Oscillations of the Venus Climate System

A.年度内反照率变化我研究了金星上反照率模式的变化如何与大气的动力学和化学有关。我用的是Akatsuki的UV成像仪拍摄的金星日边图像。每个数据集都经过主成分分析，以找到最重要的可变性模式。其中一些模式的空间模式和时间尺度对应于金星大气中已知的物理过程，如4天开尔文波、5天罗斯比波和翻转环流，而另一些模式则无法用简单的解释。因此，我能够将反照率变率分解为已知和未知的动力学，并估计每种动力学模型可归因于变率的比例。十年微量气体变化金星云顶的二氧化硫丰度已被观察到在年际到十年的时间尺度上振荡，但原因尚不清楚。我正在提出一个新的概念模型来解释这种情况。云底水丰度对云底加热和云层对流有很强的影响。云层对流混合反过来决定了大气中水丰度的梯度，从而决定了云底水的丰度。因此，对流和水的丰度形成了一个在年际到年代际时间尺度上振荡的耦合系统，这可以解释二氧化硫向云顶输送的时间尺度。这一模型将代表着我们对金星上大气长期变化的理解的根本进步。

a. Intra-Annual Albedo VariabilityI studied how changing albedo patterns on Venus are related to the dynamics and chemistry of the atmosphere. I used Venus dayside images from Akatsuki's UV Imager. Each dataset was subjected to a principal component analysis to find the most important modes of variability. The spatial patterns and the timescales of some of these modes correspond to known physical processes in the atmosphere of Venus such as the 4-day Kelvin wave, 5-day Rossby waves, and the overturning circulation, while some others defy a simple explanation. I have thus been able to breakdown the albedo variability into known and unknown dynamics and estimated what fraction of variability can be attributed to each dynamical mode.b. Decadal Trace Gas VariabilitySulfur dioxide abundances at the cloud-top of Venus have been observed to oscillate on interannual to decadal timescales but the causes are unknown. I am proposing a new conceptual model to explain this occurrence. The water abundance at the base of the clouds, has a strong influence on the cloud-base heating and cloud level convection. The cloud level convective mixing in turn determines the gradient of water abundance in the atmosphere, and thereby the cloud-base water abundance. Thus, the convection and water abundance form a coupled system which oscillates on interannual to decadal timescales, which can explain the timescale of variability in the transport of sulfur dioxide to the cloud tops. This model will represent a fundamental advance of our understanding of long-term atmospheric variability on Venus.