Status of AMSR2 Level-1 Products(Ver. 2.0)
Japan Aerospace Exploration Agency
Earth Observation Research Center
March 25, 2015
1

Contents
1. L1A and L1B products
2. L1R product3. Intercalibration2

1. L1A and L1B products• Update highlights - Cold load (CSM) correction
No.
Item
1 Correction for increase in CSM
Antenna Temperature due toEarth Radiation from Main
Reflector(6.9 GHz H/V and 7.3 GHz H/V)
2 RFI Removal
3 False RFI detection(10GHz)

4 Average sample number(10GHz V-pol.)5 False RFI detection(18GHz V-pol.)Modification
Error in formula for computing position ofreflected observation data is corrected.

Impact on TB
Negligibly small (<0.03K)

Algorithm details for detection andinterpolation is improved.
Rapid variation in receiver output level due toperiodical thermal change leads to fault RFI
detection. One out of two method for RFI
detection is disabled and parameter used inanother valid method is revised
Number of scans for averaging is changed from21 to 11 in order to mitigate the error due torapid change in receiver output level.
Rapid variation in receiver output level leads
to fault RFI detection in southern high latitude
area. One out of two method for RFI detection
is disabled and parameter used in anothervalid method is revised

Near the area where RFI
happens
3K max. (@10GHz V-pol,noticeable between August
2013 and July 2014)
Less than 0.2K

0.1K max.

• Update Highlights - Hot load (HTS) correction
No.
1 RFI Removal

Item

Modification
Algorithm details for detection andinterpolation is improved.

Impact on TB
Near the area where RFI
happens3• Update highlights - Observation data correctionNo.

Item

1 Scan-bias correction(6.9GHz,7.3GHz, 10GHz)
2 Geometric calibration

Modification
Formula and parameters are revised inorder to resolve residual bias error inhigh TB area
Geolocation parameters are revised byusing long-term data more than oneyears.

Impact on TB
2.5K max.
Only in scan-edge samples.
Geometric accuracy is improved.

• Update highlights - Others
No.
Item
1 Allocation of “ interpolationflag”
2 Addition of RFI flag
(6.9 GHz, 7.3 GHz)
3 L1R weighting coefficients

4 Scan-line number

5 Land ocean flag

ModificationMistake in flag setting is corrected.

Impact on TB

None(Format specification is revised)
Processing to set C-band RFI flag onNone“pixel data quality” is added.
(Format specification is revised)
Only the source antenna patterns which Negligible small when a low frequency
convers a target antenna pattern arechannel is used as a source. ~2K max
selected and synthesized. The smoothing when a high frequency channel (≧36.5
factor is dynamically modified.
GHz) is used as a source.
Since L1R processing always requires
Negligible small. However L1R TB is
calculated as intended at every scan
±30 scans, pre and post extra scans
are extended from 20 to 30. As a result, except the extra ones.
the total scan-line number of L1B/L1R
products increases from 40 to 60.
CAUTION: L1R TBs in the extra scans (pre and post 30 scans) are not calculated
as intended. The pre and post extra scans overlap with the tail of the previous
product and the head of the next product, respectively. Usage of the next orprevious product is recommended instead of the extra scans.
Partial absence (abnormal value) fromNone
Oct.to Nov. in 2013 and from May to Sep.
in 2014. is corrected4

1. L1A and L1B products• Validation results
Tb of version 1.1 vs ∆Tb = Tb of version 2.0 - 1.1
Asc

6G‐V

Dsc

Asc

6G‐H

Dsc

Caused by modification of scan bias correction
Caused by modification of scan bias correction

Asc

7G‐V

Dsc

Asc

7G‐H

Dsc

Caused by modification of scan bias correction

Caused by modification of scan bias correction

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1. L1A and L1B products• Validation results
Tb of version 1.1 vs ∆Tb = Tb of version 2.0 - 1.1
Asc

10G‐V

Dsc

Asc

10G‐H

Dsc

Caused by modification of scan bias correction
Caused by modification of scan bias correction
Caused by modification ofaverage sample number
Caused by modification of false RFI detection
Asc

18G‐V

Dsc

Asc

18G‐H

Dsc

Caused by modification of false RFI detection

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1. L1A and L1B products• Validation results
Tb of version 1.1 vs ∆Tb = Tb of version 2.0 - 1.1
23G‐V

Asc
No diff.

