A Dual-Doppler Radar Study of Longitudinal-Mode Snowbands. Part I: A Three-Dimensional Kinematic Structure of Meso-<i>γ</i>-Scale Convective Cloud Systems within a Longitudinal-Mode Snowband

Fujiyoshi, Yasushi; Yoshimoto, Naohiro; Takeda, Takeshi

doi:10.1175/1520-0493(1998)126<0072:addrso>2.0.co;2

Cited by 31 publications

(26 citation statements)

References 31 publications

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“…Loading and evaporation cooling are known to be general factors that initiate a downdraft in deep thunderstorms (Houze 1993). The importance of the loading and (or) the evaporation, has also been pointed out in other studies on convective snow clouds based on Doppler-radar observations (Sakakibara et al 1988b;Ishihara et al 1989;Maki et al 1992;Satoh 1994;Yamada et al 1994;Yamada et al 1996;Yamada et al 1997;Fujiyoshi et al 1998). Studies based on microphysical retrieval (Sun 1999), and on numerical simulation (Ikawa et al 1987), also suggested the importance of loading and evaporation in snow clouds.…”

Section: Introductionmentioning

confidence: 67%

“…They suggested the importance of loading in a heavy snowfall region for the initiation of this strong downdraft. Fujiyoshi et al (1998) investigated a downdraft in a cloud streak, and suggested the importance of evaporation cooling near the cloud top for the initiation of the downdraft. Loading and evaporation cooling are known to be general factors that initiate a downdraft in deep thunderstorms (Houze 1993).…”

Section: Introductionmentioning

confidence: 99%

“…To elucidate them, it is necessary to examine the convective updraft in several snow clouds, and clarify the common/different features among the updrafts. Since the snow clouds are usually composed of several convective cells (e.g., Fujiyoshi et al 1992), it is possible to compare the different cases by using a convective cell. To examine various processes of development in a convective cell, we observed the three-dimensional structure of convective cells over Ishikari Bay, using two Doppler radars.…”

Section: Introductionmentioning

confidence: 99%

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Dual-Doppler Radar Observations on Factors Causing Differences in the Structure of Snow Clouds during Winter Monsoon Surges

Yamada

Uyeda

Kikuchi

et al. 2004

Journal of the Meteorological Society of Japan

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Various processes of development in a convective cell were investigated in order to clarify the factors causing differences in the structure of snow clouds. Convective cells in snow clouds were observed by two Doppler radars over Ishikari Bay, Hokkaido, Japan, during winter monsoon surges. Seven cells that allowed us to examine structural changes were selected for the investigation. From the time series of maximum reflectivity and vertical mass flux in each cell, the analyzed cells were classified into two groups: ''rapid change'' and ''slow change.'' The former was further divided into two types according to the strength of vertical wind shear in the environment: rapid change in weak shear (Rw), and rapid change in strong shear (Rs). The structure of the Rw-type changed greatly, due to the formation and the descent of a high-reflectivity core (> 30 dBZ), and the subsequent dissipation of the updraft. Since the updraft hardly tilted and collapsed when the core descended in the updraft, loading by graupel particles was suggested to be effective to terminate the updraft. The structure of the Rs-type changed greatly due to the short lifetime of the updraft that was tilted toward the downshear side due to the strong vertical shear. In contrast, the cell of slow-change group (S-type) maintained its structure because of a persistent updraft. Since the updraft, which was tilted hardly, was sustained even when a core (a 30 dBZ) descended in the updraft region, the loading effect was thought to be small due to the small amount of graupel particles. From a comparison of the three types, it was found that the different features of the cell's structure were caused by two factors: the tilt of the updraft, and the effect of loading by graupel particles. Based on these results, we discussed the maintenance process of a snow cloud composed of convective cells. The fact that convective cells in the past observational studies can also be classified in the same way as cells analyzed in the present study, was also discussed. The relationship between the growth of graupel particles, and the temperature in the environment, was also discussed.

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Section: Introductionmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dual-Doppler Radar Observations on Factors Causing Differences in the Structure of Snow Clouds during Winter Monsoon Surges

Yamada

Uyeda

Kikuchi

et al. 2004

Journal of the Meteorological Society of Japan

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“…Doppler radar observation studies over the same area also have been carried out till the present (Tsuboki et al, 1989;Fujiyoshi et al, 1992Fujiyoshi et al, , 1998Kikuchi, 1993;Katsumata et al, 1998). And the aspect of the snow clouds including the three-dimensional airflow structures with an updraft and downdraft regions has been clarifying.…”

Section: Introductionmentioning

confidence: 98%

Radar Echo Characteristics of the Localized Heavy Snowfalls around Sapporo, Japan.

