CHM (Canadian Hydrological Model)

Hydrological Model

Required Data

1. total precipitation [kg m-2]
2. air temperature [oC]
3. humidity [%]
4. wind [m s-1]
5. wind direction [deg]
6. incoming shortwave radiation [W m-2]
7. optionally, longwave [W m-2]

Data Sources

Station (ECCC & Provinces)
● CaPA + GEM (from ECCC)

Spatial Resolution

Flexible spatial; Point/HRU scale

Temporal Resolution

Sub-daily, ideally hourly or less

File Format

● Input is .nc in lat/long grid with time
● Timeseries per station stored in flat ASCII

Strengths and Limitations

● Requires constant meteorological forcing data timesteps

External and Internal Tools

● Python (xarray/pandas or R (dplyr) used to convert existing met data to CHM format.
● WindMapper generates wind speedup maps for spatial interpolation of wind (python)
● Modules exist to spatially interpolate the point data using lapse rate methods

Source Code Availability

● External tools available on github with examples: see https://github.com/Chrismarsh/CHM

Model Workflow

1. Download raw forcing data
2. Bias correction to lower wind speed and correct precipitation undercatch using filters
3. Convert met data to CHM format using external tools

Notes

● External tools available on github with examples: see https://github.com/Chrismarsh/CHM