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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

• In t r o d u c t io n o f M e t e o r o lo g ic a l S a t e l l i t e d e v e lo p m e n t in c h in a

• D e v e lo p m e n t s t a t u s o f F Y3 ( 0 2 ) d u a l-f r e q u e n c y R a in R a d a r

• F ie ld c a m p a ig n r e s u l t s

• c o n c lu s io n

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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-3PM1

2012FY-2G2013FY-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 Radar Introduction of China Spaceborne Precipitation 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 both Provide 3D precipitation structure over both ocean and land;ocean and land;

Improve the sensitivity and accuracy of Improve the sensitivity and accuracy of precipitation measurement over china and precipitation measurement over china and arrounding area;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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M a in In s t r u m e n t M a in In s t r u m e n t C h a r a c t e r is t ic sC h a r a c t e r is t ic s

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 correction

The 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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K u b a n d m e a s u r e m e n ts

Rain profile measurements comparison with TRMM-PR

K a b a n d m e a s u r e m e n ts

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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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• The radar reflectivity factor profiles of ADPR and TRMM PR

are highly consistent, which proves ADPR’s measuring

accuracy.

• Field Campaign results shows that ADPR basically satisfy the

desired performance.

• The dual-frequency precipitation radar is qualified for the

development of future spaceborne dual-frequency

precipitation radar in China.

Conclusion

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…… …… S t o p H e r eS t o p H e r e