Overview
This dataset provides in-situ surface observations archived by the Meteorological Service of Canada (MSC). It containes data from the MSC operational observation system as well as from their parteners. Therefore, not all stations are QC or maintained by MSC. The network of stations containes stations with only automatic instruments, and human observing (or manual) stations.
Provider's contact information
Environment and Climate Change Canada
donneesclimatiquesenligne-climatedataonline@ec.gc.ca
Licensing
Open Government Licence - Canada.
Variable name and units:
Hourly Precipitation Amount (mm)
Daily Total Rainfall (mm);
Daily Total Snowfall (cm);
Daily Total Precipitation (mm);
Daily Snow on the Ground (cm)
Monthly number of days with Precipitation 1.0 mm or more
Monthly Total Snowfall (cm)
Monthly Total Precipitation (mm)
Spatial coverage and resolution:
Canada, point locations.
Temporal coverage and resolution:
Time period varies per station with data for in the North starting in 1940’s or 1950’s until present.
The data is available at the hourly, daily and monthly time steps.
The data will continue to be updated regularly.
Information about observations (number, homogeneity)
The number of active stations changed over time. The following figure from Mekis et al. (2018) is presenting the locations of the surface weather stations across Canada with a Needs Index map in the background as of September 2016.
Figure 1. Surface weather stations across Canada, as of September 2016, with a Needs Index map in the background. For further details on station network evolution see Mekis et al. 2018. [Source: Mekis et al., 2018].
Most of the stations over Northern Canda are ECCC atomatic stations, stations from the Cooperative Climate Network of ECCC (a network of volunteer climate observers using high quality sensors provided and maintained by MSC), and stations from the Aviation Monitoring Station network (which include automated and staffed weather stations) operated by NAV CANADA and the Department of National Defence (DND).
Methodology
Raw and quality-controlled station observations are archived and managed by the MSC’s Archive Operations and Climate Services. Observations from different instruments are stored in different formats in the national archive. The methodology, the instruments and the location of instruments have changed in time. Many of initialy manual stations were replaced with automatic stations. The following is summarising some information regarding the manual measurements that should be considered when using historic station data.
Precipitation is defined as any and all forms of water, liquid or solid, that falls from clouds and reaches the ground. This includes drizzle, freezing drizzle, freezing rain, hail, ice crystals, ice pellets, rain, snow, snow pellets, and snow grains. Types of precipitation that originate aloft are classified under Liquid Precipitation, Freezing Precipitation and Frozen Precipitation. The measurement of precipitation is expressed in terms of vertical depth of water (or water equivalent in the case of solid forms) which reaches the ground during a stated period. The millimetre (mm) is the unit of measurement of liquid precipitation and the vertical depth of water or water equivalent is expressed to the nearest 0.2 mm. Less than 0.2 mm is called a "Trace" (also this number could vary with the instrument and the variable).
Rain is defined as the precipitation in the form of liquid water droplets greater than 0.5 mm. If widely scattered, the drop size may be smaller. The intensity of rain is based on the rate of fall. "Very light" means that the scattered drops do not completely wet a surface. "Light" means it is greater than a trace and up to 2.5 mm an hour. "Moderate" means the rate of fall is between 2.6 mm to 7.5 mm per hour. "Heavy" means 7 mm per hour or more.
Rain, drizzle, freezing rain, freezing drizzle and hail were usually measured at manual stations using the standard Canadian rain gauge, a cylindrical container 40 cm high and 11.3 cm in diameter. The precipitation is funnelled into a plastic graduate that serves as the measuring device. The standard rain gauge has changed over time and many types (some manual, some automatic) are now used (i.e. nipher, tb3, type b, genor, pluvio, TBRG, lambrecht).
Snowfall is the measured depth of newly fallen snow, measured using a snow ruler. Measurements are made at several points which appear representative of the immediate area, and then averaged. "Precipitation" in Canadian Climate Normals tables is the water equivalent of all types of precipitation.
At most ordinary stations the water equivalent of snowfall is computed by dividing the measured amount by ten. At principal stations it is usually determined by melting the snow that falls into Nipher gauges. These are precipitation gauges designed to minimize turbulence around the orifice, and are high enough above the ground to prevent most blowing snow from entering. The amount of snow determined by this method normally provides a more accurate estimate of precipitation than using the "ten-to-one" rule. Even at ordinary climate stations the normal precipitation values will not always be equal to rainfall plus one tenth of the snowfall. Missing observations is one cause of such discrepancies.
Precipitation measurements are usually made four times daily at principal stations. At ordinary sites they are usually made once or twice per day.
The total hourly precipitation is the total precipitation amount for minutes 00 through 60, inclusive, computed as the sum of the four 15-minute precipitation amounts. Precipitation amounts are stored in mm with a resolution of 0.1 mm. Prior to December 10, 2013, quality checks were not performed at the ingest stage and the status of the data is "R" (raw). From December 10, 2013, onward basic automatic quality assessment of the data is being performed at the ingest stage and the status of the data is "Q".
