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

Shpund, Jacob; Хаин, А.; Lynn, Barry; Fan, Jiwen; Han, Bin; Ryzhkov, Alexander V.; Snyder, Jeffrey C.; Dudhia, Jimy; Gill, D. R.

doi:10.1029/2019jd030576

Cited by 25 publications

(26 citation statements)

References 117 publications

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“…Lynn et al (2015), Khain et al (2016), Shpund, Khain, and Rosenfield (2019), and Shpund, Khain, Lynn et al (2019) describe in detail the SBM in WRF. The main specific features of the scheme are (a) all microphysical processes are described using the basic microphysical equations without parameterization, and (b) the scheme solves the equation for particle size distributions.…”

Section: Methodsmentioning

confidence: 99%

“…The model output frequency was every 15 min, and each simulation duration was for 66 h. Two days were allowed for model spin-up of the background aerosol, dust, and urban aerosol fields. , Khain et al (2016), Shpund, Khain, and Rosenfield (2019), and Shpund, Khain, Lynn et al (2019) describe in detail the SBM in WRF. The main specific features of the scheme are (a) all microphysical processes are described using the basic microphysical equations without parameterization, and (b) the scheme solves the equation for particle size distributions.…”

Section: Model Descriptionmentioning

confidence: 99%

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Using Factor Separation to Elucidate the Respective Contributions of Desert Dust and Urban Pollution to the 4 January 2020 Tel Aviv Lightning and Flash Flood Disaster

et al. 2020

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A numerical investigation was conducted to assess the possible impact of desert dust and urban aerosols on a very intense and deadly thunderstorm that occurred within the Tel Aviv metropolitan area on 4 January 2020. For these purposes, the cloud drop nucleation scheme within the spectral (bin) microphysics scheme (SBM) in the Weather Research and Forecasting Model (WRF) was coupled with the GoCart (desert) dust model and with hourly surface observations of urban aerosols. Using SBM integrated mass contents and simulated vertical velocities, the dynamic lightning scheme was able to forecast lightning rates within thunderclouds developing in an environment of marine or marine/continental aerosols with dust and/or urban aerosol forcings. Of these aerosol forcings (or factors), the urban aerosols (pollution) intensified lightning rates in convective clouds forming at and just off the Israeli coastline (referred to as the Urban Aerosol Lightning Enhancement Effect; ULE). The inclusion of continental aerosols with dust and urban aerosol sources resulted in the simulation exhibiting the most intense lightning and precipitation storm (referred to as Large Aerosol Small Aerosol Invigoration Effect; LASI). Yet, a comparison of model results and observations suggests that it was the combination of desert dust and urban aerosols alone that focused storm development over western Tel Aviv. The result was that high lightning rates initially focused over western Tel Aviv were accompanied by and then succeeded by a period of heavy rain that led to deadly flooding. Plain Language Summary The possible role of urban pollution on lightning and rainfall was investigated using a sophisticated cloud model embedded in a weather forecast model. The cloud model takes into account the impact of different sources of dust, including desert dust on cloud formation, and intensification into thunderstorm producing clouds. The day chosen for study was a day with lots of lightning and even deadly flooding in the city of Tel Aviv, Israel. The results showed that urban pollution intensifies lightning rates and precipitation amounts over the city. When large raindrops produced on large dust particles interacted with small drops produced from urban pollution, intense lightning and rainfall was forecast to occur in the area of deadly flooding. Hence, to forecast the intensity and location of severe storms, forecasts should take into account different sources of dust and pollution.

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Section: Methodsmentioning

confidence: 99%

Section: Model Descriptionmentioning

confidence: 99%

Using Factor Separation to Elucidate the Respective Contributions of Desert Dust and Urban Pollution to the 4 January 2020 Tel Aviv Lightning and Flash Flood Disaster

et al. 2020

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“…Several important differences between these models are highlighted here, with additional details presented in appendix A. First, six of the models utilized two-moment (2M) bulk microphysical parameterizations with varying levels of sophistication, whereas WRF-SBM used a spectral bin microphysics scheme with recent updates as detailed in Shpund et al (2019). Three models either prognose or diagnose supersaturation (RAMS, NU-WRF, WRF-SBM), while the other four models utilize saturation adjustment-a model process in which any liquid supersaturation that develops at a model grid point is completely eliminated at each time step via condensation onto already formed hydrometeors.…”

