Observations of Quasi-Stationary and Shallow Orographic Snow Clouds: Spatial Distributions of Supercooled Liquid Water and Snow Particles

Kusunoki, Kenichi; Murakami, Masataka; Orikasa, Narihiro; Hoshimoto, Mizuho; Tanaka, Yoshinobu; Yamada, Yoshiyuki; Mizuno, Hakaru; Hamazu, Kyosuke; Watanabe, Hideyuki

doi:10.1175/mwr2874.1

Cited by 16 publications

(12 citation statements)

References 20 publications

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“…Another explanation for the deviations in N 0 might come from the special orographic conditions at the UFS. Kusunoki et al [2005] reported increasing snow aggregation because of stronger upwinds and turbulence in a mountainous orography. These larger particles would consequently result in lower values for N 0 and λ , i.e., a broader SSD.…”

Section: Rt Model Results For 8 February 2009mentioning

confidence: 99%

Snow scattering signals in ground‐based passive microwave radiometer measurements

Kneifel¹,

Löhnert²,

Battaglia³

et al. 2010

J. Geophys. Res.

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[1] This paper investigates the influence of snow microphysical parameters on the enhancement of ground-based passive microwave brightness temperature (TB) measurements. In addition to multispectral passive microwave observations between 20 and 150 GHz, a 35 GHz cloud radar and a 2-D video disdrometer for in situ measurements of snowfall were deployed as part of the "towards an optimal estimation-based snowfall characterization algorithm" campaign in the winter season of 2008-2009 at an Alpine environment located at 2650 m mean sea level. These observations are combined with nearby radiosonde ascents and surface standard meteorological measurements to reconstruct the atmospheric state (i.e., fields of temperature, humidity, snow, and liquid water contents) and are subsequently used as input for a microwave radiative transfer (RT) model. We investigate the sensitivity of the missing information about snow shape and snow particle size distribution (SSD) on the microwave TB measurements using the disdrometer data as a rough constraint. For an extended case study, we found that TBs at 90 and 150 GHz are significantly enhanced because of scattering of surface radiation at snow crystals and that this enhancement is clearly correlated with the radar derived snow water path (SWP < 0.2 kg m −2 ). RT simulations highlight the strong influence of the vertical distribution of cloud liquid water (liquid water path LWP < 0.1 kg m −2 ) on the TB, which in extreme cases, can fully obscure the snow scattering signal. TB variations of the same magnitude can also be caused by typical variations in SSD parameters and particle shape similar to results obtained by space-borne studies. Ground-based stations with their infrastructural capabilities in combining active and passive microwave observations have the potential to disentangle the influences of different snow shape, SSD, and SWP in snow retrievals, thus supporting current and future satellite missions.

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Section: Rt Model Results For 8 February 2009mentioning

confidence: 99%

Snow scattering signals in ground‐based passive microwave radiometer measurements

Kneifel¹,

Löhnert²,

Battaglia³

et al. 2010

J. Geophys. Res.

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“…structure of snowflakes depend strongly on the atmospheric conditions of ice cloud evolution (e.g., Kusunoki et al 2004Kusunoki et al , 2005. Because large snowflakes tend to originate when the sticking probability of snow particles increases in a relatively warm atmosphere, the melting process is another important factor in the shape and structure of falling snowflakes (e.g., Fujiyoshi 1986).…”

Section: Discussionmentioning

confidence: 99%

Radar Backscattering Computations for Fractal-Shaped Snowflakes

Ishimoto¹

2008

Journal of the Meteorological Society of Japan

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We propose a model for large snowflakes based on the fractal nature of their particle shapes. Monte Carlo simulations were conducted to make particles with a fractal dimension of 1.8 to 2.4. The roundness parameter for the projected images of the modeled particles was derived, and an average roundness of approximately 0.4 for particles with fractal dimension 2.1 was indicated; this average roundness matched reported values measured for large ice aggregates. The finite difference time domain method was used to calculate the backscattering cross-sections of ice particles with a fractal dimension of 2.1 and a particle diameter of up to ～20 mm at microwave frequencies of 95 GHz, 35 GHz, and 9.8 GHz. The results were compared with those of equivalent-volume spheres and randomly oriented equivalent-volume hexagonal columns. Our snowflake model had smaller values of radar backscattering cross-sections than did the equivalent-volume spheres in the size range out of the Rayleigh regime. Furthermore, large differences in backscattering cross-sections between the snowflake model and the equivalent-volume hexagonal column were confirmed, in particular at a frequency of 35GHz.

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“…Concomitant cold-air outbreaks (Mitnik, 1992) gain heat and moisture over the relatively warm waters of the SOJ and Tsushima current, destabilizing the atmosphere and generating clouds and precipitation (e.g., Hozumi & Magono, 1984;Tsuchiya & Fujita, 1967). Sea-effect precipitation systems then reach the northwest Japanese coast, where they are modified by coastal, inland, and orographic effects (e.g., Campbell et al, 2018;Estoque & Ninomiya, 1976;Kawamoto et al, 1963;Kusunoki et al, 2005;Nakai & Endoh, 1995;Saito et al, 1996;Yoshihara et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Sea‐Effect Clouds and Precipitation Over the Sea of Japan Region as Observed by A‐Train Satellites

2019

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Prolific winter (December‐January‐February) snowfall occurs over northwest Japan due to frequent sea‐effect precipitation that develops during cold‐air outbreaks over the Sea of Japan (SOJ). Knowledge of sea‐effect clouds and precipitation across the SOJ region has historically been constrained, however, by limited offshore in situ observations and remote‐sensing limitations. This paper uses sensors from National Aeronautics and Space Administration (NASA)'s A‐Train Satellite Constellation to examine winter sea‐effect properties in the SOJ region. The analysis shows that cloud and precipitation occurrence generally increases across the SOJ from Asia to Japan, as potential sea‐effect periods with an along‐orbit mean sea surface to 850‐hPa temperature difference ≥13 °C comprise a majority of the total clouds and precipitation. Sea‐effect clouds and precipitation occur most frequently in an arc‐shaped area that extends from the western SOJ, where the Japan‐Sea Polar‐Airmass Convergence Zone (JPCZ) is common, to the coast of Honshu, and then northward to Hokkaido. Radar, lidar, and column water path statistics along A‐Train orbital tracks show that sea‐effect precipitation is deepest along the central Honshu coast and becomes shallower but more frequent with northward extent. Precipitation amount and frequency maximize along the coast and adjacent mountains but decline with inland extent, most abruptly downstream of higher mountain barriers. This work illustrates that air‐sea interactions, coastal geometry, and regional topography strongly modulate cloud and precipitation patterns during sea‐effect periods in the SOJ region.

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Observations of Quasi-Stationary and Shallow Orographic Snow Clouds: Spatial Distributions of Supercooled Liquid Water and Snow Particles

Cited by 16 publications

References 20 publications

Snow scattering signals in ground‐based passive microwave radiometer measurements

Snow scattering signals in ground‐based passive microwave radiometer measurements

Radar Backscattering Computations for Fractal-Shaped Snowflakes

Characteristics of Sea‐Effect Clouds and Precipitation Over the Sea of Japan Region as Observed by A‐Train Satellites

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