Montana Mesonet Quality Control Procedures

We perform operational and daily quality checks on station data to ensure the data reported by our stations is reliable and accurate. We currently perform four tests that are recommended by the Oklahoma Mesonet:

  1. Range Test: For a given measurement, an upper and lower threshold of reasonable measurement values are provided. If the measurement falls outside of those values, a flag is raised.
  2. Step Test: For two consecutive measurements of a given variable, the difference between the two values is compared to a maximum allowable “step” size. If the difference is larger than the step size, a flag is raised.
  3. Persistence Test: The standard deviation of all values of a given variable over the course of a day is calculated. If the standard deviation is smaller than a specified threshold value, a flag is raised for all values that day.
  4. Shared Sensor Test: If a given sensor observes more than one variable, all variables reported for a time step will be removed if a check fails on an associated variable. For example, the rain gauges at HydroMet stations record both precipitation and the maximum rate of precipitation over a 5-minute interval. If the maximum precipitation rate fails any of the three tests listed above but precipitation does not, precipitation will still be flagged by this test.

Below is a table showing the QA/QC value that are used for each element reported by our stations for all the tests given above. Note that this is an example for the Absarokee HydroMet stations. The values below can change slightly depending on the exact make and model deployed at a station:

Element Units Valid Min. Range Valid Max. Range Allowed Step Size Min. Daily Std. Dev. Shared Element
Air Temperature degC -80 60 10 0.1  
Atmospheric Pressure kPa 60 110 10 0.001  
Bulk EC mS cm^-1 0 6 0.5 0  
Gust Speed m s^-1 0 100 80 0.1 wind_spd
Max Precip Rate mm hr^-1 0 3000 125 0 ppt
Pluviometer Fill Level mm 0 1800 25 0  
Soil Pore EC mS cm^-1 0 6 0.5 0  
Precipitation mm 0 500 25 0 ppt_max_rate
Soil Rel. Permittivity   1 100 0.5 0  
Relative Humidity percent 0 100 20 0.1  
Snow Depth cm 0 950 10 0 snow_depth_q
Snow Depth Quality   0 600 600 0  
Soil Temperature degC -40 60 5 0  
Soil VWC percent 0 100 2.5 0  
Solar Radiation W m^-2 0 2000 800 0.1  
Wind Direction arcdeg 0 360 360 0.1 wind_dir_sd
Wind Direction SD arcdeg 0 180 90 0.1 wind_dir
Wind Speed m s^-1 0 100 40 0.1  

All the code used to perform these QA/QC checks is open-source and available on our GitHub at