4.6 Article

Size-Dependent Characteristics of Surface-Rooted Three-Dimensional Convective Objects in Continental Shallow Cumulus Simulations

Journal

Publisher

AMER GEOPHYSICAL UNION
DOI: 10.1029/2021MS002612

Keywords

LES; shallow convection; parametrization; plumes; cumulus; continental

Funding

  1. U.S. Department of Energy's Atmospheric System Research, an Office of Science Biological and Environmental Research program [DE-SC0017999]
  2. Cleveland State University Faculty Research and Development award
  3. Projekt DEAL
  4. U.S. Department of Energy (DOE) [DE-SC0017999] Funding Source: U.S. Department of Energy (DOE)

Ask authors/readers for more resources

This paper presents a unique methodology for studying shallow continental convection, using a segmentation algorithm to identify individual 3D objects and analyzing their properties. The results show that the width of the objects significantly affects their kinematic and thermodynamic properties, especially above cloud base.
A segmentation algorithm is applied to high resolution simulations of shallow continental convection to identify individual convective 3D objects within the convective boundary layer, in order to investigate which properties of the objects vary with the object width. The study analyses the geometry of the objects, along with their profiles of vertical velocity and total water, to assess various assumptions often used in spectral mass-flux convection schemes. The methodology of this paper is unique in that we use (a) a novel application of the watershed algorithm to detect individual objects in the constantly evolving continental boundary layer efficiently, and (b) an unprecedentedly large number of simulations being analyzed. In total, 26 days of LASSO simulations at the Atmospheric Radiation Measurement Southern Great Plains site are analyzed, yielding roughly one million objects. Plume-like surface-rooted objects are found to be omnipresent, the vertical extent of which is strongly dependent on the object width. The vertical velocity and moisture anomaly profiles of the widest objects are roughly consistent with the classic buoyancy-driven rising plume model. The kinematic and thermodynamic properties of the objects vary with object width. This width dependence is strongest above cloud base, but much weaker below. Finally the impact of neglecting the contribution of covariances to the vertical moisture flux, which is commonly used in mass-flux parameterizations, is investigated. The average effect of neglecting covariances increases linearly with object width, leading to a 20% flux underestimation for 2 km wide objects. Implications of the results for spectral convection scheme development are briefly discussed.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.6
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available