Bjørg Rognerud

• Hvidsten, Dag; Stordal, Frode; Lager, Malin; Rognerud, Bjørg; Kristiansen, Bjørn Erik; Matussek, Andreas; Gray, Jeremy & Stuen, Snorre (2015). Borrelia burgdorferi sensu lato-infected Ixodes ricinus collected from vegetation near the Arctic Circle. Ticks and Tick-borne Diseases.  ISSN 1877-959X.  6(6), s 768- 773 . doi: 10.1016/j.ttbdis.2015.07.002 Fulltekst i vitenarkiv.
• Lindholm, Markus; Hessen, Dag Olav; Færøvig, Per-Johan; Rognerud, Bjørg; Andersen, Tom & Stordal, Frode (2015). Is distribution of cold stenotherms constrained by temperature? The case of the Arctic fairy shrimp (Branchinecta paludosa O.F. Müller 1788). Journal of Thermal Biology.  ISSN 0306-4565.  53, s 46- 52 . doi: 10.1016/j.jtherbio.2015.08.005
• Isaksen, Ivar S A; Berntsen, Terje Koren; Dalsøren, Stig Bjørløw; Eleftheratos, K.; Orsolini, Yvan; Rognerud, Bjørg; Stordal, Frode; Søvde, Ole Amund; Zerefos, C & Holmes, Chris D. (2014). Atmospheric Ozone and Methane in a Changing Climate. Atmosphere.  ISSN 2073-4433.  5(3), s 518- 535 . doi: 10.3390/atmos5030518 Fulltekst i vitenarkiv. Vis sammendrag

  Ozone and methane are chemically active climate-forcing agents affected by climate–chemistry interactions in the atmosphere. Key chemical reactions and processes affecting ozone and methane are presented. It is shown that climate-chemistry interactions have a significant impact on the two compounds. Ozone, which is a secondary compound in the atmosphere, produced and broken down mainly in the troposphere and stratosphre through chemical reactions involving atomic oxygen (O), NOx compounds (NO, NO2), CO, hydrogen radicals (OH, HO2), volatile organic compounds (VOC) and chlorine (Cl, ClO) and bromine (Br, BrO). Ozone is broken down through changes in the atmospheric distribution of the afore mentioned compounds. Methane is a primary compound emitted from different sources (wetlands, rice production, livestock, mining, oil and gas production and landfills).Methane is broken down by the hydroxyl radical (OH). OH is significantly affected by methane emissions, defined by the feedback factor, currently estimated to be in the range 1.3 to 1.5, and increasing with increasing methane emission. Ozone and methane changes are affected by NOx emissions. While ozone in general increase with increases in NOx emission, methane is reduced, due to increases in OH. Several processes where current and future changes have implications for climate-chemistry interactions are identified. It is also shown that climatic changes through dynamic processes could have significant impact on the atmospheric chemical distribution of ozone and methane, as we can see through the impact of Quasi Biennial Oscillation (QBO). Modeling studies indicate that increases in ozone could be more pronounced toward the end of this century. Thawing permafrost could lead to important positive feedbacks in the climate system. Large amounts of organic material are stored in the upper layers of the permafrost in the yedoma deposits in Siberia, where 2 to 5% of the deposits could be organic material. During thawing of permafrost, parts of the organic material that is deposited could be converted to methane. Furthermore, methane stored in deposits under shallow waters in the Arctic have the potential to be released in a future warmer climate with enhanced climate impact on methane, ozone and stratospheric water vapor. Studies performed by several groups show that the transport sectors have the potential for significant impacts on climate-chemistry interactions. There are large uncertainties connected to ozone and methane changes from the transport sector, and to methane release and climate impact during permafrost thawing.

