A new application of a multifrequency submillimeter radiometer in determining the microphysical and macrophysical properties of volcanic plumes: A sensitivity study

Baran, Anthony J.

doi:10.1029/2011jd016781

Cited by 9 publications

(5 citation statements)

References 72 publications

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“…Observations also included combinations of ground‐based lidars and sunphotometers [ Marenco and Hogan , 2011; Ansmann et al , 2010; Gasteiger et al , 2011; Chazette et al , 2011], ground‐based in situ sampling [ Flentje et al , 2010; Bukowiecki et al , 2011] and a balloon ascent [ Harrison et al , 2010]. In addition, satellite remote sensing products were used operationally and explored in post‐event analysis [ Clarisse et al , 2010; Francis et al , 2012; Newman et al , 2012; Millington et al , 2012; Baran , 2012. The remote sensing measurements made by the FAAM aircraft are detailed by Marenco et al [2011], and Newman et al [2012].…”

Section: Introductionmentioning

confidence: 99%

In situ observations of volcanic ash clouds from the FAAM aircraft during the eruption of Eyjafjallajökull in 2010

et al. 2012

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During April–May 2010 the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe‐146 aircraft flew 12 flights targeting volcanic ash clouds around the UK. The aircraft observed ash layers between altitudes of 2–8 km with peak mass concentrations typically between 200–2000μg/m3, as estimated from a Cloud and Aerosol Spectrometer (CAS). A peak value of 2000–5000 μg/m3 was observed over Scotland on 14 May 2010, although with considerable uncertainty due to the possible contamination by ice. Aerosol size distributions within ash clouds showed a fine mode (0.1–0.6 μm) associated with sulphuric acid and/or sulphate, and a coarse mode (0.6–35 μm) associated with ash. The ash mass was dominated by particles in the size range 1–10 μm (volume‐equivalent diameter), with a peak typically around 3–5μm. Electron‐microscope images and scattering patterns from the SID‐2H (Small Ice Detector) probe showed the highly irregular shape of the ash particles. Ash clouds were also accompanied by elevated levels of SO2 (10–100 ppbv), strong aerosol scattering (50–500 × 10−6 m−1), and low Ångstrom exponents (−0.5 to 0.4) from the 3‐wavelength nephelometer. Coarse‐mode mass specific aerosol extinction coefficients (kext), based on the CAS size distribution varied from 0.45–1.06 m2/g. A representative value of 0.6 m2/g is suggested for distal ash clouds (∼1000 km downwind) from this eruption.

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Section: Introductionmentioning

confidence: 99%

In situ observations of volcanic ash clouds from the FAAM aircraft during the eruption of Eyjafjallajökull in 2010

et al. 2012

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“…The need to consider particle shape in detail increases with frequency and is the highest for hydrometeors containing ice. Aerosols can in general be neglected for microwave radiative transfer, but measurements of volcanic ash are another potential application of sub-millimetre radiometry (Baran, 2012a).…”

Section: Motivationmentioning

confidence: 99%

Response to referees

Eriksson¹

2018

Preprint

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A main limitation today in simulations and inversions of microwave observations of ice hydrometeors (cloud ice, snow, hail, etc.) is the lack of data describing the interaction between electromagnetic waves and the particles. To improve the situation, the development of a comprehensive dataset of such "scattering properties" has been started. The database aims at giving a broad coverage in both frequency (1 to 886 GHz) and temperature (190 to 270 K), to support both passive and active current and planned measurements, and to provide data corresponding to the full Stokes vector. This first version of the database is restricted to totally random particle orientation. Data for 34 particle sets, i.e. habits, have been generated. About 17 of the habits can be classified as single crystals, three habits can be seen as heavily rimed particles, and the remaining habits are aggregates of different types, e.g. snow and hail. The particle sizes considered vary between the habits, but maximum diameters of 10 and 20 mm are typical values for the largest single crystal and aggregate particles, respectively, and the number of sizes per habit is at least 30. Particles containing liquid water are also inside the scope of the database, but this phase of water is so far only represented by a liquid sphere habit. The database is built upon the netCDF4 file format. Interfaces to browse, extract and convert data for selected radiative transfer models are provided in MATLAB and Python. The database and associated tools are publicly available from Zenodo (

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“…Thus, the sub-millimetre region can act as an important constraint on retrievals of ice cloud properties using radar, solar and infrared radiometric measurements. This is why sub-millimetre instrumentation is required on board aircraft, such as the International Sub-millimetre Airborne Radiometer (ISMAR) [12,13], and in space to measure the total amount of ice mass contained in the Earth's atmosphere.…”

Section: Introductionmentioning

confidence: 99%

The applicability of physical optics in the millimetre and sub-millimetre spectral region. Part I: The ray tracing with diffraction on facets method

Baran

Hesse

Sourdeval

2017

Journal of Quantitative Spectroscopy and Radiative Transfer

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Future satellite missions, from 2021 onwards, will obtain near-global measurements of cirrus at microwave and sub-millimetre frequencies. To realise the potential of these observations, fast and accurate light scattering methods are required to calculate scattered millimetre and sub-millimetre intensities from complex ice crystals. Here, the applicability of the ray tracing with diffraction on facets method (RTDF) in predicting the bulk scalar optical properties and phase functions of randomly oriented hexagonal ice columns and hexagonal ice aggregates at millimetre frequencies is investigated. The applicability of RTDF is shown to be acceptable down to size parameters of about 18, between the frequencies of 243 and 874 GHz. It is demonstrated that RTDF is generally well within about 10% of T-matrix solutions obtained for the scalar optical properties assuming hexagonal ice columns. Moreover, on replacing electromagnetic scalar optical property solutions obtained for the hexagonal ice aggregate with the RTDF counterparts at size parameter values of about 18 and greater, the bulk scalar optical properties can be calculated to generally well within ±5% of an electromagnetic-based database. The RTDF-derived bulk scalar optical properties result in brightness temperature errors to generally within about ±4 K at 874 GHz. Differing microphysics assumptions can easily exceed such errors. Similar findings are found for the bulk scattering phase functions. This finding is owing to the scattering solutions being dominated by the processes of diffraction and reflection, both being well described by RTDF. The impact of centimetre-sized complex ice crystals on interpreting cirrus polarisation measurements at sub-millimetre frequencies is discussed.

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A new application of a multifrequency submillimeter radiometer in determining the microphysical and macrophysical properties of volcanic plumes: A sensitivity study

Cited by 9 publications

References 72 publications

In situ observations of volcanic ash clouds from the FAAM aircraft during the eruption of Eyjafjallajökull in 2010

In situ observations of volcanic ash clouds from the FAAM aircraft during the eruption of Eyjafjallajökull in 2010

Response to referees

The applicability of physical optics in the millimetre and sub-millimetre spectral region. Part I: The ray tracing with diffraction on facets method

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