On the reversibility of transitions between closed and open cellular convection
The two-way transition between closed and open cellular convection is addressed in an idealized cloud-resolving modeling framework. A series of cloud-resolving simulations shows that the transition between closed and open cellular states is asymmetrical and characterized by a rapid ("runaway&qu...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2015-07-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/15/7351/2015/acp-15-7351-2015.pdf |
| _version_ | 1811267436967624704 |
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| author | G. Feingold I. Koren T. Yamaguchi J. Kazil |
| author_facet | G. Feingold I. Koren T. Yamaguchi J. Kazil |
| author_sort | G. Feingold |
| collection | DOAJ |
| description | The two-way transition between closed and open cellular
convection is addressed in an idealized cloud-resolving modeling framework.
A series of cloud-resolving simulations shows that the transition between
closed and open cellular states is asymmetrical and characterized by a rapid
("runaway") transition from the closed- to the open-cell state but slower
recovery to the closed-cell state. Given that precipitation initiates the
closed–open cell transition and that the recovery requires a suppression of
the precipitation, we apply an ad hoc time-varying drop concentration to
initiate and suppress precipitation. We show that the asymmetry in the
two-way transition occurs even for very rapid drop concentration
replenishment. The primary barrier to recovery is the loss in turbulence
kinetic energy (TKE) associated with the loss in cloud water (and associated
radiative cooling) and the vertical stratification of the boundary layer
during the open-cell period. In transitioning from the open to the closed
state, the system faces the task of replenishing cloud water fast enough to
counter precipitation losses, such that it can generate radiative cooling and
TKE. It is hampered by a stable layer below cloud base that has to be
overcome before water vapor can be transported more efficiently into the
cloud layer. Recovery to the closed-cell state is slower when radiative
cooling is inefficient such as in the presence of free tropospheric clouds or
after sunrise, when it is hampered by the absorption of shortwave radiation.
Tests suggest that recovery to the closed-cell state is faster when the
drizzle is smaller in amount and of shorter duration, i.e., when the
precipitation causes less boundary layer stratification. Cloud-resolving
model results on recovery rates are supported by simulations with a simple
predator–prey dynamical system analogue. It is suggested that the observed
closing of open cells by ship effluent likely occurs when aerosol intrusions
are large, when contact comes prior to the heaviest drizzle in the early
morning hours, and when the free troposphere is cloud free. |
| first_indexed | 2024-04-12T21:02:34Z |
| format | Article |
| id | doaj.art-76722aa12535499394d5c7f3bbca5aa5 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-04-12T21:02:34Z |
| publishDate | 2015-07-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-76722aa12535499394d5c7f3bbca5aa52022-12-22T03:16:49ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242015-07-0115137351736710.5194/acp-15-7351-2015On the reversibility of transitions between closed and open cellular convectionG. Feingold0I. Koren1T. Yamaguchi2J. Kazil3Chemical Sciences Division, NOAA Earth System Research Laboratory (ESRL), Boulder, Colorado, USAWeizmann Institute, Rehovot, IsraelChemical Sciences Division, NOAA Earth System Research Laboratory (ESRL), Boulder, Colorado, USAChemical Sciences Division, NOAA Earth System Research Laboratory (ESRL), Boulder, Colorado, USAThe two-way transition between closed and open cellular convection is addressed in an idealized cloud-resolving modeling framework. A series of cloud-resolving simulations shows that the transition between closed and open cellular states is asymmetrical and characterized by a rapid ("runaway") transition from the closed- to the open-cell state but slower recovery to the closed-cell state. Given that precipitation initiates the closed–open cell transition and that the recovery requires a suppression of the precipitation, we apply an ad hoc time-varying drop concentration to initiate and suppress precipitation. We show that the asymmetry in the two-way transition occurs even for very rapid drop concentration replenishment. The primary barrier to recovery is the loss in turbulence kinetic energy (TKE) associated with the loss in cloud water (and associated radiative cooling) and the vertical stratification of the boundary layer during the open-cell period. In transitioning from the open to the closed state, the system faces the task of replenishing cloud water fast enough to counter precipitation losses, such that it can generate radiative cooling and TKE. It is hampered by a stable layer below cloud base that has to be overcome before water vapor can be transported more efficiently into the cloud layer. Recovery to the closed-cell state is slower when radiative cooling is inefficient such as in the presence of free tropospheric clouds or after sunrise, when it is hampered by the absorption of shortwave radiation. Tests suggest that recovery to the closed-cell state is faster when the drizzle is smaller in amount and of shorter duration, i.e., when the precipitation causes less boundary layer stratification. Cloud-resolving model results on recovery rates are supported by simulations with a simple predator–prey dynamical system analogue. It is suggested that the observed closing of open cells by ship effluent likely occurs when aerosol intrusions are large, when contact comes prior to the heaviest drizzle in the early morning hours, and when the free troposphere is cloud free.http://www.atmos-chem-phys.net/15/7351/2015/acp-15-7351-2015.pdf |
| spellingShingle | G. Feingold I. Koren T. Yamaguchi J. Kazil On the reversibility of transitions between closed and open cellular convection Atmospheric Chemistry and Physics |
| title | On the reversibility of transitions between closed and open cellular convection |
| title_full | On the reversibility of transitions between closed and open cellular convection |
| title_fullStr | On the reversibility of transitions between closed and open cellular convection |
| title_full_unstemmed | On the reversibility of transitions between closed and open cellular convection |
| title_short | On the reversibility of transitions between closed and open cellular convection |
| title_sort | on the reversibility of transitions between closed and open cellular convection |
| url | http://www.atmos-chem-phys.net/15/7351/2015/acp-15-7351-2015.pdf |
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