La convergence du flux de vapeur d'eau et son potentiel comme variable hydrologique de surface

Abstract

Hydrology is often oriented on the terrestrial branch of the hydrologic cycle. In a watershed, the amount of water vapor can change due to atmospheric transport. The horizontal convergence of the moisture flux (C) constitutes the net input of water vapor in a given region. For long time periods and on a watershed’s spatial scale, the horizontal convergence of the moisture flux should equal the water runoff of the watershed region. Keeping track of C should be an interesting way of increasing the efficiency of hydrological models. The global objective of this project is to quantify the hydrological cycle in the Canadian Regional Climate Model (CRCM) to evaluate if the horizontal convergence of the moisture flux can be used as an informative variable in hydrological models. The CRCM is useful to model complex hydrologic phenomena at regional scale and calculates components of the cycle that are difficult to obtain in the field. The results show that convergence is equal to the runoff on the climatic temporal scale. The temporal annual series also shows large correlation between the runoff and the convergence (r >0.8). On the monthly time scale, the relation is not as obvious because the atmospheric and terrestrial reservoirs also hold transiting water. During winter, the monthly convergence in the Nordic watersheds is approximately equal to the variation of the snow cover. The error in the simulated hydrological balance varies between 0 and 10% on the climatic time scale. This is much less than the error obtained by similar studies using reanalyses. At this scale, the term of error is related to the semi-Lagrangian computational scheme and possibly to the correction of the hydrological balance integrated in the MRCC. Increasing error on the monthly (0 to 30%) and daily (0 to 100%) time scales is due to a 6 hours temporal gap between the averaged variables and instantaneous variables in the recording scheme of the MRCC.

Date	8 Nov 2013
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	François Brissette (Supervisor) & Daniel Caya (Co-supervisor)