Blar i Bergen Open Research Archive på forfatter "Otterå, Odd Helge"
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The 11 year solar cycle UV irradiance effect and its dependency on the Pacific Decadal Oscillation
Guttu, Sigmund; Orsolini, Yvan J.; Stordal, Frode; Otterå, Odd Helge; Omrani, Nour-Eddine (Journal article; Peer reviewed, 2021)The stratospheric, tropospheric and surface impacts from the 11 year ultraviolet solar spectral irradiance (SSI) variability have been extensively studied using climate models and observations. Here, we demonstrate using ... -
Arctic/Atlantic exchanges via the Subpolar Gyre
Langehaug, Helene Reinertsen; Medhaug, Iselin; Eldevik, Tor; Otterå, Odd Helge (Peer reviewed; Journal article, 2012)In the present study we investigate the decadal variability in the strength and shape of the Subpolar Gyre (SPG) in a 600-year pre-industrial simulation using the Bergen Climate Model. The atmospheric influence on the SPG ... -
Attribution of multi-annual to decadal changes in the climate system: The Large Ensemble Single Forcing Model Intercomparison Project (LESFMIP)
Smith, Doug M.; Gillett, Nathan P.; Simpson, Isla R.; Athanasiadis, Panos J.; Baehr, Johanna; Bethke, Ingo; Bilge, Tarkan Aslan; Bonnet, Rémy; Boucher, Olivier; Findell, Kirsten L.; Gastineau, Guillaume; Gualdi, Silvio; Hermanson, Leon; Leung, L. Ruby; Mignot, Juliette; Müller, Wolfgang A.; Osprey, Scott; Otterå, Odd Helge; Persad, Geeta G.; Scaife, Adam A.; Schmidt, Gavin A.; Shiogama, Hideo; Sutton, Rowan T.; Swingedouw, Didier; Yang, Shuting; Zhou, Tianjun; Ziehn, Tilo (Journal article; Peer reviewed, 2022)Multi-annual to decadal changes in climate are accompanied by changes in extreme events that cause major impacts on society and severe challenges for adaptation. Early warnings of such changes are now potentially possible ... -
A brief history of climate – the northern seas from the Last Glacial Maximum to global warming
Eldevik, Tor; Risebrobakken, Bjørg; Bjune, Anne Elisabeth; Andersson, Carin; Birks, Harry John Betteley; Dokken, Trond Martin; Drange, Helge; Glessmer, Mirjam Sophia; Li, Camille; Nilsen, Jan Even Øie; Otterå, Odd Helge; Richter, Kristin; Skagseth, Øystein (Peer reviewed; Journal article, 2014-12)The understanding of climate and climate change is fundamentally concerned with two things: a well-defined and sufficiently complete climate record to be explained, for example of observed temperature, and a relevant ... -
Effects of solar irradiance forcing on the ocean circulation and sea-ice in the North Atlantic in an isopycnic coordinate ocean general circulation model
Otterå, Odd Helge; Drange, Helge (Peer reviewed; Journal article, 2004)The sensitivity of the ocean circulation to changes in solar irradiance is examined using an isopycnic coordinate, global ocean general circulation model (OGCM) coupled to a thermodynamic/dynamic sea-ice model. In the ... -
Effects of solar irradiance forcing on the ocean circulation and sea-ice in the North Atlantic in an isopycnic coordinate ocean general circulation model
Otterå, Odd Helge; Drange, Helge (Tellus;56A(2), Journal article, 2004-03)The sensitivity of the ocean circulation to changes in solar irradiance is examined using an isopycnic coordinate, global ocean general circulation model (OGCM) coupled to a thermodynamic/dynamic sea-ice model. In the ... -
Impact of solar irradiance and geomagnetic activity on polar NOx, ozone and temperature in WACCM simulations
Tartaglione, Nazario; Toniazzo, Thomas; Orsolini, Yvan J.; Otterå, Odd Helge (Journal article; Peer reviewed, 2020)The response of the atmosphere to solar irradiance and geomagnetic activity is analyzed in experiments with the Whole Atmosphere Community Climate Model (WACCM) under idealized forcings. Four experiments are carried out ... -
Impacts of UV Irradiance and Medium-Energy Electron Precipitation on the North Atlantic Oscillation during the 11-Year Solar Cycle
Guttu, Sigmund; Orsolini, Yvan; Stordal, Frode; Otterå, Odd Helge; Omrani, Nour-Eddine; Tartaglione, Nazario; Verronen, Pekka T.; Rodger, Craig J.; Clilverd, Mark A. (Journal article; Peer reviewed, 2021)Observational studies suggest that part of the North Atlantic Oscillation (NAO) variability may be attributed to the spectral ultra-violet (UV) irradiance variations associated to the 11-year solar cycle. The observed ... -
Inception of the Northern European Ice Sheet due to contrasting ocean and insolation forcing
