Academic Journal
Variation and balance of positive air ion concentrations in a boreal forest
| العنوان: | Variation and balance of positive air ion concentrations in a boreal forest |
|---|---|
| المؤلفون: | Hõrrak, U., Aalto, P. P., Salm, J., Komsaare, K., Tammet, H., Mäkelä, J. M., Laakso, L., Kulmala, M. |
| المساهمون: | Institute of Physics Tartu, University of Tartu, Department of Physical Sciences Helsinki, Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Tampere University of Technology Tampere (TUT) |
| المصدر: | ISSN: 1680-7316. |
| بيانات النشر: | HAL CCSD European Geosciences Union |
| سنة النشر: | 2008 |
| المجموعة: | Institut national des sciences de l'Univers: HAL-INSU |
| مصطلحات موضوعية: | [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere |
| الوصف: | International audience ; Air ions are characterized on the basis of measurements carried out in a boreal forest at the Hyytiälä SMEAR station, Finland, during the BIOFOR III campaign in spring 1999. The air ions were discriminated as small ions (charged molecular aggregates of the diameter of less than 2.5 nm), intermediate ions (charged aerosol particles of the diameter of 2.5?8 nm), and large ions (charged aerosol particles of the diameter of 8?20 nm). Statistical characteristics of the ion concentrations and the parameters of ion balance in the atmosphere are presented separately for the nucleation event days and non-event days. In the steady state, the ionization rate is balanced with the loss of small ions, which is expressed as the product of the small ion concentration and the ion sink rate. The widely known sinks of small ions are the recombination with small ions of opposite polarity and attachment to aerosol particles. The dependence of small ion concentration on the concentration of aerosol particles was investigated applying a model of the bipolar diffusion charging of particles by small ions. When the periods of relative humidity above 95% and wind speed less than 0.6 m s ?1 were excluded, then the small ion concentration and the theoretically calculated small ion sink rate were closely negatively correlated (correlation coefficient ?87%). However, an extra ion loss term of the same magnitude as the ion loss onto aerosol particles is needed for a quantitative explanation of the observations. This term is presumably due to the small ion deposition on coniferous forest. The hygroscopic growth correction of the measured aerosol particle size distributions was also found to be necessary for the proper estimation of the ion sink rate. In the case of nucleation burst events, the concentration of small positive ions followed the general balance equation, no extra ion loss in addition to the deposition on coniferous forest was detected, and the hypothesis of the conversion of ions into particles in the ... |
| نوع الوثيقة: | article in journal/newspaper |
| اللغة: | English |
| Relation: | hal-00296439; https://hal.science/hal-00296439; https://hal.science/hal-00296439/document; https://hal.science/hal-00296439/file/acp-8-655-2008.pdf |
| الاتاحة: | https://hal.science/hal-00296439 https://hal.science/hal-00296439/document https://hal.science/hal-00296439/file/acp-8-655-2008.pdf |
| Rights: | info:eu-repo/semantics/OpenAccess |
| رقم الانضمام: | edsbas.57F59541 |
| قاعدة البيانات: | BASE |
| الوصف غير متاح. |