Investigating the vertical and spatial extent of radon-based classification of the atmospheric mixing state and impacts on seasonal urban air quality.

A recently-developed radon-based method for combined classification of both diurnal and synoptic timescale changes in the atmospheric mixing state is applied to 1-year of observations in Ljubljana (capital of Slovenia). Five diurnal-timescale mixing classes (#1 to #5) were defined for each season along with an additional mixing class (#6) in non-summer months, representative of synoptic-timescale changes of the atmospheric mixing state associated with "persistent temperature inversion" (PTI) events. Seasonal composite radiosonde profiles and mean sea level pressure charts within each mixing class are used to demonstrate the link between prevailing synoptic conditions and the local mixing state, which drives changes in urban air quality.

Atmospheric concentrations and sources of black carbon over tropical Australian waters.

Black carbon (BC) aerosols significantly contribute to radiative budgets globally, however their actual contributions remain poorly constrained in many under-sampled ocean regions. The tropical waters north of Australia are a part of the Indo-Pacific warm pool, regarded as a heat engine of global climate, and are in proximity to large terrestrial sources of BC aerosols such as fossil fuel emissions, and biomass burning emissions from northern Australia. Despite this, measurements of marine aerosols, especially BC remain elusive, leading to large uncertainties and discrepancies in current chemistry-climate models for this region.

Radon-based atmospheric stability classification in contrasting sub-Alpine and sub-Mediterranean environments.

A recently-developed radon-based technique is used to investigate relative changes in summertime atmospheric stability at two sites in Slovenia with contrasting geographical settings. Although atmospheric stability for both sites (50 km apart) was shown to be governed by similar synoptic conditions, their contrasting settings caused differences in mixing conditions for each stability category. At the urban sub-Alpine site Ljubljana, situated within a topographic basin, wind speeds associated with the most stable conditions were 0.

Baseline characterisation of source contributions to daily-integrated PM observations at Cape Grim using Radon-222.

We discuss 15 years (2000-2015) of daily-integrated PM samples from the Cape Grim Station. Ion beam analysis and positive matrix factorisation are used to identify six source-type fingerprints: fresh sea salt (57%); secondary sulfate (14%); smoke (13%); aged sea salt (12%); soil dust (2.4%); and industrial metals (1.

Statistical analysis of Seoul air quality to assess the efficacy of emission abatement strategies since 1987.

The combined influences of recent mitigation measures on urban air quality have been assessed using hourly observations of the criteria air pollutants (NO, NO, O, CO, and SO) made from the Yongsan district of Seoul, Korea, over 26years (1987 to 2013). A number of data selection criteria are proposed in order to minimize variability associated with temporal changes (at diurnal, weekly, and seasonal timescales) in source strengths, their spatial distribution, and the atmospheric volume into which they mix. The temporal constraints required to better characterize relationships between observed air quality and changes in source strengths in Seoul were identified as: (i) a 5-hour diurnal sampling window (1300-1700h), (b) weekday measurements (Monday to Friday only), and (c) summer measurements (when pollutant fetch is mostly Korea-specific, and mean wind speeds are the lowest).

Atmospheric stability effects on potential radiological releases at a nuclear research facility in Romania: Characterising the atmospheric mixing state.

A radon-based nocturnal stability classification scheme is developed for a flat inland site near Bucharest, Romania, characterised by significant local surface roughness heterogeneity, and compared with traditional meteorologically-based techniques. Eight months of hourly meteorological and atmospheric radon observations from a 60 m tower at the IFIN-HH nuclear research facility are analysed. Heterogeneous surface roughness conditions in the 1 km radius exclusion zone around the site hinder accurate characterisation of nocturnal atmospheric mixing conditions using conventional meteorological techniques, so a radon-based scheme is trialled.

Progress in the reduction of carbon monoxide levels in major urban areas in Korea.

Long-term trends in observed carbon monoxide (CO) concentrations were analyzed in seven major South Korean cities from 1989 to 2013. Temporal trends were evident on seasonal and annual timescales, as were spatial gradients between the cities. As CO levels in the most polluted cities decreased significantly until the early 2000s, the data were arbitrarily divided into two time periods (I: 1989-2000 and II: 2001-2013) for analysis.