convective rain and snow specific water content in Code Table 4.2

[sebvi]

Branch

https://github.com/wmo-im/GRIB2/tree/issue-24

Summary and purpose

ECMWF is requesting 2 new parameters to represent convective rain and snow specific water content.

Action proposed

ECMWF kindly asks the team to review the proposal and accept it during the next session.

Discussions

ECMWF is developing the possibility to generate fields of specific water contents (kg/kg) for convective rain and snow.

These 2 parameters are equivalent to the existing specific rain and snow water content parameters:

• specific rain water content kg/kg discipline=0 category=1 code=85

• specific snow water content kg/kg discipline=0 category=1 code=86

  It is unclear if the two parameters above represents only large-scale, non convective specific water content or the total (large scale + convective). i We would like to request two new parameters : specific rain water content (convective) kg/kg specific snow water content (convective) kg/kg

Detailed proposal

add a new entries in Code Table 4.2, discipline 0, category 1:	Code	Name	Units
124	specific rain water content (convective)	kg/kg
125	specific snow water content (convective)	kg/kg

This proposal takes into account issues #15 and #20 to avoid code entry clash.

[efucile]

@sebvi should they be rain specific water content snow specific water content ?

[sebvi]

I thought so as well @efucile but entry 83-86 in the same table were using that strange ordering (as mentioned in my proposal). I am happy to change because it is more correct but I would then propose to do an editorial change to entries 83-86 to stay consistent

[efucile]

entries 83-86 to facilitate discussion.

Product discipline 0 - Meteorological products, parameter category 1: moisture

code	name	units
83	Specific cloud liquid water content	kg/kg
84	Specific cloud ice water content	kg/kg
85	Specific rainwater content	kg/kg
86	Specific snow water content	kg/kg

[chenxiaoxia2019]

@sebvi Hi, Sebastien. A new branch has been created. As you mentioned in #issue 20, it is common to see clashes when it comes to the parameter. So it is with this one. I proposed to change from 124 to 144, from 125 to 145. Is it okay? FYI, Code Table 4.2

24

124 changed to 144 125 changed to 145

17

122-127

15

122 changed to 143

20

123 changed to 128

[sebvi]

@chenxiaoxia2019 The entries and the branch seem ok to me. However, while checking, I noticed that most of the parameters in the table are specified in kg kg-1 (instead of kg/kg). Maybe we should change the 2 entries to units kg kg-1 More generally we should do a consistency editorial change and change all units containing "/" to the negative exponent notation (in a separate branch only addressing this)

[amilan17]

change units of these entries to kg kg-1 @chenxiaoxia2019

[amilan17]

SUMMARY: Add entries, 144 & 145, to Code Table 4.2, discipline 0, category 1.

[amilan17]

Approved by FT-2020-2.