Hey, Yannis
What's this "De Martone" index, you also mention at your site, about?

Hey Wijke,

it's an index of dryness actually, calculated by the formula:

I = P/(10+T) for the annual de Martone index, where P stands for annual
precipitation and T fot the annual mean temperature, or
I'=12P'(10+T') for the monthly de Martone index, where P' is the monthly
precipitation and T' the monthly mean temperature.

It is said that de Martone index values lower than 20 account for the
necessity of watering the soil. The de Martone index is one of the many that
have been internationally proposed for 'counting' how dry or wet an area is.
It is easy to use and calculate, as all weather stations provide with
temperature and precipitation data.
The annual de Martone index for my site stands at 15, with monthly values
varying between 1.8 in June and 38.3 in December. More climatic data for my
site can be found on the newly updated
http://dias.aueb.gr/~ikarag/climate/terpsithea.html.

Yannis, E. Athens
+31.2C, RH 38%