Ion production rate in a boreal forest based on ion, particle and radiation measurements

[摘要] In this study the ion production rates in a boreal forest werestudied based on two different methods: 1) cluster ion andparticle concentration measurements, 2) external radiation andradon concentration measurements.Both methods produced reasonableestimates for ion production rates. The average ion productionrate calculated from aerosol particle size distribution and airion mobility distribution measurements was 2.6 ion pairs cm^-3s^-1,and based on external radiation and radon measurements,4.5 ion pairs cm^-3s^-1. The first method based on ion and particlemeasurements gave lower values for the ion production ratesespecially during the day. A possible reason for this is thatparticle measurements started only from 3nm, so the sink of smallions during the nucleation events was underestimated. It mayalso be possible that the hygroscopic growth factors of aerosolparticles were underestimated.Another reason for thediscrepancy is the nucleation mechanism itself. If the ions aresomehow present in the nucleation process, there could have beenan additional ion sink during the nucleation days.

[学科分类] 大气科学