Found 10001 publications. Showing page 124 of 401:
2018
Atlantic multidecadal oscillation modulates the impacts of Arctic sea ice decline
The Arctic sea ice cover has been rapidly declining in the last two decades, concurrent with a shift in the Atlantic Multidecadal Oscillation (AMO) to its warm phase around 1996/1997. Here we use both observations and model simulations to investigate the modulation of the atmospheric impacts of the decreased sea ice cover in the Atlantic sector of the Arctic (AASIC) by the AMO. We find that the AASIC loss during a cold AMO phase induces increased Ural blocking activity, a southeastward‐extended snowpack, and a cold continent anomaly over Eurasia in December through northerly cold air advection and moisture transport from the Arctic. The increased Ural blocking activity and more extended Eurasian snowpack strengthen the upward propagation of planetary waves over the Siberian‐Pacific sector in the lower stratosphere and hence lead to a weakened stratospheric polar vortex and a negative Arctic Oscillation (AO) phase at the surface in February. However, corresponding to the AASIC loss during a warm AMO phase, one finds more widespread warming over the Arctic and a reduced snowpack over Northern Eurasia in December. The stratosphere‐troposphere coupling is suppressed in early winter and no negative AO anomaly is found in February. We suggest that the cold AMO phase is important to regulate the atmospheric response to AASIC decline, and our study provides insight to the ongoing debate on the connection between the Arctic sea ice and the AO.
2018
Assessing, quantifying and valuing the ecosystem services of coastal lagoons
The natural conservation of coastal lagoons is important not only for their ecological importance, but also because of the valuable ecosystem services they provide for human welfare and wellbeing. Coastal lagoons are shallow semi-enclosed systems that support important habitats such as wetlands, mangroves, salt-marshes and seagrass meadows, as well as a rich biodiversity. Coastal lagoons are also complex social-ecological systems and the ecosystem services that lagoons deliver provide livelihoods, benefits wellbeing and welfare to humans. This study assessed, quantified and valued the ecosystem services of 32 coastal lagoons. The main findings of the study were: (i) the definitions of ecosystem services are still not generally accepted; (ii) the quantification of ecosystem services is made in many different ways, using different units; (iii) the evaluation in monetary terms of some ecosystem service is problematic, often relying on non-monetary evaluation methods; (iv) when ecosystem services are valued in monetary terms, this may represent very different human benefits; and, (v) different aspects of climate change, including increasing temperature (SST), sea-level rise (SLR) and changes in rainfall patterns threaten the valuable ecosystem services of coastal lagoons.
2018
I prosjektet ble det utført målinger av kvikksølv (Hg) i luft ved en stasjon og prøvetaking og analyse av Hg i nedbør ved to stasjoner, samt analyse av Hg i 14 storfisk fra Pasvikvassdraget. Måleresultatene for Hg i luft i Karpdalen viser bakgrunnsnivåer rundt 1,3 - 1,4 ng/m3. Forhøyede konsentrasjoner av Hg samsvarer med forhøyede konsentrasjoner av SO2 (episoder). Det er derfor sannsynliggjort at episodene skyldes utslipp fra samme kilde eller kildeområder på russisk side. Konsentrasjoner av Hg i nedbør og avsetning er høyere på Svanvik enn i Karpdalen, men lavere enn bakgrunnsstasjoner i Sør-Norge. Analyser av Hg i fisk viser at de største fiskene (gjedde, ørret, abbor) har verdier over grenseverdi på 0,5 mg/kg. Sik viste lave verdier.
NILU
2018
The Zeppelin Observatory is an atmospheric monitoring station located on the northwest coast of Spitzbergen island, in the Svalbard archipelago. The station provides background air composition, meteorological and climatological data for numerous research projects. The observatory is located on a mountain ridge in a region with complex topography that affects local atmospheric circulation processes. Research question: How the seasonal data collected at the Zeppelin observatory and Ny-Ålesund station (Fig. 2b), a temporarily station in the settlement, is affected by: 1) micrometeorological conditions 2) mesoscale dynamics 3) local air pollution
2018
CITI-SENSE Citizens' Observatories Architecture
This paper introduces the architecture of the CITI-SENSE Citizens’ Observatories based on the ISO 19119 reference model. It describes the various parts of the architecture including boundary services with sensors and apps and data management services with the CITI-SENSE data model. It also describes the Web Feature Service (WFS) storage support and the reusable visualisation widgets used for both apps and web portals in various Citizens’ Observatories.
2018
2018
2018
Rapporten viser overskridelser av tålegrenser for forsuring av vann og jord, samt overgjødslingseffekter på vegetasjon, med
avsetningsverdier for perioden 2012–2016. Det er kun en liten reduksjon i areal med overskridelse siden forrige periode: For
vann, ved bruk av SSWCoaa-modellen er 7% av Norges areal overskredet (8% i forrige periode). Bruk av FABoaa-modellen, som
forutsetter et mye større forsuringsbidrag fra nitrogen, gir en overskridelse på 19% av Norges areal (20% i forrige periode).
Overskredet areal for overgjødslingseffekter på vegetasjon er 20% (21% i forrige periode). Tålegrensene for forsuring av
skogsjord er ikke overskredet. Noen oppdateringer av tålegrensene har blitt gjort, primært for overgjødsling av vegetasjon. Det
er også benyttet en ny metode for beregning av avsetninger. Ingen av endringene gav store forskjeller i totalt overskredet areal,
men noen forskjeller i hvor man finner overskridelser og størrelsen på overskridelsene.
Norsk institutt for vannforskning (NIVA)
2018
Accurate gas velocity measurements in emission plumes are highly desirable for various atmospheric remote sensing applications. The imaging technique of UV SO2 cameras is commonly used to monitor SO2 emissions from volcanoes and anthropogenic sources (e.g. power plants, ships). The camera systems capture the emission plumes at high spatial and temporal resolution. This allows the gas velocities in the plume to be retrieved directly from the images. The latter can be measured at a pixel level using optical flow (OF) algorithms. This is particularly advantageous under turbulent plume conditions. However, OF algorithms intrinsically rely on contrast in the images and often fail to detect motion in low-contrast image areas. We present a new method to identify ill-constrained OF motion vectors and replace them using the local average velocity vector. The latter is derived based on histograms of the retrieved OF motion fields. The new method is applied to two example data sets recorded at Mt Etna (Italy) and Guallatiri (Chile). We show that in many cases, the uncorrected OF yields significantly underestimated SO2 emission rates. We further show that our proposed correction can account for this and that it significantly improves the reliability of optical-flow-based gas velocity retrievals.
In the case of Mt Etna, the SO2 emissions of the north-eastern crater are investigated. The corrected SO2 emission rates range between 4.8 and 10.7 kg s−1 (average of 7.1 ± 1.3 kg s−1) and are in good agreement with previously reported values. For the Guallatiri data, the emissions of the central crater and a fumarolic field are investigated. The retrieved SO2 emission rates are between 0.5 and 2.9 kg s−1 (average of 1.3 ± 0.5 kg s−1) and provide the first report of SO2 emissions from this remotely located and inaccessible volcano.
2018
Uptake and effects of 2, 4, 6 - trinitrotoluene (TNT) in juvenile Atlantic salmon (Salmo salar)
Elsevier
2018
2017
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2017
2017
2017