Northern Hemisphere and Regional Temperature Reconstructions: readme file
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               World Data Center for Paleoclimatology, Boulder
                                  and
                     NOAA Paleoclimatology Program
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NOTE: PLEASE CITE ORIGINAL REFERENCES WHEN USING THIS DATA!!!!!

NAME OF DATA SET:  Northern Hemisphere and Regional Temperature Reconstructions
LAST UPDATE: 3/2002 (Original Receipt by WDC Paleo)

CONTRIBUTORS: Keith R. Briffa, Philip D. Jones, Fritz H. Schweingruber,
Timothy J. Osborn, I.C. Harris, S.G. Shiyatov, and E.A. Vaganov.

IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2002-015

SUGGESTED DATA CITATION: Briffa, K.R., et al., 2002, 
Northern Hemisphere and Regional Temperature Reconstructions.  
IGBP PAGES/World Data Center-A for Paleoclimatology 
Data Contribution Series #2002-015
NOAA/NGDC Paleoclimatology Program, Boulder CO, USA.

ORIGINAL REFERENCE:  Briffa, K.R., T.J. Osborn, F.H. Schweingruber, 
I.C. Harris, P.D. Jones, S.G. Shiyatov, and E.A. Vaganov, 2001,
Low-frequency temperature variations from a northern tree ring density network,
Journal of Geophysical Research, 106 D3 (16-Feb-2001) 2929-2941.

GEOGRAPHIC REGION: Northern Hemisphere above 20 North Latitude
PERIOD OF RECORD: 1000-1997 A.D. 

LIST OF FILES: readme_briffa2001.txt (this file), 
briffa2001jgr2.xls, briffa2001jgr3.xls  (Microsoft Word format)
briffa2001jgr2.txt, briffa2001jgr3.txt (Tab-delimited text format) 


ABSTRACT:
We describe new reconstructions of northern extratropical summer temperatures 
for nine subcontinental-scale regions and a composite series representing quasi 
"Northern Hemisphere" temperature change over the last 600 years. These series 
are based on tree ring density data that have been processed using a novel 
statistical technique (age band decomposition) designed to preserve greater 
long-timescale variability than in previous analyses. We provide time-dependent 
and timescale-dependent uncertainty estimates for all of the reconstructions. 
The new regional estimates are generally cooler in almost all precalibration 
periods, compared to estimates obtained using earlier processing methods, 
particularly during the 17th century. One exception is the reconstruction 
for northern Siberia, where 15th century summers are now estimated to be 
warmer than those observed in the 20th century. In producing a new Northern 
Hemisphere series we demonstrate the sensitivity of the results to the 
methodology used once the number of regions with data, and the reliability 
of each regional series, begins to decrease. We compare our new hemisphere 
series to other published large-regional temperature histories, 
most of which lie within the 1s confidence band of our estimates over 
most of the last 600 years. The 20th century is clearly shown by all of 
the palaeoseries composites to be the warmest during this period. 


DESCRIPTION: 
Reconstructions of Northern Hemisphere and Regional April-September 
Temperature based on 387 tree ring density chronologies.   Regions 
are as follows and are mapped in Figure 1 of Briffa et al. 2001.

NEUR  Northern Europe
SEUR  Southern Europe
NSIB  Northern Siberia
ESIB  Eastern Siberia
CAS   Central Asia
TIBP  Tibetan Plateau
WNA   Western North America
NWNA  Northwestern North America
ECCA  Eastern and Central Canada

Plate 2, 
Reconstructions of 9 regional April-September Temperature Series:
The accompanying Table contains reconstructions, from Plate 2,
of April-September mean temperature (as degree C anomalies
from the 1961-1990 mean) for each of the regions defined
in Figure 1. These are based on tree-ring density, processed
using the age-band decomposition (ABD) standardisation procedure
that aims to maintain low frequencies in the reconstructed data.
The interannual values are provided here and must be smoothed with 
a 10-year low-pass filter to correspond with curves shown in Plate 2.

The skill of the reconstructions generally deteriorates back in 
time, due to fewer chronologies available within each region and 
the early sections of the series (as delineated by the vertical 
red bars in Plate 2) could be considered not sufficiently reliable. 


Plate 3, Comparison of 6 large-scale reconstructions:
The following reconstructions have been taken from the source
references, and then RECALIBRATED to obtain estimates of 
April-September mean temperatures from all land regions north
of 20N.  All series are temperature anomalies in degrees C with
respect to the 1961-1990 mean.  Note that in Plate 3 of Briffa
et al. (2001) all the series had been smoothed, while the data
listed below are unsmoothed (though column 5 never had any
sub-5-year variability even when unsmoothed).