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Microwave Sensors Subgroup (MSSG) Report

DONG, Xiaolong, MSSG Chair

National Space Science Center, Chinese Academy of Sciences & National Remote Sensing Center of China (NSSC/CAS, NRSCC) Email: [email protected]

CEOS WGCV-38 co-hosted by NOAA, USGS & NASA Sept 30-Oct 2, College Park, MD, USA

mailto:[email protected]

CEOS WGCV-38 Sept 30-Oct 2,2014, College Park, MD, USA

OUTLINE

Missions and objectives Recent requirements and challenges Focuses and progresses Future work and recommendations


Missions & Objectives of MSSG Missions:

The mission of the Microwave Sensors subgroup is to foster high quality calibration and validation of microwave sensors for remote sensing purposes. These include both active and passive types, airborne and spaceborne sensors.

Objectives Facilitate international cooperation and co-ordination in microwave sensor

calibration / validation activities by sharing information on sensor development and field campaigns.

Promote accurate calibration and validation of microwave sensors, through standardisation of terminology and measurement practices.

Provide a forum for discussion of current issues and for exchange of technical information on evolving technologies related to microwave sensor calibration / validation.

Provide calibration/validation support to CEOS virtual constellations and data application groups/communities by coordination of reference sites for both passive and active microwave sensors, and standardization of quality assurance of microwave remote sensing data.


MSSG covers passive and active…

All EO sensors operated in microwave spectrum, except SAR

Works currently focuses on: Microwave Radiometers (sounders, imagers) Radar Scatterometers Radar Altimeters

Other related aspects: GNSS and GNSS-Reflected signal applications Spaceborne weather radars: Cloud and Precipitation Radars (e.g

PR, CPR) Ice sounders and GPR


Characteristics of Microwave Sensors

Relatively low spatial resolution (km, tens of km, hundreds of km) for atmospheric, oceanic, large-scale terrestrial environmental applications

Data dependent on sensor and processing (model, retrieval, algorithm, cal/val)

Importance of processing and quality control


Recent Requirements and Challenges

Climate and global change applications Higher requirements, especially for climate and global change

applications: sensitivity, accuracy, stability, traceability; Cross-calibration requirements of sensors flown on different

spacecrafts and developed by different agencies;

No traceable standards available for microwave sensors; New developed sensors

Polarized radiometers and scatterometers Interferometric synthetic aperture radiometers Scatterometers for terrestrial applications Wide swath and SAR altimeters…


Many new techniques need to be developed for cal/val…

High precision requirements: Brightness temperature: 0.1K Sea level: 1mm Backscattering coefficient: 0.1dB

Cross-calibration/validation requirements: Traceable reference for processing or historical data Small shift of sensor parameters (frequency,

bandwidth, on-board calibrators,…) Calibration models/algorithms for different sensors by

different agencies


Priorities and focuses

Level 1 data Brightness temperature for MW radiometer Backscattering coefficient for radar scatterometer

Models and algorithms Radiometric standard for MW Noise source calibrator RAM calibrator Measurement and characterization


Current status and difficulty of the group

No focused tasks and fixed active group members

Activities constrained by non-technical factors Data access and exchange


Updates from WGCV-38

Attend GSICS Microwave Subgroup tele-meeting (March 28)

Attend International Ocean Surface Wind Vector (IOSWV) Science Team meeting (June 2-4)

Organized invited sessions in IGARSS 2014, discussion with OSVW VC people (July 18)

Progresses on calibration of altimeter Progresses on evaluation of wet tropspheric

path delay Progresses on scatterometer


Cross-calibration of altimetry requirements and progresses

Climate and global change research requires long-term data with continuance;

Sea level products related to orbit and algorithms (corrections) and requires x-cal and val

HY-2A altimeter with Jason-1/2 (NSOAS, CNES, ESA), cross comparison/calibration by NSOAS/SOA, CNES and ESA with very good encouraging results.

Based on bilateral cooperation, no OST involvement.


Sea level Cross-comparison: HY-2A with Janson-2

Statistics of coincidence locations

Absolute RMS deviation with average offset correction:

8.3cm, with correlation coefficient of 0.978.


