Eruption Of Kasatochi Volcano Research Articles

Biological responses of Crested and Least auklets to volcanic destruction of nesting habitat in the Aleutian Islands, Alaska

ABSTRACT Crested Auklets (Aethia cristatella) and Least Auklets (A. pusilla) are crevice-nesting birds that breed in large mixed colonies at relatively few sites in the Aleutian Island archipelago, Bering Sea, Gulf of Alaska, and Sea of Okhotsk. Many of these colonies are located on active volcanic islands. The eruption of Kasatochi volcano, in the central Aleutians, on August 7, 2008, completely buried all crevice-nesting seabird habitat on the island. This provided an opportunity to examine the response of a large, mixed auklet colony to a major geological disturbance. Time-lapse imagery of nesting habitat indicated that both species returned to the largest pre-eruption colony site for several years, but subsequently abandoned it within 5 yr after the eruption. In 2010, a rockfall site in a cove north of the old colony site began to accumulate talus, and groups of auklets were observed using the site in 2011. Use of the new colony appeared to coincide with the abandonment of the old colony site by both ...

WRF-Chem modeling of sulfur dioxide emissions from the 2008 Kasatochi Volcano

We use the Weather Research Forecasting with Chemistry (WRF-Chem) model to simulate the evolution, dispersion and conversion of the sulfur dioxide (SO<sub>2</sub>) plume generated by the 2008 eruption of Kasatochi Volcano in Alaska, USA. About 1.7 Tg of SO<sub>2</sub> were dispersed into the atmosphere during three distinct explosive events. Stratospheric sulfur dioxide conversion chemistry is detailed and model output is compared to remote sensing retrievals from the Ozone Monitoring Instrument (OMI). WRF-Chem generated SO<sub>2</sub> column densities and plume locations similar to those from OMI retrievals as the plume traveled from the North Pacific through the continental United States and Canada. Analysis of SO<sub>2</sub> conversion established an eight day lifetime of SO<sub>2</sub> for the Kastaochi plume, which is a slightly shorter lifetime than derived by other modeling methods.

The ocean response to volcanic iron fertilisation after the eruption of Kasatochi volcano: a regional-scale biogeochemical ocean model study

Abstract. In high-nutrient–low-chlorophyll regions, phytoplankton growth is limited by the availability of water-soluble iron. The eruption of Kasatochi volcano in August 2008 led to ash deposition into the iron-limited NE Pacific Ocean. Volcanic ash released iron upon contact with seawater and generated a massive phytoplankton bloom. Here we investigate this event with a one-dimensional ocean biogeochemical column model to illuminate the ocean response to iron fertilisation by volcanic ash. The results indicate that the added iron triggered a phytoplankton bloom in the summer of 2008. Associated with this bloom, macronutrient concentrations such as nitrate and silicate decline and zooplankton biomass is enhanced in the ocean mixed layer. The simulated development of the drawdown of carbon dioxide and increase of pH in surface seawater is in good agreement with available observations. Sensitivity studies with different supply dates of iron to the ocean emphasise the favourable oceanic conditions in the NE Pacific to generate massive phytoplankton blooms in particular during July and August in comparison to other months. By varying the amount of volcanic ash and associated bio-available iron supplied to the ocean, model results demonstrate that the NE Pacific Ocean has higher, but limited capabilities to consume CO2 after iron fertilisation than those observed after the volcanic eruption of Kasatochi.

Volcanic ash as fertiliser for the surface ocean

Abstract. Iron is a key limiting micro-nutrient for marine primary productivity. It can be supplied to the ocean by atmospheric dust deposition. Volcanic ash deposition into the ocean represents another external and so far largely neglected source of iron. This study demonstrates strong evidence for natural fertilisation in the iron-limited oceanic area of the NE Pacific, induced by volcanic ash from the eruption of Kasatochi volcano in August 2008. Atmospheric and oceanic conditions were favourable to generate a massive phytoplankton bloom in the NE Pacific Ocean which for the first time strongly suggests a connection between oceanic iron-fertilisation and volcanic ash supply.

Atmospheric distribution and removal of volcanic ash after the eruption of Kasatochi volcano: A regional model study

