cc: Alan Robock <robock@envsci.rutgers.edu>, Ronald Stouffer <Ronald.Stouffer@noaa.gov>, Norman Grody <Norman.Grody@noaa.gov>
date: Tue Jun 22 17:05:53 2004
from: Phil Jones <p.jones@uea.ac.uk>
subject: Re: Surface Trend in Antarctic
to: Konstantin Vinnikov <kostya@atmos.umd.edu>
Kostya,
I'm off home now and will not be in again until July 5. We're moving house on Friday
and there is still some packing to be done and then all the unpacking. The move is only
2 miles from where we are now - the new house is bigger and has character, some beams
and part of it was built in the 18th century.
For the Antarctic you can take the grid box time series and use those. Apart from a
couple of the boxes over the Peninsula and for McMurdo/Scott, the stations are all
well separated so a grid box time series is a station time series. So that they are
exact you need to use the data from the CRUTEM2 dataset, so you don't have the odd
SST value in during summer and there is no variance correction.
Cheers
Phil
PS I might check my email occasionally whilst away, but only occasionally and then
only when Ruth is out !
At 11:19 22/06/2004 -0400, Konstantin Vinnikov wrote:
Dear Phil,
We can average gridded data globally or hemispherically to analyze
global trends. But as soon as we wish to analyze regional trends we have
to estimate trend at each station and then to average trend estimates for
latitudinal zones and regions. I don't like to use gridded data for trend
analyzes. But we have no choice now.
I understand that all data in zone 75S-85S are really from Land stations,
not SST. So we will use time series of zonal means temperature anomalies
for 75S-85S. For all other latitudinal belts we will obtain time series
for land and ocean and use weighted averages of trend estimates for land
and ocean. Will it be ok for now?
Specifically for Antarctic it would be usefull to look at trends in
stations data. Can you send me 1978-2004 time series of monthly anomalies
of Antarctic stations used in your data set?
Kostya
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr. Konstantin Y. Vinnikov Office: (301) 405-5382
Department of Meteorology Home: (301) 779-2970
University of Maryland Fax: (301) 314-9482
College Park, MD 20742 E-mail: kostya@atmos.umd.edu
On Tue, 22 Jun 2004, Phil Jones wrote:
>
> Kostya,
> There are only 3-4 grid boxes with data in this zone. All come almost
> totally from
> the land stations at Vostok, McMurdo/Scott and Halley, so three
> points/boxes. The marine
> boxes come from ships entering the Ross Sea - probably to reach any bases
> on the coast
> in this sector. Even though there are only 3 grid boxes with data, they
> are likely to be
> much more representative as they will be near complete. The marine data
> will come from
> summer months only and then probably only when sea ice free or been
> cleared by an
> icebreaker. Also I would not have much faith in the SST climatology in
> the region as it will
> involve significant estimation and is likely biased as measurements only
> come from
> ocean observations.
>
> Cheers
> Phil
>
> PS I'm moving house on Friday - just 2 miles away from where we are now.
> I'll be away after
> today until July 5. I will likely be in the odd day next week.
>
> At 21:48 21/06/2004 -0400, Alan Robock wrote:
> >Dear Kostya,
> >
> >I do not understand how you weight this band 91% land, if most of the
> >land grid points are missing. Why don't you just equally average all
> >the grid points that have data, whether they are land or ocean?
> >
> >Alan
> >
> >Professor Alan Robock
> > Editor, JGR - Atmospheres
> > Director, Center for Environmental Prediction
> >Department of Environmental Sciences Phone: +1-732-932-9478
> >Rutgers University Fax: +1-732-932-8644
> >14 College Farm Road E-mail: robock@envsci.rutgers.edu
> >New Brunswick, NJ 08901-8551 USA [1]http://envsci.rutgers.edu/~robock
> >
> >
> >On Mon, 21 Jun 2004, Konstantin Vinnikov wrote:
> >
> > > Dear Phil,
> > >
> > > I have a problem with trend estimate for zone 75S-85S.
> > >
> > > 1. I defined that land grids are more than 50% land.
> > > Ocean grids -less than 50% of land.
> > >
> > > 2. 11.1978-2.2004 trend for land temperature is equal to -0.50K/10yr
> > > for ocean temperature +0.14K/10yr
> > > for Zonal averages +0.14K/10yr
> > > 3. Weighted trend (91%Land+9%Ocean)=-0.44K/10yr is obveousely not correct.
> > >
> > > Land area is 91% of this latitudinal zone. This means that the most of
> > > existing data are really for costal area, only.
> > >
> > > My question is, which of these estimates should be ploted in Figure 1 of
> > > our paper.
> > >
> > > My feeling is that we have to use weighted averages for every latitudinal
> > > zone, but not for this one. For zone 75S-85S I would prefer to plot trend
> > > in zonal averages +0.14K/10yr.
> > >
> > > What do you think?
> > >
> > > Kostya
> > >
> > >
> > >
> > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > Dr. Konstantin Y. Vinnikov Office: (301) 405-5382
> > > Department of Meteorology Home: (301) 779-2970
> > > University of Maryland Fax: (301) 314-9482
> > > College Park, MD 20742 E-mail: kostya@atmos.umd.edu
> > >
>
> 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.jones@uea.ac.uk
> NR4 7TJ
> UK
>
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>
>
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.jones@uea.ac.uk
NR4 7TJ
UK
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