern volcanic eruptions on the Pacific sea surface temperature (SST) and the different response mechanisms arising due to differences in the volcanic forcing structure are investigated using the Community Earth System Model Last Millennium Ensemble (CESM-LME). Analysis of the simulations indicates that the Pacific features a significant El Niño–like SST anomaly 5–10 months after northern and tropical eruptions, and with a weaker such tendency after southern eruptions, possibly reflective of the weaker magnitude of these eruptions. The Niño-3 index peaks with a lag of one and a half years after northern and tropical eruptions. Two years after all three types of volcanic eruptions, a La Niña–like SST anomaly pattern over the equatorial Pacific is observed, which seems to form an El Niño–Southern Oscillation (ENSO) cycle. The westerly wind anomaly over the western to central Pacific plays an essential role in favoring the development of an El Niño following all three types of eruptions. Thus, the key point of the question is to find the causes of the westerly wind enhancement. The shift of the intertropical convergence zone (ITCZ) can explain the El Niño–like response to northern eruptions, which is not applicable for tropical or southern eruptions. The ocean dynamical thermostat mechanism is the fundamental cause of the anomalous westerly wind for all three types of eruptions.

scholarly journals Assessing the impact of large volcanic eruptions of the Last Millennium on Australian rainfall regimes

2017 ◽  
Author(s):  
Stephanie Blake ◽  
Sophie C. Lewis ◽  
Allegra N. LeGrande
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Regional Climate ◽  
Volcanic Eruptions ◽  
Explosive Volcanism ◽  
Climate Forcing ◽  
Last Millennium ◽  
Precipitation Anomalies ◽  
The Impact

Abstract. Explosive volcanism is an important natural climate forcing, impacting global surface temperatures and regional precipitation. Although previous studies have investigated aspects of the impact of tropical volcanism on various ocean-atmosphere systems and regional climate regimes, volcanic eruptions remain a poorly understood climate forcing and climatic responses are not well constrained. In this study, volcanic eruptions are explored in particular reference to Australian precipitation, and both the Indian Ocean Dipole (IOD) and El Nino-Southern Oscillation (ENSO). Using nine realisations of the Last Millennium (LM) with different time-evolving forcing combinations, from the NASA GISS ModelE2-R, the impact of the 6 largest tropical volcanic eruptions of this period are investigated. Overall, we find that volcanic aerosol forcing increased the likelihood of El Nino and positive IOD conditions for up to four years following an eruption, and resulted in positive precipitation anomalies over northwest (NW) and southeast (SE) Australia. Larger atmospheric sulfate loading coincides with more persistent positive IOD and El Nino conditions, enhanced positive precipitation anomalies over NW Australia, and dampened precipitation anomalies over SE Australia.

scholarly journals Response to Comment on “No consistent ENSO response to volcanic forcing over the last millennium”

Science ◽  
2020 ◽  
Vol 369 (6509) ◽  
pp. eabc1733
Author(s):  
Sylvia G. Dee ◽  
Kim M. Cobb ◽  
Julien Emile-Geay ◽  
Toby R. Ault ◽  
R. Lawrence Edwards ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Volcanic Eruptions ◽  
Dynamical Response ◽  
Last Millennium ◽  
Surface Cooling ◽  
Central Pacific ◽  
Volcanic Forcing ◽  
Large Volcanic Eruptions

Robock claims that our analysis fails to acknowledge that pan-tropical surface cooling caused by large volcanic eruptions may mask El Niño warming at our central Pacific site, potentially obscuring a volcano–El Niño connection suggested in previous studies. Although observational support for a dynamical response linking volcanic cooling to El Niño remains ambiguous, Robock raises some important questions about our study that we address here.

scholarly journals Assessing the impact of large volcanic eruptions of the last millennium (850–1850 CE) on Australian rainfall regimes

2018 ◽  
Vol 14 (6) ◽  
pp. 811-824 ◽  
Author(s):  
Stephanie A. P. Blake ◽  
Sophie C. Lewis ◽  
Allegra N. LeGrande ◽  
Ron L. Miller
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Volcanic Eruptions ◽  
Explosive Volcanism ◽  
Climate Forcing ◽  
Last Millennium ◽  
North West ◽  
Precipitation Anomalies ◽  
The Impact

