1. 1 Development Of Space-borne Rain Radar In China: The First Results From Airborne Dual-Frequency Rain Radar Field Campaign Hu Yang, Honggang Yin, Jian Shang Qiong Wu, Yang Guo, Beidou Zhang National Satellite Meteorological Center July 26,2011 IGARSS’2011

3. 3 Roadmap of FenYun satellite Science Target: Global all weather, multispectral 3D detection 2006FY-2D 2007FY-3A (TEST) 2010FY-2F 2008FY-2E 2009FY-3B (TEST) 2011FY-3AM1 2012FY-3PM1 2012FY-2G 2013FY-4A (TEST) 2013FY-3RM (TEST) 2015FY-4EAST1 2014FY-3AM2 2017FY-3AM3 2015FY-3PM2 2016FY-4WEST1 2017FY-4MS (TEST) 2018FY-3PM3 2016FY-3RM1 2019FY-3RM2 2019 FY-4EAST2 2020 FY-4WEST2 2020 FY-4MS 2008FY3A

4. 4 Orbit coverage in FY3(02) Era FY3-Am + FY3-PM + FY3-RM will consist polar orbit earth observation constellation, combined with GPM satellites, provide Globe 3-hourly high accuracy precipitation products.

6. 6 Main Instrument Characteristics KuPR KaPR Frequency 13.6 GHz 35.5 GHz Scan angle ±20º Horizontal resolution 5 km (nadir) Range resolution 250m Observation range 18 km~-5 km sensitivity 0.5 mm/h 0.2 mm/h Antenna Side lobe level -35 dB － 30dB Range side lobe -70dB -60dB accuracy ≤ ±1 dB Independent sampling number ≥ 64 Calender Year 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Ku/Ka PR Conceptual Design Preliminary Design/Airborne flight Critical Design Sustaining Design Launch Gound System Conceptual Design System Design System integeration Operation Algorithm Conceptual Design Prototype Development Development Validation

7. 7 7 JS-RM2010 Dual-frequency Rain Radar Field Campaign Ground weather Radar Z Gnd Rain profile Z APR Inversion algorithm APR calibration Attenuation Correction Ze Rain profile Inversion algorithm Attenuation Correction Ze Radar simulator APR rain measurements simulation database TRMM-PR rain products （ 2A25 ） TRMM-PR Z PR

8. 8 ADPR(Ku/Ka) Instrument characteristics Ku Ka Fly height 5km 5km Frequency 13.6GHz 35.5GHz Swath width 3.6km 3.6km Observation range 4km ～ -3km ASL 4km ～ -3km ASL Horizontal resolution 240m 240m Vertical resolution 250m 250m sensitivity 0.25mm/h 0.1mm/h Sample rate 64 64 Beam width 2.9 °× 2.9 ° 2.9 °× 2.9 ° Scan angle range ± 20 ° ± 20 ° Dynamical range ≥ 70dB ≥ 70dB

9. Dual-Frequency Radar Airborne Field Campaign (JS-RM2010) Jun-Oct, 2010 9 Ku Radar Ka Radar

10. 10

11. Ocean surface radar backscattering characteristics 11 11 Comparing with TRMM-PR measurements over ocean surface shows that the loss of antenna radome is obvious, and the attenuation is angle dependence.

12. Calibration accuracy evaluation by using TRMM-PR measurements 12 12 1.Ku radar ocean sigma0 from TRMM-PR 2. Ku band ocean surface roughness parameter from TRMM-PR 3. Ku/Ka ocean surface roughness difference 4. Ka band ocean surface roughness from Ku measurments 5. Ka band ocean surface sigma0 from model ADPR Ku radar Cal/val by using TRMM-PR ADPR Ka Radar cal/val Ocean sigma0 from model computation

13. Antenna radiom Loss correction 13 13 The rms error of model computation is 0.78dB

14. 14 14 ADPR antenna Loss model

15. TRMM-PR Measurements over Test Area 15 15

16. ADPR Calibration Accuracy Evaluation Results 16 16 Mean bias = 0.046

18. 18 Ku band measurements Rain profile measurements comparison with TRMM-PR Ka band measurements

20. Airplane-ground comparison -20- Airplane attitude correction Processing procedures

22. Airplane-ground comparison -22- Quantitative comparison results Observation time 2010-10-11, 09:52:06~10:02:24 Matched points 4684 Maximum (dBZ) Ku ： 25.77 Ka ： 25.07 X ： 30.50 Minimum (dBZ) Ku ： -7.82 Ka ： -10.07 X ： 4.00 Mean (dBZ) Ku ： 16.38 Ka ： 14.55 X ： 19.22 RMS Ku vs. Ka ： 1.84 Ku vs. X ： 6.75 Ka vs. X ： 7.51 Correlation coefficient Ku vs. Ka ： 0.98 Ku vs. X ： 0.53 Ka vs. X ： 0.53

23. detection sensitivity -23- [Ku] The minimum detectable rain rate of airborne Ku-band radar is 0.15mm/h, which satisfies the desired performance of 0.25mm/h. [Ka] The minimum detectable rain rate of airborne Ka-band radar is 0.13mm/h, which is a little worse than the desired performance of 0.10mm/h. Given the rain attenuation and the radome’s influence, the sensitivity of Ka-band radar basically satisfies the desired performance.

24. sidelobe -24- [Ku] The sidelobe of Ku-band radar is lower than -60dB, which satisfies the desired performance. [Ka] The sidelobe of Ka-band radar is lower than -50dB, which is a little worse than the desired performance.

25. range resolution -25- [Ku] Actual 6dB range resolution of Ku-band radar is better than 250m, which satisfies the desired performance. [Ka] Actual 6dB range resolution of Ka-band radar is better than 250m, which satisfies the desired performance.

27. 27 …… Stop Here