No ice on Öskjuvatni

No ice cover on lake Öskjuvatni is causing some interest. This is clearly seen on satellite images from NASA on 2 April 2012.

Öskjuvatn is the dark spot just to the north-east of the center of the country. Image from 2 April 2012 (NASA Rapidfire).

There aren’t that many possible explanations. It seems unlikely that weather plays a crucial role, other lakes are ice covered that should experience similar conditions. That leaves increased geothermal activity as the most likely explanation. The lake is 220 m deep, so increase in geothermal activity takes a while to show on the surface.

New article about ash and health

New article in BMJ open about:

A survey of early health effects of the Eyjafjallajökull 2010 eruption in Iceland: a population-based study

In short the conclusions are:

Short-term ash exposure was associated with upper airway irritation symptoms and exacerbation of pre-existing asthma but did not contribute to serious health problems. The exposure did not impair respiratory function compared to controls. Outdoor use of protective glasses and face masks was considered protective against irritation in eyes and upper airway.

Reference:

Hanne Krage Carlsen, Thorarinn Gislason, Bryndis Benediktsdottir, Thorir Bjorn Kolbeinsson, Arna Hauksdottir, Throstur Thorsteinsson, Haraldur Briem. 2012.
A survey of early health effects of the Eyjafjallajökull 2010 eruption in Iceland: a population-based study.
BMJ Open 2012;2:e000343. doi:10.1136/bmjopen-2011-000343 (Paper on BMJ Open web site)

Dust storm from Skeiðarársandur

On 18 February 2012 there was a clear dust storm stemming from the sandur, Skeiðarársandur, south of Skeiðarárjökull, outlet of Vatnajökull, Iceland.

Satellite image (MODIS) from 13:00 show the dust storm very clearly.

Image courtesy of NASA/GSFC, Rapid Response.

The wind speed (10-min average) was quite high around noon.

Data from DataMarket.

The wind speed reaches around 15 m/s around noon at the station Kirkjubæjarklaustur – Stjórnarsandur, see location on the image below.

Image from GoogleEarth.

New article about ash during Eyjafjallajökull eruption

High levels of particulate matter in Iceland due to direct ash emissions by the Eyjafjallajökull eruption and resuspension of deposited ash

Throstur Thorsteinsson
Environment and Natural Resources and Institute of Earth Sciences, University of Iceland, Reykjavík, Iceland
Thorsteinn Jóhannsson
The Environment Agency of Iceland, Reykjavík, Iceland
Andreas Stohl and Nina I. Kristiansen
Norwegian Institute for Air Research, Kjeller, Norway

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 117, B00C05, 9 PP., 2012

Citation: Thorsteinsson, T., T. Jóhannsson, A. Stohl, and N. I. Kristiansen (2012), High levels of particulate matter in Iceland due to direct ash emissions by the Eyjafjallajökull eruption and resuspension of deposited ash, J. Geophys. Res., 117, B00C05, doi:10.1029/2011JB008756.

Abstract

The dangers to people living near a volcano due to lava and pyroclastic flows, and, on glacier- or snow-covered volcanoes, jökulhlaups, are well known. The level of risk to human health due to high concentrations of ash from direct emission and resuspension from the ground is, however, not as well known. The eruption at Eyjafjallajökull, 14 April to 20 May 2010, produced abundant particulate matter due to its explosive eruption style. Even after the volcanic activity ceased, high particulate matter (PM) concentrations were still measured on several occasions, due to resuspended ash. The 24 hour mean concentration of PM₁₀ in the small town of Vík, 38 km SE of the volcano, reached 1230 μg m⁻³, which is about 25 times the health limit, on 7 May 2010, with 10 min average values over 13,000 μg m⁻³. Even after the eruption ceased, values as high as 8000 μg m⁻³ (10 min), and 900 μg m⁻³ (24 h), were measured because of resuspension of freshly deposited fine ash. In Reykjavík, 125 km WNW of the volcano, the PM₁₀concentration reached over 2000 μg m⁻³ (10 min) during an ash storm on 4 June 2010, which should have warranted airport closure. Summarizing, our study reveals the importance of ash resuspension compared to direct volcanic ash emissions. This likely has implications for air quality but could also have detrimental effects on the quality of ash dispersion model predictions, which so far generally do not include this secondary source of volcanic ash.

For a copy, please send me an e-mail.

Particulate matter pollution during New Year’s Eve 2011/12

The concentration of PM10 reached (at GRE) 1230 micro-g/m3; average during the 30-minutes from midnight till 12:30 on 1 January 2012.

Precipitation and slow wind made sure that the peak did not last long this year.