Constructing a lookup table using RTTOV-SCATT based on Dm and phase

[Qixiang Sun]

Hi,

I’m trying to use RTTOV-SCATT to generate a lookup table of the scattering factor fz as a function of mass-weighted mean diameter (Dm) and hydrometeor phase.

The scattering factor is defined as:

fz(Dm) = [lambda^4 / (pi^5 * |Kw(lambda)|^2)] * integral{ sigma_b(D, lambda, T) * f(D; Dm) dD }

Where:
– sigma_b(D, lambda, T) is the backscattering cross-section of a particle of diameter D
– f(D; Dm) is the normalized particle size distribution with Dm as a parameter
– lambda is the radar wavelength
– T is temperature (related to phase)

I would like to generate a lookup table of fz values over a range of Dm and phase values using RTTOV-SCATT. Could you please advise whether this is possible with RTTOV-SCATT, and if so, how the input profiles should be constructed?

Thank you very much for your help.

Best regards,
Qixiang Sun

[James Hocking]

Hi Qixiang Sun,

The current RTTOV (or RTTOV-SCATT in v13 and earlier) hydrotable generation code parameterises optical properties in terms of temperature and water content. It does not support parameterisation of optical properties in terms of particle size, so it is not possible to directly use the code to do what you want.

Best wishes,
James

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