10:45 AM - 12:15 PM
[AAS10-P03] Global Warming Experiment for a Transversal Cloud Band Events
Sea Polar Airmass Convergence Zone (JPCZ) and the associated Transversal Cloud Bands perpendicular to the winter monsoon was observed in boreal winter1.In this study, we used the regional meteorological model SCALE-RM2,3 to reproduce an event that transversal cloud bands were observed. In addition, we conducted pseudo global warming experiments by uniformly increasing the sea surface temperatures and atmospheric temperatures respectively to investigate how the structures of JPCZ and Transversal Cloud Bands changed.
In this study, we focused on the event on December 25, 2021. The calculation period was from 24 to 28 December and MANL data were used for initial and boundary values. In the pseudo-global warming experiment, 6 types of experiments were conducted with initial and boundary values of "sea surface temperature only", "both sea surface temperature and atmospheric temperature", and "atmospheric temperature only" respectively raised by 2 K or 4 K.
As a result of reproduction experiments, JPCZ, Transversal Cloud Bands, and Longitudinal Cloud Bands were reproduced. In addition, the Transversal Cloud Bands formed a cloud line along the vertical shear explained in the linear theory4.
In the warming experiments, it was shown that the height of the Transversal Cloud Bands increased when "sea surface temperature only" and "both sea surface temperature and atmospheric temperature" were increased. This is probably because the latent heat flux increases when "sea surface temperature only" or "both sea surface temperature and atmospheric temperature" is increased. In addition, when "sea surface temperature only" was raised, Transversal Cloud Bands were higher than when "both sea surface and atmospheric temperatures" were raised. This is because the sensible heat flux is greater when "sea surface temperature only" is raised than when "both sea surface temperature and atmospheric temperature" are raised. These results suggest that latent heat flux and sensible heat flux are important for the height of Transversal Cloud Bands.
References
1. Murakami M., M. Hoshimoto, N., Orikasa, H. Horie H. Okamoto, H. Kuroiwa, H. Minda and K. Nakamura,2002: Inner structures of snow bands associated with the Japan Sea polar-airmass convergence zone based on aircraft observations.
2.Nishizawa, S., Yashiro, H., Sato, Y., Miyamoto, Y. & Tomita, H. Influence of grid aspect ratio on planetary boundary layer turbulence in large-eddy simulations. Geosci. Model Dev. 8, 3393–3419 (2015).
3.Sato, Y. S. Nishizawa, H. Yashiro, Y. Miyamoto, Y. Kajikawa, & H. Tomita. Impacts of cloud microphysics on trade wind cumulus: which cloud microphysics processes contribute to the diversity in a large eddy simulation? Prog. Earth Planet. Sci. 2, (2015).
4.Asai, T., 1972: Thermal instability of a shear flow turning the direction with height. J. Meteor. Soc. Japan, 50,526-532.
In this study, we focused on the event on December 25, 2021. The calculation period was from 24 to 28 December and MANL data were used for initial and boundary values. In the pseudo-global warming experiment, 6 types of experiments were conducted with initial and boundary values of "sea surface temperature only", "both sea surface temperature and atmospheric temperature", and "atmospheric temperature only" respectively raised by 2 K or 4 K.
As a result of reproduction experiments, JPCZ, Transversal Cloud Bands, and Longitudinal Cloud Bands were reproduced. In addition, the Transversal Cloud Bands formed a cloud line along the vertical shear explained in the linear theory4.
In the warming experiments, it was shown that the height of the Transversal Cloud Bands increased when "sea surface temperature only" and "both sea surface temperature and atmospheric temperature" were increased. This is probably because the latent heat flux increases when "sea surface temperature only" or "both sea surface temperature and atmospheric temperature" is increased. In addition, when "sea surface temperature only" was raised, Transversal Cloud Bands were higher than when "both sea surface and atmospheric temperatures" were raised. This is because the sensible heat flux is greater when "sea surface temperature only" is raised than when "both sea surface temperature and atmospheric temperature" are raised. These results suggest that latent heat flux and sensible heat flux are important for the height of Transversal Cloud Bands.
References
1. Murakami M., M. Hoshimoto, N., Orikasa, H. Horie H. Okamoto, H. Kuroiwa, H. Minda and K. Nakamura,2002: Inner structures of snow bands associated with the Japan Sea polar-airmass convergence zone based on aircraft observations.
2.Nishizawa, S., Yashiro, H., Sato, Y., Miyamoto, Y. & Tomita, H. Influence of grid aspect ratio on planetary boundary layer turbulence in large-eddy simulations. Geosci. Model Dev. 8, 3393–3419 (2015).
3.Sato, Y. S. Nishizawa, H. Yashiro, Y. Miyamoto, Y. Kajikawa, & H. Tomita. Impacts of cloud microphysics on trade wind cumulus: which cloud microphysics processes contribute to the diversity in a large eddy simulation? Prog. Earth Planet. Sci. 2, (2015).
4.Asai, T., 1972: Thermal instability of a shear flow turning the direction with height. J. Meteor. Soc. Japan, 50,526-532.