MED file format

[Jenny Knight]

Hi folks

I'm having to rethink my met data, given current situation affecting access (plus fyi there is a pending update of the CEH PETi data as the previous version has been superseeded and some corrections are being made). Anyway, I was just using rainfall and Potential Evap files separately.

Now I'm using the MET (CEDA hosted) data for monmouthshire/herefordshire - but I'm struggling to find the correct format for the MED file? I've found an example that uses the MED file instead of PRD and EPD (Slapton) but of course no column titles so I'm not certain how to lay my data out!

I apologise, I must have missed this in the documentation somewhere! Any help appreciated.

I did see that there was a program available to convert from Campbell logger data to MED file so this may be of use if still available? Though if I know the correct format I can probably collate what I've got by hand.

Many thanks

Hope everyone is keeping safe

Jenny

[Jenny Knight]

My other option is just to use the hourly rainfall data, and air temp data alongside the Blaney-Criddle formula. It would be useful to know of specific examples that have used this input, and if the Fortran program is available?

Thanks again

Jenny

[Steve Birkinshaw]

Hi Jenny,

As you have found out from the Slapton example the MED file for importing meteorological data into Shetran does work. The format of the file is hiding on pages 63-64 for the user guide: https://research.ncl.ac.uk/shetran/SHETRAN%20V4%20User%20Guide.pdf

However, I would not really recommend using it unless you have no choice. The format is not very nice and you need to work out what to do with missing values. It is generally more reliable to use the PRD file (rainfall) and EPD file (potential evaporation). Previously, I have taken the full meteorological data and calculated potential evaporation externally using the Penman Monteith equation with either some code or an Excel worksheet.

You might have mentioned it before but what years do you need the data for and what are you using the model for? Do you already have the hourly rainfall data? I would have thought you could do better than using the Blaney-Criddle formula for PET, although depending on what you are using the model for a simple representation of PET is often OK.

Regards,

Steve