• Eleftheratos, K.; Isaksen, Ivar S A; Zerefos, Christos S.; Nastos, P.; Tourpali, K. & Rognerud, Bjørg (2013). Ozone Variations Derived by a Chemical Transport Model. Water, Air and Soil Pollution.  ISSN 0049-6979.  224(6) . doi: 10.1007/s11270-013-1585-2
• von Hobe, Marc; Bekki, S.; Borrmann, S.; Cairo, F.; D'Amato, F.; Di Donfrancesco, G; Dörnbrack, A.; Ebersoldt, A.; Ebert, M.; Emde, C.; Engel, I.; Ern, Manfred; Frey, W.; Genco, S.; Griessbach, S.; Grooß, J.-U.; Gulde, T.; Günther, G.; Hösen, E.; Hoffmann, L.; Homonnai, V.; Hoyle, Christopher; Isaksen, Ivar S A; Jackson, D.R.; Jánosi, I. M.; Jones, R.L.; Kandler, K; Kalicinsky, C.; Keil, A.; Khaykin, S. M.; Khosrawi, F.; Kivi, R.; Kuttippurath, J.; Laube, J. C.; Lefevre, F; Lehmann, R.; Ludmann, S.; Luo, BP; Marchand, M.; Meyer, J.; Mitev, V; Molleker, S.; Müller, R.; Oelhaf, H.; Olschewski, F.; Orsolini, Yvan; Peter, T.; Pfeilsticker, K.; Piesch, C.; Pitts, Mike C.; Poole, Lamont R.; Pope, F. D.; Ravegnani, F.; Rex, M.; Riese, M.; Rockmann, T; Rognerud, Bjørg; Roiger, A.; Rolf, C.; Santee, M. L.; Scheibe, M; Schiller, C.; Schlager, H.; Siciliani de Cumis, M.; Sitnikov, N.; Søvde, Ole Amund; Spang, R.; Spelten, N.; Stordal, Frode; Sumińska-Ebersoldt, O.; Ulanovski, A.; Ungermann, J.; Viciani, S.; Volk, C.M.; vom Scheidt, M.; von der Gathen, P.; Walker, K.; Wegner, T.; Weigel, R.; Weinbuch, S.; Wetzel, G.; Wienhold, F. G.; Wohltmann, I.; Woiwode, W.; Young, I. A. K.; Yushkov, V.; Zobrist, B. & Stroh, F. (2013). Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions (RECONCILE): activities and results. Atmospheric Chemistry and Physics.  ISSN 1680-7316.  13(18), s 9233- 9268 . doi: 10.5194/acp-13-9233-2013 Fulltekst i vitenarkiv.
• Isaksen, Ivar S A; Zerefos, C; Wang, W-C; Balis, D.; Eleftheratos, K.; Rognerud, Bjørg; Stordal, Frode; Berntsen, Terje Koren; Lacasce, Joseph Henry; Søvde, Ole Amund; Oliviè, Dirk Jan Leo; Orsolini, Yvan; Zyrichidou, I.; Prather, M.J. & Tuinder, O. N. E. (2012). Attribution of the Arctic ozone column deficit in March 2011. Geophysical Research Letters.  ISSN 0094-8276.  39(L24810) . doi: 10.1029/2012GL053876 Vis sammendrag

  Arctic column ozone reached record low values (∼310 DU) during March of 2011, exposing Arctic ecosystems to enhanced UV-B. We identify the cause of this anomaly using the Oslo CTM2 atmospheric chemistry model driven by ECMWF meteorology to simulate Arctic ozone from 1998 through 2011. CTM2 successfully reproduces the variability in column ozone, from week to week, and from year to year, correctly identifying 2011 as an extreme anomaly over the period. By comparing parallel model simulations, one with all Arctic ozone chemistry turned off on January 1, we find that chemical ozone loss in 2011 is enhanced relative to previous years, but it accounted for only 23% of the anomaly. Weakened transport of ozone from middle latitudes, concurrent with an anomalously strong polar vortex, was the primary cause of the low ozone When the zonal winds relaxed in mid-March 2011, Arctic column ozone quickly recovered.

