A study on the cloud formation and modification processes and numerical modeling of YAMASE clouds

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'Yamase' clouds are one of typical marine boundary-layer clouds, for which the present state-of-the-art performance of weather prediction models and general circulation models is not good enough to properly simulate. Yamase clouds frequently appear over the northwest Pacific region, east off the coast of the Sanriku district, in summer season under easterly cool winds blown out from Okhotsk anti-cyclones. The purpose of the present study is to clarify the formation and evolution processes and the microphysical and radiative properties of Yamase clouds through synthetic observations from such platforms as ship, aircraft, and satellites. The study also aims to improve the performance of numerical models for marine boundary-layer clouds by developing better cloud-parameterization.From the shipboard experiment, we could, for the first time, observe time-variation of the maritime boundary layer in a Yamase event from its beginning to ending. The observational data were used to validate the … More numerical simulations of the Yamase event. From the aircraft observation, we could obtain good in-situ data of microphysical properties of several low-level clouds, for which NOAA satellites observed simultaneously. We compared the cloud microphysical properties retrieved from the NOAA/AVHRR data with those from the aircraft observation. From the comparison, it is shown that the satellite remote sensing of cloud parameters from NOAA/AVHRR data could yield reasonable results. By means of the satellite remote sensing, we studied cloud macro-and micro-physical properties over a wide area of North western-Pacific region. By using these observational data, we analyzed the heat exchange between the sea surface and the atmosphere for Yamase cases and non-Yamase cases. The analysis revealed that the heat exchange along the sea surface and the atmosphere for Yamase cases and non-Yamase cases. The analysis revealed that the heat exchange along the air-mass trajectory plays an important role in formation and evolution of Yamase clouds. We have improved performance of the non-hydrostatic model used to simulate Yamase events by modifying the cloud-radiation and turbulence schemes as well as cloud-parameterizations. We have also developed a few efficient schemes of the 3-dimensional radiative transfer equation for inhomogeneous clouds. The results of the present study may cast a new light on the studies of marine boundary-layer clouds including Yamase clouds. Less