Browsing Bergen Open Research Archive by Author "Koseki, Shunya"

Now showing items 1-20 of 20

    • Atmospheric signature of the Agulhas current 

      Nkwinkwa Njouodo, Arielle Stela; Koseki, Shunya; Keenlyside, Noel; Rouault, Mathieu (Journal article; Peer reviewed, 2018)
      Western boundary currents play an important role in the climate system by transporting heat poleward and releasing it to the atmosphere. While their influence on extratropical storms and oceanic rainfall is becoming ...

    • Causes of the large warm bias in the Angola–Benguela Frontal Zone in the Norwegian Earth System Model 

      Koseki, Shunya; Keenlyside, Noel; Demissie, Teferi Dejene; Toniazzo, Thomas; Counillon, Francois; Bethke, Ingo; Ilicak, Mehmet; Shen, Mao-Lin (Journal article; Peer reviewed, 2018)
      We have investigated the causes of the sea surface temperature (SST) bias in the Angola–Benguela Frontal Zone (ABFZ) of the southeastern Atlantic Ocean simulated by the Norwegian Earth System Model (NorESM). Similar to ...

    • Disentangling the impact of Atlantic Niño on sea-air CO2 flux 

      Koseki, Shunya; Tjiputra, Jerry; Fransner, Sara Filippa Krusmynta; Crespo, Lander Rodriguez; Keenlyside, Noel Sebastian (Journal article; Peer reviewed, 2023)
      Atlantic Niño is a major tropical interannual climate variability mode of the sea surface temperature (SST) that occurs during boreal summer and shares many similarities with the tropical Pacific El Niño. Although the ...

    • Framework for an Ocean-Connected Supermodel of the Earth System 

      Counillon, Francois Stephane; Keenlyside, Noel Sebastian; Wang, Shuo; Devilliers, Marion; Gupta, Alok Kumar; Koseki, Shunya; Shen, Mao-Lin (Journal article; Peer reviewed, 2023)
      A supermodel connects different models interactively so that their systematic errors compensate and achieve a model with superior performance. It differs from the standard non-interactive multi-model ensembles (NI), which ...

    • Frontogenesis of the Angola-Benguela Frontal Zone 

      Koseki, Shunya; Giordani, Herve; Goubanova, Katerina (Peer reviewed; Journal article, 2019-02-08)
      A diagnostic analysis of the climatological annual mean and seasonal cycle of the Angola–Benguela Frontal Zone (ABFZ) is performed by applying an ocean frontogenetic function (OFGF) to the ocean mixing layer (OML). The ...

    • Impact of the Agulhas Current on Southern Africa Precipitation: A Modeling Study 

      Nkwinkwa, Arielle Stela Imbol; Rouault, Mathieu; Keenlyside, Noel Sebastian; Koseki, Shunya (Journal article; Peer reviewed, 2021)
      The Agulhas Current (AC) creates a sharp temperature gradient with the surrounding ocean, leading to a large turbulent flux of moisture from ocean to atmosphere. We use two simulations of the Weather Research and Forecasting ...

    • Influences of Lake Malawi on the spatial and diurnal variability on local precipitation 

      Koseki, Shunya; Mooney, Priscilla A. (Peer reviewed; Journal article, 2019)
      We investigate how the intensity and spatial distribution of precipitation vary around Lake Malawi on a diurnal timescale, which can be valuable information for water resource management in tropical south-eastern African ...

    • 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 ...

    • Intraseasonal and synoptic modulation of diurnal surface solar radiation over Reunion island in the South-West Indian Ocean 

      Tang, Chao; Mialhe, Pauline; Pohl, Benjamin; Morel, Béatrice; Wild, Martin; Koseki, Shunya; Abiodun, Babatunde; Bessafi, Miloud; Lennard, Chris; Kumar Beeharry, Girish; Lollchund, Roddy; Cunden, Tyagaraja S.M.; Singh, Swati (Journal article; Peer reviewed, 2023)
      Understanding the space-time variability of Surface Solar Radiation (SSR) is mandatory for the prediction and, eventually, the skillful forecasting of photovoltaic energy production. This paper addresses the modulation of ...

