Possible effects of vulcanism on Arctic sea ice?

[oren]

Thanks kassy.

4 Summary and Discussion
The HT volcanic eruption produced stratospheric enhancements of both water and aerosols (sulfate after SO2 oxidation). Our analysis shows that the aerosol and water vapor enhancements persisted from 15 Januray to 1 July 2022. Between 22 and 32 km the enhancements are confined mostly to the SH tropics as is evident from observations and consistent with a trajectory analysis. This isolation of the stratospheric SH tropics from the NH tropics is consistent with tropical ozone observations (Stolarski et al., 2014). Below about 20 km, the aerosol observations and trajectory analyses show that aerosols and water mostly disperse out of the SH tropics. The trajectories suggest that most of the aerosols move to the SH with a smaller amount moving into the NH. Above 40 km the trajectory model suggests that eruption material moves into the Northern Hemisphere as part of the cross-hemispheric upper stratospheric circulation (Schoeberl and Strobel, 1978; Holton & Wehrbein, 1980).

By mid-February, the tropical mid-stratosphere aerosol and water vapor enhancements are slightly offset from each other, with the water vapor anomaly about 1 km higher. The two distinct layers continue separate over the 5½ months period following the eruption. The ascent speed of the water vapor anomaly is consistent with the magnitude of the upward branch of the large-scale residual circulation. The descent of the aerosol layer is consistent with the gravitational settling of particles ∼1.2 μm consistent with an independent analysis by Legras et al. (2022). Smaller particles will be carried upward by the circulation and evaporate in the warmer layers above.

Tropical temperatures at 26 km, 15°S show anomalous decreases about a month after the eruption and are coincident with the water vapor enhancement at that altitude. This temperature decrease is also seen in sonde measurements (Vömel et al., 2022). IR radiative transfer computations show that the temperature decrease is correlated with enhanced water vapor IR cooling as might be expected (de Forster and Shine, 1999). The short-wave heating and long wave cooling by aerosols appear to roughly cancel (Silletto et al., 2022). Thus, the temperature change appears to be part of the dynamical response to the increased H2O IR cooling. The other part of the response will be a circulation adjustment (Coy et al., 2022). The Newtonian cooling rate calculated from observed temperature and cooling rate changes is consistent with previous computations (Newman & Rosenfield, 1997).

To explore the formation of the water vapor anomaly, we use a simple model of the eruption. In the model we define an eruption top altitude, we assume that there is a decreasing amount of water injected above that altitude and the relative humidity below that altitude is 100%. The water vapor then disperses zonally. Our model water vapor matches the zonal mean MLS measurements 1 month after the eruption and is consistent with the range of MLS H2O measurements made shortly after the eruption (M22).

Our simple model suggests that even larger water vapor anomalies would have formed if the volcanic eruption had lofted water into higher, warmer stratospheric air. On the other hand, smaller water vapor anomalies would have occurred for lower altitude injections or higher latitude injections into colder stratospheric air. This, along with the fact that most volcanic eruptions in the recent past were not submarine may explain why water vapor enhancements have not been as large in previous eruptions (e.g., St. Helens-Murcray et al., 1981; Calbuco-Sioris et al., 2016; Kasatochi-Schwartz et al., 2013).

[kassy]

A follow up on the HT eruption.

According to the KNMI the water vapour from the HT eruption. Parts of the stratosphere particularly in the southern hemisphere cool more then 10 degrees. This then causes additional downwelling radiation was warms up the lower atmosphere.

First calculations find an addition in 2023 of 0,1C globally. The effect is biggest in the first two years and will then decline with the water vapour.

Lots of research is in the works globally. Scientists are looking at gloabl and specific regional effects. Other subjects are changes of winds at great height, changes in the ozone layer. It will get it´s own dedicated sections at some scientific conferences.

https://www.knmi.nl/over-het-knmi/nieuws/onverwacht-klimaateffect-van-de-vulkaanuitbarsting-hunga-tonga-in-2022

Some graphs on link (10HpA temp anomaly for july). Not more detail in the article.
 

[NotaDenier]

https://www.science.org/doi/10.1126/science.adg2551


Editor’s summary

The Hunga Tonga–Hunga Ha’apai eruption of 2022 injected huge amounts of water into the stratosphere and caused a large, rapid loss of ozone. Evan et al. collected in situ data on water, aerosols, and ozone in the volcanic plume and combined them with remote sensing observations to show that heterogeneous chlorine activation on humidified volcanic aerosols was the cause of the massive ozone loss that occurred. This loss was primarily triggered by the synergistic effects of strong humidification, radiative cooling, and added aerosol surface area, and this observation supports the suggestion that excess midlatitude stratospheric water associated with convection changes due to global warming could drive increases in lower stratospheric ozone loss. —H. Jesse Smith

[binntho]

I was just about to grumble about the spelling of "vulcanism" vs. "volcanism", but came across the following definition - has anybody else seen or heard of this?

volcanism = extrusive igneous activity
vulcanism = extrusive and intrusive igneous activity

The latter could be said to be effective under the Greenland ice sheet, where (apparently) the underlying bedrock is still warmer than expected, quite possibly due to intrusions caused by the Icelandic hotspot before it moved to Iceland.