• Balis, D.; Isaksen, Ivar S A; Zerefos, C.S.; Zyrichidou, I.; Eleftheratos, K.; Tourpali, K.; Bojkov, R.; Rognerud, Bjørg; Stordal, Frode; Søvde, Amund & Orsolini, Yvan (2011). Observed and modelled record ozone decline over the Arctic during winter/spring 2011. Geophysical Research Letters.  ISSN 0094-8276.  38(L23801) . doi: 10.1029/2011GL049259 Vis sammendrag

  This work describes observational and modelling results of the ozone depletion which took place during the winter/spring of 2011 in the Arctic stratosphere. Assimilated total ozone data from GOME-2 were used to estimate the integrated ozone mass deficit at polar latitudes and the Oslo CTM2 model calculated low winter/spring ozone values over the Arctic, which compare well with the satellite observations. Model runs with and without chemistry in the Arctic during the winter/spring of 2011 show that the very low Arctic stratospheric air temperatures led to significant chemical ozone loss. The calculated winter/spring ozone mass deficit (O3MD) reached extreme high values in 2011 (2700 Mt) and the seasonal zonal mean total ozone extreme low values of 333DU. Dynamics have set up the conditions for cold temperatures in the lower stratosphere in winter/spring of 2011. Comparison of ozone columns with the previous 13 years shows record low ozone column values during winter/spring in the Arctic in 2011. A comparison is also given with similar model studies for the overall warmer winter/spring of 2010 which show higher ozone column values and significantly less chemical ozone loss. The interannual variability of column ozone over the northern polar region is, as expected, highly correlated with the corresponding year-to-year variability of the seasonally-averaged temperatures in the lower stratosphere.

• Eleftheratos, Kostar; Cerefos, Christos S.; Gerasopoulos, Evangelos; Isaksen, Ivar S A; Rognerud, Bjørg; Dalsøren, Stig Bjørløw & Varotsos, Panayotis A. (2011). A note on the comparison between total ozone from Oslo CTM2 and SBUV satellite data. International Journal of Remote Sensing.  ISSN 0143-1161.  32(9), s 2535- 2545 . doi: 10.1080/01431161003698401
• Søvde, Ole Amund; Orsolini, Yvan; Jackson, D.R.; Stordal, Frode; Isaksen, Ivar S A & Rognerud, Bjørg (2011). Estimation of Arctic O-3 loss during winter 2006/2007 using data assimilation and comparison with a chemical transport model. Quarterly Journal of the Royal Meteorological Society.  ISSN 0035-9009.  137(654), s 118- 128 . doi: 10.1002/qj.740 Vis sammendrag

  The evolution of Arctic stratospheric O3 throughout the winter and spring of 2006/2007 is estimated by a state-of-the-art chemical transport model (CTM) and by a 3D-Var assimilation system using O3 data from the Earth Observing System (EOS) Microwave Limb Sounder (MLS) and Solar Backscatter Ultraviolet Radiometer (SBUV/2) satellites. Modelled and assimilated O3 compare well with MLS measurements. The aim of this article is to compare O3 loss estimates derived from the CTM and data-assimilation results, and as a result point to further developments in the method of inferring O3 loss using data assimilation. The methods for inferring O3 loss are discussed and compared with other published methods. The assimilation-system vertical transport is found to be too fast, in agreement with an earlier study, although this affects only the O3 reference field used for the loss estimation. Improving the O3 reference in the assimilation method used here provides a maximum vortex average O3 loss range of 0.8–1.2 ppmv at 68 hPa and 1.0–1.5 ppmv at 46 hPa, peaking at the beginning of March. The corresponding CTM values are 1.4 and 1.6 ppmv, respectively, with the peak lagging the assimilation by a few days at 46 hPa. We show that using a passive tracer as reference for O3 loss does not provide the best estimate for polar stratospheric cloud (PSC)-related loss for this winter; up to 40% of total O3 loss is shown not to be related to PSCs or heterogenous chemistry. Hence, the use of a passive O3 reference for estimating PSC-related O3 loss should be made with care. In addition to the vortex average losses, we estimate an innermost vortex O3 loss of 1.4 ppmv due to PSCs only. Transport effects and differences between the CTM and the assimilation system are discussed, and possible improvements for both models are suggested.

