Simulation with data assimilation using the LOVECLIM climate model 
constrained by the Mann et al.(2009) reconstruction.
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               World Data Center for Paleoclimatology, Boulder 
                                  and 
                     NOAA Paleoclimatology Program 
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NOTE: Please cite original reference when using these data, 
plus the data file URL and date accessed. 

NAME OF DATA SET: Simulation with data assimilation using the LOVECLIM 
climate model constrained by the Mann et al.(2009) reconstruction.
 
LAST UPDATE: 2/2012 (Original receipt by WDC Paleo) 
CONTRIBUTORS: Goosse, H., E. Crespin, S. Dubinkina, M.F. Loutre, 
M.E. Mann, H. Renssen, Y. Sallaz-Damaz, and D. Shindell.
IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2012-013 


WDC PALEO CONTRIBUTION SERIES CITATION: 
Goosse, H., et al. 2012. 
Simulation with data assimilation using the LOVECLIM climate model 
constrained by the Mann et al.(2009) reconstruction. 
IGBP PAGES/World Data Center for Paleoclimatology 
Data Contribution Series # 2012-013. 
NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. 


ORIGINAL REFERENCE: 
Goosse, H., E. Crespin, S. Dubinkina, M.F. Loutre, M.E. Mann, 
H. Renssen, Y. Sallaz-Damaz, and D. Shindell.  2012. 
The role of forcing and internal dynamics in explaining 
the "Medieval Climate Anomaly". 
Climate Dynamics, doi: 10.1007/s00382-012-1297-0 

ABSTRACT: 
Proxy reconstructions suggest that peak global temperature 
during the past warm interval known as the Medieval Climate 
Anomaly (MCA, roughly 950-1250 AD) has been exceeded only 
during the most recent decades. To better understand the 
origin of this warm period, we use model simulations 
constrained by data assimilation establishing the spatial 
pattern of temperature changes that is most consistent 
with forcing estimates, model physics and the empirical 
information contained in paleoclimate proxy records. 
These numerical experiments demonstrate that the 
reconstructed spatial temperature pattern of the MCA 
can be explained by a simple thermodynamical response 
of the climate system to relatively weak changes in radiative 
forcing combined with a modification of the atmospheric 
circulation, displaying some similarities with the positive 
phase of the so-called Arctic Oscillation, and with northward 
shifts in the position of the Gulf Stream and Kuroshio currents. 
The mechanisms underlying the MCA are thus quite different 
from anthropogenic mechanisms responsible for modern global 
warming. 



ADDITIONAL REFERENCES: 
Mann, M.E., Z. Zhang, S. Rutherford, R.S. Bradley, M.K. Hughes, 
D. Shindell, C. Ammann, G. Faluvegi, and F. Ni. 2009. 
Global Signatures and Dynamical Origins of the Little Ice Age 
and Medieval Climate Anomaly. 
Science, Vol. 326, pp. 1256-1260, 27 November 2009. 
DOI: 10.1126/science.1177303 

Dubinkina, S., H. Goosse, Y. Sallaz-Damaz, E. Crespin, and M. Crucifix. 2011. 
Testing a particle filter to reconstruct climate changes over the past centuries. 
International Journal of Bifurcation and Chaos, 21 (12) 3611-3618. 

Goosse, H., V. Brovkin, T. Fichefet, R. Haarsma, J. Jongma, P. Huybrechts, 
A. Mouchet, F. Selten, P.-Y. Barriat, J.-M. Campin, E. Deleersnijder, 
E. Driesschaert, H. Goelzer, I. Janssens, M.-F. Loutre, M.A. Morales Maqueda, 
T. Opsteegh, P.-P. Mathieu, G. Munhoven, E. Petterson, H. Renssen, D.M. Roche, 
M. Schaeffer, C. Severijns, B. Tartinville, A. Timmermann, and N. Weber. 2010. 
Description of the Earth system model of intermediate complexity 
LOVECLIM version 1.2. 
Geosc Mod Develop 3: 603-633 

van Leeuwen, P.J. 2009. 
Particle filtering in geophysical systems. 
Month Weath Rev 137: 4089-4114



GEOGRAPHIC REGION: Global
PERIOD OF RECORD: 500 - 2000 AD


FUNDING SOURCES: 
F.R.S.- FNRS (Belgium), Belgian Federal Science Policy Office 
(Research Program on Science for a Sustainable Development), 
EU (project Past4future), US NSF Paleoclimate program (ATM-0902133). 



DATA FILE URLS: 
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/gcmoutput/goosse2012/ts_loveclim_assim_mann2009.nc
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/gcmoutput/goosse2012/ts_loveclim_assim_mann2009.txt
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/gcmoutput/goosse2012/readme-goosse2012.txt 



DESCRIPTION: 
We have performed simulations with the LOVECLIM climate model 
(Goosse et al. 2010) using a so-called "particle filter" 
(van Leeuwen 2009; Dubinkina et al. 2011) that constrains model 
results to follow the signal provided by an annual mean surface 
temperature reconstruction based on a global proxy data network 
(Mann et al. 2009). The central variable in our results is thus 
also the annual mean temperature. The data constrain is applied 
only over the region 30-90°N so this is the only region where 
a good agreement with the reconstruction is expected. 


The data is in the file ts_LOVECLIM_ASSIM_MANN2009.nc. 
It includes annual mean temperatures on a Gaussian 62 x 32 grid. 
The data is in netCDF format and contains one variable, ts, 
the surface temperature in the model in °C for the period 501AD-2000AD. 
It is the best estimate provided by the data assimilation method.