AMSR-E Science meeting 03/June/2010
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Mitsubishi Space Software CO.,LTD.
RFI in the radiometric calibration data
Yuji Taniguchi (Mitsubishi Space Software Co.,Ltd.)
Akira Shibata ( Japan Aerospace Exploration Agency)
AMSR-E Science meeting, 03/June/2010, Huntsville
DD8040-10-AMSR001
AMSR-E Science meeting 03/June/2010
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Mitsubishi Space Software CO.,LTD.
Increase of irregular count value of AMSR-E calibration sources; Cold Sky Mirror Count and Hot Load Count.Radio-Frequency interference(RFI) might cause the increment.
1. Preface
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2. Influence of RFI to calibration sources
Irregular points detection using standard deviation.Convert the calibration source count to the voltage.Calculate standard deviation using 8 points in the scan azimuth direction, 11 lines in the along track direction. Easier to detect anomaly.
alongtrack
direction
scan azimuth direction
11scan
8 points near the center
2.4
2.45
2.5
2.55
2.6
2.65
1 201 401 601 801 1001 1201 1401 1601 1801走査番号
[mV]
電圧
値
0
0.05
0.1
0.15
0.2
標準
偏差
CSM 平均値標準偏差
1/Nov/2008 Path146 Descending6.9GHz Cold Sky Mirror Count
Standard deviation
CSM Count
Unusual rises are detected
Voltage [m
V]
Standard deviation [m
V]
Scan Number
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2 Influence of RFI to calibration sources ( Time series )Occurrence timing of RFIInvestigate level 1 products observed from June 2002 to December 2009.Plot the maximum standard deviation for each products as shown below
200736.5GHz V-pol.
AscendingCold Sky Mirror
Reflection of the moonThis effect is already known.We neglected it and focus on the other anomalies.
Standard deviation [m
V]
Date( 1 year)
1 /Jan. 3 1 /Dec.
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6.9GHz
- Cold Sky Mirror Count -
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Ascending Descending
2002
2003
2004
2005
2006
2007
2008
2009
2002
2003
2004
2005
2006
2007
2008
2009
2.1 Influence of RFI to calibration sources ( Time series ) Cold Sky Mirror Count 6.9GHz V-pol (x-axis : date )
The RFI has always occurred.Where do these occur?
We estimated the sub-satellite point.
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6.9GHz Vpol Descending 6.9GHz Hpol Descending
6.9GHz Vpol Ascending 6.9GHz Hpol AscendingYearly Maximum value of standard deviation(2008)
2.1 Specify the area of interference source Cold Sky Mirror Count 6.9GHz
・ RFI occurs in the specific land areas.
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-1770
-1760
-1750
-1740
-1730
-1720
-1710
-1700
-1690
1 201 401 601 801 1001 1201 1401 1601 1801Scan Number
Cold
Sky M
irror
Coun
t (av
erag
e)
CSM 06V45Count≒4.5K
18/Aug./2003 Path 185 Descending
This effect is removedat the Level 1B brightness temperature.
Europe
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10.7GHz
- Cold Sky Mirror Count -
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Ascending Descending
2002
2003
2004
2005
2006
2007
2008
2009
2002
2003
2004
2005
2006
2007
2008
2009
Since July 2007
2.2 Influence of RFI to calibration sources ( Time series ) Cold Sky Mirror Count 10.7GHz V-pol (x-axis : date )
Unusual rises
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10.7GHz Vpol Ascending 10.7GHz Hpol AscendingYearly Maximum value of standard deviation(2007)
10.7GHz Vpol Descending 10.7GHz Hpol Descending
2.2 Specify the area of interference source Cold Sky Mirror Count 10.7GH z
RFI was detected in the East Coast(U.S.) sometime West Coast(U.S.) Europe
Since July 2007
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-420
-415
-410
-405
-400
-395
-390
-385
-380
1 201 401 601 801 1001 1201 1401 1601 1801Scan Number
Cold
Sky M
irror
Cou
nt(av
erag
e)
CSM 10V
6Count≒2.4K
02/Dec./2008 Path 91 Ascending
U.S. East Coast This effect is removedat the Level 1B brightness temperature.