• Isaksen, Ivar S A; Granier, C; Myhre, Gunnar; Berntsen, Terje Koren; Dalsøren, Stig Bjørløw; Gauss, M; Klimont, Z; Benestad, R; Bousquet, P; Collins, W; Cox, T; Eyring, V; Fowler, D; Fuzzi, S; Jockel, P; Laj, P; Lohmann, U; Maione, M; Monks, P; Prevot, ASH; Raes, F; Richter, A; Rognerud, Bjørg; Schulz, M; Shindell, D; Stevenson, DS; Storelvmo, T; Wang, WC; van Weele, M; Wild, M & Wuebbles, D (2009). Atmospheric composition change: Climate-Chemistry interactions. Atmospheric Environment.  ISSN 1352-2310.  43(33), s 5138- 5192 . doi: 10.1016/j.atmosenv.2009.08.003
• Myhre, Gunnar; Nilsen, Jørgen Skredsvik; Gulstad, Line; Shine, KP; Rognerud, Bjørg & Isaksen, Ivar S A (2007). Radiative forcing due to stratospheric water vapour from CH4 oxidation. Geophysical Research Letters.  ISSN 0094-8276.  34 . doi: 10.1029/2006GL027472
• Andersen, SB; Weatherhead, EC; Stevermer, A; Austin, J; Bruhl, C; Fleming, EL; de Grandpre, J; Grewe, V; Isaksen, Ivar S A; Pitari, G; Portmann, RW; Rognerud, Bjørg; Rosenfield, JE; Smyshlyaev, S; Nagashima, T; Velders, GJM; Weisenstein, DK & Xia, J (2006). Comparison of recent modeled and observed trends in total column ozone. Journal of Geophysical Research (JGR).  ISSN 0148-0227.  111 . doi: 10.1029/2005JD006091
• Rummukainen, Markku; Isaksen, Ivar S A; Rognerud, Bjørg & Stordal, Frode (1999). A global model tool for three-dimensional multiyear stratospheric chemistry simulations: Model description and first results. Journal of Geophysical Research (JGR).  ISSN 0148-0227.  104(D21), s 26437- 26456
• Zerefos, C.S.; Tourpali, K.; Bojkov, R.B.; Balis, D.S.; Rognerud, Bjørg & Isaksen, Ivar S A (1997). Solar activity-total column ozone relationships:Osercations and model studies with heterogeneous chemistry. Journal of Geophysical Research (JGR).  ISSN 0148-0227.  102(D1), s 1561- 1569

Se alle arbeider i Cristin

• Haigh, Joanna & Rognerud, Bjørg (2004). Solar Influence on Climate and Environment (SOLICE) Final report.
• Rognerud, Bjørg (2004). Oslo-CTM2 Model description and results.
• Braathen, Geir O.; Arlander, B.; Dahlback, Arne; Danielsen., T.; Engelsen, O.; Fløisand, I.; Gauss, Michael; Hansen, G.; Hoppe, Ulrich; Høiskar, Britt Ann Kåstad; Isaksen, Ivar S A; Kjeldstad, B.; Kylling, A.; Orsoloni, Y.; Rognerud, Bjørg & Stordal, Frode (2001). The Coordinated Ozone and UV project (COZUV). Vis sammendrag

  COZUV (Coordinated Ozone and UV project) is a joint Norwegian project within stratospheric ozone and UV research. It started in January 1999 and runs through 2002. The main objectives are to gain increased understanding of the processes that lead to ozone loss in the Arctic and at middle latitudes and to understand how changes in the ozone layer affects the amount of UV radiation that hits the ground.

• Rognerud, Bjørg; Isaksen, Ivar S A & Gauss, Michael (2000). Polar Vortex Change (PVC): Long-term change in Arctic vortex chemistry, modelling.

Se alle arbeider i Cristin