I’m still puzzled by the two versions of Core A dD from Steig — they don’t seem to be the same data, though maybe I just haven’t graphed them right yet, since the chronology isn’t presented the same way. The newer version that Steig sent me and that Steve has put up on CA is almost a linear transformation of the archived d18O, but not close enough to have been generated that way for illustrative purposes. But the earlier version that Steig had recently put on his website looks much more different than the d18O series.

Here I want to record six plots from six ice cores from Siple Dome data that are linked below (first link). Of interest to me generally in this matter is analysis of temperature proxies that are closely located.

I processed the raw ice core data using the R code provided above by SteveM in this thread. Five cores covered the 1901-1994 time period and one core (Core C) covered 1837-1994. For better comparison I show only the 1901-1994 periods for all six cores. The del D and O18 data had a very high correlation within in each core and thus I show only the del D plots. The plots are shown in the last link below in this post.

The cores were resolved to greater than annual resolution and thus when I averaged the readings for the resultant annual mean I could have included some differences year to year depending on the portion of each season captured in the mean. The annual data was an average of at least 3 evenly spaced readings which should make the seasonal effect minimal, but since I handled all cores essentially the same the comparisons are unaffected.

The calculated trends for the 1901-1994 and 1956-1994 periods for all cores had no statistically significance for being different than 0. Viewing the plots shows obvious differences from core to core, but without better meta data it is not possible to know the potential origins of those differences.

http://nsidc.org/data/waiscores/iso.html

http://img254.imageshack.us/img254/6020/sipledomesixcores.png

http://hurricane.ncdc.noaa.gov/pls/paleox/f?p=517:1:859780108795203:::APP:PROXYDATASETLIST:7:

Dyer Plateau −70.66 −64.5 2,002 del O18 1989
Siple Station −75.92 −84.15 1,054 del O18 1983
01–5 ITASE −77.06 −89.14 1,239 del O18 1999
00–5 ITASE −77.68 −123.99 1,828 del D 1999
01–2 ITASE −77.84 −102.91 1,336 del O18 1999
01–3 ITASE −78.12 −95.65 1,620 del D 1999
00–1 ITASE −79.38 −111.23 1,791 del D 1999
Siple Dome A core −81.65 −148.81 615 del D 1993

Of the eight cores in the table above 5 were individual measurements and 3 (Siple Station and Dome and Dyer Plateau) were a composite. The 5 ITASE ice cores are also plotted together as a composite as are all 8 together. These 8 cores were used in the Steig paper showing an unprecedented 1940s warming and is linked above. Why the data for the composite 3 ice cores were not listed separately is beyond me at this point. The data for these 5 individual and the composite of 3 cores were found in NOAA link are specifically at the link:

ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/west-antarctic-iso2008.txt

The 2 other individual cores found at the NOAA site are listed below with the link to the data. The 3 cores in the new and old Steig data are not listed at the NOAA site and the data were found at the sites noted above in this thread.

Gomez Ice Core d18O Data
Gomez, SW Antarctic Peninsula: 73.59°S, 70.36°W, 1400 m

ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/gomez/gomez2009d18o.txt

Talos Dome Ice Core Deuterium Data
TD core: 72°48´S; 159°06´E; 2316 m. elev.

ftp://ftp.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/talos/talos_dd.txt

I have plotted (1900 to approximately 2000) the 3 composites in the first link below , the 5 ITASE cores in the second link and Gomez, Talos and the 3 Steig cores in the third link. While some of the proxy series structure is similar there are definite differences. It is easy to see differences in the 1940s temperature relative to the series and the differing trends in the series. The trends and AR1s were calculated for the two periods of time. The first was based on the time period from 1900 to 1995 and the second from 1956 to 1995. The trends were tested for significance at p=0.05 with the formula by Quenouille for AR1 adjustment for degrees of freedom.

1900 to 1995:

Old Steig del O18: Positive trend not significant
Old Steig del D: Negative trend not significant
New Steig del D: Negative trend not significant
ITASE 00-1 del O18: Positive trend not significant
ITASE 00-5 del D: Negative trend not significant
ITASE 01-2 del O18: Negative trend not significant
ITASE 01-3 del D: Positive trend not significant
ITASE 01-5 del O18: Positive trend significant
Gomez del O18: Positive trend significant
Talos del D: Negative trend not significant
Composite of Siple Dome, Siple Station and Dyer Plateau: Positive trend not significant

1956 to 1995:

Old Steig del O18: Negative trend not significant
Old Steig del D: Negative trend not significant
New Steig del D: Negative trend significant
ITASE 00-1 del O18: Positive trend significant
ITASE 00-5 del D: Negative trend not significant
ITASE 01-2 del O18: Positive trend not significant
ITASE 01-3 del D: Positive trend not significant
ITASE 01-5 del O18: Positive trend significant
Gomez del O18: Positive trend significant
Talos del D: Negative trend not significant
Composite of Siple Dome, Siple Station and Dyer Plateau: Positive trend significant

I see differences in trends from one series to another even though the individual trend series do not always have significant trends. Del D tends to produce more negative trends while del O18 produces more positive ones. My question remains that if we cannot know with any certainty how localized the water was that evaporated originally (producing the del factor for the stable isotopes) and subsequently fell in the ice core area we cannot know how different these ice core proxies would be if the effect was related to local temperatures only. A second question is how different would we expect these Antarctica regional temperatures to be, i.e. are we looking at local variability or differences in proxy response for near same temperature changes. We know that the Peninsula has warmed faster than the remainder of Antarctica and East Antarctica has probably little of no warming over the periods measured for trends here. Most of the proxies here are from West Antarctica near the Peninsula and/or Southern Ocean and one in the Peninsula.

