Vertical Structure of Ice Clouds and Vertical Air Motion from Vertically Pointing Cloud Radar Measurements
The vertical structure of ice clouds and vertical air motion (<i>V<sub>air</sub></i>) were investigated using vertically pointing Ka-band cloud radar. The distributions of reflectivity (<i>Z</i>), Doppler velocity (<i>V<sub>D</sub></i>), an...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-10-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/13/21/4349 |
| _version_ | 1797511859090227200 |
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| author | Bo-Young Ye GyuWon Lee |
| author_facet | Bo-Young Ye GyuWon Lee |
| author_sort | Bo-Young Ye |
| collection | DOAJ |
| description | The vertical structure of ice clouds and vertical air motion (<i>V<sub>air</sub></i>) were investigated using vertically pointing Ka-band cloud radar. The distributions of reflectivity (<i>Z</i>), Doppler velocity (<i>V<sub>D</sub></i>), and spectrum width (SW) were analyzed for three ice cloud types, namely, cirrus, anvil, and stratiform clouds. The radar parameters of the cirrus clouds showed narrower distributions than those of the stratiform and anvil clouds. In the vertical structures, the rapid growth of <i>Z</i> and <i>V<sub>D</sub></i> occurred in the layer between 8 and 12 km (roughly a layer of −40 °C to −20 °C) for all ice clouds. The prominent feature in the stratiform clouds was an elongated “S” shape in the <i>V<sub>D</sub></i> near 7–7.5 km (at approximately −16 °C to −13 °C) due to a significant decrease in an absolute value of <i>V<sub>D</sub></i>. The mean terminal fall velocity (<i>V<sub>t</sub></i>) and <i>V<sub>air</sub></i> in the ice clouds were estimated using pre-determined <i>V<sub>t</sub></i>–<i>Z</i> relationships (<i>V<sub>t</sub></i> = <i>aZ<sup>b</sup></i>) and the observed <i>V<sub>D</sub></i>. Although the cirrus clouds demonstrated wide distributions in coefficients <i>a</i> and exponents <i>b</i> depending on cloud heights, they showed a smaller change in <i>Z</i> and <i>V<sub>t</sub></i> values compared to that of the other cloud types. The anvil clouds had a larger exponent than that of the stratiform clouds, indicating that the ice particle density of anvil clouds increases at a faster rate compared with the density of stratiform clouds for the same <i>Z</i> increment. The significant positive <i>V<sub>air</sub></i> appeared at the top of all ice clouds in range up to 0.5 m s<sup>−1</sup>, and the anvil clouds showed the deepest layer of upward motion. The stratiform and anvil clouds showed a dramatic increase in vertical air motion in the layer of 6–8 km as shown by the rapid decrease of <i>V<sub>D</sub></i>. This likely caused increase of supersaturation above. A periodic positive <i>V<sub>air</sub></i> linked with a significant reduction in <i>V<sub>D</sub></i> appeared at the height of 7–8 km (approximately −15 °C) dominantly in the stratiform clouds. This layer exhibited a bi-modal power spectrum produced by pre-existing larger ice particles and newly formed numerous smaller ice particles. This result raised a question on the origins of smaller ice particles such as new nucleation due to increased supersaturation by upward motion below or the seeder-feeder effect. In addition, the retrieved <i>V<sub>air</sub></i> with high-resolution data well represented a Kelvin-Helmholtz wave development. |
| first_indexed | 2024-03-10T05:53:54Z |
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| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-10T05:53:54Z |
| publishDate | 2021-10-01 |
| publisher | MDPI AG |
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| series | Remote Sensing |
