Physical Sciences Division
Published March 21, 2024 | Version v1
Journal article Open

Temperature, humidity, and ionisation effect of iodine oxoacid nucleation

Creators

  • 1. University of Helsinki
  • 2. European Organisation for Nuclear Research
  • 3. University of Lisbon
  • 4. École polytechnique fédérale de Lausanne
  • 5. Paul Scherrer Institute
  • 6. Goethe University Frankfurt am Main
  • 7. Russian Academy of Sciences
  • 8. University of Chicago

Description

Iodine oxoacids are recognised for their significant contribution to the formation of new particles in marine and polar atmospheres. Nevertheless, to incorporate the iodine oxoacid nucleation mechanism into global simulations, it is essential to comprehend how this mechanism varies under various atmospheric conditions. In this study, we combined measurements from the CLOUD (Cosmic Leaving OUtdoor Droplets) chamber at CERN and simulations with a kinetic model to investigate the impact of temperature, ionisation, and humidity on iodine oxoacid nucleation. Our findings reveal that ion-induced particle formation rates remain largely unaffected by changes in temperature. However, neutral particle formation rates experience a significant increase when the temperature drops from +10 °C to −10 °C. Running the kinetic model with varying ionisation rates demonstrates that the particle formation rate only increases with a higher ionisation rate when the iodic acid concentration exceeds 1.5 × 107 cm−3, a concentration rarely reached in pristine marine atmospheres. Consequently, our simulations suggest that, despite higher ionisation rates, the charged cluster nucleation pathway of iodic acid is unlikely to be enhanced in the upper troposphere by higher ionisation rates. Instead, the neutral nucleation channel is likely to be the dominant channel in that region. Notably, the iodine oxoacid nucleation mechanism remains unaffected by changes in relative humidity from 2% to 80%. However, under unrealistically dry conditions (below 0.008% RH at +10 °C), iodine oxides (I2O4 and I2O5) significantly enhance formation rates. Therefore, we conclude that iodine oxoacid nucleation is the dominant nucleation mechanism for iodine nucleation in the marine and polar boundary layer atmosphere.

Notes

Due to the large number of authors, only the first 20 and the University of Chicago authors are included on the above author list. Please download the article for the complete list of authors.

Data availability

The data have been made available on zenodo in the CERN CLOUD experiment community with the https://doi.org/10.5281/zenodo.10797483.

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Additional details

Identifiers

DOI
10.1039/D4EA00013G
Other
oai:uchicago.tind.io:14686

Funding

CERN
École polytechnique fédérale de Lausanne
European Union
764991 (CLOUD-MOTION)
Alfred Kordelin Foundation
220257
Research Council of Finland
337549
Research Council of Finland
337552
Research Council of Finland
302958
Research Council of Finland
1359331
Research Council of Finland
349659
Research Council of Finland
1325656
Research Council of Finland
311932
Research Council of Finland
334792
Research Council of Finland
316114
Research Council of Finland
325647
Research Council of Finland
325681
Research Council of Finland
347782
Academy of Finland
352431
Jane and Aatos Erkko Foundation
Wihuri Foundation
European Research Council
742206
National Natural Science Foundation of China
42175118
Vienna Science and Technology Fund
VRG22-003
German Federal Ministry of Education and Research
01LK1601C
German Federal Ministry of Education and Research
01LK2201B
German Federal Ministry of Education and Research
01LK1601A
German Federal Ministry of Education and Research
01LK2201A
Swiss National Science Foundation
200021_169090
Swiss National Science Foundation
206021_198140
Swiss National Science Foundation
200020_172602
Swiss National Science Foundation
200021_213071
Swiss National Science Foundation
20FI20_172622
National Science Foundation
AGS-1801280
National Science Foundation
AGS-2215522
National Science Foundation
AGS-2027252
National Science Foundation
AGS-2215489
National Science Foundation
AGS-2132089
National Science Foundation
AGS-1602086
National Science Foundation
AGS-1801329
National Science Foundation
AGS-2215527

UChicago Information

Division(s)
Physical Sciences Division
Department(s)
Geophysical Sciences