Cloud‐Resolving Model Intercomparison of an MC3E Squall Line Case: Part II. Stratiform Precipitation Properties

Han, Bin; Fan, Jiwen; Varble, Adam; Morrison, Hugh; Williams, C. R.; Chen, Baojun; Dong, Xiquan; Giangrande, Scott; Хаин, А.; Mansell, Edward R.; Milbrandt, Jason A.; Shpund, Jacob; Thompson, Gregory

doi:10.1029/2018jd029596

Cited by 46 publications

(62 citation statements)

References 89 publications

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“…Furthermore, Figure illustrates that both SR1 and SR2 IWPs are representative of 20–70% of their corresponding CC values in both the LS and PS cases, and up to 95% for the TS case, while their PRs are only 8–25% of their CC values. These values further confirm not only that the SR PRs may depend on IWPs but also that the microphysics properties of ice particles such as hydrometer types and size distribution may play an important role (Han et al, ). The variation in IWP values may also be represented by the differences in the thermodynamic properties shown in Table .…”

Section: Resultssupporting

confidence: 65%

“…Considering the possible mismatches between the CSA classification and radar‐derived precipitation due to surface wind, the grid boxes that were classified as SR but had PRs greater than 10 mm/hr have been excluded from the analysis for SR. The 10‐mm/hr threshold is often used to discriminate convective precipitation (Han et al, ; Leary & Houze, ; Penide et al, ; Wang et al, ), and previous studies have found that less than 3% of rain rates classified as stratiform are above the 10‐mm/hr threshold (Wang et al, ). The total precipitation amount of pixels having rain rates greater than 10 mm/hr account for less than 8% of the total stratiform precipitation amount in our analysis.…”

Section: Methodsmentioning

confidence: 99%

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Understanding Ice Cloud‐Precipitation Properties of Three Modes of Mesoscale Convective Systems During PECAN

Cui

Dong

et al. 2019

JGR Atmospheres

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This study analyzes the precipitation and ice cloud microphysical features of three common modes of linear mesoscale convective systems during the Plains Elevated Convection at Night (PECAN) campaign. Three cases, one for each linear mesoscale convective system archetype (trailing stratiform, leading stratiform, and parallel stratiform precipitation), are selected. We focus primarily on analyzing ice cloud microphysical properties and precipitation rates (PRs) over the classified convective core (CC) and stratiform rain (SR) regions, as well as the two stratiform regions that developed behind (SR1) and ahead (SR2) of the convective line relative to the storm motion. In the three selected cases, the ice water path (IWP) and PR have strong correlations in the CC, but not in the SR. In terms of the temporal evolution of the mean IWPs and PRs, both CC and SR IWPs, as well as CC PRs, reach peaks quickly but take a longer time to dissipate than the increase period. For all the three cases, both SR1 and SR2 IWPs are 20–70% of their corresponding CC values in both the leading stratiform and parallel stratiform cases and up to 95% for the trailing stratiform case, while all of their PRs are only 7–25% of their CC values. These values suggest not only that the SR PRs may depend on IWPs but also that the microphysical properties of ice particles such as habit and size distribution may play an important role. Utilizing cloud‐resolving simulations of these systems may provide better understanding of the physical meanings behind the results in the future.

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Section: Resultssupporting

confidence: 65%

Section: Methodsmentioning

confidence: 99%

Understanding Ice Cloud‐Precipitation Properties of Three Modes of Mesoscale Convective Systems During PECAN

Cui

Dong

et al. 2019

JGR Atmospheres

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“…The threshold of 15 mm hr −1 seems high because we use the instantaneous rain rate in every 6‐min frequency, not the hourly scale rain rate. This surface rain rate‐based separation follows Han et al (). As discussed in Han et al (), the radar reflectivity‐based methods (e.g., Steiner et al, ) may not be suited for potentially biased simulated radar reflectivity.…”

Section: Resultsmentioning

confidence: 99%

“…This surface rain rate‐based separation follows Han et al (). As discussed in Han et al (), the radar reflectivity‐based methods (e.g., Steiner et al, ) may not be suited for potentially biased simulated radar reflectivity. We have also tested with a different threshold such as 10 mm hr −1 , and the conclusion remains the same.…”

