NOCN03 CWAO 151831

GENOT TLTP. NO. 002

A NEW LIMITED AREA VERSION OF THE REGIONAL FORECAST SYSTEM WILL
BECOME OPERATIONAL AT THE CANADIAN METEOROLOGICAL CENTRE.

STARTING ON OCTOBER 20 2010 WITH THE 12 UTC RUN THE CANADIAN GEM
REGIONAL FORECAST SYSTEM WILL BE MODIFIED TO INCORPORATE A LIMITED
AREA VERSION OF THE GEM MODEL REFERRED TO AS REG-LAM3D. CHANGES TO
THE ANALYSES WILL ALSO BE PROVIDED TO THE MODEL.

1. REVIEW OF THE MODIFICATIONS TO THE REGIONAL FORECAST SYSTEM.

CHANGES TO THE FORECAST MODEL

THE DOMAIN OF THE REG-LAM3D AT 15KM IS SLIGHTLY BIGGER THAN THE
HIGH-RESOLUTION GRID OF THE CURRENT REGIONAL MODEL. THE 15 KM GRID
HAS BEEN EXTENDED TO THE WEST AND TO THE SOUTH. THE REG-LAM3D IS
PILOTED, HOURLY, BY A GLOBAL VERSION OF GEM AT 55 KM WHICH
REPRESENTS AN INCREASE IN RESOLUTION FOR MOST OF THE DOMAIN OUTSIDE
THE LAM DOMAIN ITSELF. OTHERWISE NO CHANGES HAVE BEEN MADE TO THE
PHYSICS AND DYNAMICS OF THE MODEL. THIS NEW SYSTEM WILL ALLOW
ADDITIONAL DEVELOPMENT OF THE PHYSICS IN THE BOUNDARY LAYER.

CHANGES TO THE ANALYSIS

THE INTRODUCTION OF A LIMITED AREA MODEL BROUGHT SIGNIFICANT
TECHNICAL CHANGES IN THE WAY THE ANALSYS IS PERFORMED. IN ADDITION
OF THESE CHANGES, THE ANALYSIS IS NOW PERFORMED AT T200 (100KM)
OVER THE LAM DOMAIN INSTEAD OF T108 (180KM) GLOBALLY AND NEW
BACKGROUND ERROR STATISTICS OVER 4 SEASONS HAVE BEEN COMPUTED USING
THE NMC METHOD. THIS NEW SYSTEM WILL NOW ALLOW THE DEVELOPMENT OF
NEW APPROACHES AND THE ASSIMILATION NEW TYPE OF DATA.

2. OUTPUTS

ADJUSTMENTS TO SOME PRODUCTS WERE NEEDED AS THEY COVER AREAS
OUTSIDE THE DOMAIN OF THE REG-LAM3D. A BLENDING METHOD, USING
INFORMATION FROM THE PILOT TO COMPLETE THESE PRODUCTS OUTSIDE THE
LAM DOMAIN IS USED. EVENTHOUGH THE NEW FORECAST SYSTEM INVOLVES THE
NEED TO RUN A PILOT TO SUPPORT THE REG-LAM3D, THE COMPUTATIONAL
COST OF RUNNING A DRIVING GLOBAL MODEL AND A LAM IS THE SAME AS
WITH THE PREVIOUS SYSTEM. THE PILOT GLOBAL GEM MODEL AND THE
REG-LAM3D WILL PRACTICALLY BE RUNNING AT THE SAME TIME AND
CONSEQUENTLY NO CHANGES TO THE TIME OF AVAILABILITY OF THE PRODUCTS
ARE EXPECTED.

3. FORECAST EVALUATION

OBJECTIVE AND SUBJECTIVE VERIFICATIONS OF THE REG-LAM3D OVER A
THREE MONTH PARALLEL RUN REVEALED NO DIFFERENCE IN THE QUALITY OF
FORECASTS. IN MOST CASES NO SIGNIFICANT DIFFERENCES WERE NOTED IN
COMPARISON WITH THE CURRENT REGIONAL MODEL. SPECIAL ATTENTION WAS
GIVEN TO WEATHER SYSTEMS OVER THE ATLANTIC OCEAN, SPECIALLY THE
ONES THAT WOULD TRACK ALONG THE EASTERN BOUNDARY OF THE DOMAIN
(COASTAL DEVELOPMENT), OR THE ONE MOVING FROM AN AREA OUTSIDE THE
DOMAIN (TROPICAL STORMS) AND NO DETERIORATION OF THE FORECAST WAS
NOTED. WITH NO IMPACTS ON THE MODEL BIASES NO IMPACTS WERE
CONSEQUENTLY NOTED ON THE SCRIBE OUTPUTS.

THE REG-LAM3D MODEL WILL NOW PILOT THE AIR QUALITY FORCAST MODEL
GEM-MACH15. THIS CONFIGURATION WAS EVALUATED OVER SUMMER AND WINTER
PERIODS WHICH CONFIRMED NO SIGNIFICANT DIFFERENCES IN FORECASTS OF
CHEMICAL SPECIES.

FOR MORE DETAILS PLEASE REFER TO THE TECHNICAL NOTE ON THIS TOPIC
WHICH WILL BE MADE AVAILABLE AT:
HTTP://WWW.SMC.EC.GC.CA/CMC/OP_SYSTEMS/RECENT_E.HTML

FOR SPECIFIC QUESTIONS CONCERNING THIS IMPLEMENTATION, YOU CAN
WRITE TO:
PRODUCTION-INFO(AT)CMC.EC.GC.CA

GRIMES ADMA - MSC / SMA - SMC TORONTO