Can pollen affect precipitation?
<p>Large primary bioparticles such as pollen can be abundant in the atmosphere; for example near-surface pollen concentrations above 10 000 particles per cubic metre can occur during intense pollination periods. On one hand, due to their large size (10–100 <span class="inline-formula&q...
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Copernicus Publications
2025-01-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/25/183/2025/acp-25-183-2025.pdf |
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| author | M. Prank J. Tonttila J. Tonttila X. Shang S. Romakkaniemi T. Raatikainen |
| author_facet | M. Prank J. Tonttila J. Tonttila X. Shang S. Romakkaniemi T. Raatikainen |
| author_sort | M. Prank |
| collection | DOAJ |
| description | <p>Large primary bioparticles such as pollen can be abundant in the atmosphere; for example near-surface pollen concentrations above 10 000 particles per cubic metre can occur during intense pollination periods. On one hand, due to their large size (10–100 <span class="inline-formula">µ</span>m), pollen can act as giant cloud condensation nuclei and enhance the collision–coalescence process in clouds that leads to drizzle formation. On the other hand, in humid conditions pollen is known to rupture and release many fine particles that can increase the cloud stability by reducing the droplet size. Additionally, both whole pollen grains and the sub-pollen particles released by pollen rupture are known to act as ice-nucleating particles (INPs). Due to these complex interactions, the role of pollen in modulating the cloud cover and precipitation remains uncertain.</p>
<p>We used the UCLALES-SALSA (UCLA Large-Eddy Simulation Code and Sectional Aerosol module for Large-Scale Applications) large eddy simulator for simulating birch pollen effects on liquid- and mixed-phase clouds. Our simulations show that the pollen concentrations observed during the most intense pollination seasons can locally enhance precipitation from both liquid- and mixed-phase clouds, while more commonly encountered pollen concentrations are unlikely to cause a noticeable change. The liquid precipitation enhancement depended linearly on the emitted pollen flux in both liquid- and mixed-phase clouds; however, the slope of this relationship was case-dependent. Ice nucleation happened at a relevant degree only if the process of rupturing pollen producing large number of fine ice-nucleating particles was included in the simulations. The resulting precipitation saturated for the highest INP concentrations. Secondary ice formation by rime splintering had only a minor effect in the considered 1 d timescale.</p> |
| format | Article |
| id | doaj-art-098f29fd44434dedaa430bc58b8307c7 |
| institution | Kabale University |
| issn | 1680-7316 1680-7324 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj-art-098f29fd44434dedaa430bc58b8307c72025-01-08T07:57:12ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242025-01-012518319710.5194/acp-25-183-2025Can pollen affect precipitation?M. Prank0J. Tonttila1J. Tonttila2X. Shang3S. Romakkaniemi4T. Raatikainen5Climate System Research Unit, Finnish Meteorological Institute, Helsinki, 00560, FinlandAtmospheric Research Centre of Eastern Finland, Finnish Meteorological Institute, Kuopio, 70211, FinlandCSC – IT Center for Science Ltd., Espoo, 02101, FinlandAtmospheric Research Centre of Eastern Finland, Finnish Meteorological Institute, Kuopio, 70211, FinlandAtmospheric Research Centre of Eastern Finland, Finnish Meteorological Institute, Kuopio, 70211, FinlandClimate System Research Unit, Finnish Meteorological Institute, Helsinki, 00560, Finland<p>Large primary bioparticles such as pollen can be abundant in the atmosphere; for example near-surface pollen concentrations above 10 000 particles per cubic metre can occur during intense pollination periods. On one hand, due to their large size (10–100 <span class="inline-formula">µ</span>m), pollen can act as giant cloud condensation nuclei and enhance the collision–coalescence process in clouds that leads to drizzle formation. On the other hand, in humid conditions pollen is known to rupture and release many fine particles that can increase the cloud stability by reducing the droplet size. Additionally, both whole pollen grains and the sub-pollen particles released by pollen rupture are known to act as ice-nucleating particles (INPs). Due to these complex interactions, the role of pollen in modulating the cloud cover and precipitation remains uncertain.</p> <p>We used the UCLALES-SALSA (UCLA Large-Eddy Simulation Code and Sectional Aerosol module for Large-Scale Applications) large eddy simulator for simulating birch pollen effects on liquid- and mixed-phase clouds. Our simulations show that the pollen concentrations observed during the most intense pollination seasons can locally enhance precipitation from both liquid- and mixed-phase clouds, while more commonly encountered pollen concentrations are unlikely to cause a noticeable change. The liquid precipitation enhancement depended linearly on the emitted pollen flux in both liquid- and mixed-phase clouds; however, the slope of this relationship was case-dependent. Ice nucleation happened at a relevant degree only if the process of rupturing pollen producing large number of fine ice-nucleating particles was included in the simulations. The resulting precipitation saturated for the highest INP concentrations. Secondary ice formation by rime splintering had only a minor effect in the considered 1 d timescale.</p>https://acp.copernicus.org/articles/25/183/2025/acp-25-183-2025.pdf |
| spellingShingle | M. Prank J. Tonttila J. Tonttila X. Shang S. Romakkaniemi T. Raatikainen Can pollen affect precipitation? Atmospheric Chemistry and Physics |
| title | Can pollen affect precipitation? |
| title_full | Can pollen affect precipitation? |
| title_fullStr | Can pollen affect precipitation? |
| title_full_unstemmed | Can pollen affect precipitation? |
| title_short | Can pollen affect precipitation? |
| title_sort | can pollen affect precipitation |
| url | https://acp.copernicus.org/articles/25/183/2025/acp-25-183-2025.pdf |
| work_keys_str_mv | AT mprank canpollenaffectprecipitation AT jtonttila canpollenaffectprecipitation AT jtonttila canpollenaffectprecipitation AT xshang canpollenaffectprecipitation AT sromakkaniemi canpollenaffectprecipitation AT traatikainen canpollenaffectprecipitation |