SMOS: Principles of Operation of the MIRAS instrument Prof. A. Camps
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Transcript of SMOS: Principles of Operation of the MIRAS instrument Prof. A. Camps
ICMARS 2010Jodhpur – India December 16th, 2010 1/47
SMOS: Principles of Operation & First Results
SMOS: SMOS: Principles of Operation Principles of Operation
of the MIRAS instrumentof the MIRAS instrument
Prof. A. CampsDept. de Teoria del Senyal i Comunicacions
Universitat Politècnica de Catalunya and IEEC/CRAE-UPCE-mail: [email protected]
…on behalf of many people (many anonymous) that kept this dream alive and make it happen
devoted to Prof. Cal Swift… the pioneer
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SMOS: Principles of Operation & First Results
Outline of the presentation:
1. Basic principles2. Imaging in Synthetic Aperture Radiometers:
2.1. Synthetic Aperture Radiometers2.2. Image Reconstruction Algorithms: Ideal Case
3. The SMOS Mission4. MIRAS instrument description
4.1. Array topology4.2. Receivers’ architecture4.3. NIR architecture4.4. DIgital COrrelator System (DICOS)4.5. CAlibration System (CAS)
5. Instrument Performance5.1. Angular Resolution5.2. Radiometric Performance: definition of terms5.3. Image Formation Through a Fourier Synthesis Process
5.4. Imaging Modes: Dual-polarization and full-polarimetric 6. Geolocalization: from director cosines grid to Earth reference frame grid and Retrieval of Geophysical Parameters
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SMOS: Principles of Operation & First Results
21
2 21 2
,( , )
1
*B ph recnn
T TF , ,FT
Channel 2
Channel 1
0( , ) ( , )u v x y
*1 2
1 2 1 2
1 12
B
V u,v = t b t bk BB GG
H1(f)
H2(f)
b1(t)
b2(t)
*1 2
12
bb
Complex Correlator
= antenna spacing normalized to the wavelength
sinsin,cossin,
Baseline
• Spatial resolution is achieved by cross-correlating the signals collected by a number of antennas• Antennas can have a wide beam or a narrow one in one or two directions
( , ) ( , )V u v F T Ideal case: - Identical antenna patterns
- Negligible spatial decorrelation - No antenna positioning errors
2D Fourier Transform
1. Basic Principles
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SMOS: Principles of Operation & First Results
2.1. Synthetic Aperture Radiometers using Fourier Synthesis:
VLA, New Mexico, Socorro
ESTAR(1 D Aperture Synthesis)
NASA
Radioastronomy Earth Observation (concept proposed in 1983 by LeVine & Good)
MIRAS(2 D Aperture Synthesis)
ESA
( , ) ( , )V u v F T
2. Imaging in Synthetic Aperture Radiometers
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SMOS: Principles of Operation & First Results
• Differences between radio-astronomy and Earth observation:
- Large antenna spacing
- Very narrow field of view (FOV)
- Obliquity factor (1/cos ) can be approximated by 1
- Antenna patterns are approximatedly constant (amplitude and phase)
over the FOV
- Typically quasi-point sources imaged over cold background
super-resolution image reconstruction algorithms can be used
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SMOS: Principles of Operation & First Results
. After the successful results of ESTAR radiometer (1988),
the European Space Agency starts in 1993 the first feasibility studies to apply synthetic aperture microwave radiometry in two dimensions:
. MIRAS concept is born: Microwave Imaging Radiometer by Aperture Synthesis
. First studies (1993-95): led by Matra Marconi Space as the prime contractor
. 1995 Soil Moisture and Ocean Salinity Workshop (ESTEC, the Netherlands)Aperture Synthesis Microwave Radiometry is the only technique capable of measuring soil moisture and ocean salinity with enough accuracy and spatial resolution.
SSS image derived from the ’“Electronically Steered Thinned Array Radiometer (ESTAR)”. Error = 0.3 psu (D. M. LeVine et al., NASA Goddard).
