A Recharge Oscillator Model for Interannual Variability in Venus' Clouds

TL;DR

This paper introduces a recharge oscillator model linking water abundance and convective variability in Venus's clouds, explaining observed interannual sulfur dioxide fluctuations with coupled oscillations on 3-9 year timescales.

Contribution

The study presents a novel conceptual recharge-discharge oscillator model that connects radiative water effects to convective variability in Venus's atmosphere.

Findings

Oscillations in convective strength and water abundance occur on 3-9 year timescales.

The oscillation period depends on radiative cooling and eddy mixing times.

The model explains interannual sulfur dioxide variability observed in Venus.

Abstract

Sulfur dioxide is a radiatively and chemically important trace gas in the atmosphere of Venus and its abundance at the cloud-tops has been observed to vary on interannual to decadal timescales. This variability is thought to come from changes in the strength of convection which transports sulfur dioxide to the cloud-tops, {although} the dynamics behind such convective variability are unknown. Here we propose a new conceptual model for convective variability that links the radiative effects of water abundance at the cloud-base to convective strength within the clouds, which in turn affects water transport within the cloud. The model consists of two coupled equations which are identified as a recharge-discharge oscillator. The solutions of the coupled equations are finite amplitude sustained oscillations in convective strength and cloud-base water abundance on 3-9 year timescales. The characteristic oscillation timescale is given by the geometric mean of the radiative cooling time and the eddy mixing time near the base of the convective clouds.