Development of the Hydrometeor Videosonde

The occurrence and amount of graupel precipitation over the Japan Islands are studied using routine surface observation data at 150 stations.The results of statistical analysis of the annual and monthly number of days with graupel for 1971-1986 in the geographical map and in annual cycles show that graupel fall is predominant in winter over the Japan Sea coastal area in Tohoku and Hokuriku District.Furthermore, monthly precipitation amount of graupel in January for 1982-1986 at five stations in the coastal area are statistically estimated to be at least one-fourth to one-third of the monthly precipitation amount. Based on the statistical results of graupel precipitation, weather modification potential by cloud seeding is discussed.

Section: Introductionmentioning

confidence: 99%

Statistical Characteristics of Graupel Precipitation over the Japan Islands

Mizuno¹

1992

“…The present HYVIS is a reformed version of the MRI-HYVIS originally developed by Murakami and Matsuo (1990), which were previously used to investigate microphysical structures of a few frontal ice-clouds (Mizuno et al 1994;Uchiyama et al 1999). The former HYVIS was improved to get a better image resolution and a larger sampling volume in tenuous ice-clouds (Orikasa and Murakami 1997).…”

Section: Jaccs Cirrus Experimentsmentioning

confidence: 99%

Radiative Properties of Mid-latitude Frontal Ice-Clouds Observed by the Shortwave and Longwave Radiometer-Sondes

Yoshida

Asano

Yamamoto³

et al. 2004

In the Japanese Cloud and Climate Study (JACCS) cirrus experiment, simultaneous measurements of cloud radiative and microphysical properties were conducted by using the combined-sonde (radiometersonde þ hydrometeor-video-sonde (HYVIS)) observation system at the Meteorological Research Institute (MRI), located at (36.05 N, 140.13 E) in Tsukuba, Japan, during early summer seasons from 1995 to 1999. We have analyzed the radiative properties of frontal ice-clouds observed by the shortwave and longwave radiometer-sondes (Asano et al. 2004). To interpret the observed radiative flux profiles, we have also performed radiative transfer calculations for horizontally homogeneous atmospheric models, where the single-scattering properties of ice-clouds were computed by anomalous diffraction theory for ice-crystals observed by HYVIS. On an average of the observed frontal ice-clouds, the shortwave reflectance, transmittance and absorptance were estimated to be 0.41 G 0.03, 0.51 G 0.06, and 0.08 G 0.09, respectively, for the averaged ice-cloud layer with a mean visible optical thickness of 4.6 and a mean geometrical thickness of 5.4 km (mean volume extinction coefficient of 0.85 km À1 ). The ice-clouds were significantly heated by absorption of solar radiation in daytime. On the other hand, the mean effective emittance was estimated to be about 0.86 G 0.37, showing that the frontal ice-clouds never acted as blackbody for longwave radiation. The lower parts of ice-cloud layers were heated by absorption of longwave radiation from the surface and the atmosphere below the ice-clouds, while the upper parts were cooled by emission of longwave radiation to space. The shortwave and longwave heating profiles could make the daytime ice-cloud layers thermodynamically unstable.

“…The special sonde used in this study is called the Hydrometeor Video Sonde (HYVIS). This sonde was developed at the MRI to measure the vertical profile of cloud microphysical composition (Murakami and Matsuo, 1990). Using this sonde, we can observe hydrometeor particles in the range of -10ttm to 1mm in size.…”

Section: Other Instrumentsmentioning

confidence: 99%

Ground-Based Cirrus Observation

Uchiyama¹,

Fukabori²

1999

A ground-based observation system has been developed at the Meteorological Research Institute (MRI) for simultaneous measurements of cloud structure and radiative properties of high-level ice clouds. In this observation system, the cloud microphysical quantities and spectral radiances in the region of the 10um window could be simultaneously observed by a Hydrometeor Video Sonde (HYVIS) and a Fourier Transform Infrared (FTIR) spectro-radiometer. On the basis of the results measured by HYVIS, the size distribution of ice particles was approximated by the power law distribution, and the simulation calculations of observed radiances were made for the some combination of the lower limit of power law distribution (r1) and the optical thickness at 10.5um (Tlo.5). Using these data, the minimum error point is searched in the error map. By this method, we retrieve optical thickness and particle size information.The optically thin, medium and thick cases were analyzed in order to investigate the characteristic of our retrieval method. It is found that the optical thickness determined the magnitude of observed radiance, and size distributions determined the slope of the spectrum in the 860 to 980cm-1 region. The simulated and observed radiances agree within +2mW/(m2 sr cm-1), except the 9.6um ozone band and the root mean squares error 1.2mW/(m2 sr cm-1). The error analysis showed that though 5% systematic error is permitted to optical thickness retrieval in some cases, 1% systematic error causes large errors in the size information retrieval, and that a +500m height error corresponds to 1 to 3% radiance error. Furthermore, the values estimated from the radiance in the region of wavenumber 860 to 980cm-1 were almost the same as those from radiance in the whole region, and the optical thickness may be determined from data in the region 1080 to 1200cm-1 without being affected by the size distribution. We also retrieved 1O.5 and effective radius (reff) using the log-normal size distribution within the same degree of error as obtained by the power law model. Furthermore, we investigated the relationship between the parameters retrieved. The ratio of the visible optical thickness at 0.5,um (T0.5) to the infrared one at 10.5um (T1o.5) on June 22 is 0.4 to 1.0, and that on June 30 is 1.0 to 1.8. There is a tendency that the ratio of T1o.5 to T0.5 becomes large as the effective radius increases. We also investigated the relation between n o.5 and the effective radius (reff) of log-normal size distribution. The relation between them changes case by case. There is a negative correlation between them in the case of June 22. In the case of June 30, the effective radius is scattered between 20 and 85um.Concurrent NOAA-11 satellite data over the Tsukuba area were also analyzed. The results show that observation from the satellite is consistent with the ground based observation, and that the large difference of the brightness temperature observed by the different window channels is closely related to the existence of small ice part...