    • Modelling a tropical-like cyclone in the Mediterranean Sea under present and warmer climate 

      Koseki, Shunya; Mooney, Priscilla A.; Cabos, William; Angel Gaertner, Miguel; de la Vara, Alba; Gonzalez-Aleman, Juan Jesus (Journal article; Peer reviewed, 2021)
      This study focuses on a single Mediterranean hurricane (hereafter medicane), to investigate its response to global warming during the middle of the 21st century and assesses the effects of a warmer ocean and a warmer ...

    • Regional atmospheric response to the Benguela Niñas 

      Koseki, Shunya; Imbol Koungue, Rodrigue Anicet (Journal article; Peer reviewed, 2021)
      We investigate how the atmosphere is affected by the cold sea surface temperature (SST) anomalies of the Benguela Niñas using reanalysis data and a high-resolution atmospheric model. A composite analysis of reanalysis data ...

    • 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 ...

    • 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 ...

    • Role of wind stress in driving SST biases in the tropical Atlantic 

      Voldoire, Aurore; Exarchou, Eleftheria; Sánchez-Gómez, Emilia; Demissie, Teferi Dejene; Deppenmeier, Anna-Lena; Frauen, Claudia; Goubanova, Katarina; Hazeleger, Wilco; Keenlyside, Noel; Koseki, Shunya; Prodhomme, Chloé; Shonk, Jonathan; Toniazzo, Thomas; Traoré, Abdoul-Khadre (Journal article; Peer reviewed, 2019-03-13)
      Coupled climate models used for long-term future climate projections and seasonal or decadal predictions share a systematic and persistent warm sea surface temperature (SST) bias in the tropical Atlantic. This study attempts ...

    • Seasonality of coastal upwelling trends in the Mauritania-Senegalese region under RCP8.5 climate change scenario 

      Vázquez, R.; Parras-Berrocal, I.M.; Koseki, Shunya; Cabos, W.; Sein, D.V.; Izquierdo, A. (Journal article; Peer reviewed, 2023)
      The Mauritania-Senegalese upwelling region (MSUR), the southernmost region of the Canary current upwelling system, is well-known for its coastal productivity and the key role it plays in enriching the oligotrophic open ...

    • Supermodeling Improving Predictions with an Ensemble of Interacting Models 

      Schevenhoven, Francine Janneke; Keenlyside, Noel Sebastian; Counillon, Francois Stephane; Gupta, Alok Kumar; Koseki, Shunya; Shen, Mao-Lin (Journal article; Peer reviewed, 2023)
      The modeling of weather and climate has been a success story. The skill of forecasts continues to improve and model biases continue to decrease. Combining the output of multiple models has further improved forecast skill ...

    • Tropical Atlantic variability: Observations and modeling 

      Cabos, William; de la Vara, Alba; Koseki, Shunya (Peer reviewed; Journal article, 2019-08-27)
      We review the state-of-the-art knowledge of Tropical Atlantic Variability (TAV). A well-developed observing system and sustained effort of the climate modeling community have improved our understanding of TAV. It is dominated ...

    • Unique relationship between tropical rainfall and SST to the north of the Mozambique Channel in boreal winter 

      Koseki, Shunya; Bhatt, Bhuwan Chandra (Journal article; Peer reviewed, 2017)
      In this study, we investigate a possible mechanism for the dichotomy in climatology of marine rainfall and sea surface temperature (SST) over a part of the Southwest Indian Ocean (SWIO) during boreal winter (January and ...

    • Upper tropospheric cloud-radiation interaction induced by monsoon surge over the South China Sea 

      Koseki, Shunya; Fonseca, Ricardo; Koh, Tieh-Yong; Teo, Chee-Kiat (Journal article; Peer reviewed, 2023)
      We have investigated cloud formation over the South China Sea in the upper troposphere and its impacts on the radiation budget of the troposphere and ocean surface under monsoon surges using satellite and reanalysis products ...

    • Weakening of the Atlantic Niño variability under global warming 

      Rodriguez Crespo, Lander; Prigent, Arthur; Keenlyside, Noel Sebastian; Koseki, Shunya; Svendsen, Lea; Richter, Ingo; Sánchez-Gómez, Emilia (Journal article; Peer reviewed, 2022)
      The Atlantic Niño is one of the most important patterns of interannual tropical climate variability, but how climate change will influence this pattern is not well known due to large climate model biases. Here we show that ...