Tuesday, March 27, 2012

2876.txt

cc: David Gallego <dgalpuyatXYZxyz.es>, "Frits B. Koek" <koek@knmi.nl>, konnen@planet.nl, Ricardo Garcia Herrera <rgarciahatXYZxyz.ucm.es>
date: Mon, 22 Jan 2007 08:48:06 +0000 (GMT)
from: Dennis Wheeler <dennis.wheeleratXYZxyzderland.ac.uk>
subject: Re: New historical series and some post-CLIWOC results
to: Phil Jones <p.jonesatXYZxyz.ac.uk>

Dear David and Ricardo,

This is a fascinating paper, made the more so because it is based on
data from an area that I know and like very much. I have only a few
comments to make:

1. air pressure: we discussed this generally at the time of the
Carmona meeting and Rob Allen and I were both concerned that when you
corrected for altitude, temperature and gravity the resulting
corrections lowered the air pressure. On any reasonable basis, however
numerically imprecise the adjustment might be, the consequence of the
change should be to increase pressure. The allowance for height from
45m to sea level and temperatures down to zero C would both have this
consequence, and I estimate a correction in the order of +2 degrees for
most days. What effect would this different direction and magnitude of
correction have on the record and its comparison with present day data?
2. wind force terms: it would be useful to include a table that
summarises the overall frequency of the terms used. Was the vocabulary
confined to �fresquito�, �muy fresco�,�frescachon�, �recio�
and �fuerte�? If so it is different to the vocabulary used in the
Fisica Celeste records kept in the early 1800s at nearby San Fernando
also by naval officers (I have a complete set of these observations and
think that I posted a copy to you Ricardo � if not, let me know). I
have copied below my table (only for September-October 1805 so it�s a
small sample please note) of the correlation between the latter
vocabulary and that recorded off-shore by the English blockading fleet.
Notice how this Spanish set has categories for �calma� and �flojo� at
the lower end of the scale and is similar to the 4 or 5 point scale
widely used by landsmen across Europe at the time. These terms
associate nicely with the English neo-Beaufort terms. It would be
interesting to conduct a similar comparison with the Cadiz set. I�m
persuaded by your arguments that the Cadiz observer might be interested
in gusts rather than in mean wind forces. For a harbour master this
makes sense as it is such gusts that could create a risk for the vessel
when in or approaching the Bay. Cadiz is a notoriously hazardous
harbour to get in and out of even today and maritime manuals carry
various warnings.


Beaufort scale/
C�diz term calms to light airs light breezes moderate breezes
fresh & strong breezes moderate gales and above
force 0-1 2 4 5/6 7+
calma 1 0 0 0 0
flojo 0 5 4 0 0
fresquita 0 5 3 6 1
recargada 0 0 0 2 2

3. I�m not sure how far this can be done, but is there a
possibility of cross-referring with the Urrutia brothers� records? They
have thrice data for wind direction (sunrise, midday and sunset),
usefully summarised at the end of each year and there are some notes on
wind force although the scale is difficult to interpret. I don�t think
that Mariano has used these observations, but I have the complete set
here in Sunderland (copies of the original papers). Their scale is, if
my understanding is correct �calma�, �ventolino�,�flojo�, �fresco�. But
I haven�t worked with these data and this is just a first guess. I
might be quite wrong but it�s another 4-point scale similar to that
used in San Fernando and widely elsewhere. Your scale is certainly
different and seemingly �gusty� in bias. In have attached, in case you
haven�t seen them, a typical page from the Urrutia brothers documents.
4. More generally, I�m inclined to agree with Phil�s observation
that tower top observations might be a little different to those closer
to the sea surface. This is not only because of the height differences
but also because observations at sea have a different general setting
to those over land where, even in Cadiz, boundary layers influences
would be more marked. This is, however, more a matter for speculation I
suggest rather than firm evidence.
5. I�m working on the Cadiz � Gibraltar data sets 1520 to 1850 but
have only preliminary results. Working on my own with this sort of
thing it takes time and number crunching can be time-consuming as we
all know. But I�m making progress and hope to report back soon. My
general view is that I�d have much more confidence in the Cadiz data
for this period than with those from Gibraltar. The monthly means of
the latter might look OK, but the daily obs give cause for some
concern. I really have to get this written up for some small
publication somewhere.

