Exploiting the favourable alignment of CALIPSO's descending orbital tracks over Sweden to study aerosol characteristics
One of the key knowledge gaps when estimating aerosol forcing and their role in air quality is our limited understanding of their vertical distribution. As an active lidar in space, the CALIOP-CALIPSO is helping to close this gap. The descending orbital track of CALIPSO follows elongated semi-major...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Stockholm University Press
2013-10-01
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| Series: | Tellus: Series B, Chemical and Physical Meteorology |
| Subjects: | |
| Online Access: | http://www.tellusb.net/index.php/tellusb/article/download/21155/pdf_1 |
| _version_ | 1818572035853385728 |
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| author | Manu Anna Thomas Abhay Devasthale Michael Kahnert |
| author_facet | Manu Anna Thomas Abhay Devasthale Michael Kahnert |
| author_sort | Manu Anna Thomas |
| collection | DOAJ |
| description | One of the key knowledge gaps when estimating aerosol forcing and their role in air quality is our limited understanding of their vertical distribution. As an active lidar in space, the CALIOP-CALIPSO is helping to close this gap. The descending orbital track of CALIPSO follows elongated semi-major axis of Sweden, slicing its atmosphere every 2–3 d, thus providing a unique opportunity to characterise aerosols and their verticality in all seasons irrespective of solar conditions. This favourable orbital configuration of CALIPSO over Sweden is exploited in the present study. Using five years of night-time aerosol observations (2006–2011), we investigated the vertical distribution of aerosols. The role of temperature inversions and winds in governing this distribution is additionally investigated using collocated AIRS-Aqua and ERA-Interim Reanalysis data. It is found that the majority of aerosols (up to 70%) are located within 1 km above the surface in the lowermost troposphere, irrespective of the season. In summer, convection and stronger mixing lift aerosols to slightly higher levels, but their noticeable presence in the upper free troposphere is observed in the winter half of the year, when the boundary layer is decoupled due to strong temperature inversions separating local sources from the transport component. When southerly winds prevail, two or more aerosol layers are most frequent over southern Sweden and the polluted air masses have higher AOD values. The depolarisation ratio and integrated attenuated backscatter of these aerosol layers are also higher. About 30–50% of all aerosol layers are located below the level where temperature inversions peak. On the other hand, relatively cleaner conditions are observed when the winds have a northerly component. |
| first_indexed | 2024-12-14T18:52:04Z |
| format | Article |
| id | doaj.art-9d5233ee9f4c44daaa670ec8c0305e4f |
| institution | Directory Open Access Journal |
| issn | 1600-0889 |
| language | English |
| last_indexed | 2024-12-14T18:52:04Z |
| publishDate | 2013-10-01 |
| publisher | Stockholm University Press |
| record_format | Article |
| series | Tellus: Series B, Chemical and Physical Meteorology |
| spelling | doaj.art-9d5233ee9f4c44daaa670ec8c0305e4f2022-12-21T22:51:13ZengStockholm University PressTellus: Series B, Chemical and Physical Meteorology1600-08892013-10-0165011010.3402/tellusb.v65i0.21155Exploiting the favourable alignment of CALIPSO's descending orbital tracks over Sweden to study aerosol characteristicsManu Anna ThomasAbhay DevasthaleMichael KahnertOne of the key knowledge gaps when estimating aerosol forcing and their role in air quality is our limited understanding of their vertical distribution. As an active lidar in space, the CALIOP-CALIPSO is helping to close this gap. The descending orbital track of CALIPSO follows elongated semi-major axis of Sweden, slicing its atmosphere every 2–3 d, thus providing a unique opportunity to characterise aerosols and their verticality in all seasons irrespective of solar conditions. This favourable orbital configuration of CALIPSO over Sweden is exploited in the present study. Using five years of night-time aerosol observations (2006–2011), we investigated the vertical distribution of aerosols. The role of temperature inversions and winds in governing this distribution is additionally investigated using collocated AIRS-Aqua and ERA-Interim Reanalysis data. It is found that the majority of aerosols (up to 70%) are located within 1 km above the surface in the lowermost troposphere, irrespective of the season. In summer, convection and stronger mixing lift aerosols to slightly higher levels, but their noticeable presence in the upper free troposphere is observed in the winter half of the year, when the boundary layer is decoupled due to strong temperature inversions separating local sources from the transport component. When southerly winds prevail, two or more aerosol layers are most frequent over southern Sweden and the polluted air masses have higher AOD values. The depolarisation ratio and integrated attenuated backscatter of these aerosol layers are also higher. About 30–50% of all aerosol layers are located below the level where temperature inversions peak. On the other hand, relatively cleaner conditions are observed when the winds have a northerly component.http://www.tellusb.net/index.php/tellusb/article/download/21155/pdf_1aerosolsCALIPSOvertical distributionair quality |
| spellingShingle | Manu Anna Thomas Abhay Devasthale Michael Kahnert Exploiting the favourable alignment of CALIPSO's descending orbital tracks over Sweden to study aerosol characteristics Tellus: Series B, Chemical and Physical Meteorology aerosols CALIPSO vertical distribution air quality |
| title | Exploiting the favourable alignment of CALIPSO's descending orbital tracks over Sweden to study aerosol characteristics |
| title_full | Exploiting the favourable alignment of CALIPSO's descending orbital tracks over Sweden to study aerosol characteristics |
| title_fullStr | Exploiting the favourable alignment of CALIPSO's descending orbital tracks over Sweden to study aerosol characteristics |
| title_full_unstemmed | Exploiting the favourable alignment of CALIPSO's descending orbital tracks over Sweden to study aerosol characteristics |
| title_short | Exploiting the favourable alignment of CALIPSO's descending orbital tracks over Sweden to study aerosol characteristics |
| title_sort | exploiting the favourable alignment of calipso x0027 s descending orbital tracks over sweden to study aerosol characteristics |
| topic | aerosols CALIPSO vertical distribution air quality |
| url | http://www.tellusb.net/index.php/tellusb/article/download/21155/pdf_1 |
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