LOVECLIM Climate Model Simulation Constrained by Mann et al. 2009 Reconstruction Goosse, H.; Crespin, E.; Dubinkina, S.; Loutre, M.F.; Mann, M.E.; Renssen, H.; Sallaz-Damaz, Y.; Shindell, D. Goosse, H. Crespin, E. Dubinkina, S. Loutre, M.F. Mann, M.E. Renssen, H. Sallaz-Damaz, Y. Shindell, D. Medieval Climate Anomaly (MCA) earth science/paleoclimate/paleoclimatic modeling (latitude,null,null,degree north,null,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (age,null,null,year Common Era,null,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/paleoclimatic modeling (surface air temperature,null,null,degree Celsius,annual,paleoclimatic modeling,anomalized,null,N,null) earth science/paleoclimate/paleoclimatic modeling (longitude,null,null,degree east,null,paleoclimatic modeling,null,null,N,null) earth science/paleoclimate/model (Global>LATITUDE >LONGITUDE ) 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. STUDY NOTES: 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. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Goosse, H. Investigator : Crespin, E. Investigator : Dubinkina, S. Investigator : Loutre, M.F. Investigator : Mann, M.E. Investigator : Renssen, H. Investigator : Sallaz-Damaz, Y. Investigator : Shindell, D. 2012-02-10 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/12483 https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/goosse2012/ts_loveclim_assim_mann2009.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/goosse2012/readme-goosse2012.txt https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/goosse2012/ts_loveclim_assim_mann2009.txt https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/goosse2012/ts_loveclim_assim_mann2009.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/goosse2012/readme-goosse2012.txt https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/goosse2012/ts_loveclim_assim_mann2009.txt English https://www.ncdc.noaa.gov/paleo/study/12483 https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/goosse2012/ts_loveclim_assim_mann2009.nc https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/goosse2012/readme-goosse2012.txt https://www1.ncdc.noaa.gov/pub/data/paleo/gcmoutput/goosse2012/ts_loveclim_assim_mann2009.txt 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 START YEAR: 500 AD * END YEAR: 2000 AD -180 -90 180 90