Understanding the Influence of Convective Clustering on the Width of the ITCZ
Abstract
The spatial organization of convection has been shown to have a large impact on the atmospheric energetic budget in simulations in idealized radiative convective equilibrium configurations. Since the tropical large-scale circulation has also been shown to respond to changes in the atmospheric energy budget, this raises the question whether the spatial organization of convection affects the large-scale atmospheric circulation. We tackle this question by investigating the link between the zonal organization of convection, such as is common in the intertropical convergence zone (ITCZ), and the large-scale circulation. With a combination of observational and meteorological reanalysis data we show that stronger zonal convective clustering is associated with a wider ITCZ and reduced equatorial precipitation. Simulations in idealized aquaplanet configurations suggest furthermore that the zonal convective clustering can by itself cause the observed behavior. In the simulations we can explain this behavior with an energetic argument: Convective clustering leads to a reduction of the atmospheric cloud-radiative effect that leads to a wider meridional distribution of atmospheric heating, to a weakening of the mean meridional circulation and to a widening of the ITCZ.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A54E..02P
- Keywords:
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- 3310 Clouds and cloud feedbacks;
- ATMOSPHERIC PROCESSES;
- 3314 Convective processes;
- ATMOSPHERIC PROCESSES;
- 3319 General circulation;
- ATMOSPHERIC PROCESSES;
- 1616 Climate variability;
- GLOBAL CHANGE