The 8 ice cores from the Steig paper, showing a warm 1940s decade as a composite, consist of 7 core locations spread out over West Antarctica and near the Southern Ocean and one core from the Peninsula (Dyer Plateau). The Steig paper uses a composite of all 8 and indicates an association with the SST of the Southern Ocean. I am not at all sure why one would simply show a composite and not the individual ice core measurements. We have Siple Dome as an individual core(s) from Steig in previously presented (old) and recently presented (new) cores but we do not have Dyer Plateau and Siple Station as individual cores. Dyer Plateau would be of interest since it is on the fast warming Peninsula. Gomez core (not in the Steig paper) is on the SW Peninsula and it does show significant warming in both the 1900-1995 and 1956-1995 periods. Gomez actually extends to 2005 and shows significant warming to there from both 1900 and 1956. I wonder if the Dyer Plateau is overwhelming the effects of Siple Dome and Siple Station in Steig’s composite of 3. The Talos ice core is located, I guess, technically in East Antarctica, but is near both West Antarctica and the Southern Ocean. It shows cooling in both periods measured, but the data from that core is so noisy that the cooling does not show significance.

Next I might look at differences series of ice cores to determine whether the difference series will show significant trends – as I suspect a number of differences will.

I did find 6 high resolution ice cores with stable isotope measurements versus depth from Siple Dome at the link below. I do not have an algorithm (if that is indeed what it takes to convert depth to age) to plot stable isotope ratios to time, but this link does show that more ice cores are available than I was previously aware. Lacking depth to time conversion for comparison of these closely located ice cores, I can compare the cores based on equal depths as part of a future investigation.

http://nsidc.org/data/waiscores/iso.html

Hu and Steve, I am thinking that the “new” Steig data where we obtained an unbelievable correlation between del O18 and del D was actually meant to be either only a del D or del O18 data and either the del O18 or del D was meant to be used in a standardized graph were Del D and del O18 data were both used.

The composites found in these two linked articles produce different responses in the 1960- forward periods. In the second linked article below the composite shows the unprecedented warming in the 1940s in the Antarctica and a correlation with the warming in the regional SSTs. The 1960-forward part of the composite shows a rather straight trajectory of an upward trend.

In the first linked article below the 1960-forward part of the composite shows a trending up into the 1980s and then downward with no overall trend appearing – on eyeballing the plot. The plot shows the 1940s warming but not to the extent of the plot in the second linked article. This first linked article shows the undulating and cyclically appearing nature of the proxy response over the last 200 years and shows why selecting endpoints for a trend over this period could affect greatly the trend produced.

If all these ice core data were all available a more interesting comparison of the individual cores could be made.

http://faculty.washington.edu/steig/papers/recent/SchneiderSteigGRL2006.pdf

Antarctic temperatures over the past two centuries from ice cores, by
David P. Schneider, Eric J. Steig, Tas D. van Ommen, Daniel A. Dixon,
Paul A. Mayewski, Julie M. Jones, and Cecilia M. Bitz

Law Dome 2000 (stack)
Siple Station
Dronning Maud Land (several sites)
US ITASE 2000-1
US ITASE 2000-5

http://www.pnas.org/content/105/34/12154.full

Ice cores record significant 1940s Antarctic warmth related to tropical climate variability, by David P. Schneider and Eric J. Steig

Dyer Plateau
Siple Station
01–5 ITASE
00–5 ITASE
01–2 ITASE
01–3 ITASE
00–1 ITASE
Siple Dome A core

I also have to look up the article on ice core sampling in the Antarctica that Steig coauthored before Steig (09). I was pouzzled since it was not references in Steig (09). The core finds as I recall did not agree with Steig (09) and showed a cyclical climate pattern. I do not know at this point if those core(s) are different than those we are currently looking plotting.

A=read.table("http://www.climateaudit.info/data/ice/siple_dome_steig_20120515.txt",sep="\t",header=TRUE)
	A$depth=apply(A[,1:2],1,mean,na.rm=T)
	A$year=1950-siplef(A$depth)
	A=A[A$year>=1000,]
	fm=lm(delD~del18O,A)
	fm1=update(fm,delD~del18O-1)
#Multiple R-squared: 0.9999,     Adjusted R-squared: 0.9999 
#F-statistic: 4.583e+06 on 1 and 246 DF,  p-value: < 2.2e-16 

While both series indicate an elevated plateau late in the series, the calculated trends indicate no significant trends from 1850 to 1994 and significant negative trends from 1956 to 1994. The results are summarized directly below. Not much here to support AGW or Steig (09). Note in the post above I incorrectly referred to this Nature article coauthored by Eric Steig as Steig(08).

Period 1850 to 1994:

delD Slope=-0.0046 SE Slope=0.0271 Prob= 0.86
delO18 Slope=-0.00055 SE Slope=0.0034 Prob=0.87

Period 1956 to 1994:

delD Slope=-0.3637 SE Slope=0.155 Prob= 0.029
delO18 Slope=-0.0458 SE Slope=0.0193 Prob=0.027

http://img43.imageshack.us/img43/1276/newsteigsipledome.png