Wednesday, June 12, 2024

GHCN V4 changes.

AS I mentioned in my previous post, GHCN results have been coming through more slowly. I have been following a rule for posting, that I wait for 3800 non-US land stations to report. In April I was a little short, but in May, only 3320 stations by the 11th. So I investigated to see what is going on.
 
It seems that just a few countries are reporting a lot fewer stations than before; specifically, Canada, Australia and Scandinavian countries. It could be said that their previous roster of stations was excessive, but this is a drastic change. Here is a table of the recent numbers of leading countries:
May23JanFebMarAprMay
USA636563086333625162204867
Non-US Total488844974588439439123319
CAN872774883872724164
RUS500532545543510504
SWE2062042051841010
CHINA20020119987200201
GER167168168169160160
FIN1681651691692929
JAP59150150150150150
AUS540133133139137136
NOR1091111101102122
SPAIN98100100978484
INDO939292989299

The US is low but that may be temporary, and anyway, it has far more than needed. But Canada is way down, and Australia has been down all this year. Sweden, Finland and Norway have been down for two months, but the coverage before was excessive. So I'm not worried about the change - I just note it.
To see what this looks like in detail, here is my home state of Victoria in April 2023, and then in April 2024:

Before the change, there were 9 stations in the Melbourne metro area, now just two, which seems reasonable. But it leaves most of the Victoria interior without data.
 
Anyway, for now I'll use data from 3200 non-US stations as the trigger for posting.

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