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18.7GHz
- Cold Sky Mirror Count -
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Ascending Descending
2002
2003
2004
2005
2006
2007
2008
2009
2002
2003
2004
2005
2006
2007
2008
2009
Since September 2007
2.3 Influence of RFI to calibration sources ( Time series ) Cold Sky Mirror Count 18.7GHz V-pol (x-axis : date )
Reflection of the moon
Unusual rises
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18.7GHz Vpol Descending 18.7GHz Hpol Descending
18.7GHz Vpol Ascending 18.7GHz Hpol AscendingMonthly Maximum value of standard deviation(Feb./2008)
2.3 Specify the area of interference source Cold Sky Mirror Count 18.7GH z
RFI was detected the specific area:・ The north side of the Hawaii・ Near the Antarctic Peninsula
Reflection of the moonReflection of the moon
Since Feb. 2008.
Since Sep. 2007.
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-392
-390
-388
-386
-384
-382
-380
1 201 401 601 801 1001 1201 1401 1601 1801Scan Number
CSM
18V
- 416
-415
-414
-413
-412
-411
-410
CSM
18H
CSM 18VCSM 18H
6Count≒2.4K2Count≒0.8K
2Count≒0.8K
07/Oct./2009 Path 167 Ascending
The north side of the HawaiiThis effect is not removedat the Level 1B brightness temperature.
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6.9GHz
- Hot Load Count-
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Ascending Descending
2002
2003
2004
2005
2006
2007
2008
2009
2002
2003
2004
2005
2006
2007
2008
2009
2.1 Influence of RFI to calibration sources ( Time series ) Hot Load Count 6.9GHz V-pol (x-axis : date )
The RFI has always occurred.
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6.9GHz Vpol Descending 6.9GHz Hpol Descending
6.9GHz Vpol Ascending 6.9GHz Hpol AscendingYearly Maximum value of standard deviation(2008)
2.2 Specify the area of interference source Hot Load Count 6.9GHz
RFI was detected the specific area: Europe China(East) U.S
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1360
1380
1400
1420
1440
1460
1480
1500
1520
1 201 401 601 801 1001 1201 1401 1601 1801Scan Number
Hot L
oac C
ount
(aver
age)
06V06H
18Count≒1.8K12Count≒1.2K
16/May/2008 Path 35 Ascending
This effect is not removedat the Level 1B brightness temperature.
Europe
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10.7GHz
- Hot Load Count -
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Ascending Descending
2002
2003
2004
2005
2006
2007
2008
2009
2002
2003
2004
2005
2006
2007
2008
2009
2.1 Influence of RFI to calibration sources ( Time series ) Hot Load Count 10.7GHz V-pol (x-axis : date )
The RFI has often occurred.
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10.7GHz Hpol Descending
10.7GHz Hpol Ascending
2.2 Specify the area of interference source Hot Load Count 10.7GHz
10.7GHz Vpol Descending
10.7GHz Vpol AscendingYearly Maximum value of standard deviation(2005)
RFI was detected the specific area: Europe West Coast(U.S.)
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310
315
320
325
330
335
340
345
350
355
360
1 201 401 601 801 1001 1201 1401 1601 1801Scan Number
Hot L
oad C
ount
10V(
aver
age)
320
325
330
335
340
345
350
355
360
Hot L
oad C
ount
10H(
aver
age)
10V10H
19/Oct./2005 Path 15 Ascending
2count≒0.8K
8Count≒3.2K
This effect is not removedat the Level 1B brightness temperature.
Europe
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18.7GHz
- Hot Load Count -
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Ascending Descending
2002
2003
2004
2005
2006
2007
2008
2009
2002
2003
2004
2005
2006
2007
2008
2009
2.1 Influence of RFI to calibration sources ( Time series ) Hot Load Count 18.7GHz V-pol (x-axis : date )
The RFI has few occurred.
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18.7GHz Vpol Descending 18.7GHz Hpol Descending
18.7GHz Vpol Ascending 18.7GHz Hpol AscendingYearly Maximum value of standard deviation(2004)
2.2 Specify the area of interference source Hot Load Count 18.7GHz
RFI was detected the specific area: East Coast(U.S.)
