Strong day-to-day variability of the Asian Tropopause Aerosol Layer (ATAL) in August 2016 at the Himalayan foothills
<p>The South Asian summer monsoon is associated with a large-scale anticyclonic circulation in the upper troposphere and lower stratosphere (UTLS), which confines the air mass inside. During boreal summer, the confinement of this air mass leads to an accumulation of aerosol between about 13 an...
| Main Authors: | , , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2020-11-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/20/14273/2020/acp-20-14273-2020.pdf |
| _version_ | 1818531583712296960 |
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| author | S. Hanumanthu B. Vogel R. Müller S. Brunamonti S. Brunamonti S. Fadnavis D. Li D. Li P. Ölsner M. Naja B. B. Singh K. R. Kumar S. Sonbawne H. Jauhiainen H. Vömel B. Luo T. Jorge F. G. Wienhold R. Dirkson T. Peter |
| author_facet | S. Hanumanthu B. Vogel R. Müller S. Brunamonti S. Brunamonti S. Fadnavis D. Li D. Li P. Ölsner M. Naja B. B. Singh K. R. Kumar S. Sonbawne H. Jauhiainen H. Vömel B. Luo T. Jorge F. G. Wienhold R. Dirkson T. Peter |
| author_sort | S. Hanumanthu |
| collection | DOAJ |
| description | <p>The South Asian summer monsoon is associated with a large-scale anticyclonic circulation in the upper troposphere and lower stratosphere (UTLS), which confines the air mass inside. During boreal
summer, the confinement of this air mass leads to an accumulation of
aerosol between about 13 and 18 km (360
and 440 K potential temperature); this accumulation of aerosol
constitutes the Asian Tropopause Aerosol Layer (ATAL). We present
balloon-borne aerosol backscatter measurements of the ATAL performed
by the Compact Optical Backscatter Aerosol Detector (COBALD)
instrument in Nainital in northern India in August 2016, and compare
these with COBALD measurements in the post-monsoon time in November
2016. The measurements demonstrate a strong variability of the ATAL's
altitude, vertical extent, aerosol backscatter intensity and cirrus
cloud occurrence frequency. Such a variability cannot be deduced from
climatological means of the ATAL as they are derived from satellite
measurements. To explain this observed variability we performed a
Lagrangian back-trajectory analysis using the Chemical Lagrangian
Model of the Stratosphere (CLaMS). We identify the transport pathways
as well as the source regions of air parcels contributing to the ATAL
over Nainital in August 2016. Our analysis reveals a variety of
factors contributing to the observed day-to-day variability of the
ATAL: continental convection, tropical cyclones (maritime convection),
dynamics of the anticyclone and stratospheric intrusions. Thus, the air
in the ATAL is a mixture of air masses coming from different atmospheric
altitude layers. In addition, contributions from the model boundary
layer originate in different geographic source regions. The location
of the strongest updraft along the backward trajectories reveals a cluster
of strong upward transport at the southern edge of the Himalayan
foothills. From the top of the convective outflow level (about
13 km; 360 K) the air parcels ascend slowly to ATAL
altitudes within a large-scale upward spiral driven by the diabatic
heating in the anticyclonic flow of the South Asian summer monsoon at
UTLS altitudes. Cases with a strong ATAL typically show boundary<span id="page14274"/> layer
contributions from the Tibetan Plateau, the foothills of the Himalayas
and other continental regions below the Asian monsoon. Weaker ATAL
cases show higher contributions from the maritime boundary layer,
often related to tropical cyclones, indicating a mixing of clean
maritime and polluted continental air. On the one hand increasing
anthropogenic emissions in the future are expected due to the strong
growth of Asian economies; on the other hand the implementation of new
emission control measures (in particular in China) has reduced
the anthropogenic emissions of some pollutants
contributing to the ATAL substantially. It needs to be monitored in the future whether the thickness and intensity of the ATAL will further
increase, which will likely impact the surface climate.</p> |
| first_indexed | 2024-12-11T17:34:21Z |
| format | Article |
| id | doaj.art-ed441bd66d3345bb9cb3ed6a7dd9306b |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-11T17:34:21Z |
| publishDate | 2020-11-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-ed441bd66d3345bb9cb3ed6a7dd9306b2022-12-22T00:56:43ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242020-11-0120142731430210.5194/acp-20-14273-2020Strong day-to-day variability of the Asian Tropopause Aerosol Layer (ATAL) in August 2016 at the Himalayan foothillsS. Hanumanthu0B. Vogel1R. Müller2S. Brunamonti3S. Brunamonti4S. Fadnavis5D. Li6D. Li7P. Ölsner8M. Naja9B. B. Singh10K. R. Kumar11S. Sonbawne12H. Jauhiainen13H. Vömel14B. Luo15T. Jorge16F. G. Wienhold17R. Dirkson18T. Peter19Institute of Energy and Climate Research (IEK-7), Forschungszentrum Jülich, Jülich, GermanyInstitute of Energy and Climate Research (IEK-7), Forschungszentrum Jülich, Jülich, GermanyInstitute of Energy and Climate Research (IEK-7), Forschungszentrum Jülich, Jülich, GermanyInstitute for Atmospheric and Climate Science (IAC), Swiss Federal Institute of Technology (ETH), Zürich, SwitzerlandSwiss Federal Laboratory for Materials Science and Technology (EMPA), Laboratory for Air Pollution/Environmental Technology, Dübendorf, SwitzerlandIndian Institute of Tropical Meteorology (IITM), Pune, IndiaInstitute of Energy and Climate Research (IEK-7), Forschungszentrum