Abstract
Abstract. The historical simulations of sea ice during 1979 to 2005 by the Coupled Model Intercomparison Project Phase 5 (CMIP5) are compared with satellite observations, Global Ice-Ocean Modeling and Assimilation System (GIOMAS) output data and Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) output data in this study. Forty-nine models, almost all of the CMIP5 climate models and earth system models with historical simulation, are used. For the Antarctic, multi-model ensemble mean (MME) results can give good climatology of sea ice extent (SIE), but the linear trend is incorrect. The linear trend of satellite-observed Antarctic SIE is 1.29 (±0.57) × 105 km2 decade−1; only about 1/7 CMIP5 models show increasing trends, and the linear trend of CMIP5 MME is negative with the value of −3.36 (±0.15) × 105 km2 decade−1. For the Arctic, both climatology and linear trend are better reproduced. Sea ice volume (SIV) is also evaluated in this study, and this is a first attempt to evaluate the SIV in all CMIP5 models. Compared with the GIOMAS and PIOMAS data, the SIV values in both the Antarctic and the Arctic are too small, especially for the Antarctic in spring and winter. The GIOMAS Antarctic SIV in September is 19.1 × 103 km3, while the corresponding Antarctic SIV of CMIP5 MME is 13.0 × 103 km3 (almost 32% less). The Arctic SIV of CMIP5 in April is 27.1 × 103 km3, which is also less than that from PIOMAS SIV (29.5 × 103 km3). This means that the sea ice thickness simulated in CMIP5 is too thin, although the SIE is fairly well simulated.
Highlights
The Coupled Model Intercomparison Project Phase 5 (CMIP5) provides a very useful platform for studying climate change
Our study shows the following: that the performance of Arctic sea ice simulation is better than that of Antarctic sea ice simulation, that sea ice extent simulation is better than sea ice volume simulation, and that mean state simulation is better than long-term trend simulation
The first ensemble realizations of the 49 CMIP5 historical simulations are evaluated in terms of the performance of sea ice
Summary
The Coupled Model Intercomparison Project Phase 5 (CMIP5) provides a very useful platform for studying climate change. Turner et al (2013) first assessed CMIP5 Antarctic SIE simulations using 18 models, and summarized that the majority of these models have too little SIE at the minimum sea ice period of February, and the mean of these 18 models’ SIE shows a decreasing trend over 1979–2005, opposite to the satellite observation that exhibits a slight increasing trend. Polvani et al (2013) used four CMIP5 models to study the cause of observed Antarctic SIE increasing trend under the conditions of increasing greenhouse gases and stratospheric ozone depletion. Stroeve et al (2012) evaluated CMIP5 Arctic SIE trends using 20 CMIP5 models They found that the seasonal cycle of SIE was well represented, and that the simulated SIE decreasing trend was more consistent with the observations over the satellite era than that of CMIP3 models but still smaller than the observed trend.
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