Organization and Environmental Properties of Extreme-Rain-Producing Mesoscale Convective Systems

Schumacher, Russ S.; Johnson, Richard H.

doi:10.1175/mwr2899.1

Cited by 345 publications

(321 citation statements)

References 27 publications

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“…Yet other possibilities may exist. One of them is a line or cluster of quasistationary or back-building convection generated by the collision of the outflow from storm-generated cold pools and the prevailing flow at the cold-pool boundary (Doswell et al, 1996;Schumacher and Johnson, 2005;Didlake and Houze, 2009;Houze, 2010). Apparently additional investigations are warranted.…”

Section: Model Simulation and Discussionmentioning

confidence: 99%

Mesoscale processes for super heavy rainfall of Typhoon Morakot (2009) over Southern Taiwan

et al. 2011

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Abstract.Within 100 h, a record-breaking rainfall, 2855 mm, was brought to Taiwan by typhoon Morakot in August 2009 resulting in devastating landslides and casualties. Analyses and simulations show that under favorable largescale situations, this unprecedented precipitation was caused first by the convergence of the southerly component of the pre-existing strong southwesterly monsoonal flow and the northerly component of the typhoon circulation. Then the westerly component of southwesterly flow pushed the highly moist air (mean specific humidity >16 g/kg between 950 and 700 hPa from NCEP GFS data set) eastward against the Central Mountain Range, and forced it to lift in the preferred area. From the fine-scale numerical simulation, not only did the convergence itself provide the source of the heavy rainfall when it interacted with the topography, but also convective cells existed within the typhoon's main rainband. The convective cells were in the form of small rainbands perpendicular to the main one, and propagated as wave trains downwind. As the main rainband moved northward and reached the southern CMR, convective cells inside the narrow convergence zone to the south and those to the north as wave trains, both rained heavily as they were lifted by the west-facing mountain slopes. Those mesoscale processes were responsible for the unprecedented heavy rainfall total that accompanied this typhoon.

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Section: Model Simulation and Discussionmentioning

confidence: 99%

Mesoscale processes for super heavy rainfall of Typhoon Morakot (2009) over Southern Taiwan

et al. 2011

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“…This was the same definition used in previous analyses (Gutowski et al 2007(Gutowski et al , 2008(Gutowski et al , 2010. Our analysis focused on the winter season [DecemberFebruary (DJF)], when synoptic dynamics are more important than in the warmer months, when smallerscale convective events may be more important (e.g., Schumacher andJohnson 2005, 2006). The assumption here is that winter events will be governed more by the resolved circulation (Gutowski et al 2008).…”

Section: Analysesmentioning

confidence: 99%

“…This may be because of winters in this region producing less precipitation than other seasons (e.g., Dirmeyer and Kinter 2010) or a lower frequency of very heavy events compared to the rest of the year (Schumacher and Johnson 2006). However, heavy rainfall on frozen ground, with or without snow, can cause substantial flash flooding, as the surface is unable to absorb and hold moisture as effectively as in the warmer seasons (Huff and Angel 1992).…”

