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- Buehler, Stefan, et al.
(författare)
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A concept for a satellite mission to measure cloud ice water path, ice particle size, and cloud altitude
- 2007
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Ingår i: Quarterly Journal of the Royal Meteorological Society. - : Wiley. - 0035-9009 .- 1477-870X. ; 133:S2, s. 109-128
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Tidskriftsartikel (refereegranskat)abstract
- A passive satellite radiometer operating at submillimetre wavelengths can measure cloud ice water path (IWP), ice particle size, and cloud altitude. The paper first discusses the scientific background for such measurements. Formal scientific mission requirements are derived, based on this background and earlier assessments. The paper then presents a comprehensive prototype instrument and mission concept, and demonstrates that it meets the requirements. The instrument is a conically scanning 12-channel radiometer with channels between 183 and 664 GHz, proposed to fly in tandem with one of the Metop satellites. It can measure IWP with a relative accuracy of approximately 20% and a detection threshold of approximately 2 g m−2. The median mass equivalent sphere diameter of the ice particles can be measured with an accuracy of approximately 30 µm, and the median IWP cloud altitude can be measured with an accuracy of approximately 300 m. All the above accuracies are median absolute error values; root mean square error values are approximately twice as high, due to rare outliers.
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| 2. |
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| 3. |
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| 4. |
- Teichmann, C., et al.
(författare)
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Understanding the polarization signal of spherical particles for microwave limb radiances
- 2006
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Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier BV. - 0022-4073 .- 1879-1352. ; 10:1, s. 179-190
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a simple conceptual model to explain that even spherical scatterers lead to a polarization difference signal for microwave limb radiances. The conceptual model relates the polarization difference measured by a limb-looking sensor situated inside a cloud with the anisotropy of the radiation. In the simulations, it was assumed that the cloud consists of spherical ice particles with a radius of ...
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| 5. |
- Sreerekha, T.R., et al.
(författare)
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A strong ice cloud event as seen by a microwave satellite sensor : simulations and observations
- 2008
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Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier BV. - 0022-4073 .- 1879-1352. ; 109:9, s. 1705-1718
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Tidskriftsartikel (refereegranskat)abstract
- In this article, brightness temperatures observed by channels of the Advanced Microwave Sounding Unit-B (AMSU-B) instrument are compared to those simulated by a radiative transfer model, which can take into account the multiple scattering due to ice particles by using a discrete ordinate iterative solution method. The input fields, namely, the pressure, temperature, humidity, and cloud water content are taken from the short range forecast from the Met Office mesoscale model (UKMES). The comparison was made for a case study on the 25 January 2002 when a frontal system associated with significant cloud was present over the UK. It is demonstrated that liquid clouds have maximum impact on channel 16 of AMSU whereas ice clouds have maximum impact on channel 20. The main uncertainty for simulating microwave radiances is the assumptions about microphysical properties, such as size distribution, shape and orientation of the cloud particles, which are not known in the mesoscale model. The article examines the impact of these parameters on the cloud signal. The polarisation signal due to oriented ice particles at these frequencies is also discussed.
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