Inferences from Simple Models of Slow, Convectively Coupled Processes
Author(s)
Emanuel, Kerry Andrew
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A framework for conceptual understanding of slow, convectively coupled disturbances is developed and applied to several canonical tropical problems, including the water vapor content of an atmosphere in radiative-convective equilibrium, the relationship between convective precipitation and column water vapor, Walker-like circulations, self-aggregation of convection, and the Madden-Julian oscillation. The framework is a synthesis of previous work that developed four key approximations: boundary layer energy quasi equilibrium, conservation of free-tropospheric moist and dry static energies, and the weak temperature gradient approximation. It is demonstrated that essential features of slow, convectively coupled processes can be understood without reference to complex turbulent and microphysical processes, even though accounting for such complexity is essential to quantitatively accurate modeling. In particular, we demonstrate that the robust relationship between column water vapor and precipitation observed over tropical oceans does not necessarily imply direct sensitivity of convection to free-tropospheric moisture. We also show that to destabilize the radiative-convective equilibrium state, feedbacks between radiation and clouds and water vapor must be sufficiently strong relative to the gross moist stability.©2019
Date issued
2019-01Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary SciencesJournal
Journal of the Atmospheric Sciences
Publisher
American Meteorological Society
Citation
Emanuel, Kerry Andrew, "Inferences from Simple Models of Slow, Convectively Coupled Processes." Journal of the Atmospheric Sciences 76, 1 (January 2019): p.195-208 DOI 10.1175/JAS-D-18-0090.1 ©2019 Author(s)
Version: Final published version
ISSN
1520-0469
0022-4928