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SMOS: Principles of Operation & First Results
Antenna Positions Spatial frequencies (u,v)
u
v
Periodic extension
2
2 2
,( , )
1
n B ph recF , T TT
( , ) ( , )V u v F T
21 elements + 2 redundant elements/arm Antenna spacing d = 0.875
Hexagonal grid in (u,v) planeNyquist criterion: d< / 3
Overlapping of 1 alias
Alias-free Alias-free Field Of View Field Of View
(AF-FOV)(AF-FOV)
Overlapping of 2 aliases
2.2. Image Reconstruction Algorithms: Ideal Case
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SMOS: Principles of Operation & First Results
In SMOS the “alias-free FOV” can be enlarged since part of the alias images are the “cold” sky (including the galaxy!) TB image limited by Earth replicas
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.2
0.4
0.6
0.8
1
Boresight Distance: 912.65 Km
Boresight Incidence Angle: 36.35º
-3 -2 -1 0 1 2 3
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
hsat=755.6 Km, =32.00º, d= 0.89
Extension ofAlias-Free FOV
-800 -600 -400 -200 0 200 400 600 800-200
0
200
400
600
800
1000
1200
Cross track coordinate (Km)
Alo
ng t
rack
coo
rdin
ate(
Km
)
hsat=755.9 Km, tilt=32.50 , d= 0.88
10
20
30
40
50
60
1.2032.85
2.4788.01
2.2178.62
1.7661.13
1.4348.48
1.2039.69
1.0534.97
1.2335.52
1.4939.34
2.3181.55
2.1374.95
1.7258.77
1.4046.29
1.1937.53
1.1032.62
1.3935.77
2.80101.26
2.2681.39
1.8465.47
1.5053.04
1.2544.31
5.1290.57
1.1340.12
1.2740.33
1.3951.36
1.3448.11 1.3948.00
- Pixel axial ratio a/b- Spatial resolution defined as geometric mean of axes
Iso-incidence angle contours
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SMOS: Principles of Operation & First Results
SMOS is a challenge:Particularities of 2D aperture synthesis radiometers:1) New type of instrument: - Review of the fundamental equation- Detail error model & error correction (calibration) algorithms- Image reconstruction algorithms
2) New type of observations:- Multi-look and multi-angle observations: . different pixel size and orientation . different noise and precision for each pixel- Polarization mixing:
. Earth reference frame antenna reference frame
3) New L-band and multiangular ocean and soil emission models : - Wide range of incidence angles (0º-60º)
4) New geophysical parameter retrieval algorithmstaking into account issues 1, 2 and 3 above
3. The SMOS Mission
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SMOS: Principles of Operation & First Results
Scientific measurements require a - Sun-synchronous, - dawn/dusk, and- quasi circular orbit.
Orbital parameters:• Mean altitude = 755.5 km• Eccentricity = 0.001165• Mean inclination = 98.416º• Local Time Asc. Node =6 AM• Argument of Perigee = 90º• Mean Anomaly = 306.3º
Note: The SUN is nearly always visible (97 % of the time) !!!
