NOCN03 CWAO 131930 GENOT NO. 003 LE GENOT NO. 002 EST LA VERSION FRANCAISE DU GENOT NO 003. ON TUESDAY MAY 18 2004, AT 12 UTC, THE CANADIAN METEOROLOGICAL CENTRE WILL IMPLEMENT MAJOR CHANGES TO THE OPERATIONAL REGIONAL FORECAST SYSTEM INCREASING THE HORIZONTAL RESOLUTION OF THE GEM MODEL TO 15 KM. AS WELL, NEW SATELLITE TYPE DATA WILL BE ASSIMILATED INTO THE REGIONAL DATA ASSIMILATION. SUMMARY OF THE CHANGES TO THE REGIONAL DATA ASSIMILATION SYSTEM. THE CHANGES TO THE REGIONAL DATA ASSIMILATION SYSTEM (RDAS) ARE THE SAME THAT WERE SUCCESSFULLY IMPLEMENTED IN JUNE 2003 IN THE GLOBAL SYSTEM. IT IS AN UPGRADE OF THE REGIONAL SYSTEM IN ORDER TO BRING THE TWO SYSTEMS TO THE SAME LEVEL. THE RDAS WILL MAKE USE OF SATELLITE RADIANCE DATA FROM THE AMSU/B INSTRUMENT, IN ADDITION TO THE DATA FROM THE AMSU/A INSTRUMENT THAT ARE CURRENTLY ASSIMILATED. RADIANCE DATA FROM THE 6.7 MICRON CHANNEL FROM THE GOES-W SATELLITE (GOES-IR) WILL ALSO BE ASSIMILATED. THE ADDITION OF AMSU/B AND GOES-IR DATA, WHICH ARE SENSITIVE TO BOTH ATMOSPHERIC TEMPERATURE AND MOISTURE, HAS THE MOST IMPACT OVER OCEANS WHERE MORE CHANNELS ARE ASSIMILATED. SUMMARY OF CHANGES THE REGIONAL CONFIGURATION OF THE GEM MODEL. DYNAMICAL CONFIGURATION. THE FORECAST MODEL HORIZONTAL RESOLUTION WILL INCREASE FROM .22 DEGREE (ABOUT 24 KM) TO .1375 DEGREE (ABOUT 15 KM) IN THE UNIFORM RESOLUTION PORTION OF THE GRID, WHILE THE VARIABLE RESOLUTION PORTION OF THE GRID WILL HAVE A HORIZONTAL RESOLUTION OF 3 DEGREES OR BETTER (ABOUT 330 KM) OVER THE REMAINING OF THE GLOBE. THE NUMBER OF VERTICAL LEVELS WILL BE INCREASED FROM 28 TO 58, THE TOP OF THE MODEL REMAINING AT 10 HPA. THE TIME STEP WILL BE REDUCED CONSEQUENTLY FROM 720 TO 450 SECONDS. THE DIABATIC INITIALISATION WILL BE SCALED TO THE INCREASED RESOLUTION BY REDUCING THE SPAN AND THE CUT OFF PERIOD OF THE DIGITAL FILTER FROM 6 TO 3 HOURS. A MORE SELECTIVE HORIZONTAL DIFFUSION STRATEGY WILL BE INTRODUCED REDUCING THE OVERALL FILTERING. A FORMULATION IN DEL-6 WILL BE APPLIED TO MOMENTUM VARIABLES ONLY, INSTEAD OF DEL-2 APPLIED TO ALL PROGNOSTIC VARIABLES IN THE CURRENT FORMULATION. PHYSICAL PARAMETERIZATIONS. A SUB GRID SCALE OROGRAPHIC PARAMETERIZATION WILL BE PART OF THE REGIONAL MODEL PHYSICS PACKAGE. IT CONSISTS OF TWO SCHEMES, THE GRAVITY WAVE DRAG, THAT EMULATES THE BREAKING OF MOUNTAIN WAVES IN THE STRATOSPHERE, AND A BLOCKING TERM THAT REDUCES THE WINDS IN THE TROPOSPHERE IN COMPENSATION OF THE UNRESOLVED MOUNTAINS. THE LATTER SCHEME WAS FOUND OF GREAT IMPORTANCE IN MAINTAINING THE TROPOSPHERIC UPPER-LEVEL FEATURES IN WINTER. THE KAIN-FRITSCH SCHEME WILL REPLACE THE FRITSCH-CHAPPELL SCHEME FOR THE DEEP CONVECTION. THE TRIGGER CRITERION OF