Are the birch trees in Southern England a source of Betula pollen for North London?

Abstract

Birch pollen is highly allergenic. Knowledge of daily variations, atmospheric transport and source areas of birch pollen is important for exposure studies and for warnings to the public, especially for large cities such as London. Our results show that broad-leaved forests with high birch tree densities are located to the south and west of London. Bi-hourly Betula pollen concentrations for all the days included in the study, and for all available days with high birch pollen counts (daily average birch pollen counts>80 grains/m3), show that, on average, there is a peak between 1400 hours and 1600 hours. Back-trajectory analysis showed that, on days with high birch pollen counts (n=60), 80% of air masses arriving at the time of peak diurnal birch pollen count approached North London from the south in a 180 degree arc from due east to due west. Detailed investigations of three Betula pollen episodes, with distinctly different diurnal patterns compared to the mean daily cycle, were used to illustrate how night-time maxima (2200-0400 hours) in Betula pollen counts could be the result of transport from distant sources or long transport times caused by slow moving air masses. We conclude that the Betula pollen recorded in North London could originate from sources found to the west and south of the city and not just trees within London itself. Possible sources outside the city include Continental Europe and the Betula trees within the broad-leaved forests of Southern England.

Are the Pyrenees a barrier for the transport of birch (Betula) pollen from Central Europe to the Iberian Peninsula?

“…In accordance with Skjøth et al (2009), results showed that Betula pollen amounts recorded during a single episode represented the 18-77% of the API in the control-station Bellaterra (Table 2), which indicates that Betula pollen originated outside of our study area could make a notable contribution to the airborne catch in the three sam pling stations during the main birch pollen season. Seven LRT Betula pollen outbreak episodes were registered simultaneously at the three sampling stations and three exclusively at the Bellaterra control-sta tion during the study period.…”

“…In Europe, back-trajectory modelling has been used to identify the arrival of Betula pollen from remote sources in Denmark (Mahura et al, 2007;Skjøth et al, 2007), Lithuania (Veriankaite et al, 2010), and United Kingdom (Skjøth et al, 2009. Additionally, System for Integrated modeLling of Atmospheric coMposition (SILAM) simulations have been applied to trace the origin of LRT of airborne Betula pollen in Finland (Sofiev et al, 2006;Siljamo et al, 2008), Russia (Siljamo et al, 2008) and Lithuania (Veriankaite et al, 2010).…”

MACC regional multi-model ensemble simulations of birch pollen dispersion in Europe

“…It was shown that, although the features of each specific long-range transport episode vary widely, there may be a systematic pattern in the springtime pollen redistribution in Europe with prevailing transport directions, main source and receptor regions, etc. There have been several attempts to reveal such a pattern via a multiannual analysis (Damialis and Gioulekas, 2005;Siljamo et al, 2008aSkjøth et al, 2009Skjøth et al, , 2007Smith et al, 2008;Sofiev et al, 2006a;Yli-Panula et al, 2009) but the picture is still largely incomplete.…”

Improvement in the accuracy of back trajectories using WRF to identify pollen sources in southern Iberian Peninsula

“…García-Mozo et al 2008). The computation of backward trajectories is widely used (Skjøth et al 2009;Smith et al 2008), where the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model (Draxler et al 2013) is one of the most used tools to explain atmospheric transport of pollen (e.g. Makra et al 2010;Zemmer et al 2012;Fernández-Rodriguez et al 2014;Sikoparija et al 2013).…”