Impact of dust deposition on the albedo of Vatnajökull ice cap, Iceland

Deposition of small amounts of airborne dust on glaciers causes positive radiative forcing and enhanced melting due to the reduction of surface albedo. To study the effects of dust deposition on the mass balance of Brúarjökull, an outlet glacier of the largest ice cap in Iceland, Vatnajökull, a study of dust deposition events in the year 2012 was carried out. The dust-mobilisation module FLEXDUST was used to calculate spatio-temporally resolved dust emissions from Iceland and the dispersion model FLEXPART was used to simulate atmospheric dust dispersion and deposition. We used albedo measurements at two automatic weather stations on Brúarjökull to evaluate the dust impacts. Both stations are situated in the accumulation area of the glacier, but the lower station is close to the equilibrium line. For this site ( ∼  1210 m a.s.l.), the dispersion model produced 10 major dust deposition events and a total annual deposition of 20.5 g m−2. At the station located higher on the glacier ( ∼  1525 m a.s.l.), the model produced nine dust events, with one single event causing  ∼  5 g m−2 of dust deposition and a total deposition of  ∼  10 g m−2 yr−1. The main dust source was found to be the Dyngjusandur floodplain north of Vatnajökull; northerly winds prevailed 80 % of the time at the lower station when dust events occurred. In all of the simulated dust events, a corresponding albedo drop was observed at the weather stations. The influence of the dust on the albedo was estimated using the regional climate model HIRHAM5 to simulate the albedo of a clean glacier surface without dust. By comparing the measured albedo to the modelled albedo, we determine the influence of dust events on the snow albedo and the surface energy balance. We estimate that the dust deposition caused an additional 1.1 m w.e. (water equivalent) of snowmelt (or 42 % of the 2.8 m w.e. total melt) compared to a hypothetical clean glacier surface at the lower station, and 0.6 m w.e. more melt (or 38 % of the 1.6 m w.e. melt in total) at the station located further upglacier. Our findings show that dust has a strong influence on the mass balance of glaciers in Iceland.The study described in this manuscript was supported by NordForsk as part of the two Nordic Centres of Excellence Cryosphere-Atmosphere Interactions in a Changing Arctic climate (CRAICC), and eScience Tools for Investigating Climate Change (eSTICC). Part of this work was supported by the Centre of Excellence in Atmospheric Science funded by the Finnish Academy of Sciences Excellence (project no. 272041), by the Finnish Academy of Sciences project A4 (contract 254195). Data from in situ mass balance surveys and on glacier automatic weather stations are from joint projects of the National Power Company and the Glaciology group of the Institute of Earth Science, University of Iceland. C. Groot Zwaaftink was also funded by the Swiss National Science Foundation SNF (155294), and Louise Steffensen-Schmidt, Finnur Palsson and Sverrir Gudmunds-son by the Icelandic Research Fund (project SAMAR) and the National Power Company of Iceland. Olafur Arnalds was in part funded by Icelandic Research Fund (grant no. 152248-051)Peer Reviewe

Leikskólabörn fylgjast með gangi sólar og tungls : þróunarstarf um stjörnufræði á leikskóla