Regards

Dennis


----- Original Message -----
From: Phil Jones <p.jonesatXYZxyz.ac.uk>
Date: Tuesday, January 16, 2007 4:58 pm
Subject: Re: New historical series and some post-CLIWOC results

>
> David,
> There isn't yet a paper on the Alpine/N Italian work, as that too
> is ongoing. The possible change in the seasonal cycle is hinted
> at in this paper. We're not quite sure where we are going with
> the Alpine work. There is an overlap series from one site in
> Austria, which suggests that exposure issues in summer are
> not that important, but it is just one site. This uses the same
> approach as in Manola's paper - measuring now with the old
> screens/locations, but not the old thermometers.
> The issue is hard to come to a firm conclusion. I've
> attached another paper on the issue in Sweden. It seems there
> and in the Alps the issue relates mostly to summers or the summer
> half of the year.
>
> I'll leave Dennis to comment on the CLIWOC wind relationships.
> My own view is that the comparison may not apply between
> wind at sea and wind on the coast (at the top of a tower). Shouldn't
> you reduce the wind speed from the tower to the height measured
> or felt aboard ship. The tower was 12m on land , so would have an
> effect of sea breezes. On ship the level may be 4-5m.
>
> Cheers
> Phil
>
>
> At 13:13 16/01/2007, David Gallego wrote:
> >Phil, Dennis, Gunther and everyone,
> >
> >Thank you for your inputs!
> >
> >Phil, I just received your email with the Manolas's paper.
> Thanks! Up to
> >now we could not compare our data with that of the Barcelona's
> group (I
> >don't have the IMPROVE CD). We already contacted Mariano
> Barriendos and
> >now we are waiting for his series. Hopefully within the next few
> weeks we
> >will be able to carry out some analysis. Our idea is to include
> the
> >comparison in the paper.
> >
> >Regarding the similar results for the Alpine region and Northern
> Italy, is
> >there any reference with these results already? I think it will
> be
> >extremely interesting to explicitly extend the area characterized
> for
> >warmer-than-average summers in the 1830s-1840s to southern
> Europe.
> >Unfortunately, we can't look at a continuous series for Cadiz.
> Our
> >reconstructions ends at 1852 and the present day data provided by
> the
> >national meteorology institute are rather discontinuous before
> 1960...>
> >Dennis, it's not in our paper, but we did some comparison with
> the
> >Gibraltar pressure series and at least, the monthly averages
> seemed to
> >agree quite well. We did not perform daily comparisons.
> >
> >All, regarding to the CLIWOC-relation, we are a bit concerned
> about the
> >"tone" of our discussion. We are not sure if it can be
> interpreted as if
> >the entire CLIWOC database is overestimated by a factor of 2 and
> in fact,
> >this result is strictly applicable to the Cadiz data (we?ll
> include a
> >paragraph to make this clearer in the final version). However we
> don't
> >know if some of the ideas in this new paper (measuring ?average
> wind gust?
> >rather ?average wind?) could directly affect the CLIWOC
> estimations. From
> >your experience along the CLIWOC process, do you feel we could be
> >overestimating, in any way, the wind in the process from the
> original wind
> >descriptor to m/s? (in the sense of comparison with present-day
> anemometer
> >averages). Some evidence of change in the wind averages between
> CLIWOC and
> >COADS data was suggested in figure 3 in the NAO-SOI
> reconstruction from
> >the ?Climatic Change? CLIWOC issue, and in figure 2 in our SLP
> >reconstruction based on CLIWOC data in ?Climate of the Past?.
> >
> >Cheers
> >David
> >
> >
> >
> >
> >Phil Jones escribi�:
> >
> >> David,
> >> Do you have the daily T and Pressure data for Cadiz
> digitized by the
> >> group in Barcelona? I was never that convinced by the homogeneity
> >> analysis performed on the Cadiz series. This was very
> difficult as there
> >> were no other long T series for the early 19th century and
> Gibraltar>> seemed to have some problems with pressure in the
> 1820s-1850s.
> >> I still think more can be done with Gibraltar, but this is
> up to
> >> Dennis or me finding some time, which is unlikely for a good few
> >> years yet.
> >> There were also many gaps in the Cadiz record as in
> Climatic Change
> >> in the pre-1820 period. Have you looked at the full record,
> rather than
> >> just
> >> the 1825-52 period compared to 1971-2000. We see this longer
> term warming
