Size‐Dependent Characteristics of Surface‐Rooted Three‐Dimensional Convective Objects in Continental Shallow Cumulus Simulations
Abstract 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...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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American Geophysical Union (AGU)
2022-03-01
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| Series: | Journal of Advances in Modeling Earth Systems |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2021MS002612 |
| _version_ | 1827958827358617600 |
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| author | Philipp J. Griewank Thijs Heus Roel A. J. Neggers |
| author_facet | Philipp J. Griewank Thijs Heus Roel A. J. Neggers |
| author_sort | Philipp J. Griewank |
| collection | DOAJ |
| description | Abstract 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. |
| first_indexed | 2024-04-09T15:42:19Z |
| format | Article |
| id | doaj.art-b0637a137cf74db083a5ca267016a75f |
| institution | Directory Open Access Journal |
| issn | 1942-2466 |
| language | English |
| last_indexed | 2024-04-09T15:42:19Z |
| publishDate | 2022-03-01 |
| publisher | American Geophysical Union (AGU) |
| record_format | Article |
| series | Journal of Advances in Modeling Earth Systems |
| spelling | doaj.art-b0637a137cf74db083a5ca267016a75f2023-04-27T07:53:09ZengAmerican Geophysical Union (AGU)Journal of Advances in Modeling Earth Systems1942-24662022-03-01143n/an/a10.1029/2021MS002612Size‐Dependent Characteristics of Surface‐Rooted Three‐Dimensional Convective Objects in Continental Shallow Cumulus SimulationsPhilipp J. Griewank0Thijs Heus1Roel A. J. Neggers2University of Cologne Cologne GermanyCleveland State University Cleveland OH USAUniversity of Cologne Cologne GermanyAbstract 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.https://doi.org/10.1029/2021MS002612LESshallow convectionparametrizationplumescumuluscontinental |
| spellingShingle | Philipp J. Griewank Thijs Heus Roel A. J. Neggers Size‐Dependent Characteristics of Surface‐Rooted Three‐Dimensional Convective Objects in Continental Shallow Cumulus Simulations Journal of Advances in Modeling Earth Systems LES shallow convection parametrization plumes cumulus continental |
| title | Size‐Dependent Characteristics of Surface‐Rooted Three‐Dimensional Convective Objects in Continental Shallow Cumulus Simulations |
| title_full | Size‐Dependent Characteristics of Surface‐Rooted Three‐Dimensional Convective Objects in Continental Shallow Cumulus Simulations |
| title_fullStr | Size‐Dependent Characteristics of Surface‐Rooted Three‐Dimensional Convective Objects in Continental Shallow Cumulus Simulations |
| title_full_unstemmed | Size‐Dependent Characteristics of Surface‐Rooted Three‐Dimensional Convective Objects in Continental Shallow Cumulus Simulations |
| title_short | Size‐Dependent Characteristics of Surface‐Rooted Three‐Dimensional Convective Objects in Continental Shallow Cumulus Simulations |
| title_sort | size dependent characteristics of surface rooted three dimensional convective objects in continental shallow cumulus simulations |
| topic | LES shallow convection parametrization plumes cumulus continental |
| url | https://doi.org/10.1029/2021MS002612 |
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