Abstract
Abstract. An earth system model has been developed at Beijing Normal University (Beijing Normal University Earth System Model, BNU-ESM); the model is based on several widely evaluated climate model components and is used to study mechanisms of ocean-atmosphere interactions, natural climate variability and carbon-climate feedbacks at interannual to interdecadal time scales. In this paper, the model structure and individual components are described briefly. Further, results for the CMIP5 (Coupled Model Intercomparison Project phase 5) pre-industrial control and historical simulations are presented to demonstrate the model's performance in terms of the mean model state and the internal variability. It is illustrated that BNU-ESM can simulate many observed features of the earth climate system, such as the climatological annual cycle of surface-air temperature and precipitation, annual cycle of tropical Pacific sea surface temperature (SST), the overall patterns and positions of cells in global ocean meridional overturning circulation. For example, the El Niño-Southern Oscillation (ENSO) simulated in BNU-ESM exhibits an irregular oscillation between 2 and 5 years with the seasonal phase locking feature of ENSO. Important biases with regard to observations are presented and discussed, including warm SST discrepancies in the major upwelling regions, an equatorward drift of midlatitude westerly wind bands, and tropical precipitation bias over the ocean that is related to the double Intertropical Convergence Zone (ITCZ).
Highlights
Climate models are the essential tools to investigate the response of the climate system to various forcings, to make climate predictions on seasonal to decadal time scales and to make projections of future climate (Flato et al, 2013)
The Lund– Potsdam–Jena model (LPJ)-DyN based terrestrial carbon and nitrogen interaction schemes are very different from the biogeochemistry Carbon-Nitrogen scheme used in CLM4 or Community Climate System Model version 4 (CCSM4) (Thornton and Rosenbloom, 2005; Oleson et al, 2010; Lawrence et al, 2011). (iv) The atmospheric component is an interim version of the Community Atmospheric Model version 4 (CAM4) (Neale et al, 2010, 2013) modified with a revised Zhang–McFarlane deep convection scheme (Zhang and McFarlane, 1995; Zhang, 2002; Zhang and Mu, 2005a). (v) The sea ice component is the Community Ice CodE (CICE) version 4.1 (Hunke and Lipscomb, 2010) developed at Los Alamos National Lab (LANL), while the sea ice component of CCSM4 is based on Version 4 of CICE
These variations illustrate how the Beijing Normal University (BNU)-ESM adds to the much-desired climate model diversity, and to the hierarchy of models participating in the Climate Model Intercomparison Projects phase 5 (CMIP5) (Taylor et al, 2012)
Summary
Climate models are the essential tools to investigate the response of the climate system to various forcings, to make climate predictions on seasonal to decadal time scales and to make projections of future climate (Flato et al, 2013). (v) The sea ice component is the Community Ice CodE (CICE) version 4.1 (Hunke and Lipscomb, 2010) developed at Los Alamos National Lab (LANL), while the sea ice component of CCSM4 is based on Version 4 of CICE These variations illustrate how the BNU-ESM adds to the much-desired climate model diversity, and to the hierarchy of models participating in the Climate Model Intercomparison Projects phase 5 (CMIP5) (Taylor et al, 2012). Bellenger et al (2013) used the metrics developed within the Climate Variability and Predictability (CLIVAR) Pacific Panel and additional metrics to evaluate the basic El NiñoSouthern Oscillation (ENSO) properties and associated feedbacks of BNU-ESM and other CMIP5 models. This paper provides a general description and basic evaluation of the historical climate simulated by BNU-ESM.
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