Stage 1: Torne River/Kalix River

Basin description: The Torne River flows southeast along the Swedish-Finnish border into the Bothnian Bay of the Baltic Sea, as shown in Figure 1. River flows are for all practical purposes unregulated, a natural bifurcation of the main river channel results in diversion of some of the runoff to the Kalix Basin to the south. The combined basin area is approximately 65,000 km2. The predominate vegetation is boreal forest, with significant bog areas. Less than 1% of the basin is used for agriculture. In the mountainous region to the west, the terrain rises above tree line. The basin does not contain permafrost, although seasonal freezing occurs at the higher elevations.

Purpose:

• To evaluate model representation of spatial variability in snow accumulation and ablation; and
• To evaluate representation of the surface storage effects of lakes, wetlands and bogs.

Approach:

• Spatial resolution: 1/2 degree (or metric equivalent)
• Model area: 65,000 km² (or approximately 65 grid cells)
• Temporal resolution: Hourly meteorlogical inputs provided; daily variables to be returned.
• Temporal range:
  • 1979-1988 (calibration)
  • 1989-1998 (evaluation)

• Precipitation, pressure, relative humidity,cloud cover, and air temperature will be interpolated (and disaggregated where necessary), from stations throughout the basins. Station data to be provided by SMHI.
• Wind speed: To be determined.
• Solar radiation: To be estimated using the method of Thornton and Running (1999)
• Terrestrial radiation: To be estimated using surface air temperature, cloud cover and humidity (TVA, 1972).
• Soils and land use: To be determined.

Models evaluation criteria are still being developed, but will likely include the following:

• Ability of schemes to reproduce measured water and energy fluxes over multiple seasonal cycles across a climatically diverse basin;
• Transferability of model between small catchments distributed across the modelling domain; and
• Ability of schemes to reproduce remotely-sensed snow extent throughout the accumulation and ablation seasons.

Implementation of Stage 1 of PILPS 2E began in Autumn 1999 with an invitation to participants. The project will continue as follows:

• Winter 2000: Distribution of draft Implementation Plan;
• Winter/Spring 2000: Comment period for draft Implementation Plan;
• Spring/Summer 2000: Distribution of Final Implementation Plan, forcing data made available to participants.
• Summer/Fall 2000: Three month period for model application and calibration to selected sub-basins.
• Fall 2000: Results returned to lead PI and summarized.
• Fall 2000: Summary Workshop.