SMOS Mission: SMOS
Proba-2
Transformed SS-19 missile
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SMOS: Principles of Operation & First Results
HUB
ARM A
ARM C ARM B
CMN
PD
NS (DISTRIBUTED)
NS (CENTRALISED)
LICEF
LICEF/NIR
Optical Splitter
Optical Splitter
Optical Splitter
CMN
1ST SEGMENT OF ARM C
CMN
PD
Optical Splitter
PD
CMN
1ST SEGMENT OF ARM A
LICEF
LICEF/NIR
1ST SEGMENT OF ARM B
LICEF/NIR
LCF_A_21
LCF_A_16 LCF_A_15
LCF_A_10 LCF_A_09
LCF_A_04 LCF_A_03 LCF_A_02 LCF_A_01
NIR_AB_02
LCF_AB_01
HUB UnitIn the arms In the Hub Total
LICEF 3 x 3 x 6 3 x 4 66
LICEF/NIR - 3 x 1 3
CMN 3 x 3 x 1 3 x 1 12
CCU - 1 1
NS (distributed) 3 x 3 x 1 - 9
NS (centralised) - 1 1
PD (2 to 8) 3 x 3 x 1 3 x 1 12
Optical Splitter (1 to 8) 3 x 3 x 1 3 x 1 12
Optical Splitter (2 to 12) - 1 1
TRANSMITTERS - 2 2
FILTERS - 2 2
X-ANTENNA - 1 1
UnitIn the arms In the Hub Total
LICEF 3 x 3 x 6 3 x 4 66
LICEF/NIR - 3 x 1 3
CMN 3 x 3 x 1 3 x 1 12
CCU - 1 1
NS (distributed) 3 x 3 x 1 - 9
NS (centralised) - 1 1
PD (2 to 8) 3 x 3 x 1 3 x 1 12
Optical Splitter (1 to 8) 3 x 3 x 1 3 x 1 12
Optical Splitter (2 to 12) - 1 1
TRANSMITTERS - 2 2
FILTERS - 2 2
X-ANTENNA - 1 1
UnitUnitUnitIn the armsIn the armsIn the arms In the HubIn the HubIn the Hub TotalTotalTotal
LICEFLICEF 3 x 3 x 63 x 3 x 6 3 x 43 x 4 6666
LICEF/NIRLICEF/NIR -- 3 x 13 x 1 33
CMNCMN 3 x 3 x 13 x 3 x 1 3 x 13 x 1 1212
CCUCCU -- 11 11
NS (distributed)NS (distributed) 3 x 3 x 13 x 3 x 1 -- 99
NS (centralised)NS (centralised) -- 11 11
PD (2 to 8)PD (2 to 8) 3 x 3 x 13 x 3 x 1 3 x 13 x 1 1212
Optical Splitter (1 to 8)Optical Splitter (1 to 8) 3 x 3 x 13 x 3 x 1 3 x 13 x 1 1212
Optical Splitter (2 to 12)Optical Splitter (2 to 12) -- 11 11
TRANSMITTERSTRANSMITTERS -- 22 22
FILTERSFILTERS -- 22 22
X-ANTENNAX-ANTENNA -- 11 11
4.1. Array topology• 69 antenna elements (LICEF)
• Equally distributed over the 3 arms and hub
• The acquired signal is transmitted to a central correlator unit, which computes the complex cross-correlations of all signal pairs.
4. MIRAS instrument description
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SMOS: Principles of Operation & First Results
MIRAS consists of a central structure (hub) with 15 elements, and 3 deployable arms, each one having 3 segments with 6 antennas each.
[credits EADS-CASA]
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SMOS: Principles of Operation & First Results
4.2. Receivers’ architecture:
HVCU
SWITCH ISOL LNA BPF RFAMP MIXER
IFFILTER
ATTENSLOPECORR.
IF AMPs1BITADC
IFFILTER
ATTENSLOPECORR.
IF AMPs1BITADC
SYNTH
1396 MHz
PMS
1404-1423 MHz
8-27 MHz
DI
TI
TQ
DQ
REF55.84 MHz
VCOMAIN PATH GAIN = 100 dBPMS PATH GAIN = 65 dB
TRF
ANTENNA
I
Q
DICOS
DICOS
OffsetUNCALjCAL eA
A outT aV b • PMS acts as a total Power Radiometer in each LICEF
• Needed to denormalize the “normalized” correlations (1 bit/2 level)
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SMOS: Principles of Operation & First Results
LICEF: the LIght and Cost Effective Front-end
[credits MIER Comunicaciones]
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SMOS: Principles of Operation & First Results
4.3. NIR architectureThe Noise Injection Radiometer (NIR) is fully polarimetric and operates at 1.4 GHz
3 NIRs in the hub for redundancy.
Functions:• precise measurement of Vpq(0,0) = TApq for mean value of TBpq(,) image. • measurement of noise temperature level of the reference noise source of Calibration Subsystem (CAS) absolute amplitude reference
1st LICEF unit (V-pol)
2nd LICEF unit (H-pol)
Controller unit (switches, noise injection...)
