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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

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Contents

• Introduction of Meteorological Satellite development in china

• Development status of FY3(02) dual-frequency Rain Radar

• Field campaign results

• conclusion

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Roadmap of FenYun satelliteRoadmap of FenYun satellite

Science Target: Globalall weather, multispectral3D detection

2006FY-2D

2007FY-3A (TEST)

2010FY-2F

2008FY-2E

2009FY-3B (TEST)

2011FY-3AM12012FY-3PM12012FY-2G 2013FY-4A (TEST)

2013FY-3RM (TEST)

2015FY-4EAST1

2014FY-3AM2

2017FY-3AM3

2015FY-3PM2

2016FY-4WEST1

2017FY-4MS (TEST)

2018FY-3PM3

2016FY-3RM12019FY-3RM2

2019FY-4EAST2

2020FY-4WEST2

2020FY-4MS

2008FY3A

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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.

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Introduction of China Spaceborne Precipitation Introduction of China Spaceborne Precipitation Radar Radar

The main objectives of RM satellite:

Consist a Global observation constellation system with FY3-2 AM and PM satellites, as well as GPM satellite;

Improve the severe convective system monitoring ability in china together with GPM satellite;

Provide 3D precipitation structure over Provide 3D precipitation structure over both ocean and land;both ocean and land;

Improve the sensitivity and accuracy of Improve the sensitivity and accuracy of precipitation measurement over china precipitation measurement over china and arrounding area;and arrounding area;

• Instruments onboard the PR satellite platform

Core instrument: Ku/Ka Radar

Microwave sounder

MWTS ： centre frequencies set at 50.3,51.76,52.8,53.596,54.4,54.94,55.50,57.29GHz

MWHS ： centre frequencies set at 89.0,118.75±0.2, ±0.3, ±0.8, ±1.1, ±2.5, ±3.0, ±5.0,150,183.31±1, ±1.8, ±3, ±4.5, ±7

Microwave imager

MWRI ： Centre frequencies set at 10.65,18.7,23.8,36.5,89GHz, with V/H polarization

KaPR

KuPR

MWRI

MWTS

MWHS

MWRI

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Main Instrument Main Instrument CharacteristicsCharacteristics

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

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Ground weather RadarZGnd

Rain profile

ZAPR

Inversion algorithm

APR calibration

Attenuation CorrectionZe

Rain profile

Inversion algorithm

Attenuation CorrectionZe

Radar simulator

APR rain measurements simulation database

TRMM-PR rain products（ 2A25 ）

TRMM-PRZPR

JS-RM2010 Dual-frequency Rain Radar Field Campaign

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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

ADPR(Ku/Ka) Instrument characteristics

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Dual-Frequency Radar Airborne Field Campaign (JS-RM2010)Jun-Oct, 2010

Ku Radar Ka Radar

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Ocean surface radar backscattering characteristics

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

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Calibration accuracy evaluation by using TRMM-PR measurements

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

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Antenna radiom Loss correctionThe rms error of model computation is 0.78dB

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ADPR antenna Loss model

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TRMM-PR Measurements over Test Area

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ADPR Calibration Accuracy Evaluation Results

Mean bias = 0.046

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• Carborne meteorological radar:– X-band, 9.375GHz

– 1.5°

– Volume scan

– 150m

• TRMM PR:– Ku-band, 13.6GHz

– 0.71°

– Cross-track scan, 49 angle bins per scan

– 4.3km / 5km, 0.25km

Satellite-Airplane-Ground Radar Zm Profile comparison

Volume Scan

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Ku band measurements

Rain profile measurements comparison with TRMM-PR

Ka band measurements

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Time difference is about 40 minutesMeasurements from 1.5-5Km above surface is consistent with each other, both in height and Z value;The ADPR derived Ze under 1.5Km is effected by surface return signal.

ADPR rain profile Comparison with TRMM-PR

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Airplane-ground comparison

Airplane attitude correction

Processing procedures

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Airplane-ground comparison

Vertical sections of airborne radar

and ground radar

Left ： airborne Ku/Ka-band precipitation radar

Right ： carborne X-band meteorological radar

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Airplane-ground comparison

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

Quantitative

comparison

results

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detection sensitivity

[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.

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sidelobe

[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.

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range resolution

[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.

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1. The radar reflectivity factor profiles of ADPR and

TRMM PR are highly consistent, which proves

ADPR’s measuring accuracy.

2. Field Campaign results shows that ADPR basically

satisfy the desired performance.

3. The dual-frequency precipitation radar is

qualified for the development of future

spaceborne dual-frequency precipitation radar in

China.

Conclusion

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