Blar i Geophysical Institute på forfatter "Keenlyside, Noel"

Viser treff 21-40 av 54

    • Impact of ocean and sea ice initialisation on seasonal prediction skill in the Arctic 

      Kimmritz, Madlen; Counillon, Francois; Smedsrud, Lars H.; Bethke, Ingo; Keenlyside, Noel; Ogawa, Fumiaki; Wang, Yiguo (Peer reviewed; Journal article, 2019)
      There is a growing demand for skillful prediction systems in the Arctic. Using the Norwegian Climate Prediction Model (NorCPM) that combines the fully-coupled Norwegian Earth System Model and the Ensemble Kalman filter, ...

    • Impact of Snow Initialization in Subseasonal‐to‐Seasonal Winter Forecasts With the Norwegian Climate Prediction Model 

      Li, Fei; Orsolini, Yvan; Keenlyside, Noel; Shen, Mao-Lin; Counillon, Francois; Wang, Yiguo (Peer reviewed; Journal article, 2019)
      Snow initialization has been previously investigated as a potential source of predictability atthe subseasonal‐to‐seasonal (S2S) timescale in winter and spring, through its local radiative,thermodynamical, and hydrological ...

    • Improving weather and climate predictions by training of supermodels 

      Schevenhoven, Francine Janneke; Selten, Frank; Carrassi, Alberto; Keenlyside, Noel (Peer reviewed; Journal article, 2019-11-28)
      Recent studies demonstrate that weather and climate predictions potentially improve by dynamically combining different models into a so-called “supermodel”. Here, we focus on the weighted supermodel – the supermodel's time ...

    • Inconsistent Wind Speed Trends in Current Twentieth Century Reanalyses 

      Wohland, Jan; Omrani, Nour-Eddine; Witthaut, Dirk; Keenlyside, Noel (Peer reviewed; Journal article, 2019)
      Reanalysis data underpin much research in atmospheric and related sciences. While most reanalysis only cover the last couple of decades, National Oceanic and Atmospheric Administration (20CR) and European Centre for ...

    • Insights into the Summer Diurnal Cycle over Eastern South Africa 

      Koseki, Shunya; Pohl, Benjamin; Bhatt, Bhuwan Chandra; Keenlyside, Noel; Nkwinkwa Njouodo, Arielle Stela (Journal article; Peer reviewed, 2018)
      Adopting a state-of-the-art numerical model system, we investigate how the diurnal variations in precipitation and local breeze systems are characterized by lower-boundary conditions related to the Drakensberg highland and ...

    • Key Role of the Ocean Western Boundary currents in shaping the Northern Hemisphere climate 

      Omrani, Nour-Eddine; Ogawa, Fumiaki; Nakamura, Hisashi; Keenlyside, Noel; Lubis, Sandro W.; Matthes, Katja (Peer reviewed; Journal article, 2019)
      The individual impact of North Atlantic and Pacific Ocean Western Boundary Currents (OWBCs) on the tropospheric circulation has recently been studied in depth. However, their simultaneous role in shaping the hemisphere-scale ...

    • The Madden-Julian Oscillation in a warmer world 

      Chang, Chiung-Wen June; Tseng, Wan-Ling; Huang-Hsiung, Hsu; Keenlyside, Noel; Tsuang, Ben-Jei (Peer reviewed; Journal article, 2015-07)
      Global warming's impact on the Madden-Julian Oscillation (MJO) is assessed using one of the few models capable in reproducing its key features. In a warmer climate predicted for the end of the century, the MJO increases ...

    • Marine-based multiproxy reconstruction of Atlantic multidecadal variability 

      Svendsen, Lea; Hetzinger, Steffen; Keenlyside, Noel; Gao, Yongqi (Peer reviewed; Journal article, 2014-02-28)
      Atlantic multidecadal variability (AMV) is known to impact climate globally, and knowledge about the persistence of AMV is important for understanding past and future climate variability, as well as modeling and assessing ...

    • Multiple timescales of stochastically forced North Atlantic Ocean variability: A model study 

      Mecking, Jennifer V.; Keenlyside, Noel; Greatbatch, Richard J. (Peer reviewed; Journal article, 2015-09)
      The Atlantic meridional overturning circulation (AMOC) and the subpolar gyre (SPG) are important elements in mechanisms for multidecadal variability in models in the North Atlantic Ocean. In this study, a 2000-year long ...

    • North Atlantic multi-decadal variability - mechanisms and predictability 

      Keenlyside, Noel; Ba, Jin; Mecking, Jennifer V.; Omrani, Nour-Eddine; Latif, Mojib; Zhang, Rong; Msadek, Rym (World Scientific Series on Asia-Pacific Weather and Climate, Chapter; Peer reviewed, 2015-10)
      The North Atlantic Ocean undergoes pronounced basin-wide, multi-decadal variations. The corresponding fluctuations in sea surface temperature (SST) have become known as the Atlantic Multi-decadal Oscillation (AMO) or ...