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315
320
325
330
335
340
345
350
355
1 201 401 601 801 1001 1201 1401 1601 1801Scan Number
Hot L
oad C
ount
18V(
aver
age)
340
345
350
355
360
365
370
375
380
Hot L
oad C
ount
18H(
aver
age)
18V18H7Count≒2.8K
8Count≒3.2K
27/Jan./2004 Path 110 Ascending
This effect is not removedat the Level 1B brightness temperature.
East Coast(U.S.)
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RFI has occurred almost in the same position.These sources are possibly the communication between the ground and the geostationary satellites.
2.2 Specify the area of interference source
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We examined 6.9GH z Cold Sky Mirror Count more in detail.Change the scale factor to emphasize the anomalies as shown below:
Monthly MAP (March 2009 Descending)
3 RFI from LEO’s
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A very small amount of RFI occurs. Monthly MAP (March 2009 Descending)
3 RFI from LEO’s
Scale Change
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To investigate the relationship between observation date and RFI generation, we made images of standard deviation of Cold Sky Mirror shown like below:
3 RFI from LEO’s
Periodic cycle
Standard deviation
0.00
0.01
11/Apr/2011Path 189
26/Apr/2011Path 173
North Pol.
South Pol.
time series
This RFI occurs periodic cycle with time.
alongtrack
direction
Focus on
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3 RFI from LEO’s
6Path6Path6Path6Path6Path6Path
(No.1)
(No.2)
(No.3)
(No.4)
(No.5)
(No.6)(No.7) RFI occurred each 6 orbit
cycle.
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-1780
-1770
-1760
-1750
-1740
-1730
1 201 401 601 801 1001 1201 1401 1601 1801Scan Number
Cold
Sky M
irror
Cou
nt(av
erag
e)
06V06H
15Count≒1.5K
15Count≒1.5K
13/Apr./2010 Path 219 Descending
RFI effect (No.2)
We identified the locations of each RFI occurrence which will be shown the following slides.
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Site of RFI occurrence(No.1)
12/Apr.P123
3 RFI from LEO’s Sites of RFI occurrence
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Site of RFI occurrence(No.2)
13/Apr.P219
12/Apr.P123
3 RFI from LEO’s Sites of RFI occurrence
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Site of RFI occurrence(No.3)
13/Apr.P219
12/Apr.P123
13/Apr.P082
3 RFI from LEO’s Sites of RFI occurrence
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Site of RFI occurrence(No.4)
13/Apr.P219
12/Apr.P123
13/Apr.P082
13/Apr.P178
3 RFI from LEO’s Sites of RFI occurrence
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Site of RFI occurrence(No.5)
13/Apr.P219
12/Apr.P123
13/Apr.P082
13/Apr.P178
14/Apr.P041
3 RFI from LEO’s Sites of RFI occurrence
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Site of RFI occurrence(No.6)
13/Apr.P219
12/Apr.P123
13/Apr.P082
13/Apr.P178
14/Apr.P041
14/Apr.P137
3 RFI from LEO’s Sites of RFI occurrence
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13/Apr.P219
12/Apr.P123
13/Apr.P082
13/Apr.P178
14/Apr.P041
14/Apr.P137
15/Apr.P233
Area of RFI sites are move The cause of RFI is not the communications between the geostationary satellites and the ground. Periodic cycle Effect of LEOs?
Site of RFI occurrence(No.7)
3 RFI from LEO’s Sites of RFI occurrence
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Ocean products retrieved from 6.9GHz, such as SST and SSW, are damaged seriously by RFI.(Sep.2005 Yoshikawa@MSS)
This RFI source is the Globalstar downlink beam.
3 RFI from LEO’s Which satellite is the source of RFI?
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6.9GHz RFI in Cold Sky Mirror
Globalstar
1400km112min
Aqua/AMSR-E
705km100min
CSM Viewingfield
Beacon(6.85GHz)
We think that the satellite electric wave mixed with the view of Cold Sky Mirror.Globalstar send out beacon of 6.85GHz.We investigated the positional relation between Globalstar and Aqua.
