Canadian Historical Daily Snow Depth Dataset (updated)

Overview

This dataset includes historical observations of the daily depth of snow on the ground (daily climate element 013) made at Environment and Climate Change Canada (ECCC) sites by manual ruler or by a sonic sensor equipped autostations. The history of the ECCC daily snow depth observing program is provided in Brown et al. (2021) along with a detailed intercomparison of ruler and sonic sensor observations that showed manual observations typically report more snow than a nearby sonic sensor. The database includes a measurement method flag to differentiate between the two methods. This update extends the Canadian historical daily snow depth database (originally provided on the “Canadian Snow CD” in 2000) up to the end of the 2016/17 snow season (July 31). The same procedures were applied to fill missing values and QC data - see MSC (2000) and Brown and Braaten (1998).

Daily snow depth data for the period after July 31, 2017, can be downloaded using the daily climate data extraction tool at the Canadian Centre for Climate Services (https://climate-change.canada.ca/climate-data/#/daily-climate-data), but these data will not be having the same quality control applied.

Some of the snow depth data provided in this dataset may also exist in the CanSWE dataset (an update to the Canadian Historical Snow Survey Dataset, CHSSD). However the focus of that dataset is on SWE, not snow depth, and may include additional sources. The Canadian Historical Daily Snow Depth dataset is based solely on the ECCC in situ snow depth network because these data are in the public domain.

Provider's contact information

Colleen Mortimer, colleen.mortimer@ec.gc.ca

Licensing

Licence: Open Government License - Canada.

Dataset citable as: Brown, Ross, Canadian Historical Daily Snow Depth Data, Environment and Climate Change Canada, (last access: DD MM YYYY),http://doi.org/10.18164/e75562d9-625c-4dd8-9481-682d50adf2d7, Sep 2021.

Variable name and units:

Snow depth [cm]
Station information: latitude, longitude, elevation, measurement type (ruler or automated).

Spatial coverage and resolution:

Canada, point data.

Temporal coverage and resolution:

1883 - 2017, variable frequency.

Information about observations (number, homogeneity)

Total number of measurements of either type has declined since the early 1980s. Since the mid-1990s the fraction stations using ruler measurements has declined and the fraction of automated measurements has increased (see Fig 1 from Brown et al. 2021).

Information about the technical and scientific quality

This quality-controlled dataset isolates and corrects over 2000 anomalous SD values present in the archive of raw data.
QC procedures were identical to the circa 2000 dataset. See Brown and Braaten (1998).
The automated sensor technology deployed across Canada (SR50 and SR50A sensors) is reliable and robust, with an accuracy of ± 2 cm compared with a co-located ruler observation; however there is a significant bias between the two measurement types. Thus a weather station transition from manual ruler observations to automated sensor will create a discontinuity in the historical time series. Generally station IDs are changed demarking the switch in measurement type, but exceptions were found in some cases.

Limitations and strengths for application in North Canada

Coverage of Northern Canada is less dense than other locations.
The majority of northern locations now take automated measurements (see Fig. 2 of Brown et al. 2021) so there may be breaks or discontinuities in their time series that occurred during the transitions from manual to ruler measurements.
Some Arctic sites exhibit behaviour that differs noticeably from historical manual observations (e.g., strong day-to-day variability and/or extended periods with a very shallow SD of 1–2 cm). These may well reflect local effects from blowing snow and wind scour, which are impossible to verify, and will introduce discontinuities into the historical SD record.
Dataset not restricted to Northern Canada (requires that one select pertinent data from amongst all included)
No current plans to update. Data after 2017 must be retrieved through the Canadian Centre for Climate Services (https://climate-change.canada.ca/climate-data/#/daily-climate-data) data extractor. However these are not quality controlled.

References to documents describing the methodology or/and the dataset

Brown, R. D., and R. O. Braaten, 1998: Spatial and temporal variability of Canadian monthly snow depths, 1946–1995. Atmos.-Ocean, 36, 37–54, https://doi.org/10.1080/07055900.1998.9649605.

Brown, R. D., C. Smith, C. Derksen, and L. Mudryk, 2021: Canadian In Situ Snow Cover Trends for 1955–2017 Including an Assessment of the Impact of Automation, Atmosphere-Ocean, 59:2, 77-92, http://doi.org/10.1080/07055900.2021.1911781.

Link to download the data and format of data:

[Update to new ECCC ECDC website when available]

Data publication delays mean that this data is not public yet.