Correlated noise inputs (from Noise Distribution Network)
allow phase/amplitude calibration of receivers as LICEFs & for 3rd and 4th Stokes parameters measurements
[credits TKK]
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SMOS: Principles of Operation & First Results
SMOS NIR:
T NA + TA = TUT NA + TA = TREF + TNR
Normal mode of operation: Calibrating internal noise source mode:
known (cold sky) ?
[Colliander et al., 2005]
[credits HUT]
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SMOS: Principles of Operation & First Results
4.4. DIgital COrrelator System (DICOS)
Digital signals from each LICEF are transmitted to DICOS to compute the complex cross-correlations of all signal pairs.
1 bit ADC (comparator) in each LICEF
Correlator = = NOT-XOR + up-counter
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SMOS: Principles of Operation & First Results
• Lower half: II-correlations: Nr,Nc Zr r Vr
• Upper half: IQ-correlations: Ni,Nc Zi i Vi
• Diagonal: IQ-correlations of same
element (q: quadrature errors)
• Correlations of I and Q signals with 0’s and 1’s
to compensate comparators’ threshold errors
• Correlations of 0’s and 0’s and 1’s and 1’s = Ncmax
• NCmax = 65437 for dual-pol mode (= fCLK · int)
NCmax = 43625 for full-pol mode
•Total number of products:•2556 correlations Ik-Ij •2556 correlations Ik-Qj•72 correlations Ik-Qk•72 correlations I-0•72 correlations Q-0 •72 correlations I-1 •48 correlations Q-1 •36 control correlations between 1 and 0 channels (4 for each ASIC)
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SMOS: Principles of Operation & First Results
CCU: the Correlator and Control Unit
[credits EADS-CASA]
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SMOS: Principles of Operation & First Results
4.5. CAlibration System (CAS)
Noise sources needed to calibrate the instrument.
HUB ARMS
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SMOS: Principles of Operation & First Results
* source 0* source 2* source 5* source 8
124
25
48
49
72
A
B
C
Correlated noise is injected to the receivers in two steps:first the “even” sources and then using the “odd” ones
Centralized and distributed calibration
These receivers belong tothe NIR (□: H-channel) and
do not form additional baselines
Overlapping between elements(phase & amplitude tracking
along the arms)
Overlapping between elements(phase & amplitude tracking
among arms)
Centralized Calibration(separable & non-separable
errors can be corrected) Distributed Calibration(only separable errors
can be corrected)
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SMOS: Principles of Operation & First Results
OVERALL SEGMENT ARCHITECTURE
[credits EADS-CASA]
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SMOS: Principles of Operation & First Results
6 LICEF / segment
[credits EADS-CASA]
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SMOS: Principles of Operation & First Results
MOHA
[credits EADS-CASA]
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SMOS: Principles of Operation & First Results
CAS
[credits EADS-CASA]
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SMOS: Principles of Operation & First Results
CMN
[credits EADS-CASA]
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SMOS: Principles of Operation & First Results
