Canadian monthly surface pressureVictoria Slonosky* and Edward Graham**

Environment Canada

• Stations

• Sources

• Problems

• Grids and Analysis

*McGill University, Ouranos Consortium for Regional Climate change and Adaptation** University of Fribourg , Switzerland

Sources

• World Weather Records & Monthly Climatic Data for the World

• GHCN• Canadian database (hourly

synoptic since 1953)• Miscellaneous:

– CRU/Phil Jones – Royal Engineers – Canadian archives (Environment

Canada, McGill University)– 19th century Canadian scientific

journals– Phil Trans Roy Met Soc– Academie Royale des Sciences

Common problems• Unreported (?) changes in station

location and/or station elevation: real relocations?

• “sea” and “station” transposed (Greenland)

• Confusion between “sea” and “station”

• Confusion between feet and metres

• Conversion/rounding errors• “50-foot” rule (WMO directive?)

1976• Sea level plateau corrections• Random differences between

GHCN and WWR

Charlottetown

995

1000

1005

1010

1015

1020

187418791884188918941899190419091914191919241929193419391944194919541959196419691974197919841989Year

mb

station sea

Point au Pére / Bagotville

990

995

1000

1005

1010

1015

18741879188418891894189919041909191419191924192919341939194419491954195919641969197419791984198919941999Year

Mb

Point-au-Pére Station Pressure Point-au-Pére Sea PressureBagotville Station Pressure

Clyde

1000

1005

1010

1015

1020

195319561959196219651968197119741977198019831986198919921995Year

mb

sea station

Difference Sea-Station

-2

-1

0

1

2

3

4

195319561959196219651968197119741977198019831986198919921995Year

mb

GRP sea - WWR sea

-0.4-0.35

-0.3-0.25

-0.2-0.15

-0.1-0.05

00.05

195319561959196219651968197119741977198019831986198919921995

Area-average anomaliesNorth of 67 Annual

-0.8-0.6-0.4-0.2

00.20.40.60.8

1873188118891897190519131921192919371945195319611969197719851993

South-east Annual

-1-0.8-0.6-0.4-0.2

00.20.40.6

1873188118891897190519131921192919371945195319611969197719851993

South-west Annual

-0.8-0.6-0.4-0.2

00.20.40.60.8

1873188118891897190519131921192919371945195319611969197719851993

adjusted original

Future Plans

• Analysis of pressure patterns, variability, association with temperature and precipitation

• Daily data

• 18th and 19th century data (Montreal, Quebec City, Atlantic Canada…)