S-Band Dual-Polarization Radar Observations of Winter Storms

Kennedy, Patrick C.; Rutledge, Steven A.

doi:10.1175/2010jamc2558.1

Cited by 147 publications

(138 citation statements)

References 24 publications

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“…8b, larger K MAX values are also associated with larger Z MAX even though the correlation between the quantities is weak (r 2 ≈ 0.25). The peak of K dp might therefore be considered an indication of high Z H values at lower levels, as similar relations have been documented in other locations in Europe and North America (Kennedy and Rutledge, 2011;Bechini et al, 2013;Schrom et al, 2015).…”

Section: Lower Level Of Precipitationsupporting

confidence: 70%

“…The peak of K dp , below altitudes of higher Z DR and above altitudes of higher Z H , is a well-known but still not completely understood signature observed during snowfall (Kennedy and Rutledge, 2011;Bechini et al, 2013;Schneebeli et al, 2013;Andric et al, 2013;Hubbert et al, 2014). The proximity of this signature with respect to the −15 • C level (blue line in Fig.…”

Section: Intermediate Level Of Precipitationmentioning

confidence: 81%

“…The proximity of this signature with respect to the −15 • C level (blue line in Fig. 6) has led in the past to it being associated with dendritic crystal growth (Kennedy and Rutledge, 2011). However, it was recognized that the concentration of dendrites needed to generate enhancements of this magnitude would lead to unreasonably high values of Z H when these crystals eventually aggregate (Andric et al, 2013).…”

Section: Intermediate Level Of Precipitationmentioning

confidence: 98%

“…These systems are able to provide indirect information about size, intensity, geometry, density, velocity and turbulence of falling hydrometeors (e.g., Bringi and Chandrasekar, 2001;Doviak and Zrnić, 2006). Polarimetric data have been used to identify areas of intense growth of dendritic and planar crystals (Kennedy and Rutledge, 2011;Bechini et al, 2013;Schrom et al, 2015) and to formulate hypotheses on the dominant microphysical processes occurring at various altitude levels during snowfall Andric et al, 2013;Kumjian et al, 2014). The combination of numerical modeling, radar observations and in situ data led to the development of classification methods aiming to estimate the dominant type of hydrometeors that populate the radar resolution volumes (e.g., Straka et al, 2000;Dolan and Rutledge, 2009;Bechini and Chandrasekar, 2015;Grazioli et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

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Polarimetric radar and in situ observations of riming and snowfall microphysics during CLACE 2014

et al. 2015

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Abstract. This study investigates the microphysics of winter alpine snowfall occurring in mixed-phase clouds in an inner-Alpine valley during January and February 2014. The available observations include high-resolution polarimetric radar and in situ measurements of the ice-phase and liquidphase components of clouds and precipitation. Radar-based hydrometeor classification suggests that riming is an important factor to favor an efficient growth of the precipitating mass and correlates with snow accumulation rates at ground level. The time steps during which rimed precipitation is dominant are analyzed in terms of temporal evolution and vertical structure. Snowfall identified as rimed often appears after a short time period during which the atmospheric conditions favor wind gusts and updrafts and supercooled liquid water (SLW) is available. When a turbulent atmospheric layer persists for several hours and ensures continuous SLW generation, riming can be sustained longer and large accumulations of snow at ground level can be generated. The microphysical interpretation and the meteorological situation associated with one such event are detailed in the paper. The vertical structure of polarimetric radar observations during intense snowfall classified as rimed shows a peculiar maximum of specific differential phase shift K dp , associated with large number concentrations and riming of anisotropic crystals. Below this K dp peak there is usually an enhancement in radar reflectivity Z H , proportional to the K dp enhancement and interpreted as aggregation of ice crystals. These signatures seem to be recurring during intense snowfall.

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Section: Lower Level Of Precipitationsupporting

confidence: 70%

Section: Intermediate Level Of Precipitationmentioning

confidence: 81%

Section: Intermediate Level Of Precipitationmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Polarimetric radar and in situ observations of riming and snowfall microphysics during CLACE 2014

et al. 2015

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“…Snow crystals with axis ratios near unity (spherical particles) also show K DP around 0° km -1 . Only snow crystals with small axis ratios (flat snow crystals) can produce large K DP corresponding to 0.5-2° km -1 in X-band radar observations (e.g., Kennedy and Rutledge 2011), where it should be noted that K DP is proportional to the inverse of radar wavelength, as shown in Bringi and Chandrasekar (2001). Therefore, shapes and hydrometeor types are unclear in the region of K DP near 0° km -1 for Z h < 30 dBZ, while flat snow crystals with significantly positive K DP (0.5-2° km -1 ) are not the primary particle type in the present case.…”

Section: Characteristics Of Polarimetric Parametersmentioning

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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Vertical distribution of precipitation particles in Baiu frontal stratiform intense rainfall around Okinawa Island, Japan

et al. 2015

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The vertical distribution of precipitation particles in an intensely precipitating stratiform cloud associated with the Baiu front around Okinawa Island was observed. X‐band polarimetric radar, disdrometer, and hydrometeor videosonde data were used to examine the precipitation processes. The cloud top was approximately 12 km above sea level, as convection was depressed while stratiform regions developed near Okinawa Island. In the rain region below 3 km, the mean median volume diameter of the raindrop size distribution (DSD) estimated from the radar variables was 1.55 mm, and the mean normalized intercept parameter was 104.12 mm−1 m−3 with a mean radar reflectivity of 40.5 dBZe. The DSD indicates that the stratiform precipitation was characterized by higher number concentrations of smaller drops than observed previously in convective cells in a Baiu frontal convective precipitation region around Okinawa Island. The DSD also suggests the presence of larger raindrops than in convective cells embedded in a Baiu frontal stratiform precipitation region around Okinawa Island. In the ice region at 5–6 km, just above the melting layer and 6 km below the cloud top, the differential reflectivity and specific differential phase showed positive values, and videosonde measurements revealed that the number concentration of column‐, plate‐, and capped‐column‐like crystals (maximum dimensions of ≥0.1 mm) was 112 L−1. The high number concentration of these crystals contributed to the intense stratiform rainfall associated with the Baiu front.

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S-Band Dual-Polarization Radar Observations of Winter Storms

Cited by 147 publications

References 24 publications

Polarimetric radar and in situ observations of riming and snowfall microphysics during CLACE 2014

Polarimetric radar and in situ observations of riming and snowfall microphysics during CLACE 2014

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

Vertical distribution of precipitation particles in Baiu frontal stratiform intense rainfall around Okinawa Island, Japan

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