Impact of Strong Tropical Volcanic Eruptions on ENSO Simulated in a Coupled GCM

Ohba, Masamichi; Shiogama, Hideo; Yokohata, Tokuta; Watanabe, Masahiro

doi:10.1175/jcli-d-12-00471.1

Cited by 105 publications

(165 citation statements)

References 50 publications

Supporting

Mentioning

140

Contrasting

Order By: Relevance

“…This warming event after volcanic eruptions has been reflected in many proxy data (Fig. 1) and previous simulations (Ohba et al 2013;Maher et al 2015;Stevenson et al 2016). However, the location of the maximum warming in the El Niño mature phase in Vol (Fig.…”

Section: Observed and Simulated Sst Changes In The Equatorial Pacificsupporting

confidence: 63%

“…The process by which tropical volcanic eruptions influence ENSO has been studied via numerical simulation (Mann et al 2005;Emile-Geay et al 2008;Zanchettin et al 2012;Ohba et al 2013;Ning et al 2017;Predybaylo et al 2017;Stevenson et al 2017). Mann et al (2005) explained Sea Surface temperature (SST) change over the eastern Pacific after volcanic eruptions by utilizing an air-sea coupled model (Zebiak and Cane 1987), invoking the dynamical thermostat hypothesis (Clement et al 1996).…”

Section: Introductionmentioning

confidence: 99%

“…This hypothesis argued that cooling occurrs more rapidly in the western Pacific than the eastern Pacific with the decreasing of surface shortwave radiation in the tropical Pacific, resulting in reduced zonal SST gradients. Meanwhile, Ohba et al (2013) explained the occurrence of El Niño by a land-sea cooling contrast hypothesis. They demonstrated that the rapid reduction of surface temperature over the maritime continent caused by the large volcanic eruptions may weaken the Walker circulation, leading to decreased subsurface water upwelling and then contributing to a warm phase of ENSO.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A “La Niña-like” state occurring in the second year after large tropical volcanic eruptions during the past 1500 years

et al. 2018

View full text Add to dashboard Cite

Using an ensemble of nine El Niño/Southern Oscillation (ENSO) reconstructed proxies and volcano eruption proxies for the past 1500 years, this study shows that a significant La Niña state emerges in the second year (year (2) hereafter) after large tropical volcanic eruptions. The reasons for the development of La Niña are investigated using the Community Earth System Model (CESM). In the volcanic eruption experiment (Vol), a robust La Niña signal occurs in year (2), resembling the proxy records. The eastward positioning of the western North Pacific anomalous anticyclone (WNPAC) in Vol plays a critical role in the advanced decay of year (2) warming and the strong intensification of cooling in the equatorial eastern Pacific. The enhanced easterlies located on the southern edge of the WNPAC can stimulate consecutive oceanic upwelling Kelvin waves, shallowing the thermocline in the eastern Pacific, thereby resulting in a greater cooling rate by the enhanced thermocline feedback and cold zonal advection. Over the equatorial eastern Pacific, the reduced shortwave radiation contributes to the advanced decay of warming, while the upward latent heat flux augments the strong intensification of the cooling. Essentially, the eastward positioning of the WNPAC is a result of the volcanic forcing. The volcanic effect cools the maritime continent more than its adjacent oceans, thus pushing convective anomalies eastward during year (1). This induces vertical thermal advection and upward surface latent heat flux, thereby suppressing the development of warm Sea Surface Temperature over the central-western Pacific and causing the eastward positioning of the WNPAC in Vol.

show abstract

Section: Observed and Simulated Sst Changes In The Equatorial Pacificsupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A “La Niña-like” state occurring in the second year after large tropical volcanic eruptions during the past 1500 years

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Modeling studies do not yield consistent results and show both an El Niño-like (3)(4)(5) or La Niña-like (6,7) anomalies following a tropical eruption. Recent studies have also suggested that volcanic eruptions can have a large imprint on ocean circulation, affecting the strength of the Atlantic Meridional Overturning Circulation (AMOC) (8-12) on 5-to 20-y timescales and inducing ocean heat content (OHC) anomalies (13,14) that may persist for decades.…”

