Evaluation of snow cover and snow water equivalent in the continental Arctic in CMIP5 models
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Evaluation of snow cover and snow water equivalent in the continental Arctic in CMIP5 models María Santolaria‑Otín1 · Olga Zolina1,2 Received: 17 December 2019 / Accepted: 18 August 2020 © The Author(s) 2020
Abstract Spatial and temporal patterns of snow cover extent (SCE) and snow water equivalent (SWE) over the terrestrial Arctic are analyzed based on multiple observational datasets and an ensemble of CMIP5 models during 1979–2005. For evaluation of historical simulations of the Coupled Model Intercomparison Project (CMIP5) ensemble, we used two reanalysis products, one satellite-observed product and an ensemble of different datasets. The CMIP5 models tend to significantly underestimate the observed SCE in spring but are in better agreement with observations in autumn; overall, the observed annual SCE cycle is well captured by the CMIP5 ensemble. In contrast, for SWE, the annual cycle is significantly biased, especially over North America, where some models retain snow even in summer, in disagreement with observations. The snow margin position (SMP) in the CMIP5 historical simulations is in better agreement with observations in spring than in autumn, when close agreement across the CMIP5 models is only found in central Siberia. Historical experiments from most CMIP5 models show negative pan-Arctic trends in SCE and SWE. These trends are, however, considerably weaker (and less statistically significant) than those reported from observations. Most CMIP5 models can more accurately capture the trend pattern of SCE than that of SWE, which shows quantitative and qualitative differences with the observed trends over Eurasia. Our results demonstrate the importance of using multiple data sources for the evaluation of snow characteristics in climate models. Further developments should focus on the improvement of both dataset quality and snow representation in climate models, especially ESM-SnowMIP. Keywords Snow cover · Snow water equivalent · CMIP5 models · Arctic
1 Introduction Snow is a critical component of the Arctic climate system. Over northern Eurasia and North America, the duration of snow cover ranges from 7 to 10 months per year (Brown et al. 2017), with the maximum snow extent covering over 40% of the Northern Hemisphere land area (approximately 47 × 106 km2 ) each year (Robinson and Frei 2000; Lemke Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00382-020-05434-9) contains supplementary material, which is available to authorized users. * María Santolaria‑Otín [email protected] 1
Institut des Géosciences de l’Environnement (IGE) CNRSUGA, 38041 Grenoble, France
P.P. Shirshov Institute of Oceanology of Russian Academy of Sciences, Moscow 117997, Russia
2
et al. 2007). Snow affects a variety of high-latitude climate processes and feedbacks (Cohen and Rind 1991; Groisman et al. 1994). The high reflectivity (albedo being 0.8–0.9 for dry snow) and low thermal conductivity of snow have a cooling effect and modulate snow-albedo feedback (Q
