VERIFICATION OF NUMERICAL MODELS OF LAKE ONTARIO, II. STRATIFIED CIRCULATIONS AND TEMPERATURE CHANGES

Abstract

DATA FROM THE 1972 INTERNATIONAL FIELD YEAR ON LAKE ONTARIO ARE USED TO TEST THE PERFORMANCE OF THREE-DIMENSIONAL HYDRODYNAMIC MODELS OF LARGE LAKES.THIS STUDY IS A SEQUEL TO A PREVIOUS REPORT CONCERNING THE QUASI-HOMOGENEOUS MODEL SIMULATION OF AN EPISODE ASSOCIATED WITH TROPICAL STORM AGNES DURING THE LATTER PART OF JUNE 1972.THE PRESENT PAPER IS CONCERNED WITH THE STRATIFIED MODEL SIMULATION OF THE CIRCULATION ON LAKE ONTARIO DURING AND AFTER A STORM ON 9 AUGUST 1972.IN ADDITION, THIS PAPER DISCUSSES THE TEMPERATURE PREDICTIONS AND HEAT CONTENT CHANGES FOR BOTH EPISODES.WITH REGARD TO TIME SCALES GREATER THAN THE INERTIAL PERIOD, THE WATER LEVELS AND CURRENTS COMPUTED UNDER STRATIFIED CONDITIONS AGREE WITH OBSERVATIONS TO THE SAME EXTENT AS UNDER HOMOGENEOUS CONDITIONS.STRATIFICATION APPEARS TO EXERT AN APPRECIABLE EFFECT ON THE CIRCULATION, BUT IT IS DIFFICULT TO SEPARATE BAROCLINIC AND BAROTROPIC EFFECTS BECAUSE OF THEIR INTERACTIONS.FOR INTERMEDIATE TIME SCALES, THE QUALITY OF TEMPERATURE PREDICTIONS APPEARS ACCEPTABLE WITH REFERENCE TO ADVECTIVE HEAT TRANSPORTS.LONGER TERM MECHANISMS OF THERMOCLINE FORMATION, MAINTENANCE AND EROSION ARE NOT CONSIDERED HERE IN VIEW OF THE PROPOSED USE OF THIS MODEL IN CONJUNCTION WITH AN OPERATIONAL MONITORING PROGRAM.SHORT-TERM DYNAMICAL EFFECTS WITH THE ASSOCIATED PHENOMENA OF INTERNAL WAVES ARE NOT WELL SIMULATED IN THE PRESENT EXPERIMENTS BECAUSE OF THE CHOICE OF MODEL PARAMETERS.(A.)