Simulations of Seasonal Snow in the Upper Colorado River Basin

According to Salzmann and Mearns (2012), "climate impact assessments require primarily regional- to local-scale climate data for the past and the present and scenarios for the future," noting, with respect to the future, that "regional climate models (RCMs) are among the most promising tools to simulate climate on the regional scale." However, they say that "the effective benefit of each of these RCMs and their ensembles for specific climate impact assessments remains to be proven for individual impact studies."

Against this backdrop, Salzmann and Mearns explored this issue within the context of the North American Regional Climate Change Program (NARCCAP; Mearns et al., 2009) with regard to the seasonal snow regime in the Upper Colorado River Basin. This they did by comparing NARCCAP results with in situ observations and data obtained from various reanalysis projects. So what did they learn?

The two researchers at the National Center for Atmospheric Research in Boulder, Colorado (USA) report - quite bluntly and to the point - that "the RCMs are generally too dry, too warm, simulate too little snow water equivalent, and have a too-short snow cover duration with a too-late start and a too-early end of a significant snow cover." And to these problems they add the fact that "attributing the found biases to specific features of the RCMs remains difficult or even impossible without detailed knowledge of the physical and technical specification of the models."

In light of these less-than-enthusiastic findings, it would appear that state-of-the-art RCMs still have a long, long way to go before they can be trusted to do what it is their intended mandate to do.

Additional References
Mearns, L.O., Gutowski, W., Jones, R., Leung, R., McGinnis, S., Nunes, A. and Qian, Y. 2009. A regional climate change assessment program for North America. EOS, Transactions of the American Geophysical Union 90: 311.