A comparison of sea ice dynamics models at high resolution

An elastic-viscous-plastic (EVP) model fur sea ice dynamics has recently be en proposed as a computationally efficient alternative to the viscous-plast ic (VP) model widely in use. The EVP model features a fully explicit discre tization that improves the model's efficiency, particularly on high-resolut ion grids, and adapts easily to parallel computation. Comparison of two hig h-resolution Arctic sea ice simulations, identical except for the ice dynam ics, indicates that the EVP model reproduces the VP model behavior on times cales relevant to climate studies. The ice concentration and thickness dist ributions over a l-yr integration period are remarkably similar in the two models, although the EVP model responds more rapidly and accurately to stro ng synoptic weather systems than does the VP model, compared to drifting Ar ctic buoys. A close look at rates of strain shows that elastic waves in the EVP model do not significantly alter the ice behavior in highly compact ar eas, where the waves most benefit numerical efficiency. Internal stress of the ice is also similar in the two models; both deviate from viscoplasticit y in regions of nearly rigid ice and in regions of low concentration underg oing approximately free drift motion.