NOCN03 CWAO 131830
GENOT NO. 011

GENOT NO. 010 EST LA VERSION FRANCAISE DE CE GENOT.

CHANGES TO THE WAVE FORECASTING SYSTEM 

ON THURSDAY JULY 21ST 2005 THE CANADIAN METEOROLOGICAL CENTRE WILL
IMPLEMENT MODIFICATIONS TO THE WAVE FORECAST SYSTEM OVER THE NORTHERN
DOMAINS OF THE ATLANTIC AND PACIFIC OCEANS. THIS IMPLEMENTATION WILL
ALSO INTRODUCE 4 NEW WINDOWS OF WAVE FORECAST TO COVER THE FOLLOWING
DOMAINS IN THE GREAT LAKES : ONTARIO ERIE HURON AND SUPERIOR.

ATLANTIC AND PACIFIC

MODIFICATIONS

THE NEW VERSION OF THE MODEL USES A MORE SOPHISTICATED SCHEME FOR WAVE
PROPAGATION VELOCITIES. THIS ENABLES THE MODEL TO SOLVE WAVES IN
SHALLOW WATER. THE PREVIOUS VERSION COULD ONLY DEAL WITH DEEP WATER IN
WHICH WAVE VELOCITY DEPENDS ON FREQUENCY ALONE. THE NEW VERSION HAS AN
ADDED SCHEME TO DEAL WITH SHALLOW WATER IN WHICH WAVE VELOCITY DEPENDS
ON FREQUENCY AND THE DEPTH OF THE MARINE FLOOR.

THE RESOLUTION OF THE MODEL WILL GO FROM 1.0 DEGREES TO A GREATER
RESOLUTION OF 0.5 DEGREES. ALSO THE FORECAST FREQUENCY WILL GO FROM
EVERY 6 HOURS TO FORECASTS EVERY 3 HOURS.

GRAPHICAL PRODUCTS

IT IS IMPORTANT TO NOTE THAT PRODUCTION OF THE FOLLOWING CHARTS WILL
BE DISCONTINUED : A0377C A0378C A0379C A0380C A0381C A0382C
A0383C A0384C A0385C A0386C FOR THE ATLANTIC ; A0387C A0388C
A0389C A0390C A0391C A0392C A0393C A0394C A0395C A0396C FOR THE
PACIFIC.

THESE CHARTS WILL BE REPLACED WITH SIMILAR COLOUR IMAGES IN PNG
FORMAT. THESE WILL BE SENT DIRECTLY OVER THE PDS TO THE REGIONS OF
INTEREST (IMAGES OF THE ATLANTIC TO ATLANTIC REGION AND IMAGES OF THE
PACIFIC TO PACIFIC REGION). EACH OF THESE REGIONS IS AWARE AND HAS
RECEIVED SAMPLES FOR EVALUATION. THE NEW IMAGES CONTAIN THE SAME DATA
AS THE OLD ONES WITH A FEW NOTABLE DIFFERENCES. THE LEGEND FOR THE
POINT DATA IS MORE COMPREHENSIVE AND SIGNIFICANT WAVE HEIGHTS ARE IN
COLOURED CONTOURS. IMAGES WILL BE MADE FOR ALL FORECASTS (EVERY 3
HOURS). WE HAVE CONFIRMATION THAT METMANAGER INGESTS THESE PNG FORMAT
IMAGES. THESE NEW IMAGES WILL BE AVAILABLE TO ALL REGIONS THROUGH THE
VIZAWEB VIEWER.

EVALUATION

OBJECTIVE VERIFICATIONS HAVE SHOWN THAT FORECASTS OF WAVE HEIGHTS ARE
SIGNIFICANTLY BETTER WITH THE NEW MODEL. THIS IS MOST PREDOMINANT
CLOSER TO SHORE. WE BELIEVE THAT THIS IMPROVEMENT IN COSTAL REGIONS IS
DUE JOINTLY TO THE INCREASE IN RESOLUTION AND THE SHALLOW WATER
SCHEME.

