Three-dimensional simulation of cloud street development during a cold air outbreak

Chlond, Andreas

doi:10.1007/bf00120757

Cited by 70 publications

(42 citation statements)

References 34 publications

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“…In the MPI-0 configuration scalars are advected using the monotone scheme described by Chlond (1994), while for MPI-1 scalars are advected using the positive definite method described by Bott (1989). The time integration scheme uses a combination of second-order Adams-Bashforth and Euler steps.…”

Section: Model Descriptionsmentioning

confidence: 99%

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Evaluation of Large-Eddy Simulations via Observations of Nocturnal Marine Stratocumulus

Stevens

Moeng

Ackerman

et al. 2005

Monthly Weather Review

577

803

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Data from the first research flight (RF01) of the second Dynamics and Chemistry of Marine Stratocumulus (DYCOMS-II) field study are used to evaluate the fidelity with which large-eddy simulations (LESs) can represent the turbulent structure of stratocumulus-topped boundary layers. The initial data and forcings for this case placed it in an interesting part of parameter space, near the boundary where cloud-top mixing is thought to render the cloud layer unstable on the one hand, or tending toward a decoupled structure on the other hand. The basis of this evaluation consists of sixteen 4-h simulations from 10 modeling centers over grids whose vertical spacing was 5 m at the cloud-top interface and whose horizontal spacing was 35 m. Extensive sensitivity studies of both the configuration of the case and the numerical setup also enhanced the analysis. Overall it was found that (i) if efforts are made to reduce spurious mixing at cloud top, either by refining the vertical grid or limiting the effects of the subgrid model in this region, then the observed turbulent and thermodynamic structure of the layer can be reproduced with some fidelity; (ii) the base, or native configuration of most simulations greatly overestimated mixing at cloud top, tending toward a decoupled layer in which cloud liquid water path and turbulent intensities were grossly underestimated; (iii) the sensitivity of the simulations to the representation of mixing at cloud top is, to a certain extent, amplified by particulars of this case. Overall the results suggest that the use of LESs to map out the behavior of the stratocumulus-topped boundary layer in this interesting region of parameter space requires a more compelling representation of processes at cloud top. In the absence of significant leaps in the understanding of subgrid-scale (SGS) physics, such a representation can only be achieved by a significant refinement in resolution-a refinement that, while conceivable given existing resources, is probably still beyond the reach of most centers.

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Section: Model Descriptionsmentioning

confidence: 99%

“…A time step of 0.8 s was used for all runs. The calculations are performed on eight processors of a NEC-SX6; one time step takes about 2.2 s. Further information can be found in Chlond (1992Chlond ( , 1998). …”

Section: Model Descriptionsmentioning

confidence: 99%

Evaluation of Large-Eddy Simulations via Observations of Nocturnal Marine Stratocumulus

Stevens

Moeng

Ackerman

et al. 2005

Monthly Weather Review

577

803

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“…The LES model used is a state of the art model described by Chlond [1992 and1994] of ice water content, effective radius, number density, and size distribution of ice particles generated from LESs. The dependence of the cloud albedo bias on solar zenith angle and vertical optical depth might be useful for further investigations of inhomogeneity effects on radiative properties of cirrus clouds, especially for those clouds with larger optical depths.…”

Section: Large Eddy Simulationmentioning

confidence: 99%

On the effect of cloud inhomogeneity an area averaged radiative properties of contrails

Schulz

1998

Geophysical Research Letters

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Abstract. Certainly cloud inhomogeneity is not only important for cumulus or stratocumulus clouds on which the focus of most of the current studies is. To show that the impact of contrail cirrus microphysical inhomogeneity on cloud albedo can be deduced, fields of ice water content, effective radius, number density, and size distribution of ice particles generated by large eddy simulations (LESs) have been used within two-dimensional radiative transfer schemes to elucidate the effect of cloud inhomogeneity on area average radiative properties of contrails at evolution stages in the late dispersion regime. The results obtained indicate that differences in shortwave cloud albedo between homogeneous and inhomogeneous conditions remain small for fresh contrails but can become important if contrails would attain larger optical depths. In that case larger differences were obtained at which the albedo for horizontal homogeneous conditions is always larger than the corresponding value for inhomogeneous conditions.

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“…Numerous simulations of cold air outbreaks have also been conducted [e.g., Chlond, 1992;Bakan et al, 1995;Rao and Agee, 1996;Olsson and Harrington, 2000;Brummer and Pohlmann, 2000;Flamant et al, 2001;Pagowski and Moore, 2001] as well as simulations of cloud plumes from the cooling ponds [e.g., Shannon and Everett, 1978;Leahey et al, 1979;Yamada, 1979;Khvorostyanov, 1991].…”

Section: Introductionmentioning

confidence: 99%

A springtime cloud over the Beaufort Sea polynya: Three‐dimensional simulation with explicit spectral microphysics and comparison with observations

Khvorostyanov

Curry

Gültepe³

et al. 2003

J. Geophys. Res.

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[1] This paper addresses the formation of a cloud system associated with an arctic polynya in Beaufort Sea during springtime. Data were obtained as a part of the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE) Arctic Clouds Experiment from the Canadian Convair 580 aircraft during 25 April 1998. These data include in situ observations of cloud microphysics and meteorological variables and remote measurements from satellite and airborne lidar. A three-dimensional cloud-resolving model with explicit bin-resolving cloud microphysics is used to simulate the atmospheric boundary layer and cloud evolution associated with the polynya. After initialization with the aircraft sounding profiles, a quasi-steady polynya-induced atmospheric boundary layer (ABL) and a cloud system form. Strong turbulence in the ABL occurs above the polynya, the internal thermal boundary layer (ITBL) develops and grows upward in the downwind direction, and the ABL downwind of the polynya is separated into two decoupled layers. The cloud forms in the middle of the polynya, and its upper boundary lifts downwind while the lower boundary lowers and reaches the surface beyond the polynya southern boundary as a light fog. Farther to the south, the fog evaporates and transforms into an elevated cloud plume that extends for several tens of kilometers downwind. This cloud morphology is in good agreement with the lidar observations, which showed a cloud layer extending for more than 100 km downwind, and with the numerous previous observations. The simulated microphysical properties of a mixed cloud are similar to those observed. A new ice nucleation scheme resulted in cloud plume gradual crystallization along the wind and eventual transformation into diamond dust. Detailed evaluation of the water budget, supersaturation, and crystal size spectra showed that the ice crystal supersaturation relaxation times are 10-60 min; thus deposition on the crystals is rather slow, and only 1-5% of the available vapor is deposited on the crystals. The large ice crystal supersaturation relaxation time explains the relatively slow growth and gravitational fallout of the ice crystals, as well as the extensive propagation downwind of the plume.

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Three-dimensional simulation of cloud street development during a cold air outbreak

Cited by 70 publications

References 34 publications

Evaluation of Large-Eddy Simulations via Observations of Nocturnal Marine Stratocumulus

Evaluation of Large-Eddy Simulations via Observations of Nocturnal Marine Stratocumulus

On the effect of cloud inhomogeneity an area averaged radiative properties of contrails

A springtime cloud over the Beaufort Sea polynya: Three‐dimensional simulation with explicit spectral microphysics and comparison with observations

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