• The retrieved image is the 2D convolution of the original T(,) image
with the instrument’s impulse response or equivalent array factor:
' 2 ' 2
20 ' ' 0
1
2
2 ' '0
1ˆ , , , , ', ' ' '
3
2
', ' ,
mn mn
mn mn
j u vmn mn mn mn
m n
j u v
mn mnm n
T s W u v V u v e T AF d dK
s d
AF s W u v e
5.1. Angular Resolution
2 2
*B 1 2
122 2
011 2
T , ( ) ( )1( , ) d d
1
phrec n n -j 2 u +vn
T F , F , u vV u v = er
f
• The “ideal” brightness temperature image is formed by an inverse (discrete) Fourier transform of the measured visibility samples (B = 0):
Equivalent Array Factor:same response as for an array of elements at (u,v) positions
(except for the |(.)|2)
1 0 0Τ̂ , * ΤH, = F W u v V u, v = AF , ,
Τ̂ ,
5. Instrument Performance
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SMOS: Principles of Operation & First Results
Response with rectangular window
Response with Blackmann window(rotational symmetry)
3 maxmax
max
2; 10% 15
2 3
43%
rectdB
EL
e for uu
u N d
MBE
3 31.48
90%
Blackmann rectdB dB
MBE
'sec1A main lobe ondary lobesT MBE T MBE T
W(umn,vmn): window to weight the visibility samples:• reduces side lobes• widens main lobe• increases main beam efficiency (MBE)
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SMOS: Principles of Operation & First Results
5.2. Radiometric Performance: definition of terms
Error maps: TB(,,t)
Random errors
(noise due to finite integration time)
Temporal average Zero 0
Temporal standard deviation
Radiometric sensitivity
Systematic errors
(instrumental errors)
Spatial average Radiometric bias
(scene bias)
Spatial standard deviation
Radiometric accuracy
(pixel bias)
1M
t,,T̂t,,T̂T
M
1i
2
tBiB
ysensitivit
N
1iiiB
tiiBbias ,Tt,,T̂
N1
T
2N
i i i iB Bti 1
accuracy
T̂ , ,t T ,T
N 1
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SMOS: Principles of Operation & First Results
Cut for =0N
tB
TTdT w
a
eff
RAB
222 1
),(2
3),(
Dashed lines. Theoretical formula:
Radiometric Sensitivity over ocean
[credits I. Corbella]
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SMOS: Principles of Operation & First Results
Scene Bias < 0.1 K
Accuracy < 0.5 K
Moon
Galaxy (yellowish)
Galaxy Alias
Galactic radio-source (TBC)
Cosmic Background Radiation at 3.3 K
Sun Alias
[credits DEIMOS]
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SMOS: Principles of Operation & First Results
• 45 deg singularity discarded
• All points with the same incidence angle averaged
Fresnel
V
H
Y
X
T
T
T
T
22
22
cossin
sincos
Incidence angle dependenceSingularity in the transformation antenna to Earth reference frame (dual-pol mode)
[credits I. Corbella]
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SMOS: Principles of Operation & First Results
5.3. Image Formation Through a Fourier Synthesis Process
Even in the ideal case:- Antenna spacing > /3 aliasing- Gibbs phenomenon near the sharp transitions (mainly alias borders)
In the real case:- Antenna patterns are different - Receivers’ frequency responses are different ( FWF different)- Antenna positioning errors (u,v,w)real different from (u,v,0)ideal
IHFFT cannot be used as image reconstruction methodMore sophisticated algorithms must be devisedBut it will be good that the second ones tend to IHFFT in ideal conditions
… and obviously instrumental errors must be calibrated first!
