Add page for dealing with time dimension

[paigem]

Add under Computations

Maybe add climate event techniques as well (e.g. for climate extremes)

[paigem]

Let's write as a notebook!

[paolap]

Just to avoid we duplicate, I'm happy to start this basically now, so I'll set up the notebook as for computations, start adding some content then push it sometime tomorrow and someone else can add on etc. And then we can repeat the cycle??