Dear Jim,

Just for information there are three other binary mask Standard Names 
(surface_snow_binary_mask, sunlit_binary_mask and cloud_binary_mask) providing 
a precedent for Elodie's proposal so as you say sea_binary_mask should be added 
to the collection.


Regarding your generic mask suggestion I'm not sure it gains us much as there 
can't be that many candidates out there for additional Standard Names. It also 
causes me some interoperability concerns - automated aggregation of files would 
complicated significantly by such generic labels.


For the more complex categorisation there is already a mechanism in CF, namely 
the area_type Standard Name and vocabulary. I'm not sure opening the gates to 
multiple variations on this themes would help users of the standard.


Cheers, Roy.


Please note that I partially retired on 01/11/2015. I am now only working 7.5 
hours a week and can only guarantee e-mail response on Wednesdays, my day in 
the office. All vocabulary queries should be sent to enquir...@bodc.ac.uk. 
Please also use this e-mail if your requirement is urgent.


________________________________
From: CF-metadata <cf-metadata-boun...@cgd.ucar.edu> on behalf of Jim Biard 
<jbi...@cicsnc.org>
Sent: 11 July 2017 14:33
To: cf-metadata@cgd.ucar.edu
Subject: Re: [CF-metadata] Standard name for land/sea mask


Hi.

Given the prior existence of land_binary_mask, Elodie's request for 
sea_binary_mask makes sense. Even given my request below, if Elodie needs this 
standard name, I endorse it's addition. I don't want to bog her down.

I'd like to suggest that we do something slightly more flexible and create the 
standard name discrete_mask, which could handle both these cases. It could also 
handle numerous other use cases that generally go without a standard name right 
now. The definition could be something like below.

discrete_mask: A variable with the standard name discrete_mask is used to 
indicate a finite set of discrete, related conditions that hold across the 
dimensional range of the variable. These conditions are marked by integer 
values, each of which indicates a specific condition. The particular conditions 
being indicated are defined using flag_values and flag_meanings attributes 
associated with the variable. A single element of the variable can indicate 
only one condition - bit field combinations are not allowed.

I'm thinking this way because in the particular domain Elodie is referring to, 
some files have trinary masks, sea = 0, coast = 1, land = 2, different ones 
define the numbers used to indicate the different conditions, some cover more 
cases (fresh water, for example), etc.

I do, on one level, appreciate that it can be nice to see the standard name on 
a variable and not need to look further to understand how the contents are 
implemented, but I don't think it buys us near as much as we like to think.

Grace and peace,

Jim

On 7/11/17 3:55 AM, Elodie Fernandez wrote:
Dear all,

I would like to suggest the addition of a new standard_name to describe 
land-sea masks. A standard_name already exists: land_binary_mask (
X_binary_mask has 1 where condition X is met, 0 elsewhere. 1 = land, 0 = sea.). 
But in the ocean modelling community, we have already existing files describing 
those masks, but from an "ocean point of view", so 1 is for sea and 0 is for 
land points.
So I would like to request the addition of the standard_name "sea_binary_mask",
with definition "X_binary_mask has 1 where condition X is met, 0 elsewhere. 1 = 
sea, 0 = land" and unit "1".

Best regards,
Elodie


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