Characteristics of energy and water budgets over wet sedge and tussock tundra ecosystems at North Slope in Alaska
✍ Scribed by Yoshinobu Harazono; Mayumi Yoshimoto; Masayoshi Mano; George L. Vourlitis; Walter C. Oechel
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 574 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0885-6087
No coin nor oath required. For personal study only.
✦ Synopsis
Energy budgets were measured at Arctic tundra ecosystems in Alaska, USA. Measurements were carried out over coastal tundra at Prudhoe Bay in 1994, and at wet sedge, moist and dry tussock tundra around Happy Valley in 1995. Sensible heat ¯ux, H, and latent heat ¯ux, lE, were determined by an eddy correlation technique.
Over the Arctic coastal tundra, the energy partition changed remarkably as a result of air mass conditions. Under cold and humid wild (onshore) from the Arctic Ocean, the temperature gradient over the tundra ecosystem increased, which resulted in a high level of H. Under warm and dry air mass on clear days from the inland tundra (oshore), air and soil temperatures and the water vapour de®cit increased, which resulted in an increase in lE. The same eect or air mass condition on energy partition was observed at the tundra ecosystem in Happy Valley located 135 km inland from the Arctic coast. The energy budget at wet sedge tundra was characterized as the heat storage within the water layer on a daily basis, which was partitioned mainly to lE in daytime and lE and H at night. Latent heat ¯ux, lE, was largest at wet sedge tundra and lowest at dry tussock tundra. The Bowen ratio decreased with air temperature over wet sedge and dry tussock tundra ecosystems. The aerodynamic resistance r a , and canopy resistance, r c , over the wet sedge tundra at Happy Valley had dierent levels over four major wind directions. These levels decreased with increase in wind speed. r a was slightly higher than over other vegetation, which seemed to be owing to a relatively lower wind speed, while the canopy resistance r c was lower than over other vegetation.
Global warming will aect the energy partition of the Arctic tundra ecosystem, and the warming and drying climate will increase the lE of tundra, especially in ¯ooded areas. Expanding dry tundra increases H rather than lE, which enhances the warming of the tundra ecosystem.