| spelling | doaj.art-72b16f9c4aec4962af382914c2d355b22023-11-22T21:32:09ZengMDPI AGRemote Sensing2072-42922021-10-011321434910.3390/rs13214349Vertical Structure of Ice Clouds and Vertical Air Motion from Vertically Pointing Cloud Radar MeasurementsBo-Young Ye0GyuWon Lee1Institute of Environmental Studies, Pusan National University, Busan 46241, KoreaDepartment of Astronomy and Atmospheric Sciences, Center for Atmospheric Remote Sensing (CARE), Kyungpook National University, Daegu 41566, KoreaThe vertical structure of ice clouds and vertical air motion (<i>V<sub>air</sub></i>) were investigated using vertically pointing Ka-band cloud radar. The distributions of reflectivity (<i>Z</i>), Doppler velocity (<i>V<sub>D</sub></i>), and spectrum width (SW) were analyzed for three ice cloud types, namely, cirrus, anvil, and stratiform clouds. The radar parameters of the cirrus clouds showed narrower distributions than those of the stratiform and anvil clouds. In the vertical structures, the rapid growth of <i>Z</i> and <i>V<sub>D</sub></i> occurred in the layer between 8 and 12 km (roughly a layer of −40 °C to −20 °C) for all ice clouds. The prominent feature in the stratiform clouds was an elongated “S” shape in the <i>V<sub>D</sub></i> near 7–7.5 km (at approximately −16 °C to −13 °C) due to a significant decrease in an absolute value of <i>V<sub>D</sub></i>. The mean terminal fall velocity (<i>V<sub>t</sub></i>) and <i>V<sub>air</sub></i> in the ice clouds were estimated using pre-determined <i>V<sub>t</sub></i>–<i>Z</i> relationships (<i>V<sub>t</sub></i> = <i>aZ<sup>b</sup></i>) and the observed <i>V<sub>D</sub></i>. Although the cirrus clouds demonstrated wide distributions in coefficients <i>a</i> and exponents <i>b</i> depending on cloud heights, they showed a smaller change in <i>Z</i> and <i>V<sub>t</sub></i> values compared to that of the other cloud types. The anvil clouds had a larger exponent than that of the stratiform clouds, indicating that the ice particle density of anvil clouds increases at a faster rate compared with the density of stratiform clouds for the same <i>Z</i> increment. The significant positive <i>V<sub>air</sub></i> appeared at the top of all ice clouds in range up to 0.5 m s<sup>−1</sup>, and the anvil clouds showed the deepest layer of upward motion. The stratiform and anvil clouds showed a dramatic increase in vertical air motion in the layer of 6–8 km as shown by the rapid decrease of <i>V<sub>D</sub></i>. This likely caused increase of supersaturation above. A periodic positive <i>V<sub>air</sub></i> linked with a significant reduction in <i>V<sub>D</sub></i> appeared at the height of 7–8 km (approximately −15 °C) dominantly in the stratiform clouds. This layer exhibited a bi-modal power spectrum produced by pre-existing larger ice particles and newly formed numerous smaller ice particles. This result raised a question on the origins of smaller ice particles such as new nucleation due to increased supersaturation by upward motion below or the seeder-feeder effect. In addition, the retrieved <i>V<sub>air</sub></i> with high-resolution data well represented a Kelvin-Helmholtz wave development.https://www.mdpi.com/2072-4292/13/21/4349ice cloudsvertical structurevertical air motionterminal velocitycloud radar<i>V<sub>t</sub></i>–<i>Z</i> relationship, bi-modal power spectrum |
| spellingShingle | Bo-Young Ye GyuWon Lee Vertical Structure of Ice Clouds and Vertical Air Motion from Vertically Pointing Cloud Radar Measurements Remote Sensing ice clouds vertical structure vertical air motion terminal velocity cloud radar <i>V<sub>t</sub></i>–<i>Z</i> relationship, bi-modal power spectrum |
| title | Vertical Structure of Ice Clouds and Vertical Air Motion from Vertically Pointing Cloud Radar Measurements |
| title_full | Vertical Structure of Ice Clouds and Vertical Air Motion from Vertically Pointing Cloud Radar Measurements |
| title_fullStr | Vertical Structure of Ice Clouds and Vertical Air Motion from Vertically Pointing Cloud Radar Measurements |
| title_full_unstemmed | Vertical Structure of Ice Clouds and Vertical Air Motion from Vertically Pointing Cloud Radar Measurements |
| title_short | Vertical Structure of Ice Clouds and Vertical Air Motion from Vertically Pointing Cloud Radar Measurements |
| title_sort | vertical structure of ice clouds and vertical air motion from vertically pointing cloud radar measurements |
| topic | ice clouds vertical structure vertical air motion terminal velocity cloud radar <i>V<sub>t</sub></i>–<i>Z</i> relationship, bi-modal power spectrum |
| url | https://www.mdpi.com/2072-4292/13/21/4349 |
| work_keys_str_mv | AT boyoungye verticalstructureoficecloudsandverticalairmotionfromverticallypointingcloudradarmeasurements AT gyuwonlee verticalstructureoficecloudsandverticalairmotionfromverticallypointingcloudradarmeasurements |