New particle formation in the Svalbard region 2006–2015

Other literature type English OPEN
Heintzenberg, Jost ; Tunved, Peter ; Gali, Martí ; Leck, Caroline (2016)

Events of new particle formation, (NPF), were analyzed in a ten-year data set of hourly particle size distributions recorded on Mt. Zeppelin, Spitsbergen, Svalbard. Three different types of NPF-events were identified through objective search algorithms. The first and simplest algorithm utilizes short-term increases in particle concentrations below 25&thinsp;nm, (PCT-events). The second one builds on the growth of the sub-50&thinsp;nm diameter-median, (DGR-events), and is most closely related to the classical "banana-type" of events. The third and most complex, so-called multiple-size approach to identifying NPF-events builds on a hypothesis suggesting the concurrent production of polymer gel particles at several sizes below about 60&thinsp;nm, (MEV-events). <br><br> As a first and general conclusion we can state that NPF-events are a summer phenomenon and not related to Arctic haze, which is a late winter-to-early spring event. NPF-events appear to be somewhat sensitive to the available data on precipitation. The seasonal distribution of solar flux suggests some photochemical control that may affect marine biological processes generating particle precursors and/or atmospheric photochemical processes that generate condensable vapors from precursor gases. Whereas the seasonal distribution of the biogenic methanesulfonate, (MSA), follows that of the solar flux it peaks before the maxima in NPF-occurrence. <br><br> A host of ancillary data and findings point to varying and rather complex marine biological source processes. The potential source regions for all types of new particle formation appear to be restricted to the marginal ice and open water areas between Northeastern Greenland and Eastern Svalbard. Depending on conditions yet to be clarified new particle formation may become visible as short bursts of particles around 20&thinsp;nm, (PCT-events), longer events involving condensation growth, (DGR-events), or extended events with elevated concentrations of particles at several sizes below 100&thinsp;nm, (MEV-events). The seasonal distribution of NPF-events peaks later than that of MSA and, DGR and in particular of MEV-events reach into late summer and early fall with much open, warm, and biologically active waters around Svalbard. Consequently, a simple model to describe the seasonal distribution of the total number of NPF-events can be based on solar flux, and sea surface temperature, representing environmental conditions for marine biological activity, and condensation sink, controlling the balance between new particle nucleation and their condensational growth. Based on the sparse knowledge about the seasonal cycle of gel-forming marine microorganisms and their controlling factors we hypothesize that the seasonal distribution of DGR and more so MEV-events reflect the seasonal cycle of the gel-forming phytoplankton.
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