3 RFI from LEO’s Which satellite is the source of RFI?
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Focus on GLOBALSTAR 54
AQUA
Site of RFI occurrence(No.1) 12/April/2010 18:46:10
12/Apr.P123
3 RFI from LEO’s Positional relation between Aqua and Globalstar
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GLOBALSTAR 54
AQUA
Site of RFI occurrence(No.1) 12/April/2010 18:46:10
12/Apr.P123
3 RFI from LEO’s Positional relation between Aqua and Globalstar
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GLOBALSTAR 54
Site of RFI occurrence(No.2) 13/April/2010 04:37:48
15/Apr.P233
3 RFI from LEO’s Positional relation between Aqua and Globalstar
AQUA
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GLOBALSTAR 54
Site of RFI occurrence(No.3) 13/April/2010 14:29:33
13/Apr.P082
3 RFI from LEO’s Positional relation between Aqua and Globalstar
AQUA
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GLOBALSTAR 54
Site of RFI occurrence(No.4) 14/April/2010 00:21:01
13/Apr.P178
3 RFI from LEO’s Positional relation between Aqua and Globalstar
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GLOBALSTAR 54
Site of RFI occurrence(No.5) 14/April/2010 10:12:41
14/Apr.P041
3 RFI from LEO’s Positional relation between Aqua and Globalstar
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GLOBALSTAR 54
Site of RFI occurrence(No.6) 14/April/2010 20:04:15
14/Apr.P137
3 RFI from LEO’s Positional relation between Aqua and Globalstar
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GLOBALSTAR 54
Site of RFI occurrence(No.7) 15/April/2010 05:55:55
15/Apr.P233
3 RFI from LEO’s Positional relation between Aqua and Globalstar
Positional relations between Globalstar54 and Aqua are the same in all cases.
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RFI from the specific areasRFI has occurred the radiometric calibration sources in 6.9GHz,10.7GHz and 18.7GHz.The source is possibly the communication between the ground and the geostationary satellites.
RFI from LEOIn the Cold Sky Mirror Count of 6.9GHz, RFI occurs periodic cycle, which are probably caused by Globalstar.
4.Summary
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Influence of RFI to Cold Sky Mirror •6.9GHz, the RFI has always occurred.•10.7GHz, the RFI has occurred at ascending products since Jun. 2007. •18.7GHz, the RFI has occurred at ascending products since Sep. 2007. And, the RFI has occurred at descending products since Feb. 2008.
Periodical change of RFI?Where do these occur?
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Reflection of the moon
alongtrack
direction
6.9GHz10.7GHz18.7GHz23.6GHz36.5GHz 89.0GHz
V H V H V H V H V H V H V HAhorn Bhorn
Cold Sky Mirror Count
little
big
Cold Sky Mirror Count
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2.2 Specify the area of interference source
lat. and lon. ofthe ground observation position
lat. and lon. ofthe sub-satellite position
satellite
About 3min.120scan
To locate the source of RFI, we estimated the latitude and longitude of the sub-satellite points from the ground observation points.Distances between the ground observation points and the sub-satellite points are nearly equivalent to 120 lines which corresponds to 3 minutes.We estimated the sub-satellite position using the above relationship and equidistant cylindrical projection to calculate standard deviations.
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-424
-422
-420
-418
-416
-414
-412
1 201 401 601 801 1001 1201 1401 1601 1801Scan Number
CSM
18V
- 435.0
-434.5
-434.0
-433.5
-433.0
-432.5
-432.0
-431.5
-431.0
CSM
18H
CSM 18VCSM 18H
0.6Count≒0.24K
1.3Count≒0.5K
13/Jun./2009 Path 219 Descending
Near the Antarctic Peninsula This effect is not removedat the Level 1B brightness temperature.
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Ascending Descending
2002
2003
2004
2005
2006
2007
2008
2009
2002
2003
2004
2005
2006
2007
2008
2009
Since September 2007
Since February 2008
2.1 Influence of calibration sources ( Time series ) Cold Sky Mirror Count 18.7GHz H-pol (x-axis : date )
Unusual rises
Unusual rises
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1 scene
Observation date
Plot the standard deviation
To investigate the relationship between observation date and RFI generation, we made images of standard deviation of Cold Sky Mirror shown like below:
3 RFI from LEO’s
North Pol.
South Pol.
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11/AprPath 189
26/AprPath 173
North Pol.
South Pol.0.00
0.01
Standard deviation
6.9GHz VpolDescending
standard deviation
3 RFI from LEO’s
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