Details
| Original language | English |
|---|---|
| Pages (from-to) | 597-623 |
| Number of pages | 27 |
| Journal | Journal of Advances in Modeling Earth Systems |
| Volume | 11 |
| Issue number | 3 |
| Early online date | 9 Feb 2019 |
| Publication status | Published - 21 Apr 2019 |
Abstract
To quantify the turbulent transport at gray zone length scales between 1 and 10 km, the Lagrangian evolution of the CONSTRAIN cold air outbreak case was simulated with seven large eddy models. The case is characterized by rather large latent and sensible heat fluxes and a rapid deepening rate of the boundary layer. In some models the entrainment velocity exceeds 4 cm/s. A significant fraction of this growth is attributed to a strong longwave radiative cooling of the inversion layer. The evolution and the timing of the breakup of the stratocumulus cloud deck differ significantly among the models. Sensitivity experiments demonstrate that a decrease in the prescribed cloud droplet number concentration and the inclusion of ice microphysics both act to speed up the thinning of the stratocumulus by enhancing the production of precipitation. In all models the formation of mesoscale fluctuations is clearly evident in the cloud fields and also in the horizontal wind velocity. Resolved vertical fluxes remain important for scales up to 10 km. The simulation results show that the resolved vertical velocity variance gradually diminishes with a coarsening of the horizontal mesh, but the total vertical fluxes of heat, moisture, and momentum are only weakly affected. This is a promising result as it demonstrates the potential use of a mesh size-dependent turbulent length scale for convective boundary layers at gray zone model resolutions.
Keywords
- cold air outbreak, gray zone, large eddy models, stratocumulus
ASJC Scopus subject areas
- Environmental Science(all)
- Global and Planetary Change
- Environmental Science(all)
- Environmental Chemistry
- Earth and Planetary Sciences(all)
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In: Journal of Advances in Modeling Earth Systems, Vol. 11, No. 3, 21.04.2019, p. 597-623.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Turbulent Transport in the Gray Zone
T2 - A Large Eddy Model Intercomparison Study of the CONSTRAIN Cold Air Outbreak Case
AU - de Roode, Stephan R.
AU - Frederikse, Thomas
AU - Siebesma, A. Pier
AU - Lesage, Andrew T.
AU - Chylik, Jan
AU - Field, Paul R.
AU - Fricke, Jens
AU - Gryschka, Micha
AU - Hill, Adrian
AU - Honnert, Rachel
AU - Krueger, Steve K.
AU - Lac, Christine
AU - Tomassini, Lorenzo
N1 - Funding Information: The PALM simulations with DALES including ice were performed with resources provided by the North-German Supercomputing Alliance (HLRN) and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)?Projektnummer 268020496?TRR 172, within the Transregional Collaborative Research Center ?ArctiC Amplification: Climate Relevant Atmospheric and SurfaCe Processes, and Feedback Mechanisms (AC)3.? DHARMA simulations used resources provided by the NASA High-End Computing (HEC) Program through the NASA Advanced Supercomputing (NAS) Division at Ames Research Center. The case specifics are posted at the Met Office website (http://appconv.metoffice.com/cold_air_outbreak/constrain_case/home.html). The simulation data in this study are stored at the EUCLIPSE website (www.euclipse.nl/CONSTRAIN/model.tar), with model the (case sensitive) model name, DALES, DHARMA, MONC, Meso-NH, PALM, SAM, or UCLA.
PY - 2019/4/21
Y1 - 2019/4/21
N2 - To quantify the turbulent transport at gray zone length scales between 1 and 10 km, the Lagrangian evolution of the CONSTRAIN cold air outbreak case was simulated with seven large eddy models. The case is characterized by rather large latent and sensible heat fluxes and a rapid deepening rate of the boundary layer. In some models the entrainment velocity exceeds 4 cm/s. A significant fraction of this growth is attributed to a strong longwave radiative cooling of the inversion layer. The evolution and the timing of the breakup of the stratocumulus cloud deck differ significantly among the models. Sensitivity experiments demonstrate that a decrease in the prescribed cloud droplet number concentration and the inclusion of ice microphysics both act to speed up the thinning of the stratocumulus by enhancing the production of precipitation. In all models the formation of mesoscale fluctuations is clearly evident in the cloud fields and also in the horizontal wind velocity. Resolved vertical fluxes remain important for scales up to 10 km. The simulation results show that the resolved vertical velocity variance gradually diminishes with a coarsening of the horizontal mesh, but the total vertical fluxes of heat, moisture, and momentum are only weakly affected. This is a promising result as it demonstrates the potential use of a mesh size-dependent turbulent length scale for convective boundary layers at gray zone model resolutions.
AB - To quantify the turbulent transport at gray zone length scales between 1 and 10 km, the Lagrangian evolution of the CONSTRAIN cold air outbreak case was simulated with seven large eddy models. The case is characterized by rather large latent and sensible heat fluxes and a rapid deepening rate of the boundary layer. In some models the entrainment velocity exceeds 4 cm/s. A significant fraction of this growth is attributed to a strong longwave radiative cooling of the inversion layer. The evolution and the timing of the breakup of the stratocumulus cloud deck differ significantly among the models. Sensitivity experiments demonstrate that a decrease in the prescribed cloud droplet number concentration and the inclusion of ice microphysics both act to speed up the thinning of the stratocumulus by enhancing the production of precipitation. In all models the formation of mesoscale fluctuations is clearly evident in the cloud fields and also in the horizontal wind velocity. Resolved vertical fluxes remain important for scales up to 10 km. The simulation results show that the resolved vertical velocity variance gradually diminishes with a coarsening of the horizontal mesh, but the total vertical fluxes of heat, moisture, and momentum are only weakly affected. This is a promising result as it demonstrates the potential use of a mesh size-dependent turbulent length scale for convective boundary layers at gray zone model resolutions.
KW - cold air outbreak
KW - gray zone
KW - large eddy models
KW - stratocumulus
UR - http://www.scopus.com/inward/record.url?scp=85062351037&partnerID=8YFLogxK
U2 - 10.1029/2018MS001443
DO - 10.1029/2018MS001443
M3 - Article
AN - SCOPUS:85062351037
VL - 11
SP - 597
EP - 623
JO - Journal of Advances in Modeling Earth Systems
JF - Journal of Advances in Modeling Earth Systems
SN - 1942-2466
IS - 3
ER -