A global view on stratospheric ice clouds: assessment of processes related to their occurrence based on satellite observations

<p>Ice clouds play an important role in regulating water vapor and influencing the radiative budget in the atmosphere. This study investigates stratospheric ice clouds (SICs) in the latitude range between <span class="inline-formula"><math xmlns="http://www.w3.org/1998/...

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Main Authors: L. Zou, S. Griessbach, L. Hoffmann, R. Spang
Format: Article
Language:English
Published: Copernicus Publications 2022-05-01
Series:Atmospheric Chemistry and Physics
Online Access:https://acp.copernicus.org/articles/22/6677/2022/acp-22-6677-2022.pdf
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author L. Zou
S. Griessbach
L. Hoffmann
R. Spang
author_facet L. Zou
S. Griessbach
L. Hoffmann
R. Spang
author_sort L. Zou
collection DOAJ
description <p>Ice clouds play an important role in regulating water vapor and influencing the radiative budget in the atmosphere. This study investigates stratospheric ice clouds (SICs) in the latitude range between <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>±</mo><mn mathvariant="normal">60</mn><msup><mi/><mo>∘</mo></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="26pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="3f386b3c4c65d74f8ea84f8ccc9562ae"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-6677-2022-ie00001.svg" width="26pt" height="11pt" src="acp-22-6677-2022-ie00001.png"/></svg:svg></span></span> based on the Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). As polar stratospheric clouds include other particles, they are not discussed in this work. Tropopause temperature, double tropopauses, clouds in the upper troposphere and lower stratosphere (UTLS), gravity waves, and stratospheric aerosols are analyzed to investigate their relationships with the occurrence of and variability in SICs in the tropics and at midlatitudes.</p> <p>We found that SICs with cloud-top heights of 250 m above the first lapse rate tropopause are mainly detected in the tropics. Monthly time series of SICs from 2007 to 2019 show that high occurrence frequencies of SICs follow the Intertropical Convergence Zone (ITCZ) over time in the tropics and that SICs vary interannually at different latitudes. Results show that SICs associated with double tropopauses, which are related to poleward isentropic transport, are mostly found at midlatitudes. More than 80 % of the SICs around 30<span class="inline-formula"><sup>∘</sup></span> N/S are associated with double tropopauses.</p> <p>Correlation coefficients of SICs and all the other abovementioned processes confirm that the occurrence of and variability in SICs are mainly associated with the tropopause temperature in the tropics and at midlatitudes. UTLS clouds, which are retrieved from the Atmospheric Infrared Sounder (AIRS) and used as a proxy for deep convection in the tropics and high-altitude ice cloud sources at midlatitudes, have the highest correlations with SICs in the monsoon regions and the central United States. Gravity waves are mostly related to SICs at midlatitudes, especially over Patagonia and the Drake Passage. However, the second-highest correlation coefficients show that the cold tropopause temperature, the occurrence of double tropopauses, high stratospheric aerosol loading, frequent UTLS clouds, and gravity waves are highly correlated with the SICs locally. The long-term anomaly analyses show that interannual anomalies of SICs are correlated with the tropopause temperature and stratospheric aerosols instead of the UTLS clouds and gravity waves.</p> <p>The overlapping and similar correlation coefficients between SICs and all processes mentioned above indicate strong associations between those processes themselves. Due to their high inherent correlations, it is challenging to disentangle and evaluate their contributions to the occurrence of SICs on a global scale. However, the correlation coefficient analyses between SICs and all abovementioned processes (tropopause temperature, double tropopauses, clouds in the upper troposphere and lower stratosphere (UTLS), gravity waves, and stratospheric aerosols) in this study help us better understand the sources of SICs on a global scale.</p>
