DOI: 10.25921/r902-p651
title: NOAA/WDS Paleoclimatology - Southern South America Multiproxy 1100 Year Temperature Reconstructions

description: We statistically reconstruct austral summer (winter) surface air temperature fields back to ad 900 (1706) using 22 (20) annually resolved predictors from natural and human archives from southern South America (SSA). This represents the first regional-scale climate field reconstruction for parts of the Southern Hemisphere at this high temporal resolution. We apply three different reconstruction techniques: multivariate principal component regression, composite plus scaling, and regularized expectation maximization. There is generally good agreement between the results of the three methods on interannual and decadal timescales. The field reconstructions allow us to describe differences and similarities in the temperature evolution of different sub-regions of SSA. The reconstructed SSA mean summer temperatures between 900 and 1350 are mostly above the 1901–1995 climatology. After 1350, we reconstruct a sharp transition to colder conditions, which last until approximately 1700. The summers in the eighteenth century are relatively warm with a subsequent cold relapse peaking around 1850. In the twentieth century, summer temperatures reach conditions similar to earlier warm periods. The winter temperatures in the eighteenth and nineteenth centuries were mostly below the twentieth century average. The uncertainties of our reconstructions are generally largest in the eastern lowlands of SSA, where the coverage with proxy data is poorest. Verifications with independent summer temperature proxies and instrumental measurements suggest that the interannual and multi-decadal variations of SSA temperatures are well captured by our reconstructions. This new dataset can be used for data/model comparison and data assimilation as well as for detection and attribution studies at sub-continental scales.
description: This dataset contains the austral summer (DJF) and winter (JJA) 
surface temmperature reconstructions for southern South America (SSA) 
as presented in Neukom et al. 2010.  The data are based on the 
PCR reconstruction (details see paper) and cover the following periods:
Summer: 900-1995
Winter: 1706-1995


We provide the spatial mean as well as spatially explicit datasets.

Files for the SSA Means:
Summer: SSA-Mean_Rekon_DJF_900-1995.txt
Winter: SSA-Mean_Recon_JJA_1706-1995.txt

The Files contain the following columns: 
Years, SSA-Mean temperature anomalies wrt 1901-1995 [°C], 
2SE uncertainties lower bound [°C], 2SE uncertainties upper bound [°C]

The spatial reconstructions are provided in 0.5°x0.5° resolution 
and in NetCDF and text format:
Summer: SSA_Rekon_DJF_900-1995.nc and SSA_Rekon_DJF_900-1995.txt
Winter: SSA_Rekon_JJA_1706-1995.nc and SSA_Rekon_JJA_1706-1995.txt
The text file contain the following columns: 
Year, Temperature anomalies wrt 1931-1995 [°C] of grid-cell 1, 
Temperature anomalies of grid-cell 2, ... , Temperature anomalies 
of grid-cell 9191 

The grid cells are structured as follows:
There are 9191 cells representing 101 longitudes (80.25°W to 30.25°W) 
and 91 latitudes (64.75°S to 19.75°S) 

Cell 1 represents the southwestern corner of the area (80.25°W,64.75°S)
Cell 2 represents the next cell eastward of cell 1 (79.75°W,64.75°S)
...
Cell 101 represent the southeastern corner of the area (30.25°W,64.75°S)
Cell 102 represents the coordinates (80.25°W,64.25°S)
...
Cell 9191 represents the northeastern corner of the area (30.25°W,19.75°S)
Only the land-gridcells (2358 cells) contain data, all other cells have 
"NA" values.