Wednesday, 17 January 2007
Climate-induced changes in surface energy budget in high latitudes for the past two decades: modeling studies
Exhibit Hall C (Henry B. Gonzalez Convention Center)
Evidence has shown that high latitudes have experienced significant warming in the past few decades. It is thus important to understand the response of high-latitude terrestrial ecosystems to this climate warming in terms of energy and water vapor exchange with the atmosphere. In this study, we will present the modeling results of the changing in surface energy budget in the past two decades from 1981 to 2001, using offline NCAR CLM3 land surface model. The model domain covers the entire Alaskan region. CLM3 is driven by the NARR reanalysis data from 1981 to 2001. For the entire Alaskan region, the model results indicate an increased trend in annually averaged net radiation (Rn) and sensible heat flux (H), but no obvious trend in annually averaged latent heat flux (LE). The model results are also analyzed separately for Arctic Alaska and interior Alaska to obtain variation patterns in spring (March, April, and May) and summer (June, July, and August). The variations in zonal mean Rn, H and LE showed that large variations occur in the Artic Alaska than the interior Alaska especially during the spring in which timing of snowmelt in the Arctic region was sensitive to the spring warming. In the spring, there is a slight increase trend of H for the Arctic Alaska, but a slight decrease trend of H for the interior Alaska. In summer, however, there is a slight decrease trend of H for the Arctic Alaska, and slight increase trend of H for the interior Alaska. This indicates that different ecosystems have different response to climate changes in different seasons.