[CF-metadata] Days of rain

From: Jonathan Gregory <j.m.gregory>
Date: Mon, 1 Sep 2014 17:42:13 +0100

Dear Dan

> We have several variables that we describe loosely as 'days of rain'. Strictly speaking they are a count (e.g. for a calendar month) of the number of days when the 24-hour precipitation total was greater than or equal to a threshold. We currently generate grids for three thresholds - 0.2mm, 1.0mm and 10.0mm. My intention is to use the following existing standard name:
>
> number_of_days_with_lwe_thickness_of_precipitation_amount_above_threshold
>
> My only slight problem is that the definition implies 'greater than' whereas our variables are 'greater than or equal to' the threshold. Assuming the observations have a precision of 0.1 mm ...

I think it depends on how the data have been treated. Are they rounded to the
nearest 0.1 mm? If so, a recorded value of 0.0 mm means an actual value in the
range 0.00-0.05 mm, 0.1 mm means 0.05-0.15 mm, 0.2 mm means 0.15-0.25 mm, etc.,
and your threshold of 0.2 mm in recorded precipitation is actually a threshold
of 0.15 mm. That is therefore what I would suggest as the coordinate value for
the threshold.

Best wishes

Jonathan
Received on Mon Sep 01 2014 - 10:42:13 BST