No diff.

Asc

No diff.

36G‐V

Asc

Dsc

Dsc
No diff.

23G‐H

No diff.

No diff.

36G‐H

Asc
No diff.

Dsc

Dsc
No diff.

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1. L1A and L1B products• Validation results
Tb of version 1.1 vs ∆Tb = Tb of version 2.0 - 1.1
89GA‐VAsc

No diff.

No diff.

Asc

No diff.

89GB‐V

Asc

Dsc

Dsc
No diff.

89GA‐HNo diff.

No diff.

89GB‐HAsc
No diff.

Dsc

Dsc
No diff.

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1. L1A and L1B products• Validation results for the geolocation error
35
Freq.
[GHz]

30
6.9
7.3
10
18
23
36
89

25
Reduction of error

[km]

20

Spatial res.

Geolocation err.
(RMSE) Ver1.1

ELELAZELAZ

7.3km
6.9km
5.0km
2.3km
2.4km
1.6km
1.0km

15.6km15.2km10.5km
5.3km
5.6km
4.2km
1.3km

6.3km
5.9km
3.6km
2.0km
2.0km
1.3km
0.9km

3.3km
3.5km
2.5km
1.4km
1.5km Along Track
1.3km
1.0km

AZ

62km 35km
62km 35km
41km 24km
22km 14km
26km 15km
12km 7km
5km 3km

Geolocation err.
(RMSE) Ver2.0

ELevation

15AZimuth

10

Footprint

Scan Direction

50
6.9GHｚ

7.3GHz

10GHz

18GHz

23GHz

36GHz

89GHz‐A

89GHz‐B

92. L1R product• Update highlights
In the new version of the L1R product, logics to calculate weighting
coefficients for antenna pattern synthesis were improved.
– More accurate simulation of AMSR2's antenna patterns in orbit.
– Optimization of the source antenna patterns' distribution covering
the target antenna pattern.
– Individual calculation of weighting coefficients for V and Hchannels.
– Optimization of parameters (smoothing factors) used to calculate
weighting coefficients.

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2. L1R product• Validation results

L1B 6.9H ‐ 10.7H
L1R V2 6.9H ‐ 10.7H (fit to 6.9‐GHz footprints)
If we take the difference between the L1B TB values of two channels (6.9‐ and 10.7‐GHz H in
the below example), striped (blue and red) coastlines appear because their antenna patterns
are not identical.
Meanwhile, if we take the difference between the L1R TB values of these two channels
whose target antenna patterns (6.9 GHz H) are identical, such striped coastlines must notappear. Actually, such striped coastlines do not appear completely in the L1R V2.

112. L1R product• Validation results in version 1.1

L1B 6.9H ‐ 10.7H

L1R V1.1 6.9H ‐ 10.7H (fit to 6.9‐GHz footprints)
Remaining striped coastlines indicate thatthe weighting coefficients do not calculate
correctly.

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2. L1R product
6.9H

L1R Tb Version 1.1 ‐ Version 2.0 in Aug. 201423.8H (fit to 6.9‐GHz footprints)

89H (fit to 89‐GHz footprints)

When a higher frequency channel's antenna
pattern is used as a source, and a lower
frequency channel's antenna pattern is used as atarget, the difference between the L1R Tb
Version 1.1 and Version 2.0 appears up to 2 K.
However, because the weighting coefficients inversion 2.0 are more reasonably calculated, wethink the L1R Tb values in version 2.0 approach
the true value.
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