meteohub.de

Hi there,

I was wanting to understand a little more about the evapotranspiration formula used to populate the sol0evo logical sensor.

I realise this parameter is only avaialble on the Davis Vantage stations, but was keen to know:

• Is the evapotranspiraton value calculated by the Meteobridge software, based on the necessary weather parameters supplied by the Davis (including solar radiation or is the value calculated by the Davis station itself and simple pass as a another data point to the Meteobridge

• If the value is calculated in the Meteobridge software, I was wondering where I could find more information on which formula is used. Generally people use the Penman-Monteith equation, but there are other too, and the Penman-Monteith has some nuances to the input parameters

We plan to the use the evapotranspiraton in irrigation planning and so are keen to make sure we understand exactly what is being calculated.

Mark

From what I understand Evapotranspiration (sol0evo) being only available with a Davis system and only available with certain Davis/MB combinations the value is based on the Davis derivation. There needs to be a connection between Davis console and MB for sol0evo, such as a Nano etc, an MBPro for instance reading data via RF does not show sol0evo.

The Davis method (actually 3 methods depending on the system) and ignoring the 2 GroWeather methods just leaves the Vantage Pro as calulated on the console. The Davis method is outlined in AN_28-derived-weather-variables (Derived Variables in Davis Weather Products, Application Note 28) which quite an old document but I don;t believe much has changed?

Thanks Matt for you reply and the link to Application Note 28, which has been very helpful in understanding what's at play and how and where the value is derived. We'll make some clarifications and precisely which Davis/MB combinations are in play (there about a dozen stations in the fleet) and go from there.

Mark