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28 results on '"Orikasa, Narihiro"'

2. Numerical simulation on feasibility of rain enhancement by hygroscopic seeding over kochi area, shikoku, Japan in early Summer

Author

Kuo, Wei-Chen, Yamashita, Katsuya, Murakami, Masataka, Tajiri, Takuya, Hashimoto, Akihiro, and Orikasa, Narihiro

Abstract

To investigate the feasibility of rain enhancement by cloud seeding over the target area in early summer, the effects of salt micro-powder (MP) seeding and hygroscopit flare (HF) seeding on the initial cloud microphysical structures were investigated using a detailed bin microphysics parcel model with the background atmospheric aerosol data collected from ground-based monitoring observations carried out on the windward side of the target area and seeding aerosol data collected from the coordinated flghts of seeding helicopter and in-situ measurement aircraft.Numerical seeding experiments show that size distributions of cloud droplets are broadened and onset of the rain drop formation is fastened by MP and HF seeding although MP seeding shows more remarkable seeding effects than HF seeding. MP seeding increases the mean droplet size and decreases total number concentration of cloud droplets whereas HF seeding does vice versa. According to the relationship between the increase/decrease ratio of cloud droplet number concentration and the increase/decrease ratio of surface precipitation by hygroscopic seeding obtained in previous studies, it is shown that MP seeding has a positive seeding effect, and HF seeding has a negative effect. In the numerical seeding experiments, although a range of variation in the number concentration and hygroscopicity of background aerosol particles, the amount of seeding material applied, and the change in the physico-chemical properties of the seeding aerosols for an improvement of seeding effects were also considered, the outline of the results described above remained unchanged., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Published
2023

4. Optical and microphysical properties of upper clouds measured with the Raman lidar and hydrometeor videosonde: a case study on 29 March 2004 over Tsukuba, Japan

Author

Sakai, Tetsu, Orikasa, Narihiro, Nagai, Tomohiro, Murakami, Masataka, Kusunoki, Kenichi, Mori, Kazumasa, Hashimoto, Akihiro, Matsumura, Takatsugu, and Shibata, Takashi

Subjects
Remote sensing -- Usage, Clouds -- Properties, Clouds -- Research, Earth sciences, Science and technology
Abstract

Optical and microphysical properties of the upper clouds at an altitude range of 5-11 km were measured over Tsukuba, Japan, on 29-30 March 2004 using a ground-based Raman lidar and a balloon-borne hydrometeor videosonde (HYVIS). The Raman lidar measured the vertical distributions of the particle extinction coefficient, backscattering coefficients, depolarization ratio, and extinction-to-backscatter ratio (lidar ratio) at 532 nm; further, it measured the water vapor mixing ratio. The HYVIS measured the vertical distributions of the particle size, shape, cross-sectional area, and number concentration of the cloud particles by taking microscopic images. The HYVIS measurement showed that the cloud particles were ice crystals whose shapes were columnar, bulletlike, platelike, and irregular, and 7-400 [micro]m in size. The Raman lidar measurement showed that the depolarization ratio ranged from 0% to 35% and the lidar ranged from 0.3 to 30 sr for the clouds in ice-saturated air. The comparison between the measured data and theoretical calculations of the cloud optical properties suggests that the observed variations in the depolarization ratio and lidar ratio were primarily due to the variation in the proportion of the horizontally oriented ice crystals in the clouds. The optical thickness of the cloud obtained from the lidar was about 2 times lower than that calculated from the HYVIS data, and the maximum extinction coefficient was about 5 times lower than the HYVIS data. The most probable reason for the differences is the horizontal inhomogeneities of the cloud properties between the measurements sites for the two instruments.

Published
2006

19. Multi‐wavelength radar algorithm with Doppler function for the retrieval of cloud microphysics with precipitation

Author

Okamoto, Hajime, primary, Sato, Kaori, additional, Otomo, Shotaro, additional, Hagihara, Yuichiro, additional, Yoshida, Ryo, additional, Iwanami, Koyoru, additional, Maesaka, Takeshi, additional, Murakami, Masataka, additional, Orikasa, Narihiro, additional, Nakazato, Masahisa, additional, Yamauchi, Hiroshi, additional, and Inoue, Hanako, additional

Published
2009
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26. Multi-wavelength radar algorithm with Doppler function for the retrieval of cloud microphysics with precipitation.

Author

Okamoto, Hajime, Sato, Kaori, Otomo, Shotaro, Hagihara, Yuichiro, Yoshida, Ryo, Iwanami, Koyoru, Maesaka, Takeshi, Murakami, Masataka, Orikasa, Narihiro, Nakazato, Masahisa, Yamauchi, Hiroshi, and Inoue, Hanako

Subjects
RADAR, ALGORITHMS, DOPPLER effect, MICROPHYSICS, METEOROLOGICAL precipitation, CLOUDS
Abstract

We developed the retrieval algorithm for clouds accompanying precipitation. In order to obtain the vertical structure of cloud microphysics, W-, Ka- and X- band radars with Doppler capability were used. We first considered six different particle types and the scattering properties of the non-spherical ice particles were calculated at these frequencies by using the discrete dipole approximation (DDA). Then dual wavelength ratios (DWR) and the reflectivity-weighted terminal velocities (Vtz) for the six particle types were estimated. It was found that the DWR for W- and Ka- band radars depended on particle shape, orientation and size when particle effective radius exceeds about 60 μm. DWR for Ka- and X- band radars also showed the similar dependences but for larger size than the DWR for X and Ka band radars. The Vtz also show the strong dependence on shape, orientation and size for large size. The retrieval algorithm consists of two parts; (1) large particle mode from the combination of DWRs and VTzs from W-, Ka- and X- band radars measurements and (2) small particle mode from the radar reflectivity and Vtz from Ka- band. We examined the cloud microphysics from the radar data observed in Niigata in December 2007, in the field experiment of Japanese Cloud Seeding Experiment for Precipitation Augmentation (JACSEPA). Retrievals of microphysics were performed for two cases. The retrieval results were compared with the in-situ data and found some agreement. [ABSTRACT FROM AUTHOR]

Published
2009
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28. CCN ability of atmospheric aerosols and microphysical structures of shallow warm clouds in western Japan.

Author

Murakami, Masataka, Orikasa, Narihiro, Saito, Atsushi, and Yamashita, Katsuya

Subjects
*ATMOSPHERIC nucleation, *ATMOSPHERIC aerosols, *ATMOSPHERIC spectra, *MICROPHYSICS, *ATMOSPHERIC physics, *CLOUD physics, *AIR pollution
Abstract

The aerosol size distributions and CCN spectra in the Pacific Ocean region air masses showed that their shapes were similar to those in the East Asia coastal region air masses, but total number concentrations of aerosol particles and CCN number concentrations were about 1/2 of those in the continental/polluted air masses from the East Asia coastal region. Shallow warm clouds showed a wide range of ability for producing drizzle and rain drops. Usually the ability depends on number concentrations of cloud droplets; clouds forming in maritime air mass with less CCN tend to easily produce precipitation and vise versa. [ABSTRACT FROM AUTHOR]

Published
2013
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