Decline in station numbers, coverage?
gerh...@aston.ac.uk
http://data.giss.nasa.gov/gistemp/station_data/
Is it true that weather station coverage has significantly
deteriorated over the last 20 years (impressive graphic in second link
above)?
If so, why?
Wouldn't we want better coverage to get a more accurate and detailed
measure of surface temperature trends?
Michael Tobis
In this context it's usually remarked that satellite observations are well and good, but they aren't worth much without ground truth to calibrate them.
These conversations seem to arrive at the following: this unfortunate situation is largely a consequence of
1) the somewhat anachronistic structure of science
and
2) the "impedance mismatch" between the time scales of politics and those of climate change
First, surface observations are much less "sexy" than satellite observations, and one can't build a very effective scientific career around them.
Second, the political forces that drive government are not greatly impacted by anything that happens on climate time scales, so one can't build an effective public serviuce career on that basis either.
Consequently, some blazingly obvious things worth doing (continuing to maintain existing lengthy observation series, for instance) are often left undone. They are undone because it is in nobody's personal interest to promote them, despite the fact that it is very much in the common interest that they be done.
If you think this is bad consider observational oceanography, which is more expensive and arguably more crucial (since satellite observations can only tell us about surface conditions) but equally unsupported. We do not have a single instantaneous picture of the temperature structure of any ocean.
mt
William M Connolley
On Sun, 18 Mar 2007, Michael Tobis wrote:
> Consequently, some blazingly obvious things worth doing (continuing to
> maintain existing lengthy observation series, for instance) are often left
> undone. They are undone because it is in nobody's personal interest to
> promote them, despite the fact that it is very much in the common interest
> that they be done.
Its much less clear that maintaining so many sfc stations is a good idea. Europe
is way over-dense for what you need for climate; and they aren't needed for NWP
any more. Fairly soon they won't be needed for climate either...
-W.
William M Connolley | w...@bas.ac.uk | http://www.antarctica.ac.uk/met/wmc/
Climate Modeller, British Antarctic Survey | (01223) 221479
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James Annan
> Consequently, some blazingly obvious things worth doing (continuing to
> maintain existing lengthy observation series, for instance) are often
> left undone. They are undone because it is in nobody's personal interest
> to promote them, despite the fact that it is very much in the common
> interest that they be done.
I'm sure there's some truth in that, but note that what we really need
are more observations from a hundred years ago :-)
> If you think this is bad consider observational oceanography, which is
> more expensive and arguably more crucial (since satellite observations
> can only tell us about surface conditions) but equally unsupported. We
> do not have a single instantaneous picture of the temperature structure
> of any ocean.
Don't you think that the thousands of ARGO buoys represent a massive
improvement over the previous situation, even as ship tracks are declining?
James
AdamW
that a lot of good quality stations were/are at military bases and
there's a lot fewer of those nowadays (esp. in East Anglia). Talking
to some forecasters this can cause problems as any development (esp.
cyclogenesis) in data sparse areas can mean that the models get the
systems wrong in various respects - this did contribute to the under-
forecasting of the 1987 October storm. This however is more typical at
sea and so surface land stations tend to have less affect. I have
however heard some forecasters complain about a lack of surface ob
cover in East Anglia that can make their life a little more difficult.
That said, the Met O. seems to think that they are not especially good
value for money, though there is some compromise with the introduction
AWS systems. Philip Eden tends to be the person to ask about this sort
of thing as he has been keeping careful tabs on such things as CET and
sunshine series and comparisons etc.
Michael Tobis
I stipulate that NWP hasn't gotten any worse as a consequence of reducing the number of stations, and that climate GCMs haven't been directly impacted and aren't likely to be. I agree that for operational purposes some stations may be redundant.
I don't think large scale dynamic models are all there is to climate science though. There may be questions we want to ask of continuous records that aren't directly consequential to large scale models but may shed light on underlying processes.
An example that comes to mind is that eliminating the Milwaukee and Madison stations and replacing with one of intermediate location loses information about the microclimate effects of Lake Michigan. This may be of little interest to someone planning a picnic tomorrow hundreds of miles away but it may be of consequence, say, to someone siting a large wind generation facility nearby, planning for changes in wind climate.
We can't know in advance what questions we might ask of the data. It's clear that continuity has some value, and it's not at all clear (to me) that this value has gone into the calculations of which stations to retain. I suspect this is partly because few influential people are especially career-motivated to argue for in situ data collection for scientific purposes.
It would be interesting to see an animated map of the stations referred to on the GISS site vs time. There may be systematic consolidation in some places, which would be of less concern than abrupt declines elsewhere. I recall Dr S. Hastenrath at U Wisconsin lamenting the loss of continuity at several important sites in Africa.
mt
Robert A. Rohde
maintain the surface record.
The large drop off occuring circa 1990 is not real, but rather is an
artifact of how the data is collected and transmitted. Much of the
data being collected in poorer parts of the world (e.g. Africa and
Asia) are still being recorded on paper. Those records are collected
(and if necessary translated) into a collected volume known as the
World Weather Record that is published only once a decade and has a
substantial lag time. The WWR for the 1990s was only published in the
last 6 months. So a significant number of records took more than 15
years to become available for researchers.
On top of this, there are a variety of geopolitical issues involved
whenever it comes to considering the cooperation between nations. For
example, India has decided to classify their collected climate data on
national security grounds, and will release only a sparse subset of
what really was collected.
My understanding is that the true number of ground based monitoring
stations has not changed dramatically, but that the appearance of
dramatic change simply reflects delays in data availability. It is
worth keeping in mind that when someone makes a pronouncement that X
year was the Y hottest ever, that such announcements will reflect only
reports from the ~20% of the temperature stations that transmit their
data in near real time, and such pronouncments may be revised as
additional data becomes available. On the plus side though, the data
that is available quickly does at least give some sampling across most
of the world, and satellite observations can now augment that.
-Robert A. Rohde
http://www.globalwarmingart.com/
On Mar 18, 3:57 pm, "gerha...@aston.ac.uk" <gerha...@aston.ac.uk>
wrote:
> http://www.magazine.noaa.gov/stories/mag142.htm
>
> http://data.giss.nasa.gov/gistemp/station_data/
>
> http://groups.google.com/group/de.soc.umwelt/browse_thread/thread/995...