wrote in message
oups.com...
Thanks Martin. The current end January temperatures are 1 to 2
degrees
warmer than that "February" graphic providing some correlation with
earlier thoughts.

.... I managed to locate my original post from a couple of years ago: I
think the data are still pertinent.


quote
Following some comments regarding the changes in sea surface
temperatures in recent years, I thought I would dig out the maps
published in the 'Weather in Home Waters' series and compare with
current values (actually 15th February ... roughly in the coldest point
of the annual cycle).

The averaging period used in that publication is based on period: 1854
to 1958 (punched card dataset: US Navy); There is always a problem doing
this exercise in that the data are not homogenous, and with SST
measurement in particular, arguments surround how accurate or otherwise
the data are; indeed the publication I took the long-period averages
from discuss the differences between the 'bucket' method (recommended)
and the 'intake' method.

These maps are apparently based primarily on *intake* temperatures,
which the author states had (at this time) been found to be on average
some 0.5degC *warmer* than 'real' surface SST values (intake water is
taken some way below the waterline, but is subject to warming on being
drawn through & past the ship's internal pipework, into the engine-room
area). Taking the worst case scenario then, the 'historic' map might be
regarded as a little too warm, and the differences found below perhaps
greater. That of course assumes that current values are accurate!

However, remembering these problems, the figures appear to confirm the
warming - quite significantly so in some cases.

Using some 'fixed' points: (change, degC)
60N10W: +1.5
60N00W: +1.5
50N10W: +1.0
50N00W: +2.0

Generally, across the 'Shipping Forecast' domain, +1 to +1.5degC, but
some places around +2degC, for example, large areas in the North Sea
(where data coverage should be pretty good both 'then' and 'now') &
fairly generally offshore Norwegian coastal waters. This year (Feb.2004)
in particular, the waters of the Skagerrak appear to be particularly
warm (5 or 6degC from 5-day mean, as opposed to 1 to 3 degC from
averages). Anomalies not quite so high Irish and Celtic Seas (circa +1)
or the western English Channel.

Strong patterns are there - albeit with higher values, so no sign of the
North Atlantic Drift disappearing just yet! Even the little bulge of
warmer water running southward across west Forties from the Northern
Isles is still very pronounced; also the broad 'front' of warm water
from 60N25W to north Hebrides.

The maps can be found on my web site at:-

http://homepage.ntlworld.com/booty.w...st_current.gif
(ex. Met Office for 15th Feb, 5-day mean)
http://homepage.ntlworld.com/booty.w...t_historic.gif
(ex. Weather in Home Waters, Meteorological Office, 1975)

/quote


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