Verkefnið fjallar um þróunarstarf sem tengist stjörnufræði á leikskóla. Vinna við verkefnið fór fram á leikskóla í Reykjavík og stóð yfir í níu mánuði. Þróaðar voru hugmyndir um hvernig hægt er að vinna með stjörnufræði og tengja hana við skapandi starf á leikskólanum. Einnig voru skoðuð áhrif þessarar vinnu á leikskólastarfið og hugmyndir barnanna um stjörnufræði. Viðfangsefni verkefnisins falla vel að Aðalnámskrá fyrir leikskóla frá 2011. Þar er meðal annars gert ráð fyrir að leikskólakennarar skapi aðstæður fyrir börn svo að þau öðlist merkingarbæra reynslu af fyrirbærum og hringrásum í náttúrunni. Einn þáttur verkefnisins snerist um að semja og leggja mat á árangur af kennslufræðilegum leikjum um færslu sólarinnar á himninum og útlit tunglsins. Markmiðið var að vekja athygli leikskólabarna á fyrirbærum sem tengjast stjörnufræðinni í umhverfinu og byggja grunn að reynslu og skilningi á þessum fyrirbærum. Leikskólakennararnir prófuðu sig áfram með hugmyndir sem sneru að stjörnufræði og komu með ábendingar um það sem betur mætti fara. Þeir leituðu eftir hugmyndum hjá börnunum og sköpuðu rými til þess að þau gætu sjálf unnið með stjörnufræðina í skapandi starfi. Leikskólakennarar eru í lykilhlutverki við að beina athygli barnanna að atriðum sem tengjast stjörnufræði. Með samskiptum við börnin hjálpa leikskólakennararnir þeim að byggja upp orðaforða og hugtakaskilning á þessu sviði og efla þannig málþroska þeirra. Afrakstur verkefnisins eru leiðbeiningar fyrir vísindaleiki og afurðir úr skapandi starfi, svo sem teikningar, pappalíkön og stuttmynd um geiminn. Haldið var til haga ýmsum hugmyndum og ráðleggingum frá leikskólakennurum um það hvernig hægt er að nota stjörnufræði í leikskólastarfi. Einnig var lagt mat á starfið og athugað hvaða hugmyndir börnin hafa um fyrirbæri stjörnufræðinnar og hvaðan þær hugmyndir gætu komið.The project is about developing methods to teach astronomy at preschool. It was carried out at a preschool in Reykjavik during a nine-month period. In the project various ideas on work in astronomy were developed at the same time as astronomy was integrated with creative work at the preschool. Furthermore, the impact of this kind of work on daily preschool activity and on childrens´ ideas about astronomy was assessed. The project is well aligned with the 2011 Icelandic National Curriculum for preschools where teachers are expected to create conditions for children so they can have meaningful experience of phenomena and cycles in nature. Part of the project dealt with the development and the evaluation of educational plays describing the movement of the Sun and the appearance of the Moon. The goal was to draw preschool children’s attention to astronomical objects and build a basis for their understanding of these phenomena. The preschool teachers tried out different ideas on how to work with astronomy and made suggestions for improvements. They asked the children for ideas and suggestions and made it possible for the children to work with astronomy in a creative way. The teachers are fundamental in drawing the attention of the children to astronomy. Through communication the teachers help the children to build their vocabulary and increase their understanding of science concepts and thus strengthen their language abilities. The final products of the project are guidelines for science plays and products of creative work, including drawings, paper models and a short animation about space. The thesis also contains advice and various ideas from preschool teachers on ways to use astronomy at the preschool level. Furthermore it contains an assessment of the work carried out and some comments on children’s conceptions of astronomy and where their ideas may come from

Vísindaleikir - sól og tungl : þróunarverkefni um stjörnufræði á leikskólum unnið í leikskólanum Björtuhlíð

Gefið út af Menntavísindastofnun Háskóla ÍslandsÍ þessu þróunarverkefni var unnið að því að þróa leiðir til að vinna með stjörnufræðileg viðfangsefni í leikskólastarfi og var verkefnið unnið í leikskólanum Björtuhlíð af kennurum þar og okkur höfundum skýrslunnar. Meginnálgun verkefnisins er að námsathafnirnar séu skapandi leikur frá sjónarhóli barnsins en tilraunir og athuganir á sviði náttúrufræða frá sjónarhóli leikskólakennara. Meðal annars voru þróaðir tveir vísindaleikir fyrir leikskólabörn á sviði stjörnufræði. Annar leikurinn fjallar um sólina og ferð hennar á himninum og hinn um kvartilaskipti tunglsins. Markmið þessara leikja er að börnin læri um tengsl dægraskipta og árstíðaskipta við gang sólar og um náttúrufræðilegar skýringar á breytilegu útliti tunglsins auk þess að stuðla að almennum þroska þeirra. Leikskólakennararnir leggi grunn að hugtakanámi barnsins með því að beina athygli þess að lykilþáttum í leiknum, með því að spyrja spurninga og með því að hvetja barnið til að tjá reynslu sína. Lögð er áhersla á að tengja þessa tjáningu listrænu og skapandi starfi. Þessir tveir vísindaleikir höfðuðu vel til flestra barnanna og virtust jafnframt hafa áhrif á skilning þeirra á fyrirbærunum sem unnið var með. Jafnframt þróun vísindaleikjanna tveggja var unnið í leikskólastarfinu með ýmsum öðrum hætti að stjörnufræðilegum viðfangsefnum og sú vinna tengd margvíslegu skapandi starfi. Öllu þessu starfi er lýst í þessari skýrslu í því augnamiði að gera fleiri leikskólakennurum kleift að taka upp samsvarandi starf

Færanlegur steypustóll í bakskautasteypu

Færanlegur steypustóll í bakskautasteypu. hönnun steypustóls, keyrsluvagns og keyrlubrautar. tilgangur með hönnun og smíði er að auka öryggi, þægindi og skilvirkni við steypu á bakskautum.Norðurál ehf

Design, Manufacture, and Operation of a Core Barrel for the Iceland Deep Drilling Project (IDDP)