Jülich, Jülich, GermanyKey Laboratory of Middle Atmosphere and Global Environment Observation (LAGEO), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, ChinaDeutscher Wetterdienst (DWD)/GCOS Reference Upper Air Network (GRUAN) Lead Center, Lindenberg, GermanyAryabhatta Research Institute of Observational Sciences (ARIES), Nainital, IndiaIndian Institute of Tropical Meteorology (IITM), Pune, IndiaCentre for Atmospheric Sciences, Indian Institute of Technology (IIT), New Delhi, IndiaIndian Institute of Tropical Meteorology (IITM), Pune, IndiaVaisala Oyj, Vantaa, FinlandEarth Observing Laboratory, National Center for Atmospheric Research, Boulder, CO, USAInstitute for Atmospheric and Climate Science (IAC), Swiss Federal Institute of Technology (ETH), Zürich, SwitzerlandInstitute for Atmospheric and Climate Science (IAC), Swiss Federal Institute of Technology (ETH), Zürich, SwitzerlandInstitute for Atmospheric and Climate Science (IAC), Swiss Federal Institute of Technology (ETH), Zürich, SwitzerlandDeutscher Wetterdienst (DWD)/GCOS Reference Upper Air Network (GRUAN) Lead Center, Lindenberg, GermanyInstitute for Atmospheric and Climate Science (IAC), Swiss Federal Institute of Technology (ETH), Zürich, Switzerland<p>The South Asian summer monsoon is associated with a large-scale anticyclonic circulation in the upper troposphere and lower stratosphere (UTLS), which confines the air mass inside. During boreal summer, the confinement of this air mass leads to an accumulation of aerosol between about 13 and 18 km (360 and 440 K potential temperature); this accumulation of aerosol constitutes the Asian Tropopause Aerosol Layer (ATAL). We present balloon-borne aerosol backscatter measurements of the ATAL performed by the Compact Optical Backscatter Aerosol Detector (COBALD) instrument in Nainital in northern India in August 2016, and compare these with COBALD measurements in the post-monsoon time in November 2016. The measurements demonstrate a strong variability of the ATAL's altitude, vertical extent, aerosol backscatter intensity and cirrus cloud occurrence frequency. Such a variability cannot be deduced from climatological means of the ATAL as they are derived from satellite measurements. To explain this observed variability we performed a Lagrangian back-trajectory analysis using the Chemical Lagrangian Model of the Stratosphere (CLaMS). We identify the transport pathways as well as the source regions of air parcels contributing to the ATAL over Nainital in August 2016. Our analysis reveals a variety of factors contributing to the observed day-to-day variability of the ATAL: continental convection, tropical cyclones (maritime convection), dynamics of the anticyclone and stratospheric intrusions. Thus, the air in the ATAL is a mixture of air masses coming from different atmospheric altitude layers. In addition, contributions from the model boundary layer originate in different geographic source regions. The location of the strongest updraft along the backward trajectories reveals a cluster of strong upward transport at the southern edge of the Himalayan foothills. From the top of the convective outflow level (about 13 km; 360 K) the air parcels ascend slowly to ATAL altitudes within a large-scale upward spiral driven by the diabatic heating in the anticyclonic flow of the South Asian summer monsoon at UTLS altitudes. Cases with a strong ATAL typically show boundary<span id="page14274"/> layer contributions from the Tibetan Plateau, the foothills of the Himalayas and other continental regions below the Asian monsoon. Weaker ATAL cases show higher contributions from the maritime boundary layer, often related to tropical cyclones, indicating a mixing of clean maritime and polluted continental air. On the one hand increasing anthropogenic emissions in the future are expected due to the strong growth of Asian economies; on the other hand the implementation of new emission control measures (in particular in China) has reduced the anthropogenic emissions of some pollutants contributing to the ATAL substantially. It needs to be monitored in the future whether the thickness and intensity of the ATAL will further increase, which will likely impact the surface climate.</p>https://acp.copernicus.org/articles/20/14273/2020/acp-20-14273-2020.pdf |
| spellingShingle | S. Hanumanthu B. Vogel R. Müller S. Brunamonti S. Brunamonti S. Fadnavis D. Li D. Li P. Ölsner M. Naja B. B. Singh K. R. Kumar S. Sonbawne H. Jauhiainen H. Vömel B. Luo T. Jorge F. G. Wienhold R. Dirkson T. Peter Strong day-to-day variability of the Asian Tropopause Aerosol Layer (ATAL) in August 2016 at the Himalayan foothills Atmospheric Chemistry and Physics |
| title | Strong day-to-day variability of the Asian Tropopause Aerosol Layer (ATAL) in August 2016 at the Himalayan foothills |
| title_full | Strong day-to-day variability of the Asian Tropopause Aerosol Layer (ATAL) in August 2016 at the Himalayan foothills |
| title_fullStr | Strong day-to-day variability of the Asian Tropopause Aerosol Layer (ATAL) in August 2016 at the Himalayan foothills |
| title_full_unstemmed | Strong day-to-day variability of the Asian Tropopause Aerosol Layer (ATAL) in August 2016 at the Himalayan foothills |
| title_short | Strong day-to-day variability of the Asian Tropopause Aerosol Layer (ATAL) in August 2016 at the Himalayan foothills |
| title_sort | strong day to day variability of the asian tropopause aerosol layer atal in august 2016 at the himalayan foothills |
| url | https://acp.copernicus.org/articles/20/14273/2020/acp-20-14273-2020.pdf |
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