Quantifying riming from airborne data during the HALO-(AC)<sup>3</sup> campaign
<p>Riming is a key precipitation formation process in mixed-phase clouds which efficiently converts cloud liquid to ice water. Here, we present two methods to quantify riming of ice particles from airborne observations with the normalized rime mass, which is the ratio of rime mass to the mass...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2024-03-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/17/1475/2024/amt-17-1475-2024.pdf |
| _version_ | 1797265939222233088 |
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| author | N. Maherndl M. Moser M. Moser J. Lucke J. Lucke M. Mech N. Risse I. Schirmacher M. Maahn |
| author_facet | N. Maherndl M. Moser M. Moser J. Lucke J. Lucke M. Mech N. Risse I. Schirmacher M. Maahn |
| author_sort | N. Maherndl |
| collection | DOAJ |
| description | <p>Riming is a key precipitation formation process in mixed-phase clouds which efficiently converts cloud liquid to ice water. Here, we present two methods to quantify riming of ice particles from airborne observations with the normalized rime mass, which is the ratio of rime mass to the mass of a size-equivalent spherical graupel particle. We use data obtained during the HALO-(AC)<span class="inline-formula"><sup>3</sup></span> aircraft campaign, where two aircraft collected radar and in situ measurements that were closely spatially and temporally collocated over the Fram Strait west of Svalbard in spring 2022. The first method is based on an inverse optimal estimation algorithm for the retrieval of the normalized rime mass from a closure between cloud radar and in situ measurements during these collocated flight segments (combined method). The second method relies on in situ observations only, relating the normalized rime mass to optical particle shape measurements (in situ method). We find good agreement between both methods during collocated flight segments with median normalized rime masses of 0.024 and 0.021 (mean values of 0.035 and 0.033) for the combined and in situ method, respectively. Assuming that particles with a normalized rime mass smaller than 0.01 are unrimed, we obtain average rimed fractions of 88 % and 87 % over all collocated flight segments. Although in situ measurement volumes are in the range of a few cubic centimeters and are therefore much smaller than the radar volume (about 45 m footprint diameter at an altitude of 500 m above ground, with a vertical resolution of 5 m), we assume they are representative of the radar volume. When this assumption is not met due to less homogeneous conditions, discrepancies between the two methods result. We show the performance of the methods in a case study of a collocated segment of cold-air outbreak conditions and compare normalized rime mass results with meteorological and cloud parameters. We find that higher normalized rime masses correlate with streaks of higher radar reflectivity. The methods presented improve our ability to quantify riming from aircraft observations.</p> |
| first_indexed | 2024-04-25T00:52:45Z |
| format | Article |
| id | doaj.art-6044ee8dd62140daa4f32b43c70ca08b |
| institution | Directory Open Access Journal |
| issn | 1867-1381 1867-8548 |
| language | English |
| last_indexed | 2024-04-25T00:52:45Z |
| publishDate | 2024-03-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Measurement Techniques |
| spelling | doaj.art-6044ee8dd62140daa4f32b43c70ca08b2024-03-11T14:43:10ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482024-03-01171475149510.5194/amt-17-1475-2024Quantifying riming from airborne data during the HALO-(AC)<sup>3</sup> campaignN. Maherndl0M. Moser1M. Moser2J. Lucke3J. Lucke4M. Mech5N. Risse6I. Schirmacher7M. Maahn8Leipzig Institute of Meteorology (LIM), Leipzig University, Leipzig, GermanyInstitute for Physics of the Atmosphere, Johannes Gutenberg University, Mainz, GermanyInstitute for Physics of the Atmosphere, German Aerospace Center (DLR), Weßling, GermanyInstitute for Physics of the Atmosphere, German Aerospace Center (DLR), Weßling, GermanyFaculty of Aerospace Engineering, Delft University of Technology, Delft 2629, the NetherlandsInstitute for Geophysics and Meteorology, University of Cologne, Cologne, GermanyInstitute for Geophysics and Meteorology, University of Cologne, Cologne, GermanyInstitute for Geophysics and Meteorology, University of Cologne, Cologne, GermanyLeipzig Institute of Meteorology (LIM), Leipzig University, Leipzig, Germany<p>Riming is a key precipitation formation process in mixed-phase clouds which efficiently converts cloud liquid to ice water. Here, we present two methods to quantify riming of ice particles from airborne observations with the normalized rime mass, which is the ratio of rime mass to the mass of a size-equivalent spherical graupel particle. We use data obtained during the HALO-(AC)<span class="inline-formula"><sup>3</sup></span> aircraft campaign, where two aircraft collected radar and in situ measurements that were closely spatially and temporally collocated over the Fram Strait west of Svalbard in spring 2022. The first method is based on an inverse optimal estimation algorithm for the retrieval of the normalized rime mass from a closure between cloud radar and in situ measurements during these collocated flight segments (combined method). The second method relies on in situ observations only, relating the normalized rime mass to optical particle shape measurements (in situ method). We find good agreement between both methods during collocated flight segments with median normalized rime masses of 0.024 and 0.021 (mean values of 0.035 and 0.033) for the combined and in situ method, respectively. Assuming that particles with a normalized rime mass smaller than 0.01 are unrimed, we obtain average rimed fractions of 88 % and 87 % over all collocated flight segments. Although in situ measurement volumes are in the range of a few cubic centimeters and are therefore much smaller than the radar volume (about 45 m footprint diameter at an altitude of 500 m above ground, with a vertical resolution of 5 m), we assume they are representative of the radar volume. When this assumption is not met due to less homogeneous conditions, discrepancies between the two methods result. We show the performance of the methods in a case study of a collocated segment of cold-air outbreak conditions and compare normalized rime mass results with meteorological and cloud parameters. We find that higher normalized rime masses correlate with streaks of higher radar reflectivity. The methods presented improve our ability to quantify riming from aircraft observations.</p>https://amt.copernicus.org/articles/17/1475/2024/amt-17-1475-2024.pdf |
| spellingShingle | N. Maherndl M. Moser M. Moser J. Lucke J. Lucke M. Mech N. Risse I. Schirmacher M. Maahn Quantifying riming from airborne data during the HALO-(AC)<sup>3</sup> campaign Atmospheric Measurement Techniques |
| title | Quantifying riming from airborne data during the HALO-(AC)<sup>3</sup> campaign |
| title_full | Quantifying riming from airborne data during the HALO-(AC)<sup>3</sup> campaign |
| title_fullStr | Quantifying riming from airborne data during the HALO-(AC)<sup>3</sup> campaign |
| title_full_unstemmed | Quantifying riming from airborne data during the HALO-(AC)<sup>3</sup> campaign |
| title_short | Quantifying riming from airborne data during the HALO-(AC)<sup>3</sup> campaign |
| title_sort | quantifying riming from airborne data during the halo ac sup 3 sup campaign |
| url | https://amt.copernicus.org/articles/17/1475/2024/amt-17-1475-2024.pdf |
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