09:00 〜 10:30
[PPS04-P03] Development of a 1-D Cloud Microphysics Model for Venus using bin and moment methods
★Invited Papers
キーワード：金星、雲微物理、全球気候モデル
Venus is completely shrouded by thick sulfuric acid clouds. The clouds interact with both incoming short-wave and outgoing long-wave radiation and control the Venusian climate and meteorology. Furthermore, clouds are a part of the atmospheric chemical cycle. Thus, to understand Venusian atmospheric sciences, it is essential to investigate the effects of clouds on climate, dynamics, and chemistry. The recent General Circulation Model (GCM) study by Karyu et al. (2023) simulated the cloud structure and variation qualitatively consistent with past near-infrared observations, but the implemented cloud parameterization was not entirely based on physical considerations.
The particle size distribution affects the cloud’s physical structure and radiative properties. To derive realistic size distributions, it is necessary to take into account cloud microphysical processes, such as coagulation, condensation, and evaporation. Using a 1-D cloud microphysics model, Imamura and Hashimoto (2001) (hereafter IH01) suggested that the observed particle size distribution is formed by an interaction between cloud microphysics and atmospheric dynamics. However, the previous microphysical models have been operated only for 1-D or 2-D coordinates of the atmospheric field, in which only situations with simplified effects of dynamical advection were assumed for the investigations of cloud-atmosphere interaction. On the other hand, high-resolution observational data have been accumulated in terms of cloud particle properties and atmospheric parameters by Venus Express and Akatsuki, which are often associated with cloud morphologies (e.g., McGouldrick et al., 2021). Thus, a combined simulation of cloud microphysics and atmospheric dynamics in a 3-D manner is needed for the comparison with more complex phenomena that take place in the real atmosphere.
Computation time is a major problem for the actual execution of the 3-D simulations. The bin method, which has been used in most previous studies, is not efficient enough to be implemented into a 3-D model because it needs more than a few tens of tracers to accurately calculate the size evolution. On the other hand, the moment method is efficient and feasible for coupling with a 3-D simulation because it assumes specific particle size distributions and only needs a few tracers. However, the moment method is yet to be validated under Venus conditions. Therefore, it is necessary to check the usability by comparing the moment method with the already-existing bin method before the coupling.
In this presentation, we report the current status of 1-D cloud microphysics models with the bin method and the moment method that are being developed for future coupling with a Venus GCM. The bin method is based on IH01, and the moment method is based on Määttänen et al. (2023) which has only been tested in a 0-D setting. The simulated profiles of cloud size distribution and condensational species are consistent with IH01 in the bin-method simulation. We are also planning to show the initial result of the first-ever performed moment method simulation in a 1-D setting and compare it with the bin-method simulation. In the next step, the further investigation of Venusian climate, atmospheric dynamics, and chemistry coupled with cloud microphysics is expected to be performed in a 3-D context after the implementation of the moment method into the GCM (Karyu et al., 2023).
References
Karyu, H. et al. (2023). Journal of Geophysical Research: Planets, 128, e2022JE007595.
Imamura, T., & Hashimoto, G. L. (2001). Journal of the atmospheric sciences, 58(23), 3597-3612.
Määttänen, A. et al. (2023). Advances in Space Research, 71(1), 1116-1136.
McGouldrick, K. et al. (2021). The Planetary Science Journal, 2(4), 153.
The particle size distribution affects the cloud’s physical structure and radiative properties. To derive realistic size distributions, it is necessary to take into account cloud microphysical processes, such as coagulation, condensation, and evaporation. Using a 1-D cloud microphysics model, Imamura and Hashimoto (2001) (hereafter IH01) suggested that the observed particle size distribution is formed by an interaction between cloud microphysics and atmospheric dynamics. However, the previous microphysical models have been operated only for 1-D or 2-D coordinates of the atmospheric field, in which only situations with simplified effects of dynamical advection were assumed for the investigations of cloud-atmosphere interaction. On the other hand, high-resolution observational data have been accumulated in terms of cloud particle properties and atmospheric parameters by Venus Express and Akatsuki, which are often associated with cloud morphologies (e.g., McGouldrick et al., 2021). Thus, a combined simulation of cloud microphysics and atmospheric dynamics in a 3-D manner is needed for the comparison with more complex phenomena that take place in the real atmosphere.
Computation time is a major problem for the actual execution of the 3-D simulations. The bin method, which has been used in most previous studies, is not efficient enough to be implemented into a 3-D model because it needs more than a few tens of tracers to accurately calculate the size evolution. On the other hand, the moment method is efficient and feasible for coupling with a 3-D simulation because it assumes specific particle size distributions and only needs a few tracers. However, the moment method is yet to be validated under Venus conditions. Therefore, it is necessary to check the usability by comparing the moment method with the already-existing bin method before the coupling.
In this presentation, we report the current status of 1-D cloud microphysics models with the bin method and the moment method that are being developed for future coupling with a Venus GCM. The bin method is based on IH01, and the moment method is based on Määttänen et al. (2023) which has only been tested in a 0-D setting. The simulated profiles of cloud size distribution and condensational species are consistent with IH01 in the bin-method simulation. We are also planning to show the initial result of the first-ever performed moment method simulation in a 1-D setting and compare it with the bin-method simulation. In the next step, the further investigation of Venusian climate, atmospheric dynamics, and chemistry coupled with cloud microphysics is expected to be performed in a 3-D context after the implementation of the moment method into the GCM (Karyu et al., 2023).
References
Karyu, H. et al. (2023). Journal of Geophysical Research: Planets, 128, e2022JE007595.
Imamura, T., & Hashimoto, G. L. (2001). Journal of the atmospheric sciences, 58(23), 3597-3612.
Määttänen, A. et al. (2023). Advances in Space Research, 71(1), 1116-1136.
McGouldrick, K. et al. (2021). The Planetary Science Journal, 2(4), 153.