An ensemble of AMIP simulations with prescribed land surface temperatures

• Published in: Geoscientific Model Development
• Main Authors: Ackerley, D, Chadwick, R, Dommenget, D, Petrelli, P
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus GmbH 2018
• Subjects: Earth Sciences; Atmospheric Sciences; Atmospheric Sciences not elsewhere classified; Sea ice
• Online Access: https://doi.org/10.5194/gmd-11-3865-2018; http://ecite.utas.edu.au/131922

General circulation models (GCMs) are routinely run underAtmospheric Modelling Intercomparison Project (AMIP) conditions withprescribed sea surface temperatures (SSTs) and sea ice concentrations (SICs)from observations. These AMIP simulations are often used to evaluate the roleof the land and/or atmosphere in causing the development of systematic errorsin such GCMs. Extensions to the original AMIP experiment have also beendeveloped to evaluate the response of the global climate to increased SSTs(prescribed) and carbon dioxide ( CO 2 ) as part of the Cloud FeedbackModel Intercomparison Project (CFMIP). None of these international modellinginitiatives has undertaken a set of experiments where the land conditions arealso prescribed, which is the focus of the work presented in this paper.Experiments are performed initially with freely varying land conditions(surface temperature, and soil temperature and moisture) under five differentconfigurations (AMIP, AMIP with uniform 4 K added to SSTs, AMIP SST withquadrupled CO 2 , AMIP SST and quadrupled CO 2 without the plantstomata response, and increasing the solar constant by 3.3 %). Then, theland surface temperatures from the free land experiments are used to performa set of AMIP prescribed land (PL) simulations, which are evaluatedagainst their free land counterparts. The PL simulations agree well with thefree land experiments, which indicates that the land surface is prescribed ina way that is consistent with the original free land configuration. Furtherexperiments are also performed with different combinations of SSTs, CO 2 concentrations, solar constant and land conditions. For example,SST and land conditions are used from the AMIP simulation with quadrupled CO 2 in order to simulate the atmospheric response to increased CO 2 concentrations without the surface temperature changing. Theresults of all these experiments have been made publicly available forfurther analysis. The main aims of this paper are to provide a description ofthe method used and an initial validation of these AMIP prescribed landexperiments.