The effects of warm air intrusions in the high arctic on cirrus clouds

Warm-air intrusions (WAIs) are responsible for the transportation of warm and moist air masses from the mid-latitudes into the high Arctic ( > 70° N). In this work, we study cirrus clouds that form during WAI events (WAI cirrus) and during undisturbed Arctic conditions (AC cirrus) and investi...

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Main Authors: Dekoutsidis, Georgios, Wirth, Martin, Groß, Silke
Format: Text
Language:English
Published: 2024
Subjects:
Online Access:https://doi.org/10.5194/egusphere-2023-2708
https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2708/
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spelling ftcopernicus:oai:publications.copernicus.org:egusphere116020 2024-09-09T19:21:11+00:00 The effects of warm air intrusions in the high arctic on cirrus clouds Dekoutsidis, Georgios Wirth, Martin Groß, Silke 2024-05-24 application/pdf https://doi.org/10.5194/egusphere-2023-2708 https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2708/ eng eng doi:10.5194/egusphere-2023-2708 https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2708/ eISSN: Text 2024 ftcopernicus https://doi.org/10.5194/egusphere-2023-2708 2024-08-28T05:24:15Z Warm-air intrusions (WAIs) are responsible for the transportation of warm and moist air masses from the mid-latitudes into the high Arctic ( > 70° N). In this work, we study cirrus clouds that form during WAI events (WAI cirrus) and during undisturbed Arctic conditions (AC cirrus) and investigate possible differences between the two cloud types based on their macrophysical and optical properties with a focus on relative humidity over ice (RHi). We use airborne measurements from the combined high-spectral-resolution and differential-absorption lidar, WALES, performed during the HALO-(AC) 3 campaign. We classify each research flight and the measured clouds as either AC or WAI, based on the ambient conditions, and study the macrophysical, geometrical and optical characteristics for each cirrus group. As our main parameter we choose the relative humidity over ice (RHi), which we calculate RHi by combining the lidar water vapor measurements with model temperatures. Ice formation occurs at certain RHi values depending on the dominant nucleation process taking place. RHi can thus be used as an indication of the nucleation process and the structure of cirrus clouds. We find that during WAI events the Arctic is warmer and moister and WAI cirrus clouds are both geometrically and optically thicker compared to AC cirrus. WAI cirrus clouds and the layer directly surrounding them are more frequently supersaturated, also at high supersaturations over the threshold for homogeneous ice nucleation (HOM). AC cirrus clouds have a supersaturation-dominated cloud top and a subsaturated cloud base. WAI cirrus clouds also have high supersaturations at cloud top but also at cloud base. Text Arctic Copernicus Publications: E-Journals Arctic
institution Open Polar
collection Copernicus Publications: E-Journals
op_collection_id ftcopernicus
language English
description Warm-air intrusions (WAIs) are responsible for the transportation of warm and moist air masses from the mid-latitudes into the high Arctic ( > 70° N). In this work, we study cirrus clouds that form during WAI events (WAI cirrus) and during undisturbed Arctic conditions (AC cirrus) and investigate possible differences between the two cloud types based on their macrophysical and optical properties with a focus on relative humidity over ice (RHi). We use airborne measurements from the combined high-spectral-resolution and differential-absorption lidar, WALES, performed during the HALO-(AC) 3 campaign. We classify each research flight and the measured clouds as either AC or WAI, based on the ambient conditions, and study the macrophysical, geometrical and optical characteristics for each cirrus group. As our main parameter we choose the relative humidity over ice (RHi), which we calculate RHi by combining the lidar water vapor measurements with model temperatures. Ice formation occurs at certain RHi values depending on the dominant nucleation process taking place. RHi can thus be used as an indication of the nucleation process and the structure of cirrus clouds. We find that during WAI events the Arctic is warmer and moister and WAI cirrus clouds are both geometrically and optically thicker compared to AC cirrus. WAI cirrus clouds and the layer directly surrounding them are more frequently supersaturated, also at high supersaturations over the threshold for homogeneous ice nucleation (HOM). AC cirrus clouds have a supersaturation-dominated cloud top and a subsaturated cloud base. WAI cirrus clouds also have high supersaturations at cloud top but also at cloud base.
format Text
author Dekoutsidis, Georgios
Wirth, Martin
Groß, Silke
spellingShingle Dekoutsidis, Georgios
Wirth, Martin
Groß, Silke
The effects of warm air intrusions in the high arctic on cirrus clouds
author_facet Dekoutsidis, Georgios
Wirth, Martin
Groß, Silke
author_sort Dekoutsidis, Georgios
title The effects of warm air intrusions in the high arctic on cirrus clouds
title_short The effects of warm air intrusions in the high arctic on cirrus clouds
title_full The effects of warm air intrusions in the high arctic on cirrus clouds
title_fullStr The effects of warm air intrusions in the high arctic on cirrus clouds
title_full_unstemmed The effects of warm air intrusions in the high arctic on cirrus clouds
title_sort effects of warm air intrusions in the high arctic on cirrus clouds
publishDate 2024
url https://doi.org/10.5194/egusphere-2023-2708
https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2708/
geographic Arctic
geographic_facet Arctic
genre Arctic
genre_facet Arctic
op_source eISSN:
op_relation doi:10.5194/egusphere-2023-2708
https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2708/
op_doi https://doi.org/10.5194/egusphere-2023-2708
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