Surface Atmosphere Exchange During and After Snow Melt for Different Arctic Environments During MAGS

• Main Authors: Constance M. Brown-mitic, Ian J. Macpherson, Peter H. Schuepp, Roger Bales
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: sensible heat flux; latent heat flux; energy balance; surface-atmosphere exchange; snow; Arctic; Mackenzie Basin; Tundra
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.503.3547; http://www.easternsnow.org/proceedings/2001/Brown_Constance.pdf

The arctic environment and in particular the Mackenzie Basin displays a very dynamic interrelationship between the atmosphere and the surface for the different ecosystems represented. The Canadian Twin Otter research aircraft flew a total of 24 grid and long regional transects, over tundra, forest and delta ecosystems, during the period of snow melt (late May- early June) and early summer (early July) as part of the 1999 Mackenzie Area GEWEX Study (MAGS) field campaign. Observations over tundra showed a sharp rise in the sensible heat flux at the onset of melt, reaching a maximum plateau at the end of the melting period and into early summer. The latent heat flux showed a more gradual rise with a Bowen ratio of two during melt, and continuing to rise through to early summer. The forested system demonstrated similar gradual rise in the latent heat flux, while the sensible heat flux was already high with Bowen ratios reaching three at the start of the observation period in late May. For both systems, the Bowen ratio stabilizes at approximately 1 by early summer. The gradual rise in latent heat flux can be tied to gradual thawing of the root zone and the significance of transpiration. This is corroborated with a similar gradual trend in the carbon dioxide flux. The relatively low solar elevation angle and earlier start