Impact of Icelandic dust and volcanic ash on snow and ice

• Main Author: Wittmann, Monika
• Other Authors: Þröstur Þorsteinsson, Jarðvísindadeild (HÍ), Faculty of Earth Sciences (UI), Verkfræði- og náttúruvísindasvið (HÍ), School of Engineering and Natural Sciences (UI), Háskóli Íslands, University of Iceland
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: University of Iceland, School of Engineering and Natural Sciences, Faculty of Earth Sciences 2017
• Subjects: Dust storms; Albedo; Energy balance; Glacier; Dust; Sandfok; Aska; Jöklar; Doktorsritgerðir; glacier; Ice cap; Iceland; North Atlantic; Vatnajökull
• Online Access: https://hdl.handle.net/20.500.11815/177

Located on the mid-Atlantic ridge, Iceland has the largest volcaniclastic desert on Earth, created by glacio-fluvial processes and frequent volcanic eruptions. Due to its location along the North Atlantic Storm track, Iceland frequently experiences high winds. With an abundance of loose dust (particulate matter) from sandur plains and high winds, Icelandic glaciers are exposed to dust storms and redistributed ash. Deposited material is influencing glacier albedo and therefore the surface energy balance. The effects of deposited volcanic ash on ice and snow melt were examined using laboratory and outdoor experiments to find an insulating threshold and showed that ash insulated the ice at a thickness of 9-15 mm whereas maximum melt occurred at a thickness of ≤1-2 mm. To estimate the frequency of dust events, the dispersion model FLEXDUST was used to simulate dust events on Brúarjökull, a north outlet of Vatnajökull for the year 2012. All simulated dust events showed a corresponding albedo drop at the weather stations. For the weather station B13, near the ELA on Brúarjökull, FLEXDUST produced 10 major dust deposition events and a total annual deposition of 20.5 g m-2. Surface snow samples from Vatnajökull were analysed for impurities to map the distribution over the ice cap in 2013 and 2015, as well as two 4.5 m deep firn cores on Brúarjökull were drilled in 2015. The cores reached down to the year 2006 and showed distinct dust layers for the years 2014, 2012, 2011 and 2008 and only very small amounts for the years 2007 and 2013. Á Íslandi er að finna stærstu sanda heims úr basísku gjóskugleri. Þeir hafa myndast úr eldfjallaösku frá fjölda eldgosa og við jökul- og vatnsveðrun gosbergs. Mjög vindasamt er á Íslandi vegna legu landsins í brautum lægða eftir Norður Atlantshafi . Gnægð lausra efna (svifryks) í söndum landsins og vindasöm veðrátta gerir jökla á landsins útsetta fyrir sandog öskufoki. Efnið sem sest á jöklana hefur áhrif á endurkast sólarljóss frá yfirborðinu. Yfirborðið verður dekkra og tekur upp ...