Abstract. Explosive volcanism is an important natural climate forcing, impacting global surface temperatures and regional precipitation. Although previous studies have investigated aspects of the impact of tropical volcanism on various ocean–atmosphere systems and regional climate regimes, volcanic eruptions remain a poorly understood climate forcing and climatic responses are not well constrained. In this study, volcanic eruptions are explored in particular reference to Australian precipitation, and both the Indian Ocean Dipole (IOD) and El Niño–Southern Oscillation (ENSO). Using nine realisations of the last millennium (LM) (850–1850 CE) with different time-evolving forcing combinations, from the NASA GISS ModelE2-R, the impact of the six largest tropical volcanic eruptions of this period are investigated. Overall, we find that volcanic aerosol forcing increased the likelihood of El Niño and positive IOD conditions for up to four years following an eruption, and resulted in positive precipitation anomalies over north-west (NW) and south-east (SE) Australia. Larger atmospheric sulfate loading during larger volcanic eruptions coincided with more persistent positive IOD and El Niño conditions, enhanced positive precipitation anomalies over NW Australia, and dampened precipitation anomalies over SE Australia.

scholarly journals Volcanic Eruptions, Large-Scale Modes in the Northern Hemisphere, and the El Niño–Southern Oscillation

2008 ◽  
Vol 21 (5) ◽  
pp. 910-922 ◽  
Author(s):  
Bo Christiansen
Keyword(s):  
Northern Hemisphere ◽  
El Niño ◽  
Large Scale ◽  
El Nino ◽  
Southern Oscillation ◽  
Volcanic Eruptions ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
The Pacific ◽  
The Impact

Abstract The author analyzes the impact of 13 major stratospheric aerosol producing volcanic eruptions since 1870 on the large-scale variability modes of sea level pressure in the Northern Hemisphere winter. The paper focuses on the Arctic Oscillation (AO) and the North Atlantic Oscillation (NAO) to address the question about the physical nature of these modes. The hypothesis that the phase of the El Niño–Southern Oscillation (ENSO) may control the geographical extent of the dominant mode in the Northern Hemisphere is also investigated, as well as the related possibility that the impact of the eruptions may be different according to the phase of ENSO. The author finds that both the AO and the NAO are excited in the first winter after the eruptions with statistical significance at the 95% level. Both the signal and the significance are larger for the NAO than for the AO. The excitation of the AO and the NAO is connected with the excitation of a secondary mode, which resembles an augmented Pacific–North American pattern. This mode has opposite polarity in the Atlantic and the Pacific and interferes negatively with the AO in the Pacific and positively in the Atlantic in the first winter after the eruptions, giving the superposition a strong NAO resemblance. Some evidence is found that the correlations between the Atlantic and the Pacific are stronger in the negative ENSO phase than in the positive phase, although this difference is not statistically significant when all data since 1870 are considered. The author does not find any evidence that the impact of the volcanic eruptions is more hemispheric in the negative than in the positive ENSO phase.

scholarly journals The role of tropical volcanic eruptions in exacerbating Indian droughts

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Suvarna Fadnavis ◽  
Rolf Müller ◽  
Tanusri Chakraborty ◽  
T. P. Sabin ◽  
Anton Laakso ◽  
...  
Keyword(s):  
El Niño ◽  
Climate Model ◽  
El Nino ◽  
Volcanic Eruptions ◽  
Summer Monsoon Rainfall ◽  
Indian Region ◽  
Volcanic Plume ◽  
Kelvin Wave ◽  
Central Pacific ◽  
Climate Model Simulations