Section: Resultsmentioning

confidence: 99%

Aerosol Impacts on Mesoscale Convective Systems Forming Under Different Vertical Wind Shear Conditions

et al. 2020

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Following our previous study of wind shear effect on mesoscale convective system (MCS) organization under a clean atmospheric condition using the Weather Research and Forecasting model coupled with spectral-bin microphysics, we conduct sensitivity simulations by increasing cloud condensation nuclei concentration to investigate aerosol impacts on MCSs forming under different wind shear conditions. We find that increased aerosols induce stronger updrafts and downdrafts in all MCSs. The stronger updrafts and enlarged convective core area contribute to larger vertical mass fluxes and enhance precipitation. The enhanced updrafts and vertical mass fluxes indicate convective invigoration. Increased updraft speed below 8-km altitude is attributed to enhanced condensational heating, except for the weak wind shear and strong low-level shear cases in which the enhanced low-level convergence is another contributing factor. Interestingly, above 8-km altitude, we see reduced updraft speed by the increased aerosols due to reduced vertical pressure perturbation gradient force. The accumulated rainfall and mean rain rate are increased with a greater occurrence frequency of heavy rain. Larger rain rate is seen in both convective and stratiform regions. In general, we see a higher frequency of deep clouds in the polluted condition because of invigorated convection, and more stratiform/anvil clouds, but a lower frequency of shallow warm clouds, with a larger significance for more organized MCSs. The consistently invigorated MCSs by aerosols under various wind shear conditions revealed by this study have important implications to weather and climate in warm and humid regions that are influenced by pollution.

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“…The maximum snow mass content in all simulations occurs around the 6‐km layer, followed by a decrease toward the melting level. This behavior agrees with the simulations shown in Han et al (). It seems that despite a high variability, the observations do not show such a decrease in IWC in the 1‐km depth layer above the melting level.…”

Section: Resultsmentioning

confidence: 99%

Simulating a Mesoscale Convective System Using WRF With a New Spectral Bin Microphysics: 1: Hail vs Graupel

et al. 2019

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A modified Fast Spectral Bin Microphysics scheme (FSBM‐2) embedded into the Weather Research and Forecasting (WRF) model is used to simulate a mesoscale deep convective system observed during the Midlatitude Continental Convective Clouds Experiment (MC3E). FSBM‐2 uses modified source codes as compared to the current FSBM (FSBM‐1). In contrast to FSBM‐1, FSBM‐2 can simulate hail of several centimeters in diameter and includes additional processes such as spontaneous breakup of raindrops and aerosol regeneration by drop evaporation. It is shown that allowing large hail particles of diameters exceeding about 1 cm substantially increases the agreement between the simulated and observed squall‐line structures in both the convective and stratiform regions. In contrast, if graupel particles are used to represent high‐density hydrometeors in convective areas, the ratio of convective‐to‐stratiform areas diverges from the ratio seen in observations and maximum radar reflectivities are substantially underestimated. Analysis of snow size distributions in the stratiform area shows an important link between the ice crystals formed by homogeneous freezing in the convective area to ice particle number concentration in the stratiform region. Simulated raindrop size distributions in the stratiform area below the melting level from FSBM‐2 show a good agreement with observations. The regeneration of cloud condensational nuclei (CCN) by droplet evaporation and detrainment of these CCN to the stratiform region increases the concentration of CCN there up to 8‐ to 9‐km altitude; the additional CCN penetrate clouds and produce new droplets, leading to some convection intensification.

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Cloud‐Resolving Model Intercomparison of an MC3E Squall Line Case: Part II. Stratiform Precipitation Properties

Cited by 46 publications

References 89 publications

Understanding Ice Cloud‐Precipitation Properties of Three Modes of Mesoscale Convective Systems During PECAN

Understanding Ice Cloud‐Precipitation Properties of Three Modes of Mesoscale Convective Systems During PECAN

Aerosol Impacts on Mesoscale Convective Systems Forming Under Different Vertical Wind Shear Conditions

Simulating a Mesoscale Convective System Using WRF With a New Spectral Bin Microphysics: 1: Hail vs Graupel

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