C7. Land-climate interactions

The increased recognition of the importance of land-climate interactions and feedbacks in modulating regional climate highlights the need for realistic representation of land-surface types and processes in climate models. The current versions of Canadian RCMs use adavanced state-of-the-art land-surface scheme CLASS. It was shown in some recent studies (e.g. Koster et al., 2004; Seneviratne et al., 2006) that in some areas and under some conditions, the state of the land surface systematically affects the atmospheric variability, particularly temperature and rainfall. Koster et al. (2004), within the framework of the Global Land-Atmosphere Coupling Experiment (GLACE), using highly controlled seasonal simulations with a number of GCMs studied land-atmosphere coupling strength. They quantified the impact of the land surface state, i.e. soil wetness, on boreal summer climate variability, and developed for the first time a global map showing areas where land-atmosphere interaction has the strongest effect on precipitation variability (van den Hurk et al., 2011). As discussed in van den Hurk et al. (2011), the large spread in the land-atmosphere coupling strength between the model results presented in Koster et al. (2004) is often used to illustrate the lack of understanding of the complex coupling process. CRCM5 with its new land modules and processes will be used to study land-climate interactions and feedbacks through carefully selected set of experiments. Such studies focused on the Canadian high-latitudes are lacking and will add further insight into the role played by land-atmosphere interactions in modulating the regional climate. Selected pan-Arctic simulations for current climate will also be performed to study the impact of declining sea-ice on the regional climate. Special attention will be paid to study the impact on evolving permafrost and snow cover.

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