겨울철 동해상의 대상수렴운과 그 주위의 대류운에 관한 WRF 수치모의 연구
WRF Numerical Study on the Convergent Cloud Band and Its Neighbouring Convective Clouds
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This study analyzed atmospheric conditions for the convergent cloud band (Cu-Cbline) in developing stage and its neighbouring convections formed over the East Sea on 1 February2012, by using synoptic, satellites data, and WRF numerical simulation output of highresolution. In both satellite images and the WRF numerical simulation outputs, the Cu-Cb linethat stretched out toward northwest-southeast was shown in the East Sea, and cloud lines of theL mode were aligned in accordance with the prevailing surface wind direction. However, thoseof the T mode were aligned in the direction of NE-SW, which was nearly perpendicular directionto the surface winds. The directions of the wind shear vectors connecting top winds andbottom winds of the moist layers of the L mode and the T mode were identical with those ofthe cloud lines of L mode and T mode, respectively. From the WRF simulation convection circulationswith a convergence in the lower layer of atmosphere and a divergence above 1.5 kmASL (Above Sea Level) were identified in the Cu-Cb line. A series of small sized vortexes(maximum vortex: 320 × 10−5 s−1) of meso-γ-scale formed by convergences was found alongthe Cu-Cb lines, suggesting that Cu-Cb lines, consisting of numerous convective clouds, wereclosely associated with a series of the small vortexes. There was an absolute unstable layer (∂θ/∂z < 0) between sfc and ~0.3 km ASL, and a stable layer (∂θ/∂z > 0) above ~2 km ASL overthe Cu-Cb line and cloud zones. Not only convectively unstable layers (∂θe/∂z < 0) but alsoneutral layers (∂θe/∂z ≈ 0) in the lower atmosphere (sfc~1.5 km ASL) were scattered aroundover the cloud zones. Particularly, for the Cu-Cb line there were convectively unstable layers inthe surface layer, and neutral layers (∂θe/∂z ≈ 0) between 0.2 and ~1.5 km ASL over near thecenter of the Cu-Cb line, and the neutralization of unstable layers came from the release ofconvective instability.
Abstract
This study analyzed atmospheric conditions for the convergent cloud band (Cu-Cbline) in developing stage and its neighbouring convections formed over the East Sea on 1 February2012, by using synoptic, satellites data, and WRF numerical simulation output of highresolution. In both satellite images and the WRF numerical simulation outputs, the Cu-Cb linethat stretched out toward northwest-southeast was shown in the East Sea, and cloud lines of theL mode were aligned in accordance with the prevailing surface wind direction. However, thoseof the T mode were aligned in the direction of NE-SW, which was nearly perpendicular directionto the surface winds. The directions of the wind shear vectors connecting top winds andbottom winds of the moist layers of the L mode and the T mode were identical with those ofthe cloud lines of L mode and T mode, respectively. From the WRF simulation convection circulationswith a convergence in the lower layer of atmosphere and a divergence above 1.5 kmASL (Above Sea Level) were identified in the Cu-Cb line. A series of small sized vortexes(maximum vortex: 320 × 10−5 s−1) of meso-γ-scale formed by convergences was found alongthe Cu-Cb lines, suggesting that Cu-Cb lines, consisting of numerous convective clouds, wereclosely associated with a series of the small vortexes. There was an absolute unstable layer (∂θ/∂z < 0) between sfc and ~0.3 km ASL, and a stable layer (∂θ/∂z > 0) above ~2 km ASL overthe Cu-Cb line and cloud zones. Not only convectively unstable layers (∂θe/∂z < 0) but alsoneutral layers (∂θe/∂z ≈ 0) in the lower atmosphere (sfc~1.5 km ASL) were scattered aroundover the cloud zones. Particularly, for the Cu-Cb line there were convectively unstable layers inthe surface layer, and neutral layers (∂θe/∂z ≈ 0) between 0.2 and ~1.5 km ASL over near thecenter of the Cu-Cb line, and the neutralization of unstable layers came from the release ofconvective instability.
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