Optimal Surface Temperature Reconstructions Using Terrestrial Borehole Data
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                NOAA Paleoclimatology Program
                               and
         World Data Center for Paleoclimatology, Boulder
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NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!!

NAME OF DATA SET: Optimal Surface Temperature Reconstructions Using 
Terrestrial Borehole Data

LAST UPDATE: 3/2004 (Correction to reconconstruction series for gridbox weighting)

CONTRIBUTORS: Mann, M.E., S. Rutherford, R.S. Bradley, 
M. K. Hughes, and F. T. Keimig.

IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2003-020

SUGGESTED DATA CITATION: Mann, M.E., et al., 2003,
Optimal Surface Temperature Reconstructions Using Terrestrial Borehole Data,
IGBP PAGES/World Data Center for Paleoclimatology 
Data Contribution Series #2003-020. 
NOAA/NGDC Paleoclimatology Program, Boulder CO, USA. 


ORIGINAL REFERENCES: 
Mann, M.E., S. Rutherford, R.S. Bradley, M. K. Hughes, and F. T. Keimig. 2003.
Optimal Surface Temperature Reconstructions Using Terrestrial Borehole Data, 
JGR Atmospheres, Vol. 108 No. D7,  03 April 2003 
doi: 10.1029/2002JD002532.


Rutherford, R. and M.E. Mann. 2004. 
Correction to "Optimal Surface Temperature Reconstructions Using Terrestrial Borehole Data", 
Journal of Geophysical Research Atmospheres, Vol. 109, D1 1107, doi: 10.1029/2003JD004290.


GEOGRAPHIC REGION: Global
PERIOD OF RECORD:  1000 A.D. - present


ABSTRACT: 
We derive an optimal Northern Hemisphere mean surface temperature reconstruction 
from terrestrial borehole temperature profiles spanning the past five centuries. 
The pattern of borehole ground surface temperature (GST) reconstructions 
displays prominent discrepancies with instrumental surface air temperature (SAT) 
estimates during the 20th century, suggesting the presence of a considerable amount 
of noise and/or bias in any underlying spatial SAT signal. The vast majority of 
variance in the borehole dataset is efficiently retained by its two leading eigenvectors. 
A sizable share of the variance in the first eigenvector appears to be associated 
with non-SAT related bias in the borehole data. A weak but detectable SAT signal 
appears to be described by a combination of the first two eigenvectors. 
Exploiting this eigendecomposition, application of optimal signal estimation methods 
yields a hemispheric borehole SAT reconstruction that is largely consistent with 
instrumental data available in past centuries, and is indistinguishable in its major 
features from several published long-term temperature estimates based on 
both climate proxy data and model simulations.



DESCRIPTION:
bhdata1980.txt is the raw gridded borehole trends, 480 lines by 94 columns. 
The years go 1501-1980 and the columns are the gridpoint locations as in 
columns 1 and 2 of the files eof1 and eof2

eof1.txt and eof2.txt are the weighted eofs for the 1900-1980 case. 
Column 1 is longitude, column 2 is latitude and column 3 is the standardized eof loading.

pc1.txt and pc2.txt are the standardized principal components. 
column 1 is year, column 2 is the pc value.

weightrecon1980-original.txt is the originally published optimal weighted reconstruction 
for the 1900-1980 case, containing an error in gridbox weighting. 
Column 1 is year, column two is the temperature anomaly.

weightrecon1980.txt is the corrected optimal weighted reconstruction for the 1900-1980 case. 
Corrections were made in the gridbox weighting, resulting in changes to the reconstruction. 
Column 1 is year, column two is the temperature anomaly.

weightedgridded.txt is a simple areally-weighted and averaged borehole reconstruction.

gridrecon.txt is the reconstruction for each gridpoint (480 years by 94 gridpoints  
as in bhdata1980.txt). Each gridpoint has had the mean of 1900-1980 set to zero.