Impact of tundra ecosystems on the surface energy budget and climate of Alaska

The sensitivity of regional terrestrial climate to the characteristics of t undra ecosystems has been investigated by a series of sensitivity experimen ts concentrating on the summer of 1995, Validation of the NCAR Land Surface Model and the Arctic Regional Climate System Model for this season indicat e their adequacy for this study. Comparisons of the simulated climate in re sponse to a wet meadow tundra or a dry heath tundra results in an expected cooling and moistening of both the local area and the adjoining sea ice and forested regions. The impact of atmospheric cloud-radiation feedbacks is t o reduce the cooling as the summer progresses, although moistening continue s, associated with increased precipitation in some areas. The spatial varia bility of the response is dependent upon prevailing synoptic conditions, wh ich act to enhance moisture advection in certain areas. This study indicate s that vegetation variation within the Arctic has substantial climatic effe cts that extend beyond the Arctic. In addition, the perturbations in the su mmer season could have profound implications of Arctic wintertime climate a nd issues of snow-albedo feedback and spring melt.