The science program of the Iceland Deep Drilling Project (IDDP) requires as much core as possible in the transition zone to supercritical and inside the supercritical zone (>374°C), in the depth interval 2400–4500 m. The spot coring system selected has a 7 ¼" (184.15 mm) OD at 10 m length and collects a 4" (101.6 mm) diameter core using an 8 ½" (215.9 mm) OD core bit. It incorporates design characteristics, materials, clearances and bearings compatible with operation of the core barrel at temperatures as high as 600°C. Special attention was given to the volume of flushing which could be applied to the core barrel and through the bit while running in and out of the borehole and while coring. In November 2008 a successful spot coring test using the new core barrel was performed at 2800 m depth in the production well RN-17 B at Reykjanes, Iceland, where the formation temperature is 322°C. A 9.3-m hydrothermally altered hyaloclastite breccia was cored with 100% core recovery, in spite of it being highly fractured. A core tube data logger was also designed and placed inside the inner barrel to monitor the effectiveness of cooling. The temperature could be maintained at 100°C while coring, but it reached 170°C for a very short period while tripping in. The effective cooling is attributed to the high flush design and a top drive being employed, which allows circulation while tripping in or out, except for the very short time when a new drill pipe connectionis being made

Evaluation of MODIS albedo product over ice caps in Iceland and impact of volcanic eruptions on their albedo

International audienceAlbedo is a key variable in the response of glaciers to climate. In Iceland, large albedo variations of the ice caps may be caused by the deposition of volcanic ash (tephra). Sparse in situ measurements are insufficient to characterize the spatial variation of albedo over the ice caps due to their large size. Here we evaluated the latest MCD43 MODIS albedo product (collection 6) to monitor albedo changes over the Icelandic ice caps using albedo measurements from ten automatic weather stations on Vatnajökull and Langjökull. Furthermore, we examined the influence of the albedo variability within MODIS pixels by comparing the results with a collection of Landsat scenes. The results indicate a good ability of the MODIS product to characterize the seasonal and interannual albedo changes with correlation coefficients ranging from 0.47 to 0.90 (median 0.84) and small biases ranging from −0.07 to 0.09. The root-mean square errors (RMSE) ranging from 0.08 to 0.21, are larger than that from previous studies, but we did not discard the retrievals flagged as bad quality to maximize the amount of observations given the frequent cloud obstruction in Iceland. We found a positive but non-significant relationship between the RMSE and the subpixel variability as indicated by the standard deviation of the Landsat albedo within a MODIS pixel (R = 0.48). The summer albedo maps and time series computed from the MODIS product show that the albedo decreased significantly after the 2010 Eyjafjallajökull and 2011 Grímsvötn eruptions on all the main ice caps except the northernmost Drangajökull. A strong reduction of the summer albedo by up to 0.6 is observed over large regions of the accumulation areas. These data can be assimilated in an energy and mass balance model to better understand the relative influence of the volcanic and climate forcing to the ongoing mass losses of Icelandic ice caps

Replication monitor : unnið fyrir LS Retail

Í þessari skýrslu er yfirlit yfir lokaverkefni fyrir Háskólann í Reykjavík sem unnið var í samstarfi við LS Retail. LS Replication Monitor er nýtt viðmót fyrir þá sem að nota þjónustur LS Retail sem á að gera þeim kleift að fylgjast náið með stöðu flutnings gagna á milli gagnagrunna afgreiðslukassa, verslana og höfuðstöðva. Viðmótið gefur heildræna mynd yfir stöðu gagnaflutninganna en áður hefur reynst erfitt að fá slíka mynd. Eftirlitsmenn geta fengið skilaboð ef eitthvað er í ólagi, leiðrétt villurnar fljótt og örugglega og lágmarkað þannig skaða sem verður af slíkum villum

Sensitivity of Glacier Runoff to Winter Snow Thickness Investigated for Vatnajökull Ice Cap, Iceland, Using Numerical Models and Observations

Several simulations of the surface climate and energy balance of Vatnajökull ice cap, Iceland, are used to estimate the glacier runoff for the period 1980⁻2015 and the sensitivity of runoff to the spring conditions (e.g., snow thickness). The simulations are calculated using the snow pack scheme from the regional climate model HIRHAM5, forced with incoming mass and energy fluxes from the numerical weather prediction model HARMONIE-AROME. The modeled runoff is compared to available observations from two outlet glaciers to assess the quality of the simulations. To test the sensitivity of the runoff to spring conditions, simulations are repeated for the spring conditions of each of the years 1980⁻2015, followed by the weather of all summers in the same period. We find that for the whole ice cap, the variability in runoff as a function of varying spring conditions was on average 31% of the variability due to changing summer weather. However, some outlet glaciers are very sensitive to the amount of snow in the spring, as e.g., the variation in runoff from Brúarjökull due to changing spring conditions was on average 50% of the variability due to varying summer weather