Short-Term and Seasonal Variability of the Atmospheric Water Vapor Transport through the Mackenzie River Basin

Abstract

The transport of water vapor through the Mackenzie River basin, a typical high-latitude river basin, is examined for the years 1979?93, with the European Centre for Medium-Range Weather Forecasts reanalysis dataset (ERA). It is shown that the transport of water vapor through the Mackenzie basin is highly variable in space and time. This transport has two distinct modes. During the autumn, winter, and spring, moisture is transported into the basin from the southwest by extratropical cyclones. The source of this moisture is argued to be the subtropical and midlatitude central Pacific Ocean. During the summer, moisture enters the basin from the northwest, with the source region being the Arctic Ocean. The values of monthly water vapor budgets obtained with the objectively analyzed fields are compared with those obtained from interpolated radiosonde data and with other known quantitative information about the water budget of the basin. It is found that the ERA data seriously overestimate the values of monthly water budget. A discussion of various potential sources of this discrepancy is provided.