AbstractThe Indian summer monsoon rainfall (ISMR) is vital for the livelihood of millions of people in the Indian region; droughts caused by monsoon failures often resulted in famines. Large volcanic eruptions have been linked with reductions in ISMR, but the responsible mechanisms remain unclear. Here, using 145-year (1871–2016) records of volcanic eruptions and ISMR, we show that ISMR deficits prevail for two years after moderate and large (VEI > 3) tropical volcanic eruptions; this is not the case for extra-tropical eruptions. Moreover, tropical volcanic eruptions strengthen El Niño and weaken La Niña conditions, further enhancing Indian droughts. Using climate-model simulations of the 2011 Nabro volcanic eruption, we show that eruption induced an El Niño like warming in the central Pacific for two consecutive years due to Kelvin wave dissipation triggered by the eruption. This El Niño like warming in the central Pacific led to a precipitation reduction in the Indian region. In addition, solar dimming caused by the volcanic plume in 2011 reduced Indian rainfall.

Annual, Interannual, and Intraseasonal Variability of Tropical Tropopause Transition Layer Cirrus

2010 ◽  
Vol 67 (10) ◽  
pp. 3097-3112 ◽  
Author(s):  
Katrina S. Virts ◽  
John M. Wallace
Keyword(s):  
Annual Cycle ◽  
El Niño ◽  
Transition Layer ◽  
El Nino ◽  
Southern Oscillation ◽  
Cirrus Clouds ◽  
Boreal Winter ◽  
Central Pacific ◽  
Tropical Tropopause ◽  
The Pacific

Abstract Cloud fields based on the first three years of data from the Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission are used to investigate the relationship between cirrus within the tropical tropopause transition layer (TTL) and the Madden–Julian oscillation (MJO), the annual cycle, and El Niño–Southern Oscillation (ENSO). The TTL cirrus signature observed in association with the MJO resembles convectively induced, mixed Kelvin–Rossby wave solutions above the Pacific warm pool region. This signature is centered to the east of the peak convection and propagates eastward more rapidly than the convection; it exhibits a pronounced eastward tilt with height, suggestive of downward phase propagation and upward energy dispersion. A cirrus maximum is observed over equatorial Africa and South America when the enhanced MJO-related convection enters the western Pacific. Tropical-mean TTL cirrus is modulated by the MJO, with more than twice as much TTL cirrus fractional coverage equatorward of 10° latitude when the enhanced convection enters the Pacific than a few weeks earlier, when the convection is over the Indian Ocean. The annual cycle in cirrus clouds around the base of the TTL is equatorially asymmetric, with more cirrus observed in the summer hemisphere. Higher in the TTL, the annual cycle in cirrus clouds is more equatorially symmetric, with a maximum in the boreal winter throughout most of the tropics. The ENSO signature in TTL cirrus is marked by a zonal shift of the peak cloudiness toward the central Pacific during El Niño and toward the Maritime Continent during La Niña.

scholarly journals A study of the effects of westerly wind bursts on ENSO based on CESM

2019 ◽  
Vol 54 (1-2) ◽  
pp. 885-899 ◽  
Author(s):  
Xiaoxiao Tan ◽  
Youmin Tang ◽  
Tao Lian ◽  
Zhixiong Yao ◽  
Xiaojing Li ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Eastern Pacific ◽  
Parameterization Scheme ◽  
Westerly Wind ◽  
Central Pacific ◽  
El Niño Events ◽  
Wind Bursts ◽  
Westerly Wind Bursts ◽  
El Nino Events

AbstractNumerous works have indicated that westerly wind bursts (WWBs) have a significant contribution to the development of El Niño events. However, the simulation of WWBs commonly suffers from large biases in the current generation of coupled general circulation models (CGCMs), limiting our ability to predict El Niño events. In this study, we introduce a WWBs parameterization scheme into the global coupled Community Earth System Model (CESM) to improve the representation of WWBs and to study the impacts of WWBs on El Niño-Southern Oscillation (ENSO) characteristics. It is found that CESM with the WWBs parameterization scheme can generate more realistic characteristics of WWBs, in particular their location and seasonal variation of occurrence. With the parameterized WWBs, the skewness of the Niño 3 index is increased, in better agreement with observation. Eastern Pacific El Niño and central Pacific El Niño events could be successfully reproduced in the model run with WWBs parameterization. Further diagnoses show that the enhanced horizontal advection in the central Pacific and vertical advection in the eastern Pacific, both of which are triggered by WWBs, are crucial factors responsible for the improvements in ENSO simulation. Clearly, WWBs have important effects on ENSO asymmetry and ENSO diversity.

