A Theory for Strong, Long-Lived Squall Lines

Rotunno, Richard; Klemp, Joseph B.; Weisman, Morris L.

doi:10.1175/1520-0469(1988)045<0463:atfsll>2.0.co;2

Cited by 1,110 publications

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“…The shallow depth of the updraft and clouds is mainly due to the presence of a layer of rather strong stability above the 2-km level. Below the 2-km level, because the low-level onshore flows originating from the well-mixed marine boundary layer does not contain much vertical shear, the updraft forced at the leading edge of the front tends to be tilted rearward (westward) instead of rising high due to baroclinic horizontal vorticity generation at the frontal zone (Rotunno et al, 1988), which is another factor favoring shallow convection.…”

Section: Model Simulated Flow and Thermodynamic Structuresmentioning

confidence: 99%

A study on a snowband associated with a coastal front and cold-air damming event of 3–4 February 1998 along the eastern coast of the Korean Peninsula

Lee¹,

Xue

2013

Adv. Atmos. Sci.

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A 24-h simulation with the Advanced Regional Prediction System (ARPS) nonhydrostatic model is performed for the heavy snowfall event of 3-4 February 1998 along the eastern coast of Korean Peninsula; the results are used to understand the snowfall process, including why the precipitation maxima formed along the Yeongdong coastal region rather than over the mountain slope and ridge top during.The numerical simulation with a 4-km horizontal grid spacing and 43 levels reproduces very well the narrow snowband located off the eastern Korean coast, away from, instead of over, the Yeongdong coastal mountain range. The general evolution of the snowband agrees quite well with radar observations, while the water-equivalent precipitation amount agrees reasonably well with radar precipitation estimate. The simulation results clearly show that the snow band developed due to the lifting by a coastal front that developed because of the damming of cold air against the eastern slope of the coastal mountain range. The damming was enhanced by the advection of cold air by a low-level mountain-parallel jet from the north, formed due to geostrophic adjustment as the on-shore upslope air was decelerated by the mountain blocking. As the onshore flow weakened later due to synoptic-scale flow pattern change, the cold front propagated off shore and the precipitation dissipated.

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Section: Model Simulated Flow and Thermodynamic Structuresmentioning

confidence: 99%

A study on a snowband associated with a coastal front and cold-air damming event of 3–4 February 1998 along the eastern coast of the Korean Peninsula

Lee¹,

Xue

2013

Adv. Atmos. Sci.

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“…This organized convection is dominant in the life cycle of an MCS. Focusing on the mechanism of leading line/trailing stratiform type of MCSs, many studies have shown that organization of the convection is related to vertical wind shear and convective available potential energy [e.g., Moncrieff and Green, 1972;Houze, 1977;Rotunno et al, 1988;LeMone et al, 1998;Johnson et al, 2004]. If there is significant vertical wind shear at low (middle) levels, convection is usually aligned normal (parallel) to the wind shear direction [LeMone et al, 1998;Johnson et al, 2004;Cetrone and Houze, 2006], and this difference may affect how much stratiform precipitation is generated.…”

Section: Introductionmentioning

confidence: 99%

“…[4] Many studies of organized convection are based upon observations from field campaigns, such as the GARP Atlantic Tropical Experiment (GATE) [Cheng and Houze, 1979;Szoke and Zipser, 1986], Equatorial Mesoscale Experiment [Alexander and Young, 1992], The Tropical Ocean Global Atmosphere Coupled Atmosphere-Ocean Response Experiment (TOGA-COARE) [LeMone et al, 1998], and the South China Sea Monsoon Experiment [Lau et al, 2000] whereas some are based on model simulations [Moncrieff and Green, 1972;Rotunno et al, 1988]. In recent years, an increasing quantity of satellite observations provides opportunities to describe MCSs from a global perspective [Laing and Fritsch, 1997;Nesbitt et al, 2000;Schumacher et al, 2004].…”

Section: Introductionmentioning

confidence: 99%

“…With large samples of 14 years of TRMM observations during 1998-2011, the morphology of organized convection over different regions can be described with a statistical approach. Past observational and numerical simulation studies suggest that the morphology of the convection could be tightly related to the large-scale environments, especially the convective lines [Houze and Cheng, 1977;Rotunno et al, 1988;LeMone et al, 1998]. However, MCSs with large area of stratiform region, as the "history" of past convection, could have very complicated horizontal structures.…”

Section: Introductionmentioning

confidence: 99%

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Regional variation of morphology of organized convection in the tropics and subtropics

Liu

Zipser

2013

JGR Atmospheres

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[1] Properties of organized convection with large horizontal area (> 1000 km 2 ) and with different horizontal structures in the tropics and subtropics are investigated by using 14 years of Tropical Rainfall Measuring Mission observations. First, the convective features (CFs) are defined as contiguous areas of convective precipitation detected by the Tropical Rainfall Measuring Mission precipitation radar. Using the minor and major axes of fitted ellipses, the morphology of the CFs are described as closer to a circular or a line shape. Regional variations and the properties of organized convection are examined with CFs with area > 1000 km 2 after categorizing them by their shapes. Organized convection tends to have larger extent and a higher fraction of near-circular shapes over land than over ocean. Shallow organized convection with maximum radar echo top height below 4.5 km is found mainly over ocean and some coastal regions. Of all tropical oceans, most shallow organized convection is found over the east Pacific. The fraction of line shaped organized convection is higher over the ocean than over land, and is higher in the subtropics than in the tropics. More convective lines are found in winter than in summer over oceans, but more in summer over land. Organized convective lines are slightly less convectively intense indicated by lower 30 dBZ echo top heights and warmer 37 GHz brightness temperatures than those with near-circular shapes. Orientations of organized convective lines are often aligned with fronts, dry lines, warm ocean currents, coastlines, and mountain slopes. Over the subtropics, organized convective lines are tilted more east-west over land, and more north-south over oceans. The largest and the most intense convective lines are found over central Africa, Argentina, and southeast U.S. over land, and over several warm currents in subtropical oceans.

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“…These configurations are similar to those used in Xue (2002), with the main differences being the wind profile and horizontal resolution. This specified environmental condition generally supports long-lived squall lines that sometimes develop a trailing stratiform precipitation region (Thorpe et al 1982;Rotunno et al 1988). …”

Section: The Model and Convective Storm Simulationsmentioning

confidence: 58%

State and parameter estimation

Yavin¹

Numerical Studies in Nonlinear Filtering

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A Theory for Strong, Long-Lived Squall Lines

Cited by 1,110 publications

References 0 publications

A study on a snowband associated with a coastal front and cold-air damming event of 3–4 February 1998 along the eastern coast of the Korean Peninsula

A study on a snowband associated with a coastal front and cold-air damming event of 3–4 February 1998 along the eastern coast of the Korean Peninsula

Regional variation of morphology of organized convection in the tropics and subtropics

State and parameter estimation

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