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SMOS: Principles of Operation & First Results
1) Receivers relative calibration (image “contrast”)- Error model (distorsions, artifacts, blurring…)- Internal references (Tcorr, Tuncorr,…)
TB imaging in a single snap-shot (1 integration time = 1.2 s / polarization in dual-pol):
Aperture Synthesis Radiometer: 2 step calibration
TB imaging pixel by pixel through antenna scan:
Real Aperture Radiometer:1 step calibration
1) Absolute calibrationExternal references:
Thot, Tcold
2) Absolute Calibration (image accuracy)- External references (FTT, OTT…)- Thot/Tcold, ground truth, external calibration…
*** Image Reconstruction Algorithm *** *** Imaging by (e.g.) conical scan ***
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SMOS: Principles of Operation & First Results
Calibration Concept: Brief sketch
• Items that need calibration:
- NIR Gain and Offset
- PMS gain and offset (receiver and baseline amplitude errors)
- Fringe-washing function FWF (amplitude and phase errors)
- Noise that is injected to receivers during calibration
- Correlator Offsets
• Types of Calibration:
– Internal: injection of correlated or uncorrelated noise to the receivers
– External: observation of known target:
• NIR absolute calibration
• Flat-Target Transformation: to calibrate antenna pattern errors
– CAS Calibration: performed by NIR during internal calibration
– Correlator Calibration: injecting known signals
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SMOS: Principles of Operation & First Results
a. MIRAS internal calibration
Instrumental errors correction: set of measurements and mathematical relations to remove instrumental errors
INTERNAL INSTRUMENT CALIBRATION
• Characterizes the instrument behavior independently of the input signal. • It can be characterized by suitable internal known signals injected at its input: correlated/uncorrelated and hot/cold noise injection.
Error model
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SMOS: Principles of Operation & First Results
MIRAS Internal calibration
LI CEF
NI R
switchi
q
To correlator
ma
trix
Antenna
H
V
ADCIF-i
C
U
IF-q ADC
LO distribution
Clock distribution
Mixer
RF
Noise
distributionnetw
ork
PMS
Reference receiver(Noise Injection
Radiometer)
Lv
TN
TS1
C
H
V
TS2
Noise source
0
N
Matched load
Hot
Warm
kk offCC
syskk vTGv
k
offkACsys G
vvT k
k
Calibrated visibility:
njkSjkkj TSSTSST *00
*00
ˆ
)1(2
0
2
0 knSkN STTSTk
CR
CN
CCsys kkk
TTT
(*)
(*)
PMS gain PMS offset
Correlation amplitude
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SMOS: Principles of Operation & First Results
2 2
2 2*
12 1 2 1212 12 12
12 12 1
2 201 2 1
22 2
, 11, ,
1
exp 2 1
pq rec pqpqnp np
fore
T TV F
u v w
u v w
F rf
j d d
Formulation of the Problem:Instrument Equation After Internal Calibration
-30 -20 -10 0 10 20 300.6
0.65
0.7
0.75
0.8
0.85
0.9
0.95
1
1.05
time (ns)
Amplitude of fringe-washing functions
-30 -20 -10 0 10 20 30-6
-4
-2
0
2
4
6
8
time (ns)
De
g
Phase of fringe-washing function
[credits I. Corbella]
To be corrected using the Flat Target Response
( , ) ( , ) ( , )pp pp ppij ij ijV u v V u v V u v
, , ,decW u v V u v G T
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SMOS: Principles of Operation & First Results
The Flat Target Response:
-The Flat Target Response is defined by:
2 2
, , , * 2 ( ), , 2 2
1
1 1( , ;1) ( , ) ( , ) d d
1
pq p q j u vij n i n j ij
oi j
u vV u v F F r e
f
,( , ; ) ( , ; 1)pq pqij o r o r ijV u v T T T T V u v
( , ) ( , ) ( , )pp pp ppij ij ijV u v V u v V u v
defining:
( , ) ( , ; )pp
pp ppB rij ij P r
P r
T TV u v V u v T T
T T
Then the differential visibilities to be processed are:
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SMOS: Principles of Operation & First Results
• Once in a month (every week during commissioning) the platform rotates to point to the cold sky
• External calibration is used to correct for elements not included in internal calibration: switch and antenna losses
• Also the Noise Injection Radiometer (NIR) is calibrated and the Flat Target Response (FTR) measured
HERE IT GOES THE ANIMATION. T_X_skylook2.gif
HERE IT GOES THE ANIMATION. T_Y_skylook2.gif
External calibration
[credits I. Corbella]Tx and Ty while satellite is turning up
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SMOS: Principles of Operation & First Results
5.4. Imaging Modes: Dual-polarization and full-polarimetric
Dual-polarization radiometer:
MIRAS has dual-pol antennas, but only one receiver polarizations have to be measured sequentially, with an integration time of 1.2 s each
[credits M. Martin-Neira]
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SMOS: Principles of Operation & First Results
Full-polarimetric mode: (selected as operational mode for SMOS)
[credits M. Martin-Neira]
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SMOS: Principles of Operation & First Results
6. Geolocalization: from director cosines grid to Earth reference frame grid
• ISEA family of grids seem to be the best option for the SMOS Products, but EASE-Grid has
come to be popular amongst many of the Earth Observation missions of the USA, namely AQUA
(NASA/NASDA) and AQUARIUS (NASA), which are particularly interesting for comparison with the SMOS
products.
