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Aerosol

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Peter N. Sedwick – 1st expert on this subject based on the ideXlab platform

  • fractional solubility of Aerosol iron synthesis of a global scale data set
    Geochimica et Cosmochimica Acta, 2012
    Co-Authors: Edward R. Sholkovitz, Peter N. Sedwick, Thomas M Church, Alex R Baker, Claire Powell

    Abstract:

    Abstract Aerosol deposition provides a major input of the essential micronutrient iron to the open ocean. A critical parameter with respect to biological availability is the proportion of Aerosol iron that enters the oceanic dissolved iron pool – the so-called fractional solubility of Aerosol iron (%FeS). Here we present a global-scale compilation of total Aerosol iron loading (FeT) and estimated %FeS values for ∼1100 samples collected over the open ocean, the coastal ocean, and some continental sites, including a new data set from the Atlantic Ocean. Despite the wide variety of methods that have been used to define ‘soluble’ Aerosol iron, our global-scale compilation reveals a remarkably consistent trend in the fractional solubility of Aerosol iron as a function of total Aerosol iron loading, with the great bulk of the data defining an hyperbolic trend. The hyperbolic trends that we observe for both global- and regional-scale data are adequately described by a simple two-component mixing model, whereby the fractional solubility of iron in the bulk Aerosol reflects the conservative mixing of ‘lithogenic’ mineral dust (high FeT and low %FeS) and non-lithogenic ‘combustion’ Aerosols (low FeT and high %FeS). An increasing body of empirical and model-based evidence points to anthropogenic fuel combustion as the major source of these non-lithogenic ‘combustion’ Aerosols, implying that human emissions are a major determinant of the fractional solubility of iron in marine Aerosols. The robust global-scale relationship between %FeS and FeT provides a simple heuristic method for estimating Aerosol iron solubility at the regional to global scale.

  • Open-ocean deployment of a buoy-mounted Aerosol sampler on the Bermuda Testbed Mooring: Aerosol iron and sea salt over the Sargasso Sea
    Deep-Sea Research Part I: Oceanographic Research Papers, 2006
    Co-Authors: Edward R. Sholkovitz, Peter N. Sedwick

    Abstract:

    We report results from the first deployment of a buoy-mounted Aerosol sampler on the Bermuda Testbed Mooring (BTM) in the Sargasso Sea, in which a time-series of 21 Aerosol samples were collected over the period May 5-September 29, 2004. These Aerosol samples were analyzed for iron and soluble sodium (as a proxy for sea salt). Also analyzed was a time-series of 22 Aerosol samples collected over the same period at the Tudor Hill atmospheric sampling tower on Bermuda. The buoy sampler worked as intended and successfully collected a time-series of Aerosol samples, thus demonstrating that moored buoys can be used as oceanic observatories to provide information on the temporal (weekly, monthly and seasonal) variability in the concentration of Aerosol iron (and other trace elements) over the surface ocean. The magnitude and time variation of Aerosol Fe concentrations calculated from the BTM buoy samples are in close agreement with the corresponding Aerosol Fe record from the Tudor Hill tower, which is located approximately 80 km northwest of the mooring site. Both the BTM and Tudor Hill samples record periods of high Aerosol iron loadings in late June and late July 2004, reflecting the transport of soil dust from North Africa, with the highest concentration of Aerosol iron at the BTM site (0.83 μg m-3) measured in late June. Concentrations of sea-salt Aerosol calculated from the BTM samples are comparable to values measured over the Sargasso Sea and for samples collected at the Tudor Hill tower. Sea-salt Aerosols do not appear to impede the collection of mineral Aerosols by the buoy-mounted sampler. © 2006 Elsevier Ltd. All rights reserved.