Coincidence point distribution of HY-2A and Jason-1/2

HY-2A vs Jason-1

HY-2A vs Jason-2 RMS deviation: HY-2A vs Jason-1: 0.84m/s HY-2A vs Jason-2: 0.78m/s

Wind speed Cross-comparison with Janson-1/2


HY-2A vs Janson-1 HY-2A vs Jason-2

RMS deviations: vs Jason-1: 0.19m; vs Jason-2: 0.16m

Significant wave height Cross-comparison with Janson-1/2


Altimetry calibration with GNSS buoy

NSSC & NSOAS (China), TUC (Greece) & CNES Provide absolute reference for altimetry Model development ongoing

0 5 10 15 20 2511.8

12

12.2

12.4

12.6

12.8

13

13.2

13.4

13.6

13.8

测量点序号

海面

高（

m）

海面高测量点

五阶多项式拟合

6 6.2 6.4 6.6 6.8 714.5

14.51

14.52

14.53

14.54

14.55

14.56

14.57

14.58

14.59

14.6

北京时间（h）

海面

高（

m）

奇异谱估计海面高

线性拟合海面高

过顶时刻

HY-2 SSH GNSS SSH Bias

7月31日 14.639 m 14.543 m 0.096 m

8月3日 13.232 m 13.064 m 0.073 m


Cross-calibration/comparison for wet tropspheric path delay

HY-2A ACMR and Jason-2 AMR ACMR: tri-frequency (18.7, 23.8, 37GHz) AMR: dual-frequency (18.7, 23.8, 34GHz)

Cross comparisons Brightness temperature Path delay (ACMR vs AMR, ACMR vs ECMWF)


Brightness temperature

f=18.7GHz Std=1.17K,r=0.98 f=23.8GHz Std=1.74K,r=0.93 f=34GHz/37GHz Std=1.56K,r=0.95

Jason-2 AMR 亮度温度(K)

HY-2

A AC

MR

亮度

温度

(K

)

18.7 GHz 亮度温度比对

y = 0. 945 x + 12. 236

130 135 140 145 150 155

130

135

140

145

150

155

5

10

15

20

25

30

35

40

45


HY-2

A AC

MR

亮度

温度

(K)

23.8 GHz 亮度温度比对

y = 0. 939 x + 14. 818

140 150 160 170 180 190 200

140

150

160

170

180

190

200

10

20

30

40

50

60


HY-2

A AC

MR

亮度

温度

(K

)

37 GHz 亮度温度比对

y = 0. 944 x + 17. 897

150 155 160 165 170155

160

165

170

175

180

5

10

15

20

25


Path delay: ACMR vs AMR & ACMR vs ECMWF

Jason-2 AMR 湿路径延迟(m )

HY-

2A A

CM

R

湿路

径延

迟

(m)

湿路径延迟比对

r mse = 1. 437 cmmean = - 1. 266 cmst d = 0. 679 cm

y = 1. 053 x - 0. 004

-0.3 -0.25 -0.2 -0.15 -0.1 -0.05

-0.35

-0.3

-0.25

-0.2

-0.15

-0.1

-0.05

10

20

30

40

50

60

70

80

HY-2A ACMR 湿路径延迟(m )E

CM

WF

湿路

径延

迟

(m)

r mse = 1. 455 cmmean = 0. 023 cmst d = 1. 455 cm

y = 1. 014 x + 0. 002

Val i d dat a ：256802( 96. 479%)21- Jan- 2013

-0.5 -0.45 -0.4 -0.35 -0.3 -0.25 -0.2 -0.15 -0.1 -0.05

-0.4

-0.35

-0.3

-0.25

-0.2

-0.15

-0.1

-0.05

500

1000

1500

2000

2500


Future works-MW radiometry

MW radiometry Formulate tasks on specific variables: water vapor by

nadir-looking radiometer (ACMR, AMR, MWR) (ESA, NSSC/NSOAS, NOAA)

Validation of MW radiometer data with GNSS-Occultation Coordination with GSICS Microwave Subgroup

(cooperation to avoid duplicate work) Coordination with VCs (P-VC and SST-VC) for demand of

cal/val support Information change on MW radiometric references (noise

source and RAM) and standard radiometers (NSSC & BIRMM/China, NIST/US, FSUE «VNIIFTRI»/Russia, NPL/UK)


Future works-radar altimetry

Radar altimetry Exchange cross-comparison Development of absolute validation (GNSS-buoy) Development of modeling for validation (satellite with

in-situ data) Exchange of calibration site data Coordination with OST VC


Future works-scatterometer

Radar scatterometer Exchange of cross-comparison by global ocean

calibration data Continue to coordinate sigma 0 data cross-

comparison for reference sites (Amazon, Antarctic, ocean)

Standards of quality control (participation) Further support to OSVW-VC


Recommendations and proposals

Agency support with L1 data for specific cross-calibration/comparison purpose, and improve calibration and validation.

Encourage close collaboration between instrument teams and science/user community.

Thanks !

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