scholarly journals The impact of westerly wind bursts on the diversity and predictability of El Niño events: An ocean energetics perspective

2014 ◽  
Vol 41 (13) ◽  
pp. 4654-4663 ◽  
Author(s):  
Shineng Hu ◽  
Alexey V. Fedorov ◽  
Matthieu Lengaigne ◽  
Eric Guilyardi
Keyword(s):  
El Niño ◽  
El Nino ◽  
Westerly Wind ◽  
El Niño Events ◽  
Ocean Energetics ◽  
The Impact ◽  
Wind Bursts ◽  
Westerly Wind Bursts ◽  
El Nino Events

No consistent ENSO response to volcanic forcing over the last millennium

Science ◽  
2020 ◽  
Vol 367 (6485) ◽  
pp. 1477-1481 ◽  
Author(s):  
Sylvia G. Dee ◽  
Kim M. Cobb ◽  
Julien Emile-Geay ◽  
Toby R. Ault ◽  
R. Lawrence Edwards ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Global Climate ◽  
Volcanic Eruptions ◽  
Explosive Volcanism ◽  
Forced Response ◽  
Last Millennium ◽  
Superposed Epoch Analysis ◽  
Volcanic Forcing

The El Niño–Southern Oscillation (ENSO) shapes global climate patterns yet its sensitivity to external climate forcing remains uncertain. Modeling studies suggest that ENSO is sensitive to sulfate aerosol forcing associated with explosive volcanism but observational support for this effect remains ambiguous. Here, we used absolutely dated fossil corals from the central tropical Pacific to gauge ENSO’s response to large volcanic eruptions of the last millennium. Superposed epoch analysis reveals a weak tendency for an El Niño–like response in the year after an eruption, but this response is not statistically significant, nor does it appear after the outsized 1257 Samalas eruption. Our results suggest that those models showing a strong ENSO response to volcanic forcing may overestimate the size of the forced response relative to natural ENSO variability.

The Influence of the Indian Ocean on ENSO Stability and Flavor

2017 ◽  
Vol 30 (7) ◽  
pp. 2601-2620 ◽  
Author(s):  
Claudia E. Wieners ◽  
Henk A. Dijkstra ◽  
Will P. M. de Ruijter
Keyword(s):  
Indian Ocean ◽  
Spatial Pattern ◽  
El Niño ◽  
East Coast ◽  
El Nino ◽  
La Niña ◽  
Enso Cycle ◽  
Central Pacific ◽  
La Nina ◽  
The Indian Ocean

The effect of long-term trends and interannual, ENSO-driven variability in the Indian Ocean (IO) on the stability and spatial pattern of ENSO is investigated with an intermediate-complexity two-basin model. The Pacific basin is modeled using a fully coupled (i.e., generating its own background state) Zebiak–Cane model. IO sea surface temperature (SST) is represented by a basinwide warming pattern whose strength is constant or varies at a prescribed lag to ENSO. Both basins are coupled through an atmosphere transferring information between them. For the covarying IO SST, a warm IO during the peak of El Niño (La Niña) dampens (destabilizes) ENSO, and a warm IO during the transition from El Niño to La Niña (La Niña to El Niño) shortens (lengthens) the period. The influence of the IO on the spatial pattern of ENSO is small. For constant IO warming, the ENSO cycle is destabilized because stronger easterlies induce more background upwelling, more thermocline steepening, and a stronger Bjerknes feedback. The SST signal at the east coast weakens or reverses sign with respect to the main ENSO signal [i.e., ENSO resembles central Pacific (CP) El Niños]. This is due to a reduced sensitivity of the SST to thermocline variations in case of a shallow background thermocline, as found near the east coast for a warm IO. With these results, the recent increase in CP El Niño can possibly be explained by the substantial IO (and west Pacific) warming over the last decades.

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