Airborne pollen transport of Podocarpus sp.: The study of backward trajectories and associated synoptic situations

PÉREZ, C. F.; GASSMANN M.I.; BIANCHI M.M.; TONTI N.

Buenos Aires

Congreso; 9th Internationa Congress on Aerobiology; 2010

International Association for Aerobiology

Comprehension of atmospheric pollen transport episodes requires proper knowledge of the role of interacting mechanisms from different time and space scales. Examples of these mechanisms are turbulent mixing, dry and wet deposition, synoptical weather systems, location, and phenology of vegetation sources. Long-range transport was detected for some regions of Argentina, but the study of these phenomena is seldom studied. In order to establish the prevailing weather associated with these cases, we studied some examples detected in northern Patagonia. The methodology relies on the analysis of backward trajectories of air masses calculated for the days when airborne pollen of Podocarpus was detected at Bariloche aerobiological station (41.143S, 71.375W) on the east slope of the Andes. Backward trajectories were calculated with HYSPLIT 4.5 regional model developed by National Oceanographic and Atmospheric Administration. Trajectories were classified according to the mean geopotential height fields at 850 hPa from NCEP reanalysis provided by the NOAA-CIRES Climate Diagnostic Center (http://www.cdc.noaa.gov/) for the days of pollen arrival. Sixty-eight trajectories were calculated for the period 10/2001 to 01/2006, most of them coming from the Sub-Antarctic Forests in the west, where Podocarpus trees actually grow. Fewer ones coming from the East seem to be unrelated to the location of the sources. Careful inspection of the daily mean geopotential height fields at 850 hPa showed that 41% of the cases were explained by the presence of a trough over the South Atlantic Ocean. Twenty-one percent of the cases were associated with a trough with its axis over Patagonia. These two patterns seem to be very similar to those ones previously described for Weinmannia trichosperma in the same area. Only 6% of trajectories came from the east, where no Podocarpus trees are present. The associated geopotential height fields showed the presence of anticyclonic or low-pressure gradient conditions evidencing that surface local circulations could prevail.