Section: Modelsmentioning

confidence: 99%

Impacts of Varying Concentrations of Cloud Condensation Nuclei on Deep Convective Cloud Updrafts—A Multimodel Assessment

Marinescu

Heever

Heikenfeld

et al. 2021

Journal of the Atmospheric Sciences

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This study presents results from a model intercomparison project, focusing on the range of responses in deep convective cloud updrafts to varying cloud condensation nuclei (CCN) concentrations amongst seven, state-of-the-art, cloud-resolving models. Simulations of scattered convective clouds near Houston, Texas are conducted, after being initialized with both relatively low and high CCN concentrations. Deep convective updrafts are identified, and trends in the updraft intensity and frequency are assessed. The factors contributing to the vertical velocity tendencies are examined to identify the physical processes associated with the CCN-induced, updraft changes.The models show several consistent trends. In general, the changes between the High-CCN and Low-CCN simulations in updraft magnitudes throughout the depth of the troposphere are within 15% for all of the models. All models produce stronger (~+5-15%) mean updrafts from ~4–7 km above ground level (AGL) in the High-CCN simulations, followed by a waning response up to ~8 km AGL in most of the models. Thermal buoyancy was more sensitive than condensate loading to varying CCN concentrations in most of the models and more impactful in the mean updraft responses. However, there are also differences between the models. The change in the amount of deep convective updrafts varies significantly. Furthermore, approximately half the models demonstrate neutral-to-weaker (~-5-0%) updrafts above ~8 km AGL, while the other models show stronger (~+10%) updrafts in the High-CCN simulations. The combination of the CCN-induced impacts on the buoyancy and vertical perturbation pressure gradient terms better explains these middle- and upper-tropospheric updraft trends than the buoyancy terms alone.

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“…Lynn et al [27] showed that such large particles and urban aerosols enhance the convective intensity and affect cloud microphysics and charging processes, leading to lightning. The possible impacts of dust on cloud-drop (as well as ice nucleation) on simulated convective intensity will need to be investigated in a separate study using, for example, Spectral (bin) Microphysics (e.g., [27,33]).…”

Section: Aerosol Concentrationsmentioning

confidence: 99%

Impacts of Non-Local versus Local Moisture Sources on a Heavy (and Deadly) Rain Event in Israel

et al. 2021

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Motivated by poor forecasting of a deadly convective event within the Levant, the factor separation technique was used to investigate the impact of non-local versus local moisture sources on simulated precipitation and lightning rates in central and southern Israel on 25 and 26 April 2018. Both days saw unusually heavy rains, and it was hypothesized that antecedent precipitation on 25 April contributed to the development of deadly flooding late morning on the 26th, as well as strong lightning and heavy rains later the same day. Antecedent precipitation led to an increase in the precipitable water content and an overall increase in instability as measured by the Convective Available Potential Energy (CAPE). The deadly flood occurred in the area of the Tzafit river gorge (hereafter, Tzafit river), about 25 km southeast of the city of Dimona, a semi-arid region in the northeastern Negev desert. The heavy rains and strong lightning occurred throughout the Levant with local peaks in the vicinity of Jerusalem. Factor separation conducted in model simulations showed that local ground moisture sources had a large impact on the CAPE and subsequent precipitation and lightning rates in the area of Jerusalem, while non-local moisture sources enabled weak convection to occur over broad areas, with particularly strong convection in the area of the Tzafit river. The coupled impact of both moisture sources also led to localized enhanced areas of convective activity. The results suggest that forecast models for the Levant should endeavor to incorporate an accurate depiction of soil moisture to predict convective rain, especially during the typically drier spring-time season.

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

Cited by 25 publications

References 117 publications

Using Factor Separation to Elucidate the Respective Contributions of Desert Dust and Urban Pollution to the 4 January 2020 Tel Aviv Lightning and Flash Flood Disaster

Using Factor Separation to Elucidate the Respective Contributions of Desert Dust and Urban Pollution to the 4 January 2020 Tel Aviv Lightning and Flash Flood Disaster

Impacts of Varying Concentrations of Cloud Condensation Nuclei on Deep Convective Cloud Updrafts—A Multimodel Assessment

Impacts of Non-Local versus Local Moisture Sources on a Heavy (and Deadly) Rain Event in Israel

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