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Microphysics

About: Microphysics is a research topic. Over the lifetime, 2357 publications have been published within this topic receiving 90618 citations.


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TL;DR: The demonstration of the ability of the EnKF method to retrieve multiple microphysical species associated with a multiclass ice microphysics scheme, and to accurately retrieve the wind and thermodynamic variables are demonstrated.
Abstract: A Doppler radar data assimilation system is developed based on an ensemble Kalman filter (EnKF) method and tested with simulated radar data from a supercell storm. As a first implementation, it is assumed that the forward models are perfect and that the radar data are sampled at the analysis grid points. A general purpose nonhydrostatic compressible model is used with the inclusion of complex multiclass ice microphysics. New aspects of this study compared to previous work include the demonstration of the ability of the EnKF method to retrieve multiple microphysical species associated with a multiclass ice microphysics scheme, and to accurately retrieve the wind and thermodynamic variables. Also new are the inclusion of reflectivity observations and the determination of the relative role of the radial velocity and reflectivity data as well as their spatial coverage in recovering the full-flow and cloud fields. In general, the system is able to reestablish the model storm extremely well after a num...

399 citations

Journal ArticleDOI
TL;DR: In this paper, a parameterization for the horizontal subgrid-scale variability of water vapor and cloud condensate is introduced, which is used to diagnose cloud fraction in the spirit of statistically based cloud cover parameterizations.
Abstract: A parameterization for the horizontal subgrid-scale variability of water vapor and cloud condensate is introduced, which is used to diagnose cloud fraction in the spirit of statistically based cloud cover parameterizations. High-resolution cloud-resolving model data from tropical deep convective scenarios were used to justify the choice of probability density function (PDF). The PDF selected has the advantage of being bounded above and below, avoiding the complications of negative or infinite water mixing ratios, and can give both negatively and positively skewed functions as well as symmetric Gaussian-like bell-shaped curves, without discrete transitions, and is mathematically straightforward to implement. A development from previous statistical parameterizations is that the new scheme is prognostic, with processes such as deep convection, turbulence, and microphysics directly affecting the distribution of higher-order moments of variance and skewness. The scheme is able to represent the growth and decay of cirrus cloud decks and also the creation of cloud in clear sky or breakup of an overcast cloud deck by boundary layer turbulence. After introducing the mathematical framework, results using the parameterization in a climate model are shown to illustrate its behavior. The parameterization is shown to reduce cloud cover biases almost globally, with a marked improvement in the stratocumulus regions in the eastern Pacific and Atlantic Oceans.

393 citations

Journal ArticleDOI
TL;DR: In this article, a method for the parameterization of ice-phase microphysics is proposed and used to develop a new bulk micro-physics scheme, where all ice particles are represented by several physical properties.
Abstract: A method for the parameterization of ice-phase microphysics is proposed and used to develop a new bulk microphysics scheme. All ice-phase particles are represented by several physical properties that evolve freely in time and space. The scheme prognoses four ice mixing ratio variables, total mass, rime mass, rime volume, and number, allowing 4 degrees of freedom for representing the particle properties using a single category. This approach represents a significant departure from traditional microphysics schemes in which ice-phase hydrometeors are partitioned into various predefined categories (e.g., cloud ice, snow, and graupel) with prescribed characteristics. The liquid-phase component of the new scheme uses a standard two-moment, twocategory approach. The proposed method and a complete description of the new predicted particle properties (P3) scheme are provided. Results from idealized model simulations of a two-dimensional squall line are presented that illustrate overall behavior of the scheme. Despite its use of a single ice-phase category, the scheme simulates a realistically wide range of particle characteristics in different regions of the squall line, consistent with observed ice particles in real squall lines. Sensitivity tests show that both the prediction of the rime mass fraction and the rime density are important for the simulation of the squall-line structure and precipitation.

392 citations

Journal ArticleDOI
TL;DR: In this article, the European Centre for Medium-Range Weather Forecasts (ECMWF) model is used to derive the typical organization of clouds surrounding a midlatitude baroclinic system.
Abstract: Clouds simulated by the European Centre for Medium-Range Weather Forecasts (ECMWF) model are composited to derive the typical organization of clouds surrounding a midlatitude baroclinic system. Comparison of this composite of about 200 cyclones with that based on satellite data reveals that the ECMWF model quite accurately simulates the general positioning of clouds relative to a low pressure center. However, the optical depths of the model’s high/low clouds are too small/large relative to the satellite observations, and the model lacks the midlevel topped clouds observed to the west of the surface cold front. Sensitivity studies with the ECMWF model reveal that the error in high-cloud optical depths is more sensitive to the assumptions applied to the ice microphysics than to the inclusion of cloud advection or a change of horizontal resolution from 0.5625° to 1.69° lat. This reflects the fact that in the ECMWF model gravitational settling is the most rapid process controlling the abundance of ic...

386 citations

Journal ArticleDOI
TL;DR: In this paper, simulated squall lines are sensitive to both micro-physical setup and horizontal grid spacings, with either single-moment (1M) or double-moments (2M) microphysics, and either hail or graupel as the dense ice species.
Abstract: Idealizedsimulations ofthe 15May2009 squalllinefromthe SecondVerification ofthe OriginsofRotation in Tornadoes Experiment (VORTEX2) are evaluated in this study Four different microphysical setups are used, with either single-moment (1M) or double-moment (2M) microphysics, and either hail or graupel as the dense (rimed) ice species Three different horizontal grid spacings are used: Dx 5 4, 1, or 025 km (with identical vertical grids) Overall, results show that simulated squall lines are sensitive to both microphysical setupandhorizontalresolution,althoughsomequantities(ie,surfacerainfall)aremoresensitiveto Dxinthis study Simulations with larger Dx are slower to develop, produce more precipitation, and have higher cloud tops, all of which are attributable to larger convective cells that do not entrain midlevel air The highestresolution simulations have substantially more cloud water evaporation, which is partly attributable to the development of resolved turbulence For a given Dx, the 1M simulations produce less rain, more intense cold pools, and do not have trailing stratiform precipitation at the surface, owing to excessive rainwater evaporation The simulations with graupel as the dense ice species have unrealistically wide convective regions Comparison against analyses from VORTEX2 data shows that the 2M setup with hail and Dx 5 025 km producesthemostrealisticsimulationbecause(i)thissimulationproducesrealisticdistributionsofreflectivity associatedwithconvective,transition,andtrailingstratiformregions,(ii)thecoldpoolpropertiesarereasonably close to analyses from VORTEX2, and (iii) relative humidity in the cold pool is closest to observations

381 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20221
2021105
2020118
2019114
2018115
2017121