Abstract. Dust events are an important and complex constituent of the
atmospheric system that can impact Earth's climate, the environment, and
human health. The frequency of dust events in the Southern High Plains of West Texas has increased over
the past 2 decades, yet their impact on air quality in this region is
still unclear. This is due to the fact that there is only one air quality monitoring station that
measures only PM2.5 concentrations (particulate matter with
an aerodynamic diameter < 2.5 µm), and there is no information on
other PM sizes or the particle size distribution. The Aerosol Research
Observation Station (AEROS) unit provides insight into the local variation
in particle concentration during different dust events and allows for a
better understanding of the impact of dust events on air quality. As this area is prone to dust events, we were wondering if dust events
generated by different meteorological causes (synoptic vs. convective) would
present similar particle concentrations or particle size distributions. Thus, in
this project, three different dust events were measured by AEROS and
compared. Each dust event originated from a different direction and lasted a
different duration. One of the dust events was synoptic (10 April 2019) and
two were convective (5 and 21 June 2019). Measurements of particle mass and
number concentration, size distribution, and meteorological conditions for
each dust event were compared. The synoptic dust event (on 10 April) was
longer (12 h) and had stronger wind speed conditions (up to 22.1 m s−1), whereas the two respective convective dust events on 5 and 21 June lasted only 20 and 30 min and had lower wind speeds (up to 16.5 and 13.4 m s−1). Observation of PM based on daily and hourly values
showed an impact on air quality, yet measurements based on daily and hourly
values underestimate the impact of the convective dust events. Observations
based on a shorter timescale (10 min) reveal the true impact of the two
convective dust events. A comparison of the particle size distribution showed
that all three dust events presented an increase in particles in the 0.3–10 µm size range. Comparisons of the particle concentration for particles
> 5 and > 10 µm show very high
values during the dust events. Some particle sizes even
increase in concentration by ∼ 2 orders of magnitude compared
with the time before the dust event. This leads us to speculate that the impact
of convective dust events on air quality in this region is underestimated
with the current (hourly basis) method.