For climate stations operating on a 24-hour basis, before June 1, 1957, the climatological day for precipitation ended at 1230Z of the following day; from June 1, 1957, to June 30, 1961, the climatological day for precipitation ended at 1200Z of the following day; since July 1, 1961, the climatological day for precipitation ends at 0600Z of the following day. In cases where knowing time-of-observation is critical, the best approach is to check the historical inspection reports for the climate station.
Daily precipitation values are derived from: (1) the daily climate stations or Synop stations that provided daily measures separately from hourly measurements, and more resently (2) from hourly climate stations.
Monthly rainfall, snowfall and precipitation amounts represent the average or the total accumulation for a given month, and it is depending on the file.
Information about the technical and scientific quality
This dataset represents Environment and Climate Change Canada’s official station observations. Data are subject to change on an on-going basis as MSC is constantly QCing the data from ECCC stations. Not all data has the same level of QA/QC (i.e. aviation dat is not QA/QC by MSC but by NAV CANADA).
Limitations and strengths for application in North Canada
It is a challenge to sustain a cost-effective observing system over Norther Canada because of a large part of the teritory is constituted by remote areas (it is hard for technicians to fly to the site for maintenance, and they often have to wait for the thaw), and need personal to empty gauges and measure the snowfall. The special climatic conditions produce a large risk of power and telecommunication outages. Concequently, observations in Nortehrn Canada are sparse and records are often incomplete. Since stations spatially are sparse, it is hard to QC and determine the accuracy of the record.
Other challenges are related to changes in the observing network, which involves relocation and closure of sites and changes in instruments and practices. On example is the change in gauge type in manual stations and the change from manual stations to automatic stations. At manual stations, the MSC copper gauge, also called the Type A gauge, was originally used in Canada to measure daily rainfall, while the type B was introduced in 1970s. The comparison of their measurements to the WMO reference pit gauge showed that the manual Type B gauge, in service since the 1970s, provided the most accurate measurements compared to the pit gauge data. Presently many of the stations are authomatic stations.
In general, gauge-measured precipitation has a systematic bias mainly caused by wind-induced undercatch, wetting losses (water adhering to the surface of the inner walls of the gauge that cannot be measured by the volumetric method) and evaporation losses (water lost by evaporation before the observation can be made). The wind-induced undercatch is especially important in the High Arctic.
References to documents describing the methodology or/and the dataset
The manual specific for aviation observations/reports (MANOBS): http://publications.gc.ca/collections/collection_2019/eccc/En56-238-2-2018-eng.pdf and http://publications.gc.ca/collections/collection_2019/eccc/En56-238-2-2018-fra.pdf
The manual of Climatological Observations used by the Cooperative Climate Network of ECCC (MANCLIM): https://publications.gc.ca/collections/collection_2012/ec/En56-238-3-2012-eng.pdf
https://climate.weather.gc.ca/doc/Technical_Documentation.pdf
Link to download the data and format of data:
Hourly, Daily and Monthly
Database searchable by location for CSV via CDO/MSC/ECCC: https://climate.weather.gc.ca/historical_data/search_historic_data_e.html
Only Hourly:
Map based extraction tool for GeoJSON and CSV on CCCS/ECCC: https://climate-change.canada.ca/climate-data/#/hourly-climate-data
Note: Only a subset of the total stations is shown due to size limitations. The priorities for inclusion are as follows: (1) Station is currently operational, (2) Stations with long periods of record, (3) Stations that are co-located with the categories above and supplement the period of record. For additional stations not included, go to CDO/MSC/ECCC.
Only Daily
Map based extraction tool for GeoJSON and CSV on CCCS/ECCC: https://climate-change.canada.ca/climate-data/#/daily-climate-data
CSV via MSC/ECCC: https://dd.weather.gc.ca/climate/observations/daily/
Note: Only a subset of the total stations is shown due to size limitations. The priorities for inclusion are as follows: (1) Station is currently operational, (2) Stations with long periods of record, (3) Stations that are co-located with the categories above and supplement the period of record. For additional stations not included, go to CDO/MSC/ECCC.
Only Monthly
Map based extraction tool for GeoJSON and CSV on CCCS/ECCC: https://climate-change.canada.ca/climate-data/#/monthly-climate-summaries
CSV via MSC: https://dd.weather.gc.ca/climate/observations/monthly/
Publications including dataset evaluation or comparison with other data in northern Canada
There are no publications that evaluate station data specifically on northern Canada. The following papers are providing general discussions on the issues with station data in Canada, with focus on precipitation data.
Mekis, É. and L.A. Vincent, 2011: An overview of the second generation adjusted daily precipitation dataset for trend analysis in Canada. Atmosphere-Ocean, 49(2), 163-177.