Browsing by Author "Blake, D"

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    Development of an infrared pollution index to identify ground-level compositional, particle size, and humidity changes using Himawari-8
    (Elsevier, 2020-05-15) Sowden, M; Blake, D; Cohen, DD; Atanacio, AJ; Mueller, U
    Speciated air quality data informs health studies and quantitates impacts. However, monitoring is concentrated around populated regions whilst, large remote and rural regions remain unmonitored despite risks of dust-storms or wild-fires. Sub-hourly, infrared, geostationary data, such as the 10-min data from Himawari 8, could potentially be used to quantify regional air quality continually. Monitoring of Aerosol Optical Depth (AOD) is restricted to visible spectra (i.e. daytime only), while newer quantification methods using geostationary infrared (IR) data have focused on detecting the presence, or absence, of an event. Limited attention has been given to the determination of particle size and aerosol composition (such as sulfates, black carbon, sea-salt, and mineral dust), using IR exclusively, and more appropriate methods are required to improve the understanding of source impacts. Hourly data were collected for a three-year study period (July 2015 to July 2018) across the greater Sydney region in Eastern Australia from seventeen ground-based sites that measured meteorological data and quantified ambient concentrations of NO, NO2, SO2, PM2.5, PM10, and O3. This data was combined with source-apportioned categories (soil, sea-spray, smoke, secondary sulfates, and vehicles) from positive matrix factorization (PMF) of elemental aerosol collected on daily filters at five monitoring sites across the region. Regression analysis of five brightness temperature difference (BTD) infrared indices were used to determine a pollution index. The pollution index was shown to be related to humidity, particle size, and compositional changes. Unlike fixed thresholds, the continual index function can be aggregated spatially and temporarily. Good resolution is obtained between PM2.5 and O3. BTD appears insensitive to concentration, and the pollution index was used to detect and identify composition prior to determining concentration. © 2020 Elsevier Ltd.
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    Ellsworth Subglacial Lake, West Antarctica: a review of its history and recent field campaigns
    (John Wiley & Sons, Inc, 2011-01-01) Ross, N; Siegert, MJ; Rivera, A; Bentley, MJ; Blake, D; Capper, L; Clarke, R; Cockell, CS; Corr, HFJ; Harris, W; Hill, C; Hindmarsh, RCA; Hodgson, DA; King, EC; Lamb, H; Maher, B; Makinson, K; Mowlem, M; Parnell, J; Pearce, DA; Priscu, J; Smith, AM; Tait, A; Tranter, M; Wadham, JL; Whalley, WB; Woodward, JC
    Ellsworth Subglacial Lake, first observed in airborne radio echo sounding data acquired in 1978, is located within a long, deep subglacial trough within the Ellsworth Subglacial Highlands of West Antarctica. Geophysical surveys have characterized the lake, its subglacial catchment, and the thickness, structure, and flow of the overlying ice sheet. Covering 28.9 km2 , Ellsworth Subglacial Lake is located below 2.9 to 3.3 km of ice at depths of -1361 to -1030 m. Seismic reflection data have shown the lake to be up to 156 m deep and underlain by unconsolidated sediments. Ice sheet flow over the lake is characterized by low velocities (<6 m yr-1 ), flow convergence, and longitudinal extension. The lake appears to be in steady state, although the hydrological balance may vary over glacial-interglacial cycles. Direct access, measurement, and sampling of Ellsworth Subglacial Lake are planned for the 2012/2013 Antarctic field season. The aims of this access experiment are to determine (1) the presence, character, and maintenance of microbial life in Antarctic subglacial lakes and (2) the Quaternary history of the West Antarctic ice sheet. Geophysical data have been used to define a preferred lake access site. The factors that make this location suitable for exploration are (1) a relatively thin overlying ice column (~3.1 km), (2) a significant measured water depth (~143 m), (3) >2 m of sediment below the lake floor, (4) water circulation modeling suggesting a melting ice-water interface, and (5) coring that can target the deepest point of the lake floor away from marginal, localized sediment sources. © 2011 American Geophysical Union.