Tuesday, May 15, 2012

4250.txt

date: Tue Mar 13 10:32:22 2001
from: Tim Osborn <t.osbornatXYZxyz.ac.uk>
subject: Re: results
to: Scott Rutherford <srutherfordatXYZxyzginia.edu>

At 14:06 08/03/01 +0800, you wrote:
>That sound good. I'll place the data on my anonymous ftp site
>(holocene.evsc.virginia.edu/pub/sdr). I'll put both the NH mean and
>the full gridded reconstruction which will be the following:
>
>1008 gridpioints starting with 70N and 180W then running left to
>right 72 longitude points then dropping 5 degrees of latitude. The
>far right is 5N, 175E. Time goes from 1404 to 1963 down.
>
>The verification run filling 1856-1900 using just the mxd data will
>have the same format as the 1404-1963 data, but going from 1856-1998.

Scott, I've ftp'd the files now. Some problems/questions:

(1) I'm a little confused:
crua6[/cru/u2/f055/data/paleo/tapio_recons] wc *
1 560 8961 1400-warm-mxd-nhmean.ascii
561 565040 9041201 1400-warm-mxd-recongrid.ascii
144 144271 2308480 verify-warm-mxd-grid.ascii
1 143 2289 verify-warm-mxd-nhmean.ascii
The 1404-1963 should have 560 values/lines (the nhmean does, the grid has 561!), while the 1856-1998 should have 143 values/lines (the nhmean does, the grid has 144). If we have 72 longitude points and 14 latitude points (to give 72*14=1008), then 1008*560=564480 and 1008*561=565488, yet in 1400-warm-mxd-recongrid.ascii we have something in between (565040 words = values). Is there some extra header line or something? I've just realised that maybe the nhmean time series is included in the grid file as the first or last line, since the mismatch between 1008*560 and 565040 is 560 values on one line. ???

(2) The instrumental temperatures I'm using have the centre of each grid box at (e.g.) 177.5W, 77.5N. Does your 180W, 80N refer to the top-left of the grid box, or are we really using slightly offset grids?

(3) I've just spotted some 'NaN' values in the file - are those the grid points at which there was never enough observed data to try to infill the values? This makes it a little difficult to read in - though I guess I can just do a global edit and change NaN to some missing code.

(4) The values seem to have values as large as 170 or more. What are the units? Are they standardised anomalies or maybe anomalies in degrees C, but multiplied by some factor (maybe 100?). What period are they anomalies from? I assume from the the calibration period (1901-1960), but please confirm.

>I'll leave the instrumental data in both of these so you can check
>and make sure we are looking at the same gridpoints. These are all
>northern hemisphere warm-season, April-September.

(5) Do you mean that those grid boxes that originally had an observed temperature value in them, at a particular year, still have that value? Presumably there are no such values in the verification run from 1856-1900 - I guess that those are *all* infilled from the density only. For the 1400 run, I guess that *all* the values from 1856 onwards are instrumentally-based (though infilled), except for those few 'Nan' boxes that couldn't be infilled with either instrumental or MXD data. Can you confirm all these things?

(6) Is it possible to also send me the instrumental file from which you started the verification run (not the infilled version). This is just to ensure that my observed version is the same (& same coverage) as the one you're using.

Thanks for all this. Sorry for so many questions, just want to make sure I get this right first time if possible.

Cheers & hope all's well with you.

Tim


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