THE DEEP CONVECTION SCHEME WILL BE EASIER TO REACH DURING THE FIRST 6 HOUR FORECAST. THIS WILL PREVENT EXAGGERATED EXPLICIT GRID SCALE INSTABILITY TO MATERIALIZE AS THE RESULT OF THE ANALYSIS PROCESS. THE TRIGGER FUNCTION PARAMETERS WILL HAVE THE OPTIMAL TUNED VALUES AFTERWARDS. A NEW SHALLOW CONVECTION SCHEME, BASED ON A KUO SCHEME CLOSURE, WILL COMPLEMENT THE MORE SELECTIVE DEEP CONVECTION SCHEME. THIS SHALLOW CONVECTION SCHEME CAN GENERATE PRECIPITATION. THIS FEATURE WAS JUDGED VERY IMPORTANT IN SITUATIONS OF STREAMERS OVER OPEN WATERS IN WINTER, WHEN THE CONVECTION IS NOT DEEP ENOUGH TO TRIGGER THE DEEP CONVECTION SCHEME. THE VERTICAL DIFFUSION, STILL BASED ON THE TURBULENT KINETIC ENERGY THEORY, WILL NOW ACCOUNT FOR THE EXISTENCE OF CONDENSATE WATER IN THE ATMOSPHERE. IT APPLIES DIFFUSION ON CONSERVATIVE VARIABLES IN BOTH DRY AND MOIST REGIMES AND PRODUCES IMPLICIT LOW LEVEL CLOUDS AND WATER CONTENT THAT ARE TAKEN INTO ACCOUNT BY THE RADIATION SCHEME. SUMMARY OF THE OBJECTIVE AND SUBJECTIVE EVALUATIONS. EXTENSIVE PRELIMINARY TESTING IN BOTH SUMMER AND WINTER CONDITIONS WAS NECESSARY TO ACHIEVE THE FINAL CONFIGURATION. THE MODEL AND THE UPGRADED DATA ASSIMILATION SYSTEM RAN IN PARALLEL FOR THREE MONTHS, DURING WHICH TIME IT WAS COMPARED AND EVALUATED BOTH OBJECTIVELY AND SUBJECTIVELY. UPPER AIR OBJECTIVE VERIFICATIONS AGAINST OBSERVATIONS FOR WINDS, HEIGHTS, TEMPERATURE AND DEW POINT DEPRESSION, BOTH IN SUMMER AND WINTER PRELIMINARY TESTING AND PARALLEL RUNS, SHOWED POSITIVE AND STATISTICALLY SIGNIFICANT IMPROVEMENTS EITHER FOR THE RMS OR THE BIAS. AS WELL THE SUBJECTIVE EVALUATION IS CLEARLY INDICATING A BETTER SKILL OF THIS NEW MODEL IN FORECASTING THE MASS FIELD. THE COMPARISON OF SURFACE TEMPERATURE VERIFICATIONS IS NEUTRAL, EXCEPT IN WINTER WHERE THE NEW SYSTEM HAS A SLIGHTLY COLDER BIAS OVER THE WESTERN PART OF NORTH AMERICA. INVESTIGATIONS REVEALED THAT THIS COLD BIAS IS RELATED TO EXCESSIVE NOCTURNAL COOLING SOMETIME UNDER CALM (NON WINDY) AND DRY CONDITIONS ESPECIALLY IN MOUNTAINOUS AREAS. IN SPITE OF THIS ISSUE, THE OVERALL PERFORMANCE OF THE NEW SYSTEM WAS JUDGED CLEARLY SUPERIOR. OBJECTIVE PRECIPITATION VERIFICATIONS OVER NORTH AMERICA INDICATE A SMALL BUT POSITIVE IMPROVEMENT IN THE THREAT SCORE AND IN THE BIAS FOR ALMOST ALL OF THE PRECIPITATION CATEGORIES AND LEAD TIMES. THE PRECIPITATION BANDS ARE OFTEN SHARPER WITH HIGHER MAXIMA, IN GENERAL. THESE MESOSCALE STRUCTURES OF THE PRECIPITATION ARE VERY DIFFICULT TO VERIFY QUANTITATIVELY. A POSITIVE PRECIPITATION BIAS IN UPSLOPE FLOW AND A BETTER DEFINITION OF THE RAIN SHADOW WERE NOTICED IN MOUNTAINOUS AREAS. THIS NEW MODEL HANDLES THE CONVECTIVE INSTABILITY DIFFERENTLY AND