著者

MURAKAMI Masataka

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2019-009, (Released:2018-11-05)

被引用文献数

4

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A large amount of snowfall caused by snow clouds over the Sea of Japan sometimes severely affects social and economic activities in Japan. Therefore, snow clouds, which form and develop mainly over the ocean and bring heavy snowfall to populated coastal plains, have long been intensively studied from the perspective of disaster prediction and prevention. Most studies have analyzed data acquired by aerological, meteorological satellite, and radar observations, or have conducted numerical simulations. Because of the difficulties involved in accessing cloud systems over the ocean, however, few in situ observation data have been available, and up until the middle 1990s, many problems remained unsolved or their analysis and simulation results remained unvalidated. Here, knowledge gained from instrumented aircraft observations made from the middle 1990s through the early 2000s is reviewed, in particular with regard to the development of a convectively mixed boundary layer and the inner structures of longitudinal-mode cloud bands, Japan-Sea polar-air mass convergence zone cloud bands, and a polar low. Unsolved problems relating to the inner structures and precipitation mechanisms of snow clouds and the expected contributions of aircraft observations to further progress in these areas of atmospheric science are also briefly discussed.

著者

KUO Tzu-Hsien MURAKAMI Masataka TAJIRI Takuya ORIKASA Narihiro

出版者

Meteorological Society of Japan

雑誌

気象集誌. 第2輯 (ISSN:00261165)

巻号頁・発行日

pp.2019-032, (Released:2019-02-02)

被引用文献数

3

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Aluminum oxide (Al2O3) and iron oxide (Fe2O3) particles have been observed not only in industrial areas and their surroundings but also in natural atmospheric environments. These types of aerosols can influence aerosol–cloud interactions. In this study, physico-chemical properties, such as size distribution and ability to act as cloud condensation nuclei (CCN) as well as ice nucleating particles (INPs), of surrogates of ambient Al2O3 and Fe2O3 particles were investigated using a CCN counter, the Meteorological Research Institute’s (MRI’s) cloud simulation chamber, the MRI’s continuous flow diffusion chamber-type ice nucleus counter, and an array of aerosol instruments. The results indicated that their hygroscopicity parameter (κ-value) ranged from 0.01 to 0.03. This range is compatible with that of surrogates of mineral dust particles and is smaller than typical κ-values of atmospheric aerosols. On the other hand, based on their ice nucleation active surface site (INAS) densities, these materials may act as effective INPs via immersion freezing (i.e., ice nucleation triggered by particles immersed in water droplets). In the cloud chamber experiments, Al2O3 and Fe2O3 particles continuously nucleated ice crystals at temperatures < −14°C and < −20°C, respectively. This result indicates that the Al2O3 particles were better INPs than the Fe2O3 particles. Moreover, the INAS density of the Al2O3 particles was comparable to that of natural ambient dust.