94 GHz radar near-real-time calibration correction

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94 GHz radar near-real-timecalibration
correction
Nicolas Gaussiat
Progress meeting 5 Exeter 05/06 Apr 2004
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The principe of the method is as follow

• When rain rate become greater than 3 mm/h, by
  the combined effect of Mie scattering and
  attenuation, the reflectivity measured at 270
  meters above the radar is constant and the value
  should be around 19 dBZ. The calibration is
  obtained by correcting the calibration constant
  in such a way that the reflectivity measured
  match in a mean square root sense the nominal
  value. It is assumed in the calculation, a
  constant attenuation by the wet radome of 11 dB.

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First transmitter back in 1999-2002
0 15 30
45 60
75 90 105
120
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Correction applied back in 1999-2002
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Second transmitter in 2003-2004
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Correction applied in 2003 near-real-time routine
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Conclusions

• Same causes same effects

• Rain/snow on the radar change in
  loads/reflection ???

• For a better calibration method and a control
  of the possible sources of transmitter
  degradation we need to monitor the power

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