THIS WAS VERY OFTEN PREFERRED SUBJECTIVELY. THE SUBJECTIVE VERIFICATION REVEALED SOME SLIGHT IMPROVEMENTS IN THE NEW MODEL WITH RESPECT TO CLOUDS. IN PARTICULAR, THE NEW SHALLOW CONVECTION SCHEME HAS IMPROVED THE MODEL REPRESENTATION OF LOW CLOUDS OVER OPEN WATERS. PRODUCTS AND POST-PROCESSING. THE IMPACTS OF THE NEW MODEL ON PRODUCTS AND POST-PROCESSING SYSTEMS WERE ALSO ASSESSED. ALTHOUGH VERY LITTLE TRAINING DATA FROM THE NEW MODEL HAS BEEN INGESTED INTO THE UMOS (UPDATEABLE MODEL OUTPUT STATISTICS) SYSTEM, IT TURNS OUT THAT THE STATISTICAL UMOS GUIDANCE SHOW BASICALLY THE SAME SKILL AS THAT RUNNING ON THE PREVIOUS LOWER RESOLUTION MODEL. IT IS EXPECTED THAT AS MORE TRAINING DATA FROM THE NEW MODEL KEEPS BEING INGESTED INTO THE UMOS SYSTEM THE UMOS GUIDANCE WILL IMPROVE. SCRIBE (EXPERT SYSTEM TO GENERATE FORECAST PRODUCTS) HAS ALSO BEEN TESTED ON THE NEW MODEL. SINCE SCRIBE IS HEAVILY DEPENDENT ON THE STATISTICAL POST-PROCESSING GUIDANCE IT IS EXPECTED THAT THE SCRIBE PERFORMANCE WILL IMPROVE AS THE STATISTICAL GUIDANCE IMPROVES. THE INCREASED MODEL RESOLUTION BOTH HORIZONTALLY AND VERTICALLY HAS IMPACTS ON SOME OF THE FIELDS CALCULATED BASED ON THE DIRECT MODEL OUTPUTS. THEREFORE, SOME ASPECTS OF THE MODEL POST-PROCESSING HAVE BEEN REVIEWED. AS WELL THE LEVEL OF FILTERING APPLIED ON THE FIELDS OF SOME OF THE CHARTS HAS BEEN REVIEWED TO IMPROVE THE READABILITY AND USABILITY OF THE CHARTS. PROFILES AT SPECIFIC POINTS OF THE MODEL OUTPUTS SENT TO THE REGIONAL OFFICES IN BUFR FORMAT WILL CONTAIN THE FULL VERTICAL RESOLUTION (58 LEVELS) OF THE NEW MODEL. HOWEVER, THE GRIDDED DATA IN GRIB FORMAT WILL NOT CHANGE IN RESOLUTION FOLLOWING THE IMPLEMENTATION. A SEPARATE NATIONAL DATASET AT 15KM WILL BE MADE AVAILABLE TO MSC USERS SOON AFTER. AS WELL, THE RESOLUTION OF THE GRIB DATASET AVAILABLE ON THE CMC EXTERNAL SERVER WILL BE INCREASED TO 15KM AT A LATER DATE IN THE NEXT FEW WEEKS. USERS SHOULD NOT SEE MUCH CHANGE IN THE RECEPTION TIME OF THE OPERATIONAL PRODUCTS WITH THIS IMPLEMENTATION. PRODUCTS SHOULD BE RECEIVED NO LATER THAN 5 OR 10 MINUTES WITH RESPECT TO THE CURRENT RECEPTION TIME. TO MEET THIS PRODUCT TIMELINESS, THE DATA CUT-OFF TIME FOR THE START OF THE REGIONAL OPERATIONAL RUN WILL BE MOVED AHEAD BY 15 MINUTES, FROM 1H50 TO 1H35. THIS WILL COMPENSATE MOST OF THE ADDITIONAL COMPUTATIONAL TIME REQUIRED BY THE NEW MODEL AND THE RELATED DATA PROCESSING. YOU WILL FIND ADDITIONAL DETAILS ABOUT THIS IMPLEMENTATION AT THE FOLLOWING WEB SITE (TYPE IN LOWER CASE). HTTP.//WWW.SMC.EC.GC.CA/CMC/OP_SYSTEMS/RECENT_E.HTML . SPECIFIC QUESTIONS ABOUT THIS IMPLEMENTATION CAN BE DIRECTED TO PRODUCTION-INFOATCMC.EC.GC.CA. EVERELL / ADMA / SMA-SMC TORONTO