Surface fluxes and tropical intraseasonal variability: a reassessment

TL;DR

This paper reassesses the role of surface enthalpy flux feedbacks, including cloud-radiative and turbulent fluxes, in tropical intraseasonal variability, emphasizing the need for broader model evaluations.

Contribution

It highlights the significance of surface flux feedbacks in tropical variability and advocates for extensive model testing to clarify their role.

Findings

Surface fluxes correlate with intraseasonal precipitation patterns.

Sensitivity experiments suggest fluxes influence variability.

Observed data supports the importance of flux feedbacks.

Abstract

The authors argue for the hypothesis that interactive feedbacks involving surface enthalpy fluxes are important to the dynamics of tropical intraseasonal variability. These include cloud-radiative feedbacks as well as surface turbulent flux feedbacks; the former effectively act to transport enthalpy from the ocean to the atmosphere, as do the latter. Evidence in favor of this hypothesis includes the observed spatial distribution of intraseasonal variance in precipitation and outgoing longwave radiation, the observed relationship between intraseasonal latent heat flux and precipitation anomalies in regions where intraseasonal variability is strong, and sensitivity experiments performed with a small number of general circulation and idealized models. The authors argue that it would be useful to assess the importance of surface fluxes to intraseasonal variability in a larger number of comprehensive numerical models. Such an assessment could provide insight into the relevance of interactive surface fluxes to real intraseasonal variability, perhaps making it possible to rule out either theoretical explanations in which surface fluxes are crucial, or those in which they are not.