Characteristics of Moisture Flux Convergence over the Mackenzie River Basin for Water Years 1991–2008

Abstract

This paper presents a methodology and some results computed for moisture flux convergence into a region using reanalysis data from the National Centers for Environmental Prediction (NCEP) for a period of 18 years from 1991 to 2008 and from the 40-year global reanalysis data from the European Centre for Medium-range Weather Forecasts (ERA-40) for a period of 11 years from 1991 to 2001. The purpose of the study is to discuss the implied characteristics of moisture flux convergence over the Mackenzie River Basin (MRB) obtained from two different reanalysis datasets. Four analyses per day were used to compute diurnal variations in moisture flux convergence and compared with the results using two analyses per day. The research was divided into two parts. The first concentrates on the computation of moisture flux convergence into the MRB using datasets from four different times of day (00:00, 06:00, 12:00 and 18:00 utc) and comparing the results with those obtained in earlier studies by Schuster using two datasets per day. The results indicate some differences, but the two approaches are generally quite compatible. The second part deals with the computation of the moisture flux convergence into the MRB using two different datasets (NCEP and ERA-40), and the variation between them is discussed. The vertical profile of moisture flux convergence was obtained and the results reveal that the largest moisture flux convergence occurs in the height range from 850 hPa to 700 hPa.