Kikuchi

Nagaishi

Asuma

et al. 2001

Journal of the Japanese Society of Snow and Ice

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The radar echo analysis in which the heavy snowfall intensity stronger than 6cmh-1 in snow depth was recorded on the lower elevation angle of radar scanner was carried out from the viewpoint of traf fic transport facilities and localized heavy snowfall phenomena on the Ishikari Plain including Sapporo, Hokkaido, Japan. From the analysis of radar echo, it was clarified that there were high frequency areas. Furthermore, it was understood that there were some areas with sudden changes in snowfall intensity stronger than 10 cmh-1 in a limited few km2 in a horizontal scale and 10 minute duration in calm weather condition. Vertical cross section analyses across the abnormal heavy snowfall areas in which there were recorded with an intensity stronger than 6 cmh-1 by radar showed that the drastic increase of snowfall intensity occurred between 200m and 400m above the ground surface. The change of the maximum value of the radar echo intensity at around 200m level was estimated by the growth of large snowflakes which were aggregated and formed quickly under the horizontal and vertical wind shears at the same level.

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“…2005;Maesaka et al 2006). These bands have wider horizontal scales than cloud streets (e.g., Kuettner 1959Kuettner , 1971Brown 1980;Etling and Brown 1993;Atkinson and Zhang 1996;Young et al 2002;Fujiyoshi et al 1998;Renfrew and Moore 1999;Yoshimoto et al 2000;Liu et al 2004;Yamada et al 2010), commonly developing during cold-air outbreaks. Formation processes of the broad cloud bands are strongly connected with orography and surface conditions.…”

Section: Introductionmentioning

confidence: 99%

An Intensification Process of a Winter Broad Cloud Band on a Flank of the Mountain Region along the Japan-Sea Coast

Ohigashi

Tsuboki

Shusse

et al. 2014

Journal of the Meteorological Society of Japan

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During a cold-air outbreak between 25 and 27 January 2009, a broad cloud band formed along the coastal region from San-in to Hokuriku on the Sea of Japan side of the Japanese Islands. Along the mountain flank, precipitation in the cloud band was intensified. Intensification processes of the broad cloud band and microphysical characteristics of the intensified precipitation region were examined. During the lifetime of the cloud band, two low-pressure systems successively developed in the central Sea of Japan. Between the San-in and Hokuriku coastal regions located south of the low-pressure systems, westerly winds were predominant. It can be theoretically explained that the winds are blocked at least below 900 m by a high mountain region in Hokuriku. When the predominant westerly winds flowed into a high-pressure-gradient region produced by the blocking, unbalanced flow with ageostrophic winds formed. The relatively high pressure forced the westerly winds toward the left, resulting in southwesterly winds. The southwesterlies made a convergence with the predominant westerlies, the area of which corresponded to the intensified precipitation region. The correlation coefficient between vertical and horizontal polarized return signals (ρ hv ) averaged for 2 days indicates that melting particles were present below a height of several hundred meters in some periods and/or regions with surface temperature higher than 0°C. Above the melting level, the radar reflectivity (Z h ) maximum in the intensified precipitation region was more than or equal to 35 dBZ during one-third of the 2-day lifetime of the cloud band. For portions of Z h ≥ 30 dBZ, the mode of specific differential phase (K DP ) had negative values, which indicates the predominance of prolate graupel in the intensified precipitation region.

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A Dual-Doppler Radar Study of Longitudinal-Mode Snowbands. Part I: A Three-Dimensional Kinematic Structure of Meso-γ-Scale Convective Cloud Systems within a Longitudinal-Mode Snowband

Cited by 31 publications

References 31 publications

Dual-Doppler Radar Observations on Factors Causing Differences in the Structure of Snow Clouds during Winter Monsoon Surges

Dual-Doppler Radar Observations on Factors Causing Differences in the Structure of Snow Clouds during Winter Monsoon Surges

Radar Echo Characteristics of the Localized Heavy Snowfalls around Sapporo, Japan.

An Intensification Process of a Winter Broad Cloud Band on a Flank of the Mountain Region along the Japan-Sea Coast

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