IN THE ATLANTIC COMPARATIVE SCORES BETWEEN THE OPERATIONAL AND
PARALLEL FORECAST SYSTEMS WERE MADE FOR THE MONTHS OF FEBRUARY JULY
AND OCTOBER IN 2004. RESULTS SHOW SIMILAR SCORES AGAINST BUOYS OUT TO
SEA. HOWEVER AGAINST BUOYS OFF SHORE THE NEGATIVE BIAS IN WAVE
HEIGHTS IS LESSENED BY CLOSE TO 0.4 M BRINGING BIAS NEAR 0.0 M. ALSO
RMSE IN WAVE HEIGHT IS DIMINISHED BY CLOSE TO 0.4 M TO END UP
APPROXIMATELY BETWEEN 0.2 AND 0.5 M DEPENDING ON THE SEASON.

IN THE PACIFIC COMPARATIVE SCORES BETWEEN THE OPERATIONAL AND PARALLEL
FORECAST SYSTEMS COULD ONLY BE DONE FOR THE WINTER 2004-2005. FOR THIS
PERIOD BOTH BIAS AND RMSE AGAINST BUOYS OUT TO SEA WERE SLIGHTLY
BETTER FOR THE PARALLEL (BETWEEN 0.1 AND 0.2 M). HOWEVER AGAINST BUOYS
OFF SHORE THE NEGATIVE BIAS IN WAVE HEIGHTS IS LESSENED BY CLOSE TO
0.7 M BRINGING BIAS CLOSE TO -0.2 M. MOREOVER RMSE IN WAVE HEIGHT IS
DIMINISHED BY ABOUT 0.6 M BRINGING IT CLOSE TO 0.7 M.

WE ALSO NOTED THAT SCORES VARY LITTLE WITH PROJECTED FORECAST TIME.

THE SUBJECTIVE EVALUATION WAS CONDUCTED AS A COMBINED EFFORT BETWEEN
METEOROLOGISTS IN OPERATIONS FROM CMC AND THOSE FROM THE REGIONAL
CENTRES. THE RESULTS FROM THIS EVALUATION SUPPORT THE OBJECTIVE
SCORES. WE NOTE A NET IMPROVEMENT IN THE OFF SHORE FORECASTS AS WELL
AS BETTER RESOLUTION IN CERTAIN BAYS AND STRAIGHTS. THE GENERAL
CONSENSUS IS THAT WAVE HEIGHTS ARE MORE REALISTIC WITH THE NEW
FORECAST SYSTEM.

GREAT LAKES

WITH THIS IMPLEMENTATION WE ARE INTRODUCING 4 NEW FORECAST WINDOWS
OVER THE 4 DOMAINS OF LAKES ONTARIO ERIE HURON AND SUPERIOR. THE
MODEL USED IS ALSO THE IMPROVED WAM DESCRIBED ABOVE. FORECASTS
THEREFORE BENEFIT FROM THE ADVANTAGES OF THE SHALLOW WATER SCHEME BUT
ALSO BENEFIT FROM AN INCREASED RESOLUTION WHICH VARIES BETWEEN 0.05
AND 0.08 DEGREES. THESE FORECASTS WILL ALSO BE ISSUED EVERY 3 HOURS.

RESULTS OF OBJECTIVES SCORES THAT WERE DONE OVER THESE DOMAINS GIVE US
THE SAME SIGNAL THAN OVER THE NORTHERN ATLANTIC AND PACIFIC
DOMAINS. SUBJECTIVE EVALUATIONS PERFORMED BY OPERATIONAL
METEOROLOGISTS FROM ONTARIO REGION ALSO SUGGEST THAT THE MODEL IS
BEHAVING PROPERLY.

EVERELL / ADMA / SMA-SMC TORONTO