    • A North-South Contrast of Subsurface Salinity Anomalies in the Northwestern Pacific From 2002 to 2013 

      Yan, Youfang; Svendsen, Lea; Wang, Chunzai; Keenlyside, Noel; Xu, Dazhi (Peer reviewed; Journal article, 2019-03)
      This paper finds a north‐south contrast of subsurface salinity trend during 2002–2013 in the northwestern Pacific. Both Argo float data and long‐term repeat hydrographic measurements along the 137°E section show that ...

    • Ocean–atmosphere coupled Pacific Decadal variability simulated by a climate model 

      Luo, Hao; Zheng, Fei; Keenlyside, Noel; Zhu, Jiang (Journal article; Peer reviewed, 2020)
      Currently, the mechanisms for Pacific Decadal Oscillation (PDO) are still disputed, and in particular the atmosphere response to the ocean in the mid-latitude remains a key uncertainty. In this study, we investigate two ...

    • Ozone-induced climate change propped up by the Southern Hemisphere oceanic front 

      Ogawa, Fumiaki; Omrani, Nour-Eddine; Nishii, Kazuaki; Nakamura, Hisashi; Keenlyside, Noel (Peer reviewed; Journal article, 2015-11-23)
      The late twentieth century was marked by a significant summertime trend in the Southern Annular Mode (SAM), the dominant mode of tropospheric variability in the extratropical Southern Hemisphere (SH). This trend with ...

    • Pacific contribution to decadal surface temperature trends in the Arctic during the twentieth century 

      Svendsen, Lea; Keenlyside, Noel; Muilwijk, Morven; Bethke, Ingo; Omrani, Nour-Eddine; Gao, Yongqi (Journal article; Peer reviewed, 2021)
      Instrumental records suggest multidecadal variability in Arctic surface temperature throughout the twentieth century. This variability is caused by a combination of external forcing and internal variability, but their ...

    • Pacific contribution to the early twentieth-century warming in the Arctic 

      Svendsen, Lea; Keenlyside, Noel; Bethke, Ingo; Gao, Yongqi; Omrani, Nour-Eddine (Journal article; Peer reviewed, 2018)
      Arctic surface temperature warmed more than twice as fast as global temperature during the early twentieth century, similar to that during the recent global warming. This Arctic warming has been attributed to both external ...

    • Relating model bias and prediction skill in the equatorial Atlantic 

      Counillon, Francois; Keenlyside, Noel; Toniazzo, Thomas; Koseki, Shunya; Demissie, Teferi Dejene; Bethke, Ingo; Wang, Yiguo (Journal article; Peer reviewed, 2021)
      We investigate the impact of large climatological biases in the tropical Atlantic on reanalysis and seasonal prediction performance using the Norwegian Climate Prediction Model (NorCPM) in a standard and an anomaly coupled ...

    • Remarkable link between projected uncertainties of Arctic sea-ice decline and winter Eurasian climate 

      Cheung, Ho Nam; Keenlyside, Noel; Omrani, Nour-Eddine; Zhou, Wen (Journal article; Peer reviewed, 2018)
      We identify that the projected uncertainty of the pan-Arctic sea-ice concentration (SIC) is strongly coupled with the Eurasian circulation in the boreal winter (December–March; DJFM), based on a singular value decomposition ...

    • Resolving the upper-ocean warm layer improves the simulation of the Madden-Julian oscillation 

      Tseng, Wan-Ling; Tsuang, Ben-Jei; Keenlyside, Noel; Hsu, Huang-Hsiung; Tu, Chia-Ying (Peer reviewed; Journal article, 2014-09)
      Here we show that coupling a high-resolution one-column ocean model to an atmospheric general circulation model dramatically improves simulation of the Madden–Julian oscillation (MJO) to have realistic strength, period, ...

    • Role of atmosphere-ocean interactions in supermodeling the tropical Pacific climate 

      Shen, Mao-Lin; Keenlyside, Noel; Bhatt, Bhuwan Chandra; Duane, Gregory (Peer reviewed; Journal article, 2017-12-29)
      The supermodel strategy interactively combines several models to outperform the individual models comprising it. A key advantage of the approach is that nonlinear improvements can be achieved, in contrast to the linear ...

    • The role of the sea surface temperature in the atmospheric seasonal cycle of the equatorial Atlantic 

      Rodriguez Crespo, Lander; Keenlyside, Noel; Koseki, Shunya (Journal article; Peer reviewed, 2018)
      We investigate the role of sea surface temperature (SST) and land surface temperature (LST) in driving the seasonal cycle of the atmosphere (surface winds and precipitation) in the tropical Atlantic. For this we compare ...