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

Yamase云是一种典型的海洋边界层云，目前的天气预报模式和大气环流模式对它的模拟效果还不够理想。夏季，在鄂霍次克反气旋吹出的东风吹出的东风下，三陆地区以东的西北太平洋地区经常出现Yamase云。本研究的目的是通过船舶、飞机和卫星等平台的综合观测，阐明Yamase云的形成和演变过程以及微物理和辐射特性。本研究还旨在通过发展更好的云参数化来改进海洋边界层云数值模式的性能。通过船上的试验，我们首次可以观测到Yamase事件中海洋边界层从开始到结束的时间变化。使用观测数据对…进行验证对Yamase事件的更多数值模拟。从飞机观测中，我们可以获得NOAA卫星同时观测到的几个低层云的微物理性质的良好现场数据。我们将NOAA/AVHRR资料反演的云微物理特征与飞机观测的结果进行了比较。结果表明，利用NOAA/AVHRR卫星遥感云图参数可以得到较为合理的结果。利用卫星遥感技术，研究了西北太平洋地区大范围云的宏观和微观物理特征。利用这些观测资料，我们分析了Yamase个例和非Yamase个例的海面与大气之间的热量交换。分析表明，无论是Yamase病例还是非Yamase病例，沿海面和大气的热交换都是如此。分析表明，沿气团轨迹的热量交换对Yamase云的形成和发展起着重要的作用。我们通过修改云辐射和湍流方案以及云参数，改进了用于模拟Yamase事件的非静力模式的性能。我们还发展了非均匀云的三维辐射传输方程的几个有效格式。本文的研究结果可能为包括Yamase云在内的海洋边界层云的研究提供新的思路。较少

'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