Section: Introductionmentioning

confidence: 99%

Regional, Very Heavy Daily Precipitation in NARCCAP Simulations

Kawazoe

Gutowski

2013

Journal of Hydrometeorology

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The authors analyze the ability of the North American Regional Climate Change Assessment Program's ensemble of climate models to simulate very heavy daily precipitation and its supporting processes, comparing simulations that used observation-based boundary conditions with observations. The analysis includes regional climate models and a time-slice global climate model that all used approximately half-degree resolution. Analysis focuses on an upper Mississippi River region for winter (December-February), when it is assumed that resolved synoptic circulation governs precipitation. All models generally reproduce the precipitation-versus-intensity spectrum seen in observations well, with a small tendency toward producing overly strong precipitation at high-intensity thresholds, such as the 95th, 99th, and 99.5th percentiles. Further analysis focuses on precipitation events exceeding the 99.5th percentile that occur simultaneously at several points in the region, yielding so-called "widespread events. " Examination of additional fields shows that the models produce very heavy precipitation events for the same physical conditions seen in the observations. KeywordsExtreme events, Precipitation, Climate models, Regional models ABSTRACTThe authors analyze the ability of the North American Regional Climate Change Assessment Program's ensemble of climate models to simulate very heavy daily precipitation and its supporting processes, comparing simulations that used observation-based boundary conditions with observations. The analysis includes regional climate models and a time-slice global climate model that all used approximately half-degree resolution. Analysis focuses on an upper Mississippi River region for winter (December-February), when it is assumed that resolved synoptic circulation governs precipitation. All models generally reproduce the precipitation-versus-intensity spectrum seen in observations well, with a small tendency toward producing overly strong precipitation at high-intensity thresholds, such as the 95th, 99th, and 99.5th percentiles. Further analysis focuses on precipitation events exceeding the 99.5th percentile that occur simultaneously at several points in the region, yielding so-called ''widespread events.'' Examination of additional fields shows that the models produce very heavy precipitation events for the same physical conditions seen in the observations.

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“…In a recent study, Shumacher and Johnson (2005) analyzed the environmental properties of certain types of MCSs in North America. They investigated the mid-and low-level wind shear (500 hPa 925 hPa) and low-and surface-level wind shear (925 hPa 1000 hPa), and described the relationships between the wind -shear directions and the propagation direction of the MCSs.…”

Section: Resultsmentioning

confidence: 99%

“…Here, we also focused on the vertical wind shears, though we simply analyzed the wind shear between 600 hPa and 1000 hPa, for the magnitude of the 925 hPa 1000 hPa wind shear was small compared to that of 600 hPa 1000 hPa. A closer and more detailed analysis of the wind shears and comparative discussions with Shumacher and Johnson (2005) will be done in a forthcoming paper. Figure 7 is the composite shear map of 600 hPa 1000 hPa (surface wind subtracted from 600 hPa wind) of background fields of southward propagating MCSs.…”

Section: Resultsmentioning

confidence: 99%

Seasonal Variation and Environmental Properties of Southward Propagating Mesoscale Convective Systems over the Bay of Bengal

Miyakawa

Satomura

2006

SOLA

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We tracked fast moving mesoscale convective systems (MCSs) over the Bay of Bengal, counted their numbers, and analyzed the characteristics of wind and geopotential fields of when such MCSs propagate southward over the Bay. We used hourly TBB data of GMS5 IR1 (1996 for the tracking, and used 6-hourly ECMWF 40 year re-analysis data to analyze the characteristics of wind and geopotential fields.The numbers of fast moving MCSs were as follows: April 11/56 (20%); May 46/103 (45%); June 50/173 (29%); July 33/160 (21%); August 27/125 (22%); September 8/61 (13%); October 8/67 (12%); total 183/745 (25%). The fractions represent (number of southward propagating MCSs)/(total number of MCSs), and the numbers inside the parentheses are the percentages of the southward propagating MCSs.We concluded that fast southward propagation of MCSs tends to occur when a trough exists over the Bay at the height of 600 hPa, and the wind shear between the surface and the 600 hPa height has a southward component. We also found that propagation towards other directions is related with eddy disturbances over the Bay.

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Organization and Environmental Properties of Extreme-Rain-Producing Mesoscale Convective Systems

Cited by 345 publications

References 27 publications

Mesoscale processes for super heavy rainfall of Typhoon Morakot (2009) over Southern Taiwan

Mesoscale processes for super heavy rainfall of Typhoon Morakot (2009) over Southern Taiwan

Regional, Very Heavy Daily Precipitation in NARCCAP Simulations

Seasonal Variation and Environmental Properties of Southward Propagating Mesoscale Convective Systems over the Bay of Bengal

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