Ove Hermansen

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The change in aerosol properties during the transition from the more polluted spring to the clean summer in the Arctic troposphere was studied. A six-year data set of observations from Ny-Ålesund on Svalbard, covering the months April through June, serve as the basis for the characterisation of this time period. In addition four-day-back trajectories were(More)
The scope of this work was to characterize PM mass and number concentration at typical residential microenvironments in the centre of Athens and to examine the relative contribution of the indoor and outdoor sources. Three residential flats located in densely populated residential areas were studied, during a warm and cold period of 2002. PM10, PM2 and(More)
[1] By comparison of the methane mixing ratio and the carbon isotope ratio (dCCH4) in Arctic air with regional background, the incremental input of CH4 in an air parcel and the source dCCH4 signature can be determined. Using this technique the bulk Arctic CH4 source signature of air arriving at Spitsbergen in late summer 2008 and 2009 was found to be −68‰,(More)
We infer global and regional emissions of five of the most abundant hydrofluorocarbons (HFCs) using atmospheric measurements from the Advanced Global Atmospheric Gases Experiment and the National Institute for Environmental Studies, Japan, networks. We find that the total CO2-equivalent emissions of the five HFCs from countries that are required to provide(More)
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. [1] High-frequency, in situ observations from the Advanced Global Atmospheric(More)
High frequency, in situ observations from 11 globally distributed sites for the period 1994–2014 and archived air measurements dating from 1978 onward have been used to determine the global growth rate of 1,1difluoroethane (HFC-152a, CH3CHF2). These observations have been combined with a range of atmospheric transport models to derive global emission(More)
A method is introduced for evaluating recirculation in a building ventilation system from pollutant emissions in or near the building. Tracer was released at a known rate at the point of pollutant emission. Using measured tracer concentrations, the tracer release rate, and an estimate of the pollutant release rate, pollutant concentrations were estimated at(More)
In situ methane (CH(4)) measurement techniques and data from the Zeppelin Station in Ny-Alesund on Svalbard (N 78 degrees 54' E 11 degrees 53') on Mt. Zeppelin (475 m.a.s.l) are presented. The data span the time period from October 1998 to December 2003, though not continuously. The daily mean was calculated from 96 samples per day which are analysed by gas(More)
Methane stored in seabed reservoirs such as methane hydrates can reach the atmosphere in the form of bubbles or dissolved in water. Hydrates could destabilize with rising temperature further increasing greenhouse gas emissions in a warming climate. To assess the impact of oceanic emissions from the area west of Svalbard, where methane hydrates are abundant,(More)
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