Development and evaluation of pollen source methodologies for the Victorian Grass Pollen Emissions Module VGPEM1.0

Abstract

Abstract. We present the first representation of grass pollen in a 3-D dispersion model in Australia, tested using observations from eight counting sites in Victoria. The region's population has high rates of allergic rhinitis and asthma, and this has been linked to the high incidence of grass pollen allergy. Despite this, grass pollen dispersion in the Australian atmosphere has not been studied previously, and its source strength is untested. We describe 10 pollen emission source methodologies examining the strengths of different immediate and seasonal timing functions, and the spatial distribution of the sources. The timing function assumes a smooth seasonal term, modulated by an hourly meteorological function. A simple Gaussian representation of the pollen season worked well (average r=0.54), but lacked the spatial and temporal variation that the satellite-derived enhanced vegetation index (EVI) can provide. However, poor results were obtained using the EVI gradient (average r=0.35), which provides the timing when grass turns from maximum greenness to a drying and flowering period; this is due to noise in the spatial and temporal variability from this combined spatial and seasonal term. Better results were obtained using statistical methods that combine elements of the EVI dataset, a smooth seasonal term and instantaneous variation based on historical grass pollen observations (average r=0.69). The seasonal magnitude is inferred from the maximum winter-time EVI, whereas the timing of the season peak is based on the day of the year when the EVI falls to 0.05 below its winter maximum. Measurements are vital to monitor changes in the pollen season, and the new pollen measurement sites in the Victorian network should be maintained.

Temperature response measurements from eucalypts give insight into the impact of Australian isoprene emissions on air quality in 2050

“…The CSIRO Chemical Transport Model (C-CTM) is a modelling framework designed to predict the atmospheric concentrations of gases and aerosols due to emissions, transport, chemical production and loss, and deposition. In ad-dition to BVOCs, the framework has successfully predicted pollen (Emmerson et al, 2019b), health effects from shipping (Broome et al, 2016) and air quality . The C-CTM is driven by meteorology from the Conformal Cubic Atmospheric Model (CCAM; McGregor and Dix (2008)), taking boundary conditions from ERA-Interim.…”

Temperature response measurements from eucalypts give insight into the impact of Australian isoprene emissions on air quality in 2050

“…The C-CTM is a modelling framework designed to predict the atmospheric concentrations of gases and aerosols due to emissions, transport, chemical production and loss, and deposition. In addition to BVOCs, the framework has successfully predicted pollen (Emmerson et al, 2019b), health effects from shipping (Broome et al, 2016) and air quality (Chambers et al, 2019).…”

Atmospheric modelling of grass pollen rupturing mechanisms for thunderstorm asthma prediction

“…The Victorian Grass Pollen Emissions Module (VGPEM1.0) treats whole pollen as 35 μm diameter particles with a density of 1000 kg m -3 [ 23 ]. The model uses the satellite derived Enhanced Vegetation Index product to estimate the seasonal variation in grass pollen emissions, together with hourly meteorological inputs for the shorter-term variations.…”

“…The Victorian Grass Pollen Emission Module (VGPEM) [ 23 ] was developed to predict the risk of TA occurring as part of the Australian Bureau of Meteorology’s pilot forecasting system [ 24 ]. VGPEM is based on the aerodynamic properties (diameter and density) of ryegrass pollen ( Lollium perenne ).…”