B N Holben – 2nd expert on this subject based on the ideXlab platform

  • a spatio temporal approach for global validation and analysis of modis Aerosol products
    Geophysical Research Letters, 2002
    Co-Authors: Charles Ichoku, Yoram J. Kaufman, Didier Tanré, Shana Mattoo, Lorraine A Remer, I Slutsker, B N Holben

    Abstract:

    [1] With the launch of the MODIS sensor on the Terra spacecraft, new data sets of the global distribution and properties of Aerosol are beingretrieved, andneedto bevalidated andanalyzed. Asystem has been put in place to generate spatial statistics (mean, standard deviation, direction and rate of spatial variation, and spatial correlation coefficient) of the MODIS Aerosol parameters over more than 100 validation sites spread around the globe. Corresponding statistics are also computed from temporal subsets of AERONET-derived Aerosol data. The means and standard deviations of identical parameters from MODIS and AERONET are compared. Although, their means compare favorably, their standard deviations reveal some influence of surface effects on the MODIS Aerosol retrievals over land, especially at low Aerosol loading. The direction and rate of spatial variation from MODIS are used to study the spatial distribution of Aerosols at various locations either individually or comparatively. This paper introduces the methodology for generating and analyzing the data sets used by the two MODIS Aerosol validation papers in this issue. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols andparticles(0345,4801);1610GlobalChange:Atmosphere(0315, 0325); 1640 Global Change: Remote sensing; 0394 Atmospheric Composition and Structure: Instruments and techniques

  • a long term record of Aerosol optical depth from toms observations and comparison to aeronet measurements
    Journal of the Atmospheric Sciences, 2002
    Co-Authors: Omar Torres, P K Bhartia, J R Herman, A Sinyuk, Paul Ginoux, B N Holben

    Abstract:

    Observations of backscattered near-ultraviolet radiation from the Total Ozone Mapping Spectrometer (TOMS) on board the Nimbus-7 (1979‐92) and the Earth Probe (mid-1996 to present) satellites have been used to derive a long-term record of Aerosol optical depth over oceans and continents. The retrieval technique applied to the TOMS data makes use of two unique advantages of near-UV remote sensing not available in the visible or nearIR: 1) low reflectivity of all land surface types (including the normally bright deserts in the visible), which makes possible Aerosol retrieval over the continents; and 2) large sensitivity to Aerosol types that absorb in the UV, allowing the clear separation of carbonaceous and mineral Aerosols from purely scattering particles such as sulfate and sea salt Aerosols. The near-UV method of Aerosol characterization is validated by comparison with Aerosol Robotic Network (AERONET) ground-based observations. TOMS retrievals of Aerosol optical depth over land areas (1996‐2000) are shown to agree reasonably well with AERONET sun photometer observations for a variety of environments characterized by different Aerosol types, such as carbonaceous Aerosols from biomass burning, desert dust Aerosols, and sulfate Aerosols. In most cases the TOMS-derived optical depths of UV-absorbing Aerosols are within 30% of the AERONET observations, while nonabsorbing optical depths agree to within 20%. The results presented here constitute the first long-term nearly global climatology of Aerosol optical depth over both land and water surfaces, extending the observations of Aerosol optical depth to regions and times (1979 to present) not accessible to ground-based observations.

T. T. Mercer – 3rd expert on this subject based on the ideXlab platform

  • Aerosol technology: Properties, Behavior, and Measurement of Airborne Particles.
    Wiley-Interscience Publication, 1999
    Co-Authors: W. C. Hinds, T. T. Mercer

    Abstract:

    This title details the science behind airborne particles. From pollen\nto auto exhaust to ozone-destroying fluorocarbons to the technology\nbehind coating microchips and building fiber optics, airborne particles\naffect the lives of everyone on the planet. The first edition of\nHinds’s Aerosol Technology appeared in 1982 when Aerosol science\nwas a relatively new field. Since the publication of this early,\npioneering work, a great deal of research and development has been\ndone in Aerosols across a broad range of application areas, including\nthe use of Aerosols in high technology material processing and the\nadministration of therapeutic drugs, an increased awareness of bioAerosols,\nAerosol contamination in microelectronics manufacturing, and the\neffect of Aerosols on global climate. The expansion of the field,\nboth in technology and the number of scientists involved, has created\nthe need to update and expand the original book.