In August 2008, Kasatochi volcano on the Aleutian Islands erupted without much advance warning. Volcanic ash released during this eruption quickly settled out of the atmosphere, mainly into the NE Pacific Ocean. The amount of volcanic ash, as well as the ash fall area and volume into the NE Pacific Ocean, remains speculative, as only a limited number of measurements is available. We used a three‐dimensional atmosphere/chemistry‐aerosol model to determine the atmospheric distribution of SO2 and volcanic ash and its fallout after the eruption of Kasatochi volcano. In a first step, modeled atmospheric SO2 distributions are compared with satellite data, thereby evaluating the model capabilities to reasonably reproduce atmospheric transport patterns. For modeled volcanic ash mass a considerable reduction of the atmospheric content already occurred by 10 August, the second day after the eruption in accordance with satellite observations. Gravitational settling is the most efficient removal process for volcanic ash mass, exceeding dry and wet deposition by far. Assuming an ash volume of 0.3 km3 released during the eruption of Kasatochi volcano and a median ash particle diameter of 4 μm, the mass of volcanic ash removed at ground within the 0.1 mm isopach covers an area of 7.6 × 105 km2 over the NE Pacific Ocean and makes up 49% of the removed material out of the atmosphere. The amount of ash and that of iron attached to it is sufficient to explain measured seawater CO2 decrease at the ocean station Papa in August 2008 induced by iron fertilization and subsequent phytoplankton production.

Negligible climatic effects from the 2008 Okmok and Kasatochi volcanic eruptions

We used a general circulation model of Earth's climate to conduct simulations of climate response to the July 12, 2008, eruption of Okmok volcano and the August 8, 2008, eruption of Kasatochi volcano, which injected a total of 1.6 Tg of SO2 into the Arctic upper troposphere and lower stratosphere (0.1 Tg from Okmok and 1.5 Tg from Kasatochi). For the climate model simulations, we placed all the SO2 into the lower stratosphere. The temporal and spatial distribution of model predictions of sulfate aerosol optical depth agrees with measurements made by the Optical Spectrograph and InfraRed Imaging System (OSIRIS), a Canadian satellite instrument. After accounting for differences due to different wavelengths, different sampling volumes, and an overestimate of stratospheric SO2 loading in the model, the optical depths measured by OSIRIS are consistent with the modeled values. Although the shortwave radiative effects of the eruption are detectable in model output, perturbations in surface air temperature and precipitation were negligible, since the Okmok injection was quite small and the Kasatochi eruption was too late in the year for there to have been large radiative forcing in 2008 and was of insufficient magnitude for the sulfate aerosols to persist in the stratosphere into the following spring. We conducted further experiments with lower stratospheric injections of 3 and 5 Tg of SO2 into the Arctic on August 8, 2008. Although the sulfate aerosol optical depth and resulting shortwave radiative forcing increase linearly with atmospheric loading of SO2, the radiative forcing was still small due to the timing of the eruption, with little insolation by the time the sulfate aerosol cloud would form. High latitude eruptions of this size occurring in August or later in the calendar year would still be of insufficient magnitude for the sulfate aerosols to persist in the stratosphere into the following spring, and climate effects would be negligible.

Lidar observations of Kasatochi volcano aerosols in the troposphere and stratosphere

The eruption of Kasatochi volcano on 7–8 August 2008 injected material into the troposphere and lower stratosphere of the northern midlatitudes during a period of low stratospheric aerosol background concentrations. Aerosols from the volcanic plume were detected with a lidar in Halifax, Nova Scotia (44.64°N, 63.59°W) 1 week after the eruption and for the next 4 months thereafter. The volcanic origin of the plume is established using the FLEXPART Lagrangian particle transport model for both the stratosphere and troposphere. The stratospheric plume descended 47.1 ± 2.8 m/d on average as it dispersed, corresponding to a cooling rate of 0.60 ± 0.07 K/d. The descent rate was the same for the tropopause (within statistical uncertainties). The top of the plume remained steady at about 18 km altitude and was likely sustained by vertical eddy diffusion from large‐scale horizontal mixing. The lower boundary of the plume descended with the tropopause. The integrated aerosol backscatter between 15 and 19 km altitude was relatively constant at about 8 × 10−5 sr−1 for 532 nm wavelength. Observations and modeling of Kasatochi aerosols in the middle and lower troposphere indicate a possible ground impact. The volcanic contribution to surface PM2.5 did not exceed 5 μg/m3 at the measurement site.

Influence of the 2008 Kasatochi volcanic eruption on sulfurous and carbonaceous aerosol constituents in the lower stratosphere

Influences on stratospheric aerosol during the first four months following the eruption of Kasatochi volcano (Alaska) were studied using observations at 10700 ± 600 m altitude from the CARIBIC platform. Collected aerosol samples were analyzed for elemental constituents. Particle number concentrations were recorded in three size intervals together with ozone mixing ratios and slant column densities of SO2. The eruption increased particulate sulfur concentrations by a factor of up to 10 compared to periods before the eruption (1999–2002 and 2005–August 2008). Three to four months later, the concentration was still elevated by a factor of 3 in the lowermost stratosphere at northern midlatitudes. Besides sulfur, the Kasatochi aerosol contained a significant carbonaceous component and ash that declined in time after the eruption. The carbon‐to‐sulfur mass concentration ratio of the volcanic aerosol was 2.6 seven days after the eruption and reached 1.2 after 3–4 months.