Input Data Module

The first step in conducting an analysis is to upload the input data file to be used in SNOSWAB. The users can run SNOSWAB either by using the test dataset or by uploading a new dataset.
For testing SNOSWAB and better understanding how the various components of the model operate, the user can upload the test data set provided by clicking on "Try the tool using the test dataset" button. The test dataset contains three years of weather and user calibration data (UCD). UCD data consists of snow layer thickness (cm; UCD1; corresponding to SNOSWAB SNTFcm output parameter; UCD1 measured at Environment and Climate Change Canada [ECCC] Charlottetown weather station, Prince Edward Island, Canada), soil water content (%; UCD2; corresponding to SNOSWAB SWCfin output parameter; UCD2 measured at Agriculture and Agri-Food Canada [AAFC] Harrington Experimental Farm, Prince Edward Island, Canada), surface runoff (mm; UCD3; corresponding to SNOSWAB SRTact output parameter; UCD3 estimated from hydrograph separation of Bell's Creek stream discharge measured at ECCC hydrometric stations in Prince Edward Island, Canada) and stream baseflow (mm; UCD4; corresponding to SNOSWAB DRAact output parameter; UCD4 estimated from hydrograph separation of Bell's Creek stream discharge measured at ECCC hydrometric stations in Prince Edward Island, Canada). Of note, the surface runoff and stream baseflow obtained from hydrograph separation are governed by watershed scale processes, whereas surface runoff and drainage obtained with SNOSWAB are the result of field scale processes. Hence, the calibration of SRTact and DRAact using the data from the test data file (i.e. UCD3 - surface runoff and UCD4 - stream baseflow) is limited.
For using SNOSWAB the users need to upload daily timeseries. The model accepts source data sets in Comma Separated File (csv) format. The users can use the “Download Sample File” button located on the Upload User Data Page (Load Data) or the "Export Input Data - Daily" menu to obtain a correctly formatted input file that can be used as a model for populating the input data file with user data. The “Export Input Data - Daily” menu becomes available after the test or a user dataset is loaded. The user input file can be uploaded to SNOSWAB by using the "Upload user data" button. SNOSWAB allows uploading of files with maximum 7500 rows (~20 years of daily data). It is recommended to split the input data set in blocks of 20 years daily timeseries when the intent is to analyze longer time periods. It should be noted that the model cannot accommodate missing data (i.e., blank rows in required data columns) or erroneous data entries, and hence it is recommended that the integrity of the source data is verified before uploading. An error message will be displayed, and the user will be redirected to the Load Data page if inconsistencies are detected in the user file.
The input data file consists of a tabular file, with the first row dedicated to the parameter names, 1 column dedicated to calendar date, 4 columns dedicated to required input data (TEMP - daily mean air temperature; TOTPP - daily total precipitation; RAIN - daily rain; ETA - daily actual (or crop) evapotranspiration) and 5 columns reserved for optional user calibration data (UCD1 to UCD5). The required input data columns have to contain values in all rows, while the optional data columns can be left blank if data is not available. UCD data sets are not restricted to certain parameters and can include time series for any parameter that the user intends to use for comparing with the output from SNOSWAB. Examples of calibration time series datasets include thickness of snow layer, soil water content, groundwater recharge, stream baseflow, surface runoff, etc.
The number of columns, data format and the units of the various weather parameters required for the input file are shown in the table below.
SNOSWAB Input data file: format, columns, and units for input and user calibration data (UCD)
Columns DATE TEMP TOTPP RAIN ETA UCD (max. 5 columns)
Units yyyy-mm-dd °C mm mm mm user choice
Values eg. 2021-12-24 -90 to 60 0 to 1800 0 to 1800 0 to 100 user choice

  • Required data:
    DATE - use yyyy-mm-dd format;
    TEMP - daily mean air temperature;
    TOTPP - daily total precipitation;
    RAIN - daily rain;
    ETA - daily actual (or crop) evapotranspiration;
  • Optional data:
    UCD - user calibration data (up to five columns; leave blank if no data is available)
  • The model requires daily data
  • The user input data file has to be uploaded using a file with one column dedicated to calendar date, four columns dedicated to input data (TEMP, TOTPP, RAIN, ETA) and up to five columns dedicated to calibration data (UCD1 to UCD5)
  • Use the first row of the data set for column headings
  • SNOSWAB includes limited input data quality check routines and hence, the user must ensure that the input data set is suitable for analysis (e.g., check dataset for missing or erroneous values, etc.)

On this page the user can specify the beginning and the end of the growing season in the boxes provided. These dates are used for averaging the various parameters during the growing season (GS) and outside of the growing season (OGS). In SNOSWAB, it is assumed that these dates are not changing from year to year and hence, the start and end dates use the mm-dd format (the year is ignored as the same dates are applied to all years available in the input data file).

Once the input dataset is loaded to SNOSWAB via either the "Try the tool using the test data set" or "Upload user data" button an overlay window appears (i.e., "Select the UCD averaging method") asking the user to specify the method used for calculation of monthly values for each UCD timeseries (i.e., averaging vs. summation). Once this step is completed a new button ("UCD") is added to the right of the Input Data tab at the top of the page and the view switches to Graphical View. The UCD menu available at the top of the page allows the user to change the method for the calculation of monthly values for each UCD at any time. See section 4.7. for instructions regarding the inspection of datasets using tables and graphs as well as for the various options available for exporting the data.

Once the loading and inspecting of the input data is completed the user can click on the SNOW menu entry at the top of the page to advance to the first calculation module.

Consult section 3.1. and section 3.3. for more details.