> >> in winter further north in the Alpine region and northern
> Italy. In these
> >> regions there is little change in summer as well. What we
> think is
> >> happening
> >> is that the summers are too warm in the earliest years, and
> these should
> >> also show some warming. This might be less than the winters.
> >> I will show your paper to a visitor we have hear to get her
> view as
> >> well.
> >> Cheers
> >> Phil
> >>
> >>At 10:30 10/01/2007, Dennis Wheeler wrote:
> >>
> >>>David,
> >>>
> >>>Thanks for this extremely interesting item and for all your
> hard work. I
> >>>will make a more complete response next week but I'm just about
> to go to
> >>>a conference in Hull and won't be back until the weekend. It's
> good to
> >>>know that CLIWOC is still alive.
> >>>
> >>>regards and best wishes for 2007
> >>>
> >>>Dennis
> >>>
> >>>----- Original Message -----
> >>>From: David Gallego <dgalpuyatXYZxyz.es>
> >>>Date: Tuesday, January 9, 2007 3:13 pm
> >>>Subject: New historical series and some post-CLIWOC results
> >>>
> >>> > Dear all,
> >>> >
> >>> > First we wish you a happy 2007!
> >>> >
> >>> > Despite we have not been in contact for a while, during the last
> >>> > year we
> >>> > have been working with some of the CLIWOC results. We found
> a new
> >>> > historical data source which provides instrumental
> temperature and
> >>> > atmospheric pressure along with estimated wind for the city of
> >>> > Cadiz
> >>> > between 1806 and 1854 (the initial year depends on the
> variable).>>> > We
> >>> > presented some preliminary results last November in the
> MedCLIVAR>>> > workshop hosted in Carmona and now we got almost
> definitive results.
> >>> >
> >>> > First, our results indicate that autumn and winter temperatures
> >>> > (sunset)
> >>> > in the city of Cadiz have risen about 2�C in the last 150 years
> >>> > (2.7�C
> >>> > in December), while summer temperatures do show almost identical
> >>> > values.
> >>> > Second, we applied the CLIWOC dictionary to convert the wind
> >>> > estimates
> >>> > in the port to m/s.
> >>> >
> >>> > The main result (apart of the fact that we could find direct
> >>> > translation
> >>> > for 99.8% of the terms found in the Cadiz archives) is that
> while>>> > the
> >>> > seasonal behavior is almost exactly reproduced, the CLIWOC-
> >>> > translated
> >>> > wind velocities are double than modern anemometer data. We
> believe>>> > that
> >>> > �at least- when used in land-based sources, the use of the
> CLIWOC>>> > dictionary can introduce a strong bias in the
> translated wind
> >>> > forces.
> >>> > Please, find our proposed explanation in the attached draft.
> >>> >
> >>> > We have some concerns about the results and we will be
> pleased if
> >>> > you
> >>> > could assist us with our interpretation, particularly about the
> >>> > following issues:
> >>> >
> >>> > 1. What is your thinking about the surprisingly strong winter
> >>> > warming
> >>> > detected? Are there precedents for similar temperature
> increases in
> >>> > Europe? (Dennis: did you find somewhat similar for
> Gibraltar?) To
> >>> > our
> >>> > knowledge, there is not published estimation of the urban
> thermal>>> > island
> >>> > effect in Cadiz but we think that for this city this effect
> should>>> > not
> >>> > be such strong.
> >>> >
> >>> > 2. The aprox. 2x factor in the wind estimation is applicable
> at the
> >>> > wind
> >>> > conversion for the city of Cadiz. Do you think a somewhat
> similar>>> > (but
> >>> > probably of much lower magnitude) wind overestimation could be
> >>> > affecting
> >>> > the current CLIWOC database? Should the situation be similar
> in the
> >>> > German Maury collection? What is your feeling about this
> finding?>>> >
> >>> > 3. Any other comment will be welcome.
> >>> >
> >>> > Thank you,
> >>> >
> >>> > Regards,
> >>> > David
> >>> >
> >>> >
> >>
> >>Prof. Phil Jones
> >>Climatic Research Unit Telephone +44 (0) 1603 592090
> >>School of Environmental Sciences Fax +44 (0) 1603 507784
> >>University of East Anglia
> >>Norwich Email p.jonesatXYZxyz.ac.uk
> >>NR4 7TJ
> >>UK
> >>-----------------------------------------------------------------
> -----------
> >>
> >
> >Prof. Phil Jones
> >Climatic Research Unit Telephone +44 (0) 1603 592090
> >School of Environmental Sciences Fax +44 (0) 1603 507784
> >University of East Anglia
> >Norwich Email p.jonesatXYZxyz.ac.uk
> >NR4 7TJ
> >UK
> >------------------------------------------------------------------
> ----------
>

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