Understanding and modeling tropical rainfall has proven to be one of the most stubborn challenges in climate science. Tropical rainfall biases such as a double inter-tropical convergence zone (ITCZ) in the East Pacific have now persisted more than two decades despite the general improvements of climate models, and projections for the ITCZ and the monsoon systems remain uncertain in magnitude and sign.
Connected to a workshop on ITCZ and monsoons that was held at Columbia University in September 2015, we have designed the "Tropical Rain belts with an Annual cycle and Continent - Model Intercomparison Project." TRAC-MIP involves five experiments using idealized aquaplanet and land setups to explore the dynamics of tropical rainfall. By using interactive sea-surface temperatures and seasonally-varying insolation TRAC-MIP fills the gap between idealized aquaplanet simulations with prescribed SSTs and the fully-coupled realistic model simulations of CMIP5.
TRAC-MIP mostly involves state-of-the art comprehensive climate models, but it also includes a simplified model that neglects cloud and water-vapor radiative feedbacks. This will allow us to better connect the results from the TRAC-MIP comprehensive models to theoretical studies of tropical rain belt dynamics.
TRAC-MIP is part of the World Climate Research Program and its Grand Challenge on "Clouds, circulation and climate sensitivity." It addresses the question "What controls the position, strength and variability of the tropical rain belts?" raised by Bony et al. (2015).
The following documents provide more information on TRAC-MIP and describe the simulation protocol:
- TRAC-MIP presentation at the 2015 ITCZ/monsoon workshop
- TRAC-MIP simulation protocol
If you are interested in running your model for TRAC-MIP or in analyzing the simulations, please contact us at tracmip-at-gmail.com.
The model data is made available through ESGF
https://esgf-ui.ceda.ac.uk/cog/search/cmip6/
and through Pangeo:
https://catalog.pangeo.io/browse/master/climate/tracmip/
In case of questions please contact us at tracmip-at-gmail.com.
The TRACMIP introduction paper was published in the Journal of Advances in Modelling Earth Systems. The paper is open access and is available here: [TRACMIP Introduction Paper].
Aiko Voigt, Michela Biasutti, and Jack Scheff
Lamont-Doherty Earth Observatory, Columbia University, New York, USA
Institute of Meteorology and Climate Research - Department Troposphere Research, Karlsruhe Institute of Technology, Karlsruhe, Germany
Department of Geography and Earth Sciences, University of North Carolina, Charlotte, NC, USA