Mesoscale convective systems

Houze, Robert A.

doi:10.1029/2004rg000150

Cited by 1,129 publications

(1,285 citation statements)

References 138 publications

(324 reference statements)

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“…14b) appears to be a result of Ekman pumping, with frictionally induced convergence within the boundary layer and divergence immediately above the boundary layer. Midlevel convergence was collocated with the midlevel vorticity feature to the south, typical of a mesoscale convective vortex (MCV; Raymond and Jiang 1990;Bartels and Maddox 1991;Houze 2004). In addition, there was a positive temperature anomaly in the SAMURAI analysis above 6.5-km height over a negative low-level temperature anomaly (not shown), which is also characteristic of the thermal structure of a balanced midlevel vortex (Chen and Frank 1993).…”

Section: Mesoscale Analysis Of In Situ Observationsmentioning

confidence: 99%

Observations of a Nondeveloping Tropical Disturbance in the Western North Pacific during TCS-08 (2008)

Penny

Harr

Bell

2015

Monthly Weather Review

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Large uncertainty still remains in determining whether a tropical cloud cluster will develop into a tropical cyclone. During The Observing System Research and Predictability Experiment (THORPEX) Pacific Asian Regional Campaign (T-PARC)/Tropical Cyclone Structure-2008 (TCS-08) field experiment, over 50 tropical cloud clusters were monitored for development, but only 4 developed into a tropical cyclone. One nondeveloping tropical disturbance (TCS025) was closely observed for potential formation during five aircraft research missions, which provided an unprecedented set of observations pertaining to the large-scale and convective environments of a nondeveloping system. The TCS025 disturbance was comprised of episodic convection that occurred in relation to the diurnal cycle along the eastern extent of a broad low-level trough. The upper-level environment was dominated by two cyclonic cells in the tropical upper-tropospheric trough (TUTT) north of the low-level trough in which the TCS025 circulation was embedded. An in-depth examination of in situ observations revealed that the nondeveloping circulation was asymmetric and vertically misaligned, which led to larger system-relative flow on the mesoscale. Persistent environmental vertical wind shear and horizontal shearing deformation near the circulation kept the system from becoming better organized and appears to have allowed low equivalent potential temperature (u e ) air originating from one of the TUTT cells to the north (upshear) to impact the thermodynamic environment of TCS025. This in turn weakened subsequent convection that might otherwise have improved alignment and contributed to the transition of TCS025 to a tropical cyclone.

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Section: Mesoscale Analysis Of In Situ Observationsmentioning

confidence: 99%

Observations of a Nondeveloping Tropical Disturbance in the Western North Pacific during TCS-08 (2008)

Penny

Harr

Bell

2015

Monthly Weather Review

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“…In addition to cloud physical properties, environmental properties such as vertical wind shear (VWS) can play an important role in cloud formation, storm development, and convective aerosol transport [Houze, 2004;Thorpe et al, 1982;Kingsmill and Houze, 1999;Weisman and Rotunno, 2004;Moncrieff , 1978]. We derive VWS using data from the Modern-Era Retrospective analysis for Research and Applications (MERRA) [Rienecker et al, 2011], provided that MERRA successfully detects the observed convective event.…”

Section: 1002/2015jd023528mentioning

confidence: 99%

Relationships between convective structure and transport of aerosols to the upper troposphere deduced from satellite observations

Chakraborty

Wright

et al. 2015

JGR Atmospheres

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We estimate the extent of upper tropospheric aerosol layers (UT ALs) surrounding mesoscale convective systems (MCSs) and explore the relationships between UT AL extent and the morphology, location, and developmental stage of collocated MCSs in the tropics. Our analysis is based on satellite data collected over equatorial Africa, South Asia, and the Amazon basin between June 2006 and June 2008. We identify substantial variations in the relationships between convective properties and aerosol transport by region and stage of convective development. The most extensive UT ALs over equatorial Africa are associated with mature MCSs, while the most extensive UT ALs over South Asia and the Amazon are associated with growing MCSs. Convective aerosol transport over the Amazon is weaker than that observed over the other two regions despite similar transport frequencies, likely due to the smaller sizes and shorter mean lifetimes of MCSs over the Amazon. Variations in UT ALs in the vicinity of tropical MCSs are primarily explained by variations in the horizontal sizes of the associated MCSs and are largely unrelated to aerosol loading in the lower troposphere. We also identify potentially important relationships with the number of convective cores, vertical wind shear, and convective fraction during the growing and mature stages of MCS development. Relationships between convective properties and aerosol transport are relatively weak during the decaying stage of convective development. Our results provide an interpretive framework for devising and evaluating numerical model experiments that examine relationships between convective properties and ALs in the upper troposphere.

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“…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. Because the latent heating profiles for the convective and stratiform regions are different, this directly influences the vertical distribution of latent heat release [Houze, 2004]. The organized convection also plays a major role in the momentum transport.…”

Section: Introductionmentioning

confidence: 99%

“…[2] It is well known that mesoscale convective systems (MCSs) account for a large proportion of precipitation in both the tropics and the subtropics [Nesbitt et al, 2000;Houze, 2004]. They also generate large areas of clouds that play an important role in the radiation budget [Liou, 1986].…”

Section: Introductionmentioning

confidence: 99%

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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Mesoscale convective systems

Cited by 1,129 publications

References 138 publications

Observations of a Nondeveloping Tropical Disturbance in the Western North Pacific during TCS-08 (2008)

Observations of a Nondeveloping Tropical Disturbance in the Western North Pacific during TCS-08 (2008)

Relationships between convective structure and transport of aerosols to the upper troposphere deduced from satellite observations

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

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