Open AccessLMDZ6A: The Atmospheric Component of the IPSL Climate Model With Improved and Better Tuned Physics
Author(s) -
Hourdin Frédéric,
Rio Catherine,
Grandpeix JeanYves,
Madeleine JeanBaptiste,
Cheruy Frédérique,
Rochetin Nicolas,
Jam Arnaud,
Musat Ionela,
Idelkadi Abderrahmane,
Fairhead Laurent,
Foujols MarieAlice,
Mellul Lidia,
Traore AbdoulKhadre,
Dufresne JeanLouis,
Boucher Olivier,
Lefebvre MariePierre,
Millour Ehouarn,
Vig Etienne,
Jouhaud Jean,
Diallo F. Bint,
Lott François,
Gastineau Guillaume,
Caubel Arnaud,
Meurdesoif Yann,
Ghattas Josefine
Publication year - 2020
Publication title -
journal of advances in modeling earth systems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.03
H-Index - 58
ISSN - 1942-2466
DOI - 10.1029/2019ms001892
Subject(s) - climate model , convection , atmospheric physics , atmospheric convection , coupled model intercomparison project , plume , atmospheric model , environmental science , thermal , mass flux , climatology , meteorology , atmospheric sciences , physics , climate change , geology , atmosphere (unit) , mechanics , oceanography
This study presents the version of the LMDZ global atmospheric model used as the atmospheric component of the Institut Pierre Simon Laplace coupled model (IPSL‐CM6A‐LR) to contribute to the 6th phase of the international Coupled Model Intercomparison Project (CMIP6). This LMDZ6A version includes original convective parameterizations that define the LMDZ “New Physics”: a mass flux parameterization of the organized structures of the convective boundary layer, the “thermal plume model,” and a parameterization of the cold pools created by reevaporation of convective rainfall. The vertical velocity associated with thermal plumes and gust fronts of cold pools are used to control the triggering and intensity of deep convection. Because of several shortcomings, the early version 5B of this New Physics was worse than the previous “Standard Physics” version 5A regarding several classical climate metrics. To overcome these deficiencies, version 6A includes new developments: a stochastic triggering of deep convection, a modification of the thermal plume model that allows the representation of stratocumulus and cumulus clouds in a unified framework, an improved parameterization of very stable boundary layers, and the modification of the gravity waves scheme targeting the quasi‐biennal oscillation in the stratosphere. These improvements to the physical content and a more well‐defined tuning strategy led to major improvements in the LMDZ6A version model climatology. Beyond the presentation of this particular model version and documentation of its climatology, the present paper underlines possible methodological pathways toward model improvement that can be shared across modeling groups.