• Spatial partitioning of EASE-Grid is square-based and ISEA can be triangular,
hexagonal or diamond-based:
- In its hexagonal form, ISEA has a higher degree of compactness, quantize the plane with the smallest
average error and provides the greatest angular resolution. -ISEA hexagonal possesses uniform adjacency with its neighbors, unlike the square EASE-Grid.
• Both grids have uniform alignment and are based on a spherical Earth assumption.
• ISEA hexagonal at aperture 4 and resolution 9 (15km) is made up of 2,621,442 points
and the EASE-Grid at 12km has 3,244,518 points.
• EASE-Grid is congruent, whereas ISEA is not congruent, being impossible to decompose
a hexagon into smaller hexagons or aggregate hexagons into larger ones. This would be a
negative feature for real-time re-gridding, but in SMOS the grids will be pre-generated.
6. Geolocalization and Retrieval of Geophysical Parameters
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SMOS: Principles of Operation & First Results
L1 processor L2 processor L3 processor
Auxiliary data
Multi-angular emission models
OS map (1 overpass)
SM map (1 overpass)
Spatio-temporal averaging
Snap-shot 1
Snap-shot 2
Snap-shot 3
Snap-shot 4
• Atmospheric and foreign sources corrections• Use of multiangular information:
1. Th & Tv or Tx and Ty + Faraday and geometric rotations corrections:
Earth Antenna: retrieval in antenna ref frame,Antenna Earth: retrieval in Earth ref frame,
2. First Stokes parameter: I = Tx+Ty=Th+Tv. (invariant to rotations)
ICMARS 2010Jodhpur – India December 16th, 2010 45/47
SMOS: Principles of Operation & First Results
• Sample SMOS data: Pixel in different positions of SMOS swath
OS retrieval:(pin 5)
(pin 3)
ICMARS 2010Jodhpur – India December 16th, 2010 46/47
SMOS: Principles of Operation & First Results
Sample results of the application of the downscaling algorithm to a SMOS image covering the Murrumbidgee catchment, South-Eastern Australia, on January 19, 2010 (6 am). First row: 40 km SMOS soil moisture [m3/m3] over Murrumbidgee (left), and zoom into Yanco site (right). Second row: 1 km downscaled soil moisture [m3/m3] over Murrumbidgee (left), and zoom into Yanco site (right). Dots indicate the location of the soil moisture permanent stations within the Murrumbidgee catchment used for validation purposes with colors representing their measurement at the exact SMOS acquisition time (only within Yanco site). Empty areas in the images correspond to non-retrieved soil moisture or clouds masking MODIS Ts measurements.
60 km
(b) MODIS NDVI [m3/m3]
(c) MODIS LST [m3/m3]
(a) Murrumbidgee catchment
(a) 60 x 60 km Yanco site in the Murrumbidgee catchment, South-Eastern Australia, (b) 1 km MODIS NDVI, and (c) and LST [K] on January 19, 2010.
1 km downscaled SMOS soil moisture [m3/m3] using MODIS VIS/IR data
40 km SMOS soil moisture [m3/m3]
• Sample SMOS data over Australia: Murrumbidge catchement
ICMARS 2010Jodhpur – India December 16th, 2010 47/47
SMOS: Principles of Operation & First Results
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