Ocean Response to the Pinatubo and 1259 Volcanic Eruptions

Abstract

: The ocean's response to the Pinatubo and 1259 volcanic eruptions was investigated using an ocean general circulation model equipped with an energy balance model. Volcanic eruptions release gases into the atmosphere which increases the aerosol optical depth and acts to reduce the incoming short-wave radiation. For example, there was a huge volcanic eruption (Pinatubo) in 1991 which reduced the global mean radiative forcing by about 3 W m −2 . Two numerical experiments were simulated. The first experiment features the Pinatubo eruption and the second experiment simulates the much larger volcanic eruption that occurred in 1259 when the radiative forcing was reduced by 7 times compared to the Pinatubo event. With the reduced radiative forcing due to the Pinatubo eruption at about 3 W m −2 and 1259 eruption at about 21 W m −2 , the global mean sea surface temperature (SST) decreased to its lowest in the second year after each event by about 0.4 o C and 1.6 o C, respectively. Sea surface salinity (SSS) increased substantially in the northern North Pacific, northern North Atlantic, and the Southern Ocean. The reduced SST together with SSS increased ocean convection, which yielded an increase in North Atlantic Deep Water, Antarctic Bottom Water, and North Pacific Intermediate Water production and their outflows. The increase in overturning circulation eventually increased the pole-ward ocean heat fluxes. In conclusion, huge volcanic eruptions perturb the ocean substantially and their hallmarks last for more than a decade, confirming the importance of volcanic eruptions in illustrating the decadal-climate variability recorded in the paleoclimate proxy data for the past million years.

Threshold of the volcanic forcing that leads the El Niño-like warming in the last millennium: results from the ERIK simulation

“…The volcanic forcing occurred irregularly and the range between the maximum and minimum volcanic forcing is quite large at approximately 40 W/m 2 . For example, the largest volcanic forcing occurred 1259 Samalas eruption in Indonesia (Lavigne et al 2013), which is seven times larger than the scale of the Pinatubo volcanic forcing in 1991 (Kim and Kim 2012). Table 1 summarizes years when volcanic eruptions occurred.…”

Last Millennium volcanism impact on the South Atlantic Ocean

“…Yr +1 (red asterisks) displays the largest response to volcanism, fact that agrees with other studies accounting for the different averaged regions (Stenchikov et al, 2009;Balmaseda et al, 2013;Ding et al, 2014). Kim and Kim (2012) simulation results depict the largest cooling in the second year after the eruption (Yr +2). Contrary to Mignot et al (2011) for the North Atlantic Ocean and Church et al (2005) in the global average, that have observed a faster response, with surface temperatures decrease in the year of the eruption (Yr 0).…”

“…SST at Yr +1 shows a cold anomaly peak of -0.6 ∘ C, that is in the range of Stenchikov et al (2009) simulation results between 1 and 0.4K. Fact that also agrees with Kim and Kim (2012) that have observed a cooling in their model results from 0.25 to 0.8 ∘ C, the higher limit is for LM eruptions. The same magnitude of a negative anomaly is present in two different regions, 30S and ∼55S (Figure 3.11a).…”

“…Other studies in regions such as the middle, 3.1. General aspects of the Last Millennium northern high latitudes and in the Southern Ocean, have also shown an increase at the sea surface salinity after eruptions (e.g., Stenchikov et al, 2009;Kim and Kim, 2012;Ding et al, 2014;Pausata et al, 2015), fact that is consistent with a reduction of precipitation found in Trenberth and Dai (2007).…”

“…The cooling signal is expected after an eruption due to the radiative effect (e.g. Church et al, 2005;Stenchikov et al, 2009;Mignot et al, 2011;Kim and Kim, 2012;Ding et al, 2014;Stenchikov, 2016). The volcanic signal in the SST is very well represented, accounting for a small spread between the ensemble members.…”