8.6
SURFACE ENERGY FLUXES IN A BOREAL WETLAND

A E. Suyker, Univ. of Nebraska, Lincoln, NE; and S. B. Verma

Eddy correlation measurements of latent and sensible heat flux were made during two consecutive growing seasons (1994 and 1995) at a fen in central Saskatchewan as part of the Boreal Ecosystem Atmosphere Study (BOREAS). The site is a patterned fen approximately 4 km long and 450 m wide. The surface topology consists of alternating strings (higher, usually drier areas) and flarks (lower, usually wetter areas) aligned perpendicular to the hydrologic flow. The depth of peat reaches between 2-3 m in the center. Brown mosses are the predominant non-vascular plant species. Buckbean (a small shrub) and several sedges are the dominant vascular vegetation. The water table was observed to be continuously above the surface (i.e. standing water) for both growing seasons. Net radiation above the surface and energy storage in the peat surface (moss and water) were measured to examine the closure of the energy budget in each year. We will compare and contrast seasonal patterns and magnitudes of evapotranspiration in each year and compare it to other boreal and midlatitude wetlands. We will examine the diurnal variation in the storage term and establish its importance as a component of the energy budget. We will estimate equilibrium and potential evapotranspiration and study the ratio of actual to potential evapotranspiration as a function of surface water table to help evaluate the impact of water table on evapotranspiration.

The 23rd Conference on Agricultural and Forest Meteorology