Comments on: Reading meteo.ru Data

By: JerryB

JerryB — Sun, 04 Mar 2007 00:54:34 +0000

Some plain counts of data types in ndp040:

176661 TMIN
183196 TMID
160957 TMAX
182491 PRCP

indicate that some of the numbers in my previous comment don’t
quite add up to what they should. Close, but not exact.

By: JerryB

JerryB — Sun, 04 Mar 2007 00:28:36 +0000

Some counts of ndp040 data, which I suspect will match those
in meteo.ru files:

Total number of
month/year/station sets 183493

Sets containing:

All three temp types
TMIN TMID TMAX 159522

Two of three temp types
TMIN TMID 17030
TMID TMAX 1341
TMIN TMAX 67

One of three temp types
TMIN 31
TMID 5292
TMAX 16

No temperature data 194

PRCP 182480
No PRCP 1013

By: JerryB

JerryB — Sat, 03 Mar 2007 20:12:12 +0000

I found my old program for comparing GHCN monthly means with
their min and max monthly data, and ran it on Barabinsk,
for which GHCN has three sets of monthly means, each with
different numbers. For one of those sets, there are also
monthly min and max numbers in GHCN for several years,
and when min and max numbers are present, the mean for that
set is (min+max)/2, and it usually differs from the numbers
in the other two sets.

I also remembered the name of the file that I posted in January
2005 in which I listed those instances in which at that time the
GHCN monthly mean differed from (min+max)/2 by more than 0.1 C :
http://www.john-daly.com/mmmcmpr.tth

By: JerryB

JerryB — Sat, 03 Mar 2007 18:08:15 +0000

BTW, my impression is that, except in the GHCN adjusted files,
the GHCN monthly mean, min, and max, numbers are all calculated
by someone other than GHCN people.

By: JerryB

JerryB — Sat, 03 Mar 2007 18:00:03 +0000

#9, I would guess that the TMID was used to estimate the monthly mean,
and that when TMIN and TMAX were available, they were simply archived.

By: Steve McIntyre

Steve McIntyre — Sat, 03 Mar 2007 16:45:54 +0000

#9. I’ve looked at daily data for site 29612 – Barabinsk where both GSN and meteo-ru have long daily archives. Where both sites have values, they are identical. There are quite a few daily readings in which there is a TMIN but TMAX. Curiously GHCN has a number of months in which an average is given but there are no daily max values in the entire month. I wonder what they did. Either they estimated the monthly mean from the monthly minimum or there’s some other daily data which has strangely got lost from these two archives.

By: JerryB

JerryB — Sat, 03 Mar 2007 14:53:28 +0000

Re #8,

I bet a donut, or even two, that the GSN will not have the TMID numbers; both of the others will.

By: Steve McIntyre

Steve McIntyre — Sat, 03 Mar 2007 14:34:53 +0000

#7. I’m going to try to compare a daily archive from GSN to a daily archive at meteo and perhaps ndp048 for a site or two and see what turns up.

By: JerryB

JerryB — Sat, 03 Mar 2007 14:13:15 +0000

Steve,

TMID seems to be an average of several readings:

Two excerpts from ndp040.txt:

“Daily mean, minimum, and maximum temperatures are available (to the
nearest tenth of a degree Celsius) for each station. Temperature
observations were taken eight times a day from 1966-89, four times a day
from 1936-65, and three times a day from 1881-1935. Daily mean
temperature is defined as the average of all observations for each
calendar day.”

See Table 1 in ndp040.txt for more details.

“The amount of missing data varies from element to element and station to
station. Typically, the records of minimum/mean temperature are more
complete than those of maximum temperature and rainfall.”

It seems that when only two temps are listed, they probably are not TMIN
and TMAX, and my previous guess on that aspect was probably in error.

By: Steve McIntyre

Steve McIntyre — Sat, 03 Mar 2007 04:37:04 +0000

#5. Jerry – can you determine what TMID is?