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Cloud liquid water and ice content by multi-wavelength radar Nicolas Gaussiat Henri Sauvageot

Cloud liquid water and ice content by multi-wavelength radar Nicolas Gaussiat Henri Sauvageot Anthony J. Illingworth. Dual-Wavelength measurements. For a dual-wavelength pair ( Long, Short) :. DWR is due to (1) differential attenuation , (2) Mie scattering :.

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Cloud liquid water and ice content by multi-wavelength radar Nicolas Gaussiat Henri Sauvageot

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  1. Cloud liquid water and ice content by multi-wavelength radar Nicolas Gaussiat Henri Sauvageot Anthony J. Illingworth

  2. Dual-Wavelength measurements For a dual-wavelength pair ( Long, Short) : DWR is due to (1) differential attenuation , (2) Mie scattering : In clouds, Mie scattering is more often due to ice. Differential attenuation is dominated by liquid water : A 95 – 35 = 8 dB km-1/g m-3 A 35 – 3 = 2 dB km-1/g m-3

  3. Assuming a gamma distribution of scatterers : the Mie scattering term (F) is a function of D0 : 25 F3-95 20 F35-95 F[dB] 15 10 F3-35 5 0

  4. ARM case study (1) Cirrus : (2) Stratocumulus : (3) Mixed phase cloud: (3) (2) (1) Excepted in cirrus, LWC content derive from differential attenuation ignoring Mie scattering looks good, BUT…

  5. Simulatingdifferentialattenuation

  6. Principle of a triple–wavelength method With 3 frequencies 3, 35, 95 GHz : k ~ 0.2 and The system is solved using an iterative process : • First guess DWR3-35 Mie scattering only  D0 first estimate • With D0 ,Mie scattering term F3-94 is predicted • (Observed DWR3-94 – predicted F3,94)  Ad3-94 attenuation profile. • With Ad3-94  correction First guess : DWR3-35 is now corrected for attenuation When Ad and F profiles are stables LWC is derived from Ad3-94 (Ad94 – 3 = 10 dB km-1/g m-3 )

  7. Running triple-wavelength method

  8. Using triple-wavelength method in mixed phase clouds

  9. Dual-wavelength observables

  10. Merging Mie scattering and attenuation

  11. Microphysical Parameters Derived From Ad and F

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