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spelling doaj.art-d8e278eb6b424b30ade8c2ff647d9e202022-12-22T02:37:45ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242022-05-01226677670210.5194/acp-22-6677-2022A global view on stratospheric ice clouds: assessment of processes related to their occurrence based on satellite observationsL. Zou0S. Griessbach1L. Hoffmann2R. Spang3Jülich Supercomputing Centre (JSC), Forschungszentrum Jülich, Jülich, GermanyJülich Supercomputing Centre (JSC), Forschungszentrum Jülich, Jülich, GermanyJülich Supercomputing Centre (JSC), Forschungszentrum Jülich, Jülich, GermanyInstitute of Energy and Climate Research (IEK-7), Forschungszentrum Jülich, Jülich, Germany<p>Ice clouds play an important role in regulating water vapor and influencing the radiative budget in the atmosphere. This study investigates stratospheric ice clouds (SICs) in the latitude range between <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>±</mo><mn mathvariant="normal">60</mn><msup><mi/><mo>∘</mo></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="26pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="3f386b3c4c65d74f8ea84f8ccc9562ae"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-6677-2022-ie00001.svg" width="26pt" height="11pt" src="acp-22-6677-2022-ie00001.png"/></svg:svg></span></span> based on the Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). As polar stratospheric clouds include other particles, they are not discussed in this work. Tropopause temperature, double tropopauses, clouds in the upper troposphere and lower stratosphere (UTLS), gravity waves, and stratospheric aerosols are analyzed to investigate their relationships with the occurrence of and variability in SICs in the tropics and at midlatitudes.</p> <p>We found that SICs with cloud-top heights of 250 m above the first lapse rate tropopause are mainly detected in the tropics. Monthly time series of SICs from 2007 to 2019 show that high occurrence frequencies of SICs follow the Intertropical Convergence Zone (ITCZ) over time in the tropics and that SICs vary interannually at different latitudes. Results show that SICs associated with double tropopauses, which are related to poleward isentropic transport, are mostly found at midlatitudes. More than 80 % of the SICs around 30<span class="inline-formula"><sup>∘</sup></span> N/S are associated with double tropopauses.</p> <p>Correlation coefficients of SICs and all the other abovementioned processes confirm that the occurrence of and variability in SICs are mainly associated with the tropopause temperature in the tropics and at midlatitudes. UTLS clouds, which are retrieved from the Atmospheric Infrared Sounder (AIRS) and used as a proxy for deep convection in the tropics and high-altitude ice cloud sources at midlatitudes, have the highest correlations with SICs in the monsoon regions and the central United States. Gravity waves are mostly related to SICs at midlatitudes, especially over Patagonia and the Drake Passage. However, the second-highest correlation coefficients show that the cold tropopause temperature, the occurrence of double tropopauses, high stratospheric aerosol loading, frequent UTLS clouds, and gravity waves are highly correlated with the SICs locally. The long-term anomaly analyses show that interannual anomalies of SICs are correlated with the tropopause temperature and stratospheric aerosols instead of the UTLS clouds and gravity waves.</p> <p>The overlapping and similar correlation coefficients between SICs and all processes mentioned above indicate strong associations between those processes themselves. Due to their high inherent correlations, it is challenging to disentangle and evaluate their contributions to the occurrence of SICs on a global scale. However, the correlation coefficient analyses between SICs and all abovementioned processes (tropopause temperature, double tropopauses, clouds in the upper troposphere and lower stratosphere (UTLS), gravity waves, and stratospheric aerosols) in this study help us better understand the sources of SICs on a global scale.</p>https://acp.copernicus.org/articles/22/6677/2022/acp-22-6677-2022.pdf
spellingShingle L. Zou
S. Griessbach
L. Hoffmann
R. Spang
A global view on stratospheric ice clouds: assessment of processes related to their occurrence based on satellite observations
Atmospheric Chemistry and Physics
title A global view on stratospheric ice clouds: assessment of processes related to their occurrence based on satellite observations
title_full A global view on stratospheric ice clouds: assessment of processes related to their occurrence based on satellite observations
title_fullStr A global view on stratospheric ice clouds: assessment of processes related to their occurrence based on satellite observations
title_full_unstemmed A global view on stratospheric ice clouds: assessment of processes related to their occurrence based on satellite observations
title_short A global view on stratospheric ice clouds: assessment of processes related to their occurrence based on satellite observations
title_sort global view on stratospheric ice clouds assessment of processes related to their occurrence based on satellite observations
url https://acp.copernicus.org/articles/22/6677/2022/acp-22-6677-2022.pdf
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