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  Radar-estimated rainfall intensity product
  during YMC-BSM 2018 field campaign

  drafted by Satoru Yokoi, 04 Mar 2022
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1. Summary

This directory includes horizontal field of rainfall intensity at 2 km above sea level estimated from radar reflectivity and specific differential phase measured by transportable X-band Doppler radar by PAGASA during the YMC-BSM 2018 field campaign at Laoag.


2. Observation

We installed an X-band polarimetric Doppler radar (JMA-912 Rainwatcher manufactured by Japan Radio Co., Ltd) at (18.13N, 120.53E) near the northwestern coast of Luzon Island, the Philippines, in 1-31 August 2018. During the period, volume scan observations with 17 elevation angles (0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 10.0, 12.0, 16.0, 20.0, and 30.0 degrees) were performed every 10 minutes. The observation range was 120 km, and resolution of the data was 1.2 degree in azimuthal direction, and 225 m in radial direction.

Available radar variables include radar reflectivity, Doppler velocity, spectral width of Doppler velocity, differential reflectivity, differential propagation phase, specific differential phase, and co-polar correlation coefficients.


3. 2D rainfall intensity product

Rainfall intensity (R; mm/hr) was estimated from the attenuation-corrected radar reflectivity (Zh; mm^6/m^3) and specific differential phase (KDP; degree/km) data within 60 km from the radar:

R = 18.9 * KDP^0.856 (if Zh>35dBZ and KDP>0.3)
  = 0.0136*Zh^0.77 (otherwise)

This method is based on Kim and Maki (2012), with parameters being modified with reference to rain-gauge data at the PAGASA Laoag weather station (18.18N, 120.53E).

Then, R was interpolated to the cartesian (x-y) coordinate at 2 km above sea level with 1-km horizontal resolution.

The period of the product is from 0000UTC 03 August to 2350UTC 30 August 2018.

4. Data format

Data are in grads format.


5. Remarks

If you have questions, please contact ymc-joffice @ jamstec.go.jp.


6. References

Kim, D.-S., and M. Maki, 2012: Validation of composite polarimetric parameters and rainfall rates from an X-band dual-polarization radar network in the Tokyo metropolitan area. Hydrological Research Letters, 6, 76-81.

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