Setting up a Reference Evapotranspiration Calculated Channel

Reference evapotranspiration (ETo) is the daily water for a grass reference surface based on the weather, specifically solar radiation, temperature, RH and wind speed. ETo is used to help determine when to irrigate. A new reference evapotranspiration reading is calculated at the top of the hour (if you select an hourly time frame) or at midnight local time (if you select a daily time frame). Hourly readings are based on an average of all the sensor readings logged within the hour while daily readings are generated by summing hourly calculations over the past 24 hours.

To set up a reference evapotranspiration channel:

  1. From the main HOBOlink menu, click Calculated Channels and select Reference Evapotranspiration.
  2. Click New Configuration.
  3. Type a name for the reference evapotranspiration configuration.
  4. Select hourly and/or daily for the time frame.
  5. Select the temperature, RH, solar radiation, and wind speed channels to use (it is recommended that all the sensors selected are located on the same weather station).
  6. Enter the height of the wind speed sensor above the ground in meters or feet.
  7. Type the latitude and longitude of the station in degrees (use + for north and west, and use - for south and east). Consider using Google Maps or similar app on a mobile phone at the station location to obtain the latitude and longitude.
  8. Type the elevation of the station in meters above sea level. Consider using Google Maps or similar app on a mobile phone at the station location to obtain the elevation.
  9. Select the time zone for the station.
  10. Click Save. Go to the station page to see the latest values and graphs for the calculated channel. The channel is also available for maps, alarms, exports, and dashboard widgets.

To edit a reference evapotranspiration channel:

  1. From the main HOBOlink menu, click Calculated Channels and select Reference Evapotranspiration.

  2. Select the reference evapotranspiration configuration you want to edit.

  3. Make changes to any settings except the sensors selected. If you want to use different sensors, then you must create a new configuration.

  4. Click Save.

To delete a reference evapotranspiration channel:

  1. From the main HOBOlink menu, click Calculated Channels and select Reference Evapotranspiration.

  2. Select the reference evapotranspiration configuration you want to delete and click .