1. PROJECT ------------ Title: Glacial and Holocene Climates Reconstructed by Vegetation-Model Inversion Dates: 01/10/15 - 31/03/19 Funding organisation: NERC, ERC Grant no.: NERC award reference 1859127, ERC (Global Change 2.0: Unlocking the past for a clearer future (grant number 694481)) 2. DATASET ------------ Title: A new multi-variable benchmark for Last Glacial Maximum climate simulations Description: Reconstruction of climate anomalies for the Last Glacial Maximum (LGM, ca 21,000 years ago), made by combining pollen based reconstructions (from Bartlein et al. 2011) and averaged outputs of LGM simulations from the 3rd round of the Palaeoclimate Model Intercomparison Project (PMIP, Braconnot et al. 2011), under a variational data assimilation technique. This reconstruction is designed to be used for data-model comparison, specifically against the results of PMIP4. The dataset consists of 6 variables: moisture index (the ratio precipitation and equilibrium evapotranspiration), mean annual precipitation (mm), mean annual temperature (degrees C), mean temperature of the coldest month (degrees C), mean temperature of the warmest month (degrees C), growing degree days above 5 degrees C (day degrees C). The standard deviation of these variables is also given. Publication Year: 2019 Creator(s): S.F. Cleator, S.P. Harrison, N.K. Nichols, I.C. Prentice, I. Roulstone Organisation(s): University of Surrey, University of Reading, Imperial College London Rights-holder(s): S.F. Cleator, University of Surrey, University of Reading, Imperial College London References: Bartlein et al. 2011 - P. J. Bartlein, S. P. Harrison, S. Brewer, S. Connor, B. A. S. Davis, K. Gajewski, J. Guiot, T. I. Harrison-Prentice, A. Henderson, O. Peyron, I. C. Prentice, M. Scholze, H. Seppä, B. Shuman, S. Sugita, R. S. Thompson, A. E. Viau, J. Williams, and H. Wu. Pollen-based continental climate reconstructions at 6 and 21 ka: a global synthesis. Climate Dynamics, 37:775–802, 2011. Braconnot et al. 2011 - Pascale Braconnot, Sandy P. Harrison, Bette Otto-Bliesner, Ayako Abe-Ouchi, Johann Jungclaus, and Jean-Yves Peterschmitt. The Paleoclimate Modeling Intercomparison Project contribution to CMIP5. CLIVAR Exchanges, 16(56):15–19, 2011. 3. TERMS OF USE ----------------- Copyright 2019 Sean F. Cleator, University of Surrey, University of Reading, Imperial College London. This dataset is licensed by the rights-holder(s) under a Creative Commons Attribution 4.0 International Licence: https://creativecommons.org/licenses/by/4.0/. 4. CONTENTS ------------ File listing: LGM_reconstruction.csv - Last Glacial Maximum reconstruction anomalies at each grid cell. 5. METHOD and PROCESSING -------------------------- This dataset is made by combining site-based pollen reconstructions with aggregated outputs of PMIP3. The possible climates are varied and the most likely climate is found under a 3D-Variational data assimilation scheme. The uncertainty from this process is then used to screen out areas where the pollen reconstructions have had a minimal effect. By using a vegetation model, the effect of changing CO_2 concentrations on pollen reconstructions is also accounted for. The error of the resulting reconstruction is also calculated and given as 1 standard deviation from the variables. The individual fields are: lat - grid cell centre latitude lon - grid cell centre longitude MI - moisture index MAP - mean annual precipitation (mm) MAT - mean annual temperature (degrees C) MTCO - mean temperature of the coldest month (degrees C) MTWA - mean temperature of the warmest month (degrees C) GDD5 - growing degree days above 5 degrees C (days degrees C) MI SD - moisture index standard deviation MAP SD - mean annual precipitation standard deviation (mm) MAT SD - mean annual temperature standard deviation (degrees C) MTCO SD - mean temperature of the coldest month standard deviation (degrees C) MTWA SD - mean temperature of the warmest month standard deviation (degrees C) GDD5 SD - growing degree days above 5 degrees C standard deviation (days degrees C)