add new temperatures in Code table 4.2

[sebvi]

Branch

https://github.com/wmo-im/GRIB2/tree/issue-58

Summary and purpose

This document propose to add a new entries in Code table 4.2.

Action proposed

The team is requested to approve the content of this proposal for inclusion with the next update of the WMO Manual on Codes.

Discussions

ECMWF is developing a new surface module to better describe surface processes. The model includes multiple model layers of snow, ice and soil. The temperature parameter is needed in all three types of layers (soil (level 151), snow (level 114) and ice (level 152)) and over the three types of surface for snow and ice (inland water (discipline 1), soil (discipline 2) and ocean (discipline 10)).
The proposal below addresses the missing temperatures for snow and ice in the relevant disciplines. With these new entries, the fields will be encoded using missing values where the domain does not correspond to the discipline. However, global parameters, not tied to a particular surface or discipline, would be very handy! This is possibly something to look at while developing GRIB3.

Detailed proposal

ADD in Code table 4.2 discipline 1 category 2 - Inland water
Octet Parameter Units
14 Snow temperature K

ADD in Code table 4.2 discipline 2 category 3 - Soil products
Octet Parameter Units
29 Ice temperature K

ADD in Code table 4.2 discipline 10 category 2 Ice
Octet Parameter Units
13 Snow temperature (over sea ice) K

[sebvi]

branch updated. I took the liberty to add in discipline 1 category 2 the traditional ranges "Reserved", "Reserved for local use" and "missing" because these were not present.

[amilan17]

@sebvi @jitsukoh 

please verify line 1010 in GRIB2_CodeFlag_4_2_CodeTable_en.csv

https://github.com/wmo-im/GRIB2/pull/73/files#diff-6e02915ae3205f56509d9ba9ce36a0d26f69ac4fbd6c6e02a86ff3720dc062d6R1010

[sebvi]

Hi @amilan17 I am not sure I understand what you are asking me to check. Line 1010 looks ok to me

[amilan17]

@sebvi 

this line differs from the proposal in the issue #58 

Which one is correct? 

A) ...,13,,Snow temperature,,K,Operational

B) ...,13,,Snow temperature (over sea-ice),,K,Operational

[sebvi]

ahhh :) well, both are correct, the second one is more precise in a sense. Maybe we add the more precise one to avoid potential confusion?

[amilan17]

It's up to you. I'm just trying to verify that the amendment is in line with the proposal. Please let me know ASAP! Thanks.

[sebvi]

Let's use option B then :)

[amilan17]

Thanks!