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edmf [2018/09/10 10:00] – neggersedmf [2021/01/22 22:21] – external edit 127.0.0.1
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 {{:mbulk_c_2d.png?&400|}} {{:mbulk_c_2d.png?&400|}}
  
-//Figure 3. Single Column Model (SCM) results with the multi-plume ED(MF)<sup>n</sup> scheme based on discretized size distributions for the RICO shallow cumulus case. Clockwise from the top left: liquid water potential temperature $\theta_l$, total specific humidity $q_t$, and the total area fraction and volumetric mass flux of all condensed EDMF plumes combined. The simulation was performed with ED(MF)<sup>n</sup> implemented in DALES as a subgrid scheme, using an ensemble of 10 plumes. DALES was run on an 8x8 grid at grid-spacing of 10km horizontally and 40 m vertically, using a time-integration step of 300 s. Results with DALES-ED(MF)<sup>n</sup> for other cases can be found on this [[http://gop.meteo.uni-koeln.de/~neggers/EDMFn/EDMFn_plots.php|QUICKLOOK]] page. //+//Figure 3. Single Column Model (SCM) results with the multi-plume ED(MF)<sup>n</sup> scheme based on discretized size distributions for the RICO shallow cumulus case. Clockwise from the top left: liquid water potential temperature $\theta_l$, total specific humidity $q_t$, and the total area fraction and volumetric mass flux of all condensed EDMF plumes combined. The simulation was performed with ED(MF)<sup>n</sup> implemented in DALES as a subgrid scheme, using an ensemble of 10 plumes. DALES was run on an 8x8 grid at grid-spacing of 10km horizontally and 40 m vertically, using a time-integration step of 300 s. More results with the DALES-ED(MF)<sup>n</sup> model, also for other cumulus cases, can be found on this [[http://atmos.meteo.uni-koeln.de/~neggers/EDMFn/EDMFn_plots.php|QUICKLOOK]] page. //
  
 A benefit of multi plume models is that bulk properties can in principle be diagnosed from the reconstructed spectrum of rising plumes, making classically-used bulk closures obsolete. For example, plumes can condense or not, depending on their proximity to saturation. As a result, the scheme becomes sensitive to environmental humidity, a behavior that recent research has found to be an essential feature in convection schemes. The number of plumes that reach their lifting condensation level and continue as transporting cumulus clouds is automatically found by the scheme itself (see also Fig 2). An environment closer to saturation will yield a higher number of rising plumes that will condense at the top of the mixed layer, which immediately boosts the cloud base mass flux. This allows the scheme to effectively, and swiftly, find the point at which the vertical transport of mass, heat and humidity through cloud base by all plumes together exactly counteracts the effect of the destabilizing large-scale forcings. This situation corresponds to a quasi-equilibrium state, and the feedback mechanism that establishes it is called the //shallow cumulus valve// mechanism. An advantage of multi-plume MF models is that this process can be captured automatically, yielding smooth simulations for idealized prototype cumulus cases (see Fig. 3). A benefit of multi plume models is that bulk properties can in principle be diagnosed from the reconstructed spectrum of rising plumes, making classically-used bulk closures obsolete. For example, plumes can condense or not, depending on their proximity to saturation. As a result, the scheme becomes sensitive to environmental humidity, a behavior that recent research has found to be an essential feature in convection schemes. The number of plumes that reach their lifting condensation level and continue as transporting cumulus clouds is automatically found by the scheme itself (see also Fig 2). An environment closer to saturation will yield a higher number of rising plumes that will condense at the top of the mixed layer, which immediately boosts the cloud base mass flux. This allows the scheme to effectively, and swiftly, find the point at which the vertical transport of mass, heat and humidity through cloud base by all plumes together exactly counteracts the effect of the destabilizing large-scale forcings. This situation corresponds to a quasi-equilibrium state, and the feedback mechanism that establishes it is called the //shallow cumulus valve// mechanism. An advantage of multi-plume MF models is that this process can be captured automatically, yielding smooth simulations for idealized prototype cumulus cases (see Fig. 3).
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 ==== Results for prototype cumulus cases ===== ==== Results for prototype cumulus cases =====
  
-DALES-ED(MF)<sup>n</sup> basically stands for the DALES code with the ED(MF)<sup>n</sup> scheme implemented as a subgrid scheme, replacing the original Sub-Filter Scale (SFS) scheme (Smagorinsky or TKE). Results with this scheme for a set of well-known prototype cumulus cases  are provided on this [[http://gop.meteo.uni-koeln.de/~neggers/EDMFn/EDMFn_plots.php|QUICKLOOK]] page. All simulations were performed on a 8x8 microgrid with dx=dy=10 km and dt=300 sec.+DALES-ED(MF)<sup>n</sup> basically stands for the DALES code with the ED(MF)<sup>n</sup> scheme implemented as a subgrid scheme, replacing the original Sub-Filter Scale (SFS) scheme (Smagorinsky or TKE). Results with this scheme for a set of well-known prototype cumulus cases  are provided on this [[http://atmos.meteo.uni-koeln.de/~neggers/EDMFn/EDMFn_plots.php|QUICKLOOK]] page. All simulations were performed on a 8x8 microgrid with dx=dy=10 km and dt=300 sec.
  
 The cases for which the scheme is tested cover different climate regimes and convective types. Marine subtropical shallow cumulus conditions are described by the RICO and BOMEX case. Continental diurnal cycles of shallow cumulus are represented by the classic "ARM SGP" case (21 June 1997), various LASSO cases, and selected days at the mid-latitude JOYCE site in Germany. Transitional cases from stratocumulus to cumulus include the ASTEX case and the SLOW, REFERENCE and FAST case as described by Sandu et al., all of which featured in the recent SCM intercomparison study by Neggers et al. (2017) as part of the EUCLIPSE project. Finally, deep convective conditions are covered by the humidity-convection case of Derbyshire et al (2004) and a variation of the BOMEX case with modified surface fluxes described by Kuang and Bretherton (2000). The cases for which the scheme is tested cover different climate regimes and convective types. Marine subtropical shallow cumulus conditions are described by the RICO and BOMEX case. Continental diurnal cycles of shallow cumulus are represented by the classic "ARM SGP" case (21 June 1997), various LASSO cases, and selected days at the mid-latitude JOYCE site in Germany. Transitional cases from stratocumulus to cumulus include the ASTEX case and the SLOW, REFERENCE and FAST case as described by Sandu et al., all of which featured in the recent SCM intercomparison study by Neggers et al. (2017) as part of the EUCLIPSE project. Finally, deep convective conditions are covered by the humidity-convection case of Derbyshire et al (2004) and a variation of the BOMEX case with modified surface fluxes described by Kuang and Bretherton (2000).
 +
 +==== Contact =====
 +
 +For more information get in contact with [[http://www.geomet.uni-koeln.de/das-institut/mitarbeiter/griewank/|Philipp Griewank]] or [[http://www.geomet.uni-koeln.de/das-institut/mitarbeiter/neggers/|Roel Neggers]].
  
  
edmf.txt · Last modified: 2022/09/14 17:47 by ibartolo