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The effect of ice supersaturation and thin cirrus on lapse rates in the upper troposphere

Gierens, Klaus Martin and Wilhelm, Lena and Hofer, Sina and Rohs, Susanne (2022) The effect of ice supersaturation and thin cirrus on lapse rates in the upper troposphere. Atmospheric Chemistry and Physics, 22, pp. 7699-7712. Copernicus Publications. doi: 10.5194/acp-22-7699-2022. ISSN 1680-7316.

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Official URL: https://doi.org/10.5194/acp-22-7699-2022


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. 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.

Item URL in elib:https://elib.dlr.de/186876/
Document Type:Article
Additional Information:Dieses Paper ist im Rahmen des DLR-Projekts Eco2Fly entstanden.
Title:The effect of ice supersaturation and thin cirrus on lapse rates in the upper troposphere
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Gierens, Klaus MartinDLR, IPAhttps://orcid.org/0000-0001-6983-5370
Wilhelm, LenaDLR, IPAhttps://orcid.org/0000-0003-2666-8378
Rohs, SusanneFZ, Jülichhttps://orcid.org/0000-0001-5473-2934
Date:15 June 2022
Journal or Publication Title:Atmospheric Chemistry and Physics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
Page Range:pp. 7699-7712
Publisher:Copernicus Publications
Keywords:Eisübersättigte Regionen, Schichtungsstabilität der Atmosphäre, Temperaturprofil, Hebung, Strahlung
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Air Transportation and Impact
DLR - Research area:Aeronautics
DLR - Program:L AI - Air Transportation and Impact
DLR - Research theme (Project):L - Climate, Weather and Environment
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Earth System Modelling
Deposited By: Gierens, Dr.rer.nat. Klaus Martin
Deposited On:15 Jun 2022 12:42
Last Modified:15 Jun 2022 12:42

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