Finding SRIDs of UTM quadrants or define other quadrants that are not at Equator

Question

Trying to find the SRID of each official-updated ("SIRGAS 2000" or WGS84) UTM quadrant of Brazil.

I am supposing that Latitude bands can use precise local projections, so on different SRID for each quadrant. But...

PostGIS and reference websites (epsg.io or spatialreference.org) supply only SRID of the quadrant N (e.g. the SRID of quandrant "20N" is 31974 and "19N" is 31973), because its central meridians are at Equator line... And about other quadrants?.

The EPSG standard offer other (not N) SRIDs quadrants. For exemple quadrant SIRGAS 22S has SRID 31982, WGS 84 22S has SRID 32722, 25S has 32725... But not all.

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Notes

At Web and PostGIS's spatial_ref_sys table I see only 3 SRIDs, that are official and updated:

SELECT auth_name,srtext FROM spatial_ref_sys WHERE srid IN (31972,31973,31974);

All srtext say something as "PROJCS... SIRGAS 2000 / UTM zone ...". So, it shows a clue to find others, and the query returns 24 rows, but no one is for Brazil (!).

SELECT srid, auth_name, substr(srtext,1,35)||' ...' srtext_clues
FROM spatial_ref_sys
WHERE srtext ilike '%SIRGAS%2000%UTM%zone%';

When looking for a specific quadrant, for example 18H (or other any 18 that is not 18N), no return, query below is empty.
PS: and other quadrants no one is SIRGAS (neither WGS84), so no one is the "official updated projection".

SELECT srid, auth_name, substr(srtext,1,45)||' ...' srtext_clues
FROM spatial_ref_sys
WHERE srtext ilike '%UTM%zone%' AND srtext~'18[HJKLM]';

Answer 1

Oops, seems that my question is "a XY Problem"... More precisely two confusions:

1- Conceptual confusion:

• Y1 Problem: I was supposing that latitude bands of the UTM standard are Oblique Mercator, to gain precision at each "quadrant's local UTM".

• X1 Problem: of course, the name say "Transverse" (no mixed Oblique projections). Here a confirmation that there are no extra parameter. So, the grid is only a notation, like a nominal geocode for Latitude bands... The UTM Grid is not a "projection system different from UTM zone".

2- Confusion about SRID descriptions:

• Y2 Problem: "UTM zone 18N" is the quadrant 18N of the set {..., 18L, 18M, 18N, ...}, that is, the Zone 18 Latitude bands. A wrong hypothesis.

• X2 Problem: "UTM zone 18N" is the "zone 18 at Northern hemisphere", and "UTM zone 18S" the Southern.

Note. As explained in the question-body, a possible source of confusion is the EPSG standard, with many SRID variations, some non-complete sets of UTM variations.

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The "official SRID" for UTM Grid and UTM zones

Official, and easy rule-of-the-thumb. Prefer the SRID with the title "WGS 84 / UTM zone {x}{h}",
where h=Hemisphere, Southern or Northern:

• when h=S use SRID number326{x}
• when h=N use SRID number327{x}

For example for Zone 22S use x=22 and h=S, so SRID=32622.

To automatize by latitude check, use h=S when ST_Y(geom)>0, see a utmzone() function here.

Grid geocode-prefixes are all based on UTM zone number, and suffixe-letters are the Latitude bands: the letter "N" is the first letter in "northern hemisphere" — so letters "A" to "M" are southern hemisphere, "N" to "X" northern.

Official SIRGAS 2000 for Brazil

SELECT srid,  substr(srtext,9,26) as title, left(proj4text,26)||'...' as proj4text
FROM  spatial_ref_sys
WHERE srtext ilike '%SIRGAS%2000%UTM%zone%' AND srtext~'(18|19|20|21|22|23|24|25)S'
ORDER BY 3;

srid	title	proj4text
31978	SIRGAS 2000 / UTM zone 18S	+proj=utm +zone=18 +south ...
31979	SIRGAS 2000 / UTM zone 19S	+proj=utm +zone=19 +south ...
31980	SIRGAS 2000 / UTM zone 20S	+proj=utm +zone=20 +south ...
31981	SIRGAS 2000 / UTM zone 21S	+proj=utm +zone=21 +south ...
31982	SIRGAS 2000 / UTM zone 22S	+proj=utm +zone=22 +south ...
31983	SIRGAS 2000 / UTM zone 23S	+proj=utm +zone=23 +south ...
31984	SIRGAS 2000 / UTM zone 24S	+proj=utm +zone=24 +south ...
31985	SIRGAS 2000 / UTM zone 25S	+proj=utm +zone=25 +south ...

WGS84_UTMzone as alternative SRID for SIRGAS2000

SIRGAS is not world-wide, is only a South American Datum, characterized by its network of ~200 stations
   

Therefore it has non-complete UTM Zones set at ESPG standard... But is possible to confirm that SIRGAS 2000 is de jure and de facto, since ~2015, WGS 84.

It is easy to check by implementation, using the SQL query select srid, substr(srtext,9,26)||' ...' srtext_fragment, proj4text from spatial_ref_sys where srid in (6210,32623,4326):

SRID	srtext_fragment	proj4text
4326	WGS 84	+proj=longlat +datum=WGS84
6210	SIRGAS 2000/ UTMzone 23N	+proj=utm +zone=23 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m
32623	WGS 84/ UTMzone 23N	+proj=utm +zone=23 +datum=WGS84 +units=m

The old ellps=GRS80 has minimal difference (millimettric according to Wikipedia) and only impact on high precision altitude measures. On surface measurements the WGS 84 is a synonymous, as showed by towgs84=0,0,0,0,0,0,0 parameter.

SRID equivalence:

SIRGAS SRID	UTM zone	WGS 84 SRID
31978	18S	32618
31979	19S	32619
31980	20S	32620
31981	21S	32621
31982	22S	32622
31983	23S	32623
31984	24S	32624
31985	25S	32625