Mesoscale Thermodynamic Influences on Convection Initiation near a Surface Dryline in a Convection-Permitting Ensemble

Trier, Stanley B.; Romine, Glen S.; Ahijevych, David; Trapp, Robert J.; Schumacher, Russ S.; Coniglio, Michael C.; Stensrud, David J.

doi:10.1175/mwr-d-15-0133.1

Cited by 27 publications

(14 citation statements)

References 91 publications

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“…This sharp meridional moisture gradient in close proximity to the genesis region of southern Niger has a diurnal cycle analogous to drylines observed over the south-central Great Plains of the U.S. (Schaefer 1986). While thunderstorms tend to develop in their vicinity, drylines are not the triggering mechanism for convection (e.g., Ogura et al 1982;Carlson et al 1983;Trier et al 2015). However, the dryline's proximity can be an important environmental factor because convective systems that form near them tend to become stronger and better organized (Rhea 1966).…”

Section: Conditions For Mcss With Daytime Genesis <1000 Km Away From mentioning

confidence: 99%

“…As discussed in the above-mentioned studies, the primary role of the dryline is to provide a restraining inversion for lower-tropospheric turbulence that suppresses the release of convective instability too early in the day. Convection is more commonly thought to initiate near a dryline either by dry convective-scale motions arising from daytime surface heating of the planetary boundary layer (PBL), or by mesoscale thermally-direct vertical circulations driven by differential heating due to sloping terrain and/or the non-homogeneous vegetation/soil conditions (Carlson et al 1983;Trier et al 2004Trier et al , 2015.…”

Section: Introductionmentioning

confidence: 99%

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Mesoscale convective systems and nocturnal rainfall over the West African Sahel: role of the Inter-tropical front

Vizy

Cook

2017

Clim Dyn

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Section: Conditions For Mcss With Daytime Genesis <1000 Km Away From mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mesoscale convective systems and nocturnal rainfall over the West African Sahel: role of the Inter-tropical front

Vizy

Cook

2017

Clim Dyn

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“…It is a process in which a potentially unstable air parcel passes through its level of free convection (LFC) to initiate buoyant updraft growth with the release of instability. The ability to forecast when and where a new convective system will be initiated is important for disaster preparedness; therefore, CI has been extensively researched in recent decades (e.g., Campbell et al, ; Markowski et al, ; Peters & Hohenegger, ; Su & Zhai, ; Trier et al, ; Weckwerth & Parsons, ; Wilson & Roberts, ; Zhang et al, ; Ziegler & Rasmussen, ). However, predicting the precise location and timing of CI remains a challenge partly due to the lack of spatially and temporally dense observations, especially in the planetary boundary layer (PBL).…”

Section: Introductionmentioning

confidence: 99%

Convection Initiation Resulting From the Interaction Between a Quasi‐Stationary Dryline and Intersecting Gust Fronts: A Case Study

et al. 2019

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This study explores the convection initiation (CI) of a high‐impact squall line that occurred in central eastern China on 3 June 2009 based on observations and numerical modeling. The CI occurred in a scenario in which a set of intersecting gust fronts, organized in a distinct scalloped pattern, propagated toward an area of enhanced moisture produced by a near‐surface convergence line. This convergence line developed in a quasi‐stationary dryline zone. The dryline primed the preconvective environment by deepening the moist layer prior to the arrival of the intersecting gust fronts. The onset of CI occurred approximately 30 min after these intersecting gust fronts passed through the CI location, which was on the dry side of the dryline. Although these gust fronts acted as a strong signal for CI potential, CI did not occur along the entire length of the scalloped pattern of the intersecting gust fronts. The exact locations of the initiated convective cells were at the vertices of the scalloped pattern. An idealized simulation using a cloud model was conducted, demonstrating that the vertex regions were characterized by more favorable dynamical conditions for CI compared to the nonvertex regions along the scalloped outflow boundary. The greater CI probability over the vertex region was attributed to the greater magnitudes and larger vertical and horizontal extents of updrafts.

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“…Complex terrain plays important roles in the initiation and organization of convection (e.g., Rotunno and Houze, 2007;Wulfmeyer et al, 2008;Houze, 2012;Kain et al, 2013;Trier et al, 2015;Worthington, 2015;Zhao, 2015). For strong airflows encountering complex terrain, dynamic forcing can be strong enough to cause convective initiation (CI).…”

Section: Introductionmentioning

confidence: 99%

Convective initiation by topographically induced convergence forcing over the Dabie Mountains on 24 June 2010

2016

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The initiation of convective cells in the late morning of 24 June 2010 along the eastward extending ridge of the Dabie Mountains in the Anhui region, China, is studied through numerical simulations that include local data assimilation. A primary convergence line is found over the ridge of the Dabie Mountains, and along the ridge line several locally enhanced convergence centers preferentially initiate convection. Three processes responsible for creating the overall convergence pattern are identified. First, thermally-driven upslope winds induce convergence zones over the main mountain peaks along the ridge, which are shifted slightly downwind in location by the moderate low-level easterly flow found on the north side of a Mei-yu front. Second, flows around the main mountain peaks along the ridge create further convergence on the lee side of the peaks. Third, upslope winds develop along the roughly north-south oriented valleys on both sides of the ridge due to thermal and dynamic channeling effects, and create additional convergence between the peaks along the ridge. The superposition of the above convergence features creates the primary convergence line along the ridge line of the Dabie Mountains. Locally enhanced convergence centers on the primary line cause the initiation of the first convection cells along the ridge. These conclusions are supported by two sensitivity experiments in which the environmental wind (dynamic forcing) or radiative and land surface thermal forcing are removed, respectively. Overall, the thermal forcing effects are stronger than dynamic forcing given the relatively weak environmental flow.

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Mesoscale Thermodynamic Influences on Convection Initiation near a Surface Dryline in a Convection-Permitting Ensemble

Cited by 27 publications

References 91 publications

Mesoscale convective systems and nocturnal rainfall over the West African Sahel: role of the Inter-tropical front

Mesoscale convective systems and nocturnal rainfall over the West African Sahel: role of the Inter-tropical front

Convection Initiation Resulting From the Interaction Between a Quasi‐Stationary Dryline and Intersecting Gust Fronts: A Case Study

Convective initiation by topographically induced convergence forcing over the Dabie Mountains on 24 June 2010

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