The effect of ice supersaturation and thin cirrus on lapse rates in the upper troposphere
<p>In this paper, the effects of ice-supersaturated regions and thin, subvisual cirrus clouds on lapse rates are examined. For that, probability distribution and density functions of the lapse rate and the potential temperature gradients from 10 years of measurement data from the MOZAIC/IAGOS...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2022-06-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/22/7699/2022/acp-22-7699-2022.pdf |
| _version_ | 1818203901271212032 |
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| author | K. Gierens L. Wilhelm L. Wilhelm S. Hofer S. Rohs |
| author_facet | K. Gierens L. Wilhelm L. Wilhelm S. Hofer S. Rohs |
| author_sort | K. Gierens |
| collection | DOAJ |
| description | <p>In this paper, the effects of ice-supersaturated regions and thin,
subvisual cirrus clouds on lapse rates are examined. For that,
probability distribution and density functions of
the lapse rate and the potential temperature gradients from
10 years of
measurement data from the MOZAIC/IAGOS project and ERA5 reanalysis
data were produced, and an analysis of an example case of an ice-supersaturated region with a large vertical extent is performed. For
the study of the probability distribution and density functions, a
distinction is made between ice-subsaturated and ice-supersaturated air
masses (persistent contrails)
and
situations of particularly high ice supersaturation that allow the formation of optically thick and strongly warming contrails.
The estimation of the lapse rates involves two adjacent standard pressure levels of the reanalysis surrounding MOZAIC's measurement/flight points. If the upper of these levels is in the stratosphere, the distribution function for subsaturated cases shows much lower lapse rates than those of supersaturated cases. If all levels are in the troposphere, the distributions become more similar, but the average lapse rates are still higher in supersaturated than in subsaturated cases, and the distributions peak at higher values and are narrower in ice-supersaturated regions (ISSRs)
than elsewhere. This narrowing is particularly pronounced if there is substantial supersaturation.</p>
<p>For the examination of an example case, ERA5 data and forecasts
from ICON-EU (DWD) are compared. ERA5 data, in particular,
show a large ice-supersaturated region below
the tropopause, which was pushed up by uplifting air, while the data
of ICON-EU indicate areas of saturation. The lapse rate in this ice-supersaturated region (ISSR),
which is large, is associated with clouds and
high relative humidity.
Supersaturation and cloud formation result from uplifting of air layers.
The temperature gradient within an uplifting layer steepens,
for both dry and moist air.
As soon as condensation or ice formation starts in the upper part of a lifting layer,
the release of latent heat begins to decrease the lapse rate, but radiation starts to act in the opposite direction, keeping the lapse rate high. The highest lapse rates close to the stability limit can only be reached in potentially unstable situations.</p> |
| first_indexed | 2024-12-12T03:32:42Z |
| format | Article |
| id | doaj.art-d917464ad22642b9a62e0041cd51fe01 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-12T03:32:42Z |
| publishDate | 2022-06-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-d917464ad22642b9a62e0041cd51fe012022-12-22T00:39:53ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242022-06-01227699771210.5194/acp-22-7699-2022The effect of ice supersaturation and thin cirrus on lapse rates in the upper troposphereK. Gierens0L. Wilhelm1L. Wilhelm2S. Hofer3S. Rohs4Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, GermanyInstitut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, Germanynow at: Oeschger Centre for Climate Change Research and Institute of Geography, University of Bern, Bern, SwitzerlandInstitut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, GermanyIEK-8, Forschungszentrum Jülich, Jülich, Germany<p>In this paper, the effects of ice-supersaturated regions and thin, subvisual cirrus clouds on lapse rates are examined. For that, probability distribution and density functions of the lapse rate and the potential temperature gradients from 10 years of measurement data from the MOZAIC/IAGOS project and ERA5 reanalysis data were produced, and an analysis of an example case of an ice-supersaturated region with a large vertical extent is performed. For the study of the probability distribution and density functions, a distinction is made between ice-subsaturated and ice-supersaturated air masses (persistent contrails) and situations of particularly high ice supersaturation that allow the formation of optically thick and strongly warming contrails. The estimation of the lapse rates involves two adjacent standard pressure levels of the reanalysis surrounding MOZAIC's measurement/flight points. If the upper of these levels is in the stratosphere, the distribution function for subsaturated cases shows much lower lapse rates than those of supersaturated cases. If all levels are in the troposphere, the distributions become more similar, but the average lapse rates are still higher in supersaturated than in subsaturated cases, and the distributions peak at higher values and are narrower in ice-supersaturated regions (ISSRs) than elsewhere. This narrowing is particularly pronounced if there is substantial supersaturation.</p> <p>For the examination of an example case, ERA5 data and forecasts from ICON-EU (DWD) are compared. ERA5 data, in particular, show a large ice-supersaturated region below the tropopause, which was pushed up by uplifting air, while the data of ICON-EU indicate areas of saturation. The lapse rate in this ice-supersaturated region (ISSR), which is large, is associated with clouds and high relative humidity. Supersaturation and cloud formation result from uplifting of air layers. The temperature gradient within an uplifting layer steepens, for both dry and moist air. As soon as condensation or ice formation starts in the upper part of a lifting layer, the release of latent heat begins to decrease the lapse rate, but radiation starts to act in the opposite direction, keeping the lapse rate high. The highest lapse rates close to the stability limit can only be reached in potentially unstable situations.</p>https://acp.copernicus.org/articles/22/7699/2022/acp-22-7699-2022.pdf |
| spellingShingle | K. Gierens L. Wilhelm L. Wilhelm S. Hofer S. Rohs The effect of ice supersaturation and thin cirrus on lapse rates in the upper troposphere Atmospheric Chemistry and Physics |
| title | The effect of ice supersaturation and thin cirrus on lapse rates in the upper troposphere |
| title_full | The effect of ice supersaturation and thin cirrus on lapse rates in the upper troposphere |
| title_fullStr | The effect of ice supersaturation and thin cirrus on lapse rates in the upper troposphere |
| title_full_unstemmed | The effect of ice supersaturation and thin cirrus on lapse rates in the upper troposphere |
| title_short | The effect of ice supersaturation and thin cirrus on lapse rates in the upper troposphere |
| title_sort | effect of ice supersaturation and thin cirrus on lapse rates in the upper troposphere |
| url | https://acp.copernicus.org/articles/22/7699/2022/acp-22-7699-2022.pdf |
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