Tropospheric mixing and parametrization of unresolved convective updrafts as implemented in the Chemical Lagrangian Model of the Stratosphere (CLaMS v2.0)
<p>Inaccurate representation of mixing in chemistry transport models, mainly suffering from an excessive numerical diffusion, strongly influences the quantitative estimates of the stratosphere–troposphere exchange (STE). The Lagrangian view of transport offers an alternative to exploit the num...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2019-06-01
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| Series: | Geoscientific Model Development |
| Online Access: | https://www.geosci-model-dev.net/12/2441/2019/gmd-12-2441-2019.pdf |
| _version_ | 1819207911716421632 |
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| author | P. Konopka M. Tao F. Ploeger M. Diallo M. Riese |
| author_facet | P. Konopka M. Tao F. Ploeger M. Diallo M. Riese |
| author_sort | P. Konopka |
| collection | DOAJ |
| description | <p>Inaccurate representation of mixing in chemistry transport models,
mainly suffering from an excessive numerical diffusion, strongly influences
the quantitative estimates of the stratosphere–troposphere exchange (STE).
The Lagrangian view of transport offers an alternative to exploit
the numerical diffusion for parametrization of the physical mixing.
Here, we follow this concept and discuss how to extend the representation
of tropospheric transport in the Chemical Lagrangian Model of the Stratosphere (CLaMS).</p>
<p>Although the current transport scheme in CLaMS (v1.0) shows a good ability to represent transport of tracers in the
stably stratified stratosphere (Pommrich et al., 2014, and the references
therein), there are deficiencies in the representation of the effects of
convective uplift and mixing due to weak vertical stability in the troposphere.
We show how the CLaMS transport scheme was modified by including additional tropospheric mixing
and vertical transport due to unresolved convective updrafts by parametrizing these processes in terms of the dry and
moist Brunt–Väisälä frequencies.
The regions with enhanced convective updrafts in the novel CLaMS simulation covering the
2005–2008 period coincide with regions of enhanced convection as diagnosed from
the satellite observations of the outgoing longwave radiation (OLR).</p>
<p>We analyze how well this approach improves the CLaMS representation of <span class="inline-formula">CO<sub>2</sub></span> in the upper
troposphere and lower stratosphere, in particular the propagation of the <span class="inline-formula">CO<sub>2</sub></span> seasonal cycle
from the planetary boundary layer (PBL) into the lower stratosphere.
The <span class="inline-formula">CO<sub>2</sub></span> values in the PBL are specified by the CarbonTracker data set (version CT2013B),
and the Comprehensive Observation Network for TRace gases by AIrLiner (CONTRAIL)
observations are used to validate the model.
The proposed extension of tropospheric transport increases
the influence of the PBL in the middle and upper troposphere and at the same
time impacts the STE.
The effect on mean age away from the troposphere in the deep stratosphere is weak.</p> |
| first_indexed | 2024-12-23T05:31:01Z |
| format | Article |
| id | doaj.art-2e46740116534193a4fbd365cf055352 |
| institution | Directory Open Access Journal |
| issn | 1991-959X 1991-9603 |
| language | English |
| last_indexed | 2024-12-23T05:31:01Z |
| publishDate | 2019-06-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Geoscientific Model Development |
| spelling | doaj.art-2e46740116534193a4fbd365cf0553522022-12-21T17:58:29ZengCopernicus PublicationsGeoscientific Model Development1991-959X1991-96032019-06-01122441246210.5194/gmd-12-2441-2019Tropospheric mixing and parametrization of unresolved convective updrafts as implemented in the Chemical Lagrangian Model of the Stratosphere (CLaMS v2.0)P. KonopkaM. TaoF. PloegerM. DialloM. Riese<p>Inaccurate representation of mixing in chemistry transport models, mainly suffering from an excessive numerical diffusion, strongly influences the quantitative estimates of the stratosphere–troposphere exchange (STE). The Lagrangian view of transport offers an alternative to exploit the numerical diffusion for parametrization of the physical mixing. Here, we follow this concept and discuss how to extend the representation of tropospheric transport in the Chemical Lagrangian Model of the Stratosphere (CLaMS).</p> <p>Although the current transport scheme in CLaMS (v1.0) shows a good ability to represent transport of tracers in the stably stratified stratosphere (Pommrich et al., 2014, and the references therein), there are deficiencies in the representation of the effects of convective uplift and mixing due to weak vertical stability in the troposphere. We show how the CLaMS transport scheme was modified by including additional tropospheric mixing and vertical transport due to unresolved convective updrafts by parametrizing these processes in terms of the dry and moist Brunt–Väisälä frequencies. The regions with enhanced convective updrafts in the novel CLaMS simulation covering the 2005–2008 period coincide with regions of enhanced convection as diagnosed from the satellite observations of the outgoing longwave radiation (OLR).</p> <p>We analyze how well this approach improves the CLaMS representation of <span class="inline-formula">CO<sub>2</sub></span> in the upper troposphere and lower stratosphere, in particular the propagation of the <span class="inline-formula">CO<sub>2</sub></span> seasonal cycle from the planetary boundary layer (PBL) into the lower stratosphere. The <span class="inline-formula">CO<sub>2</sub></span> values in the PBL are specified by the CarbonTracker data set (version CT2013B), and the Comprehensive Observation Network for TRace gases by AIrLiner (CONTRAIL) observations are used to validate the model. The proposed extension of tropospheric transport increases the influence of the PBL in the middle and upper troposphere and at the same time impacts the STE. The effect on mean age away from the troposphere in the deep stratosphere is weak.</p>https://www.geosci-model-dev.net/12/2441/2019/gmd-12-2441-2019.pdf |
| spellingShingle | P. Konopka M. Tao F. Ploeger M. Diallo M. Riese Tropospheric mixing and parametrization of unresolved convective updrafts as implemented in the Chemical Lagrangian Model of the Stratosphere (CLaMS v2.0) Geoscientific Model Development |
| title | Tropospheric mixing and parametrization of unresolved convective updrafts as implemented in the Chemical Lagrangian Model of the Stratosphere (CLaMS v2.0) |
| title_full | Tropospheric mixing and parametrization of unresolved convective updrafts as implemented in the Chemical Lagrangian Model of the Stratosphere (CLaMS v2.0) |
| title_fullStr | Tropospheric mixing and parametrization of unresolved convective updrafts as implemented in the Chemical Lagrangian Model of the Stratosphere (CLaMS v2.0) |
| title_full_unstemmed | Tropospheric mixing and parametrization of unresolved convective updrafts as implemented in the Chemical Lagrangian Model of the Stratosphere (CLaMS v2.0) |
| title_short | Tropospheric mixing and parametrization of unresolved convective updrafts as implemented in the Chemical Lagrangian Model of the Stratosphere (CLaMS v2.0) |
| title_sort | tropospheric mixing and parametrization of unresolved convective updrafts as implemented in the chemical lagrangian model of the stratosphere clams v2 0 |
| url | https://www.geosci-model-dev.net/12/2441/2019/gmd-12-2441-2019.pdf |
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