scholarly journals Comparing ground‐based observations and a large‐eddy simulation of shallow cumuli by isolating the main controlling factors of the mass flux distribution

2019 ◽  
Vol 146 (726) ◽  
pp. 254-266 ◽  
Author(s):  
Mirjana Sakradzija ◽  
Marcus Klingebiel
Keyword(s):  
Large Eddy Simulation ◽  
Mass Flux ◽  
Flux Distribution ◽  
Controlling Factors ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Main Controlling Factors

scholarly journals On the Equivalence of Two Schemes for Convective Momentum Transport

2012 ◽  
Vol 69 (12) ◽  
pp. 3491-3500 ◽  
Author(s):  
David M. Romps
Keyword(s):  
Large Eddy Simulation ◽  
Pressure Gradient ◽  
Mass Flux ◽  
Deep Convection ◽  
Momentum Transport ◽  
Gradient Force ◽  
Pressure Gradient Force ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Convective Momentum Transport

Abstract The Gregory–Kershaw–Inness (GKI) parameterization of convective momentum transport, which has a tunable parameter C, is shown to be identical to a parameterization with no pressure gradient force and a mass flux smaller by a factor of 1 − C. Using cloud-resolving simulations, the transilient matrix for momentum is diagnosed for deep convection in radiative–convective equilibrium. Using this transilient matrix, it is shown that the GKI scheme underestimates the compensating subsidence of momentum by a factor of 1 − C, as predicted. This result is confirmed using a large-eddy simulation.

scholarly journals THERMAL LARGE EDDY SIMULATION WITH SENSIBLE HEAT FLUX DISTRIBUTION FROM VARIOUS 3D BUILDING GEOMETRIES

2015 ◽  
Vol 71 (4) ◽  
pp. I_433-I_438 ◽  
Author(s):  
Mohammed BAKKALI ◽  
Atsushi INAGAKI ◽  
Yasunobu ASHIE ◽  
Yuma YOSHIDA ◽  
Manabu KANDA ◽  
...  
Keyword(s):  
Heat Flux ◽  
Large Eddy Simulation ◽  
Flux Distribution ◽  
Sensible Heat Flux ◽  
Sensible Heat ◽  
Heat Flux Distribution ◽  
Eddy Simulation ◽  
Large Eddy

scholarly journals A Dual Mass Flux Framework for Boundary Layer Convection. Part I: Transport

2009 ◽  
Vol 66 (6) ◽  
pp. 1465-1487 ◽  
Author(s):  
Roel A. J. Neggers ◽  
Martin Köhler ◽  
Anton C. M. Beljaars
Keyword(s):  
Boundary Layer ◽  
Large Eddy Simulation ◽  
Mixed Layer ◽  
Mass Flux ◽  
Model Complexity ◽  
Cumulus Convection ◽  
Eddy Simulation ◽  
Shallow Cumulus ◽  
Large Eddy ◽  
Simulation Results

Abstract This study considers the question of what is the least complex bulk mass flux framework that can still conceptually reproduce the smoothly varying coupling between the shallow convective cloud layer and the subcloud mixed layer. To this end, the model complexity of the classic single bulk mass flux scheme is enhanced. Inspired by recent large-eddy simulation results, the authors argue that two relatively minor but key conceptual modifications are already sufficient to achieve this goal: (i) retaining a dry transporting updraft in the moist limit and (ii) applying continuous updraft area partitioning to this dual mass flux (DualM) framework. The dry updraft represents all internal mixed layer updrafts that terminate near the mixed layer top, whereas the moist updraft represents all updrafts that condense and rise out of the mixed layer as buoyant cumulus clouds. The continuous area partitioning between the dry and moist updraft is a function of moist convective inhibition above the mixed layer top. Updraft initialization is a function of the updraft area fraction and is therefore consistent with the updraft definition. It is argued that the model complexity thus enhanced is sufficient to allow reproduction of various phenomena involved in the cloud–subcloud coupling, namely (i) dry countergradient transport within the mixed layer that is independent of the moist updraft, (ii) soft triggering of moist convective flux throughout the boundary layer, and (iii) a smooth response to smoothly varying forcings, including the reproduction of gradual transitions to and from shallow cumulus convection. The DualM framework is evaluated by implementing in the Eddy Diffusivity Mass Flux (EDMF) boundary layer scheme of the ECMWF’s Integrated Forecasting System. Single column model experiments are evaluated against large-eddy simulation results for a range of different cases that span a broad parameter space of cloud–subcloud coupling intensities. The results illustrate that also in numerical practice the DualM framework can reproduce gradual transitions to and from shallow cumulus convection. Model behavior is further explored through experiments in which model complexity is purposely reduced, thus mimicking a single bulk updraft setup. This gives more insight into the new model-internal interactions and explains the obtained case results.

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