Risebrobakken, Bjørg; Dokken, Trond Martin; Otterå, Odd Helge; Jansen, Eystein; Gao, Yongqi; Drange, Helge (Peer reviewed; Journal article, 2007-01)About 115,000 years ago the last interglacial reached its terminus and nucleation of new ice sheet growth was initiated. Evidence from the northernmost Nordic Seas indicate that the inception of the last glacial was related ... -
Mid-Pliocene Atlantic Meridional Overturning Circulation simulated in PlioMIP2
Zhang, Zhongshi; Li, Xiangyu; Guo, Chuncheng; Otterå, Odd Helge; Nisancioglu, Kerim Hestnes; Tan, Ning; Contoux, Camille; Ramstein, Gilles; Feng, Ran; Otto-Bliesner, Bette L.; Brady, Esther C.; Chandan, Deepak; Richard Peltier, Peltier; Baatsen, Michiel L. J.; Von Der Heydt, Anna S.; Weiffenbach, Julia E.; Stepanek, Christian; Lohmann, Gerrit; Zhang, Qiong; Li, Qiang; Chandler, Mark A.; Sohl, Linda E.; Haywood, Alan M.; Hunter, Stephen J.; Tindall, Julia C.; Williams, Charles; Lunt, Daniel J.; Chan, Wing-Le; Abe-Ouchi, Ayako (Journal article; Peer reviewed, 2021)In the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2), coupled climate models have been used to simulate an interglacial climate during the mid-Piacenzian warm period (mPWP; 3.264 to 3.025 Ma). Here, we compare ... -
An oceanic perspective on Greenland’s recent freshwater discharge since 1850
Perner, Kerstin; Moros, Matthias; Otterå, Odd Helge; Blanz, Thomas; Schneider, Ralph R.; Jansen, Eystein (Journal article; Peer reviewed, 2019)Instrumental data evidence an accelerating freshwater release from Arctic sea ice export and the Greenland Ice Sheet over the past three decades causing cooling and freshening in the subpolar North Atlantic region. However, ... -
A Possible Feedback Mechanism Involving the Arctic Freshwater, the Arctic Sea Ice, and the North Atlantic Drift
Otterå, Odd Helge; Drange, Helge (Advances in Atmospheric Sciences;21( 5), Journal article, 2004-03-15)Model studies point to enhanced warming and to increased freshwater fluxes to high northern latitudes in response to global warming. In order to address possible feedbacks in the ice-ocean system in response to such changes, ... -
Role of volcanic forcing on future global carbon cycle
Tjiputra, Jerry; Otterå, Odd Helge (Peer reviewed; Journal article, 2011-06-16)Using a fully coupled global climate-carbon cycle model, we assess the potential role of volcanic eruptions on future projection of climate change and its associated carbon cycle feedback. The volcanic-like forcings are ... -
The sensitivity of the present day Atlantic meriodinal overturning circulation to freshwater forcing
Otterå, Odd Helge; Drange, Helge; Bentsen, Mats; Kvamstø, Nils Gunnar; Jiang, Dabang (Peer reviewed; Journal article, 2003-09-09)Mounting evidence indicates that the Atlantic Meridional Overturning Circulation (AMOC) was strongly reduced during cold climate episodes in the past, possible due to freshwater influx from glacial melting. It is also ... -
Transient response of the Atlantic Meridional Overturning Circulation to enhanced freshwater input to the Nordic Seas–Arctic Ocean in the Bergen Climate Model
Otterå, Odd Helge; Drange, Helge; Bentsen, Mats; Kvamstø, Nils Gunnar; Jiang, Dabang (Tellus A;56(4), Journal article, 2004-07-09)The transient response of the climate system to anomalously large freshwater input to the high latitude seas is examined using the newly developed Bergen Climate Model. A 150-yr twin-experiment has been carried out, ... -
Using simulations of the last millennium to understand climate variability seen in palaeo-observations: Similar variation of Iceland-Scotland overflow strength and Atlantic Multidecadal Oscillation
Lohmann, Katja; Mignot, Juliette; Langehaug, Helene Reinertsen; Jungclaus, Johann H.; Matei, Daniela; Otterå, Odd Helge; Gao, Yongqi; Mjell, Tor Lien; Ninnemann, Ulysses Silas; Kleiven, Helga Flesche (Peer reviewed; Journal article, 2015-02-10)A recent palaeo-reconstruction of the strength of the Iceland–Scotland overflow during the last 600 years suggests that its low-frequency variability exhibits strong similarity with palaeo-reconstructions of the Atlantic ... -
Vulkanar i drivhuset
Otterå, Odd Helge (Journal article, 2008) -
Warm Advection as a Cause for Extreme Heat Event in North China
Wang, Xijin; Zhang, Zhongshi; Yu, Entao; Guo, Chuncheng; Otterå, Odd Helge; Counillon, Francois Stephane (Journal article; Peer reviewed, 2024)Extreme heat events (EHEs) often hit North China, resulting in significant losses. The devastating EHE in the 1743 summer, marked as the highest temperature in the past 300 years, led to ∼11,000 fatalities. These historical ...