mentioning

confidence: 91%

Impacts of high-latitude volcanic eruptions on ENSO and AMOC

Pausata

Chafik

Caballero

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

153

161

View full text Add to dashboard Cite

Large volcanic eruptions can have major impacts on global climate, affecting both atmospheric and ocean circulation through changes in atmospheric chemical composition and optical properties. The residence time of volcanic aerosol from strong eruptions is roughly 2-3 y. Attention has consequently focused on their short-term impacts, whereas the long-term, ocean-mediated response has not been well studied. Most studies have focused on tropical eruptions; high-latitude eruptions have drawn less attention because their impacts are thought to be merely hemispheric rather than global. No study to date has investigated the long-term effects of high-latitude eruptions. Here, we use a climate model to show that large summer high-latitude eruptions in the Northern Hemisphere cause strong hemispheric cooling, which could induce an El Niño-like anomaly, in the equatorial Pacific during the first 8-9 mo after the start of the eruption. The hemispherically asymmetric cooling shifts the Intertropical Convergence Zone southward, triggering a weakening of the trade winds over the western and central equatorial Pacific that favors the development of an El Niño-like anomaly. In the model used here, the specified high-latitude eruption also leads to a strengthening of the Atlantic Meridional Overturning Circulation (AMOC) in the first 25 y after the eruption, followed by a weakening lasting at least 35 y. The long-lived changes in the AMOC strength also alter the variability of the El Niño-Southern Oscillation (ENSO).high-latitude volcanic eruptions | AMOC-ENSO interaction | volcanism P roxy data (1, 2) suggest that the strong reduction of surface insolation over the tropics associated with tropical volcanic eruptions may increase the likelihood of the El Niño-Southern Oscillation (ENSO) and a consequent reduction of the zonal sea surface temperature (SST) gradient along the equatorial Pacific. Modeling studies do not yield consistent results and show both an El Niño-like (3-5) or La Niña-like (6, 7) anomalies following a tropical eruption. Recent studies have also suggested that volcanic eruptions can have a large imprint on ocean circulation, affecting the strength of the Atlantic Meridional Overturning Circulation (AMOC) (8-12) on 5-to 20-y timescales and inducing ocean heat content (OHC) anomalies (13, 14) that may persist for decades. However, this slow recovery has been questioned and may be an artifact of experimental design (15). Furthermore, all previous work on the climate impact of volcanic eruptions has focused on tropical volcanoes; no studies have addressed the potential effects of high-latitude eruptions on ENSO. Here, we use a coupled atmospheric-ocean-aerosol model 17)] to identify the mechanisms by which high-latitude volcanic eruptions can impact ENSO behavior in both the short term (up to 2-3 y) and long term (approximately half-century), the latter being mediated by volcano-induced changes in ocean circulation.We simulate an extreme high-latitude multistage eruption starting on June 1st. We inject 100 Tg of SO...

show abstract

“…An important climatic response to eruptions is their effect on the El Niño/Southern Oscillation (6)(7)(8): Within the eruption year, previous work indicates that the tropical response appears La Niña-like (9,10), with enhanced El Niño likelihood the following year (6,11). However, debate remains regarding the significance of and mechanisms for these responses (7,8,12,13), as well as the degree to which they depend on the characteristics of the eruption [i.e., hemispheric loading (13)(14)(15), strength (8), or initial conditions (12)]. Understanding all of these factors is crucial for assessing the potential risks associated with future large eruptions.…”

mentioning

confidence: 99%

Role of eruption season in reconciling model and proxy responses to tropical volcanism

Stevenson

Fasullo

Otto‐Bliesner

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

122

149

View full text Add to dashboard Cite

However, climate models currently cannot capture all these responses. Many eruption characteristics are poorly constrained, which may contribute to uncertainties in model solutions-for example, the season of eruption occurrence is often unknown and assigned arbitrarily. Here we isolate the effect of eruption season using experiments with the Community Earth System Model (CESM), varying the starting month of two large tropical eruptions. The eruption-year atmospheric circulation response is strongly seasonally dependent, with effects on European winter warming, the Intertropical Convergence Zone, and the southeast Asian monsoon. This creates substantial variations in eruption-year hydroclimate patterns, which do sometimes exhibit La Niña-like features as in the proxy record. However, eruption-year equatorial Pacific cooling is not driven by La Niña dynamics, but strictly by transient radiative cooling. In contrast, equatorial warming the following year occurs for all starting months and operates dynamically like El Niño. Proxy reconstructions confirm these results: eruption-year cooling is insignificant, whereas warming in the following year is more robust. This implies that accounting for the event season may be necessary to describe the initial response to volcanic eruptions and that climate models may be more accurately simulating volcanic influences than previously thought.arge tropical volcanic eruptions strongly influence climate (1, 2), with important social and economic consequences (3-5). An important climatic response to eruptions is their effect on the El Niño/Southern Oscillation (6-8): Within the eruption year, previous work indicates that the tropical response appears La Niña-like (9, 10), with enhanced El Niño likelihood the following year (6, 11). However, debate remains regarding the significance of and mechanisms for these responses (7,8,12,13), as well as the degree to which they depend on the characteristics of the eruption [i.e., hemispheric loading (13-15), strength (8), or initial conditions (12)]. Understanding all of these factors is crucial for assessing the potential risks associated with future large eruptions.Climate models provide a dynamically consistent framework within which to investigate the mechanisms for El Niño/Southern Oscillation (ENSO) responses to volcanism and as such are invaluable tools. To date, however, models cannot reproduce all features of the proxy record following eruptions: The eruption year is subject to particularly large model/proxy disagreement (9, 13). Understanding the source of the disagreement is key to resolving outstanding questions regarding the physics of the eruption-year response [i.e., the degree to which the Asian monsoon is affected by eruptions or the importance of the "ocean dynamical thermostat" (16)]. There are large uncertainties associated with various aspects of volcanic aerosol forcing [i.e., overall magnitude, hemispheric symmetry, and eruption timing (17)(18)(19)(20)]. For the eruption year itself, the season of eruption occurrence is...

show abstract

Impact of Strong Tropical Volcanic Eruptions on ENSO Simulated in a Coupled GCM

Cited by 105 publications

References 50 publications

A “La Niña-like” state occurring in the second year after large tropical volcanic eruptions during the past 1500 years

A “La Niña-like” state occurring in the second year after large tropical volcanic eruptions during the past 1500 years

Impacts of high-latitude volcanic eruptions on ENSO and AMOC

Role of eruption season in reconciling model and proxy responses to tropical volcanism

Contact Info

Product

Resources

About