Wednesday, March 22, 2017 -
09:00 to 10:00


  • IASOA aerosol science page (Crepinsek) – 5 min
  • Presentation/Discussion: Establishing a Connection Between IASOA & TROPOS Cloud Group, Analysis for INP from Arctic Filter Samples (Heike) – 25 min

IASOA Aerosol Working Group

March 22, 2017


Attendees: Sara Crepinsek, Heike Wex, Jessie Creamean, Aki Virkkula, Jo Browse, Taneil Uttal, Markus Fiebig, Rachel Chang, Patrick Hayes, John Backman, John Ogren, Eija Asmi, Nicholas Spada, Bill Simpson, Rebecca Sheesley, Henrik Skov, Kostas Eleftheriadis


Role Call of group members

Establishing a Connection Between IASOA & TROPOS Cloud Group, Analysis for INP from Arctic Filter Samples (presentation by Heike Wex) – overview of TROPOS: aerosol including cloud condensation nuclei and ice nucleating particles, freezing process in clouds, filter samples for off-line analysis of INP number concentrations (NINP), high volume digital sampler, typically sampled onto quartz fiber filters, determining NINP from filter samples, based on high volume filter samples, offline analysis at TROPOS, each filter stance in water, tubes in a thermostat, detect ice nucleation during cooling, dark grey spot (frozen tube), resulting in samples over time, method suggested in Conen et al. (2012), by knowing area of total filter and area of filter stance so can derive number concentration, how to know how many particles are within a frozen vile (by freezing at specific temperature then can understand which particles are within vile have initiated the freezing, observing particle behavior as freezing is occurring), issues with contamination of filters, methods trying to point out these issues, contamination is reason why can’t go down to lower temperatures, method: wash filters off in water, shake, select 1 micro liter droplets, automated detection, this is a newer method (LINA) but it reduces contamination issues and can cover larger temperature ranges, comparing methods show they are similar but LINA method can go down to lower temps, have tried using different types of Quartz fiber and Teflon filters but still have issues with not being able to completely clean the filter (also some issues with contamination), clean Teflon filter with acid bath (set out to complete this process) or heating or washing, revisiting ice nucleation from precipitation samples, ~ NINP one order of magnitude less per 5K T-increase, at T < -20C INP are minerals, at T > -20C biological INP, biological INP can be bacteria, pollen, funal spores, algae, lychen, etc., also observed in lakes and rivers and ocean, noticing biological INP in colder environments (hence why interested in Arctic filter samples), typically can analyze 3-6 filters per day from Arctic regions only

Request of Heike Wex (contact info:

  1. At which of the Arctic stations were filter samples taken (ever, or even regularly, and with which sampling time and time resolution)?
  2. For existing filter samples, would you be willing to give Heike a punch (per filter, one of these punches with 2 cm diameter would be sufficient, or a 1.5 cm x 1.5 cm piece)?
  3. Ideally, Heike would be interested in having samples from one or two different years covering different times/conditions during these years for as much of the Arctic region as possible
  4. For those of you who say “yes”, please tell Heike so that she can discuss with you which samples you have and how to transport them

Action Items:

  • Send email about who is attending ASSW (Crepinsek)
  • Reply to Heike Wex or Jessie Creamean if interested in sending Heike filter samples (ALL)
Research Group: