Transcript GOSAT Calibration Activities in 2 Years Japan Aerospace Exploration Agency 10th GSICS Executive Panel - Global Space-based Inter-Calibration System, 10th Session of.

GOSAT Calibration Activities in 2 Years
Japan Aerospace Exploration Agency
10th GSICS Executive Panel - Global Space-based Inter-Calibration System, 10th Session of the Executive Panel
WMO, Geneva, Room: 8 JURA (8th Floor), 6 to 8 June 2011
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Introduction of GOSAT Mission
 GOSAT is
 Greenhouse gases Observing SATellite.
 Monitoring global distribution of Greenhouse
Gases from space
 Target for Carbon dioxide and Methane
 at 100-1000km spatial scale
 with relative accuracy of 1% (4ppm) for CO2
and 2% (34ppb) for CH4
 Joint project by
 JAXA (Japan Aerospace Exploration
Agency),
 NIES (National Institute for Environmental
Studies)
 MOE (Ministry of the Environment)
 Launch: 23 January 2009 by H2A launch vehicle
 Mission lifetime: 5 years to 2014
GOSAT full-scale model
GOSAT(Aichi,
satellite
at EXPO2005
Japan)at
the launch
2
site of Tanegashima
Size
Main
body
3.7 m x 1.8 m x 2.0 m
（Wing Span 13.7m）
Mass
Total
1750kg
Power
Total
3.8 KW (EOL)
Life Time
5 years
Orbit
sun synchronous orbit
Local time
Launch
13:00+/-0:15
Altitude
666km
Inclination
98deg
Repeat
3 days
Vehicle
H-IIA
Schedule
GOSAT Satellite and Sensors
TANSO=Thermal And Near
infrared Sensor for carbon
Observation
Jan. 23 2009
TANSO-FTS
(Fourier Transform Spectrometer)
TANSO-CAI
(Cloud and Aerosol Imager)
TANSO-FTS Spectral Coverage
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TANSO-FTS Specification
Ground Pointing Configuration
Mechanism and
Fore optics
Pointing
Fourier
Transform
Spectrometer
2-axes pointing mirror (fully redundant) for ground
pointing, calibration and IMC
Cross Track (+/-35 deg）
Along Track (+/-20 deg)
Field of view
IFOV =10.5 km
FOV=790 km (scan width) (latitude of 30 deg)
Speed
4, 2, 1.1 sec/ 1 Interferogram
Spectral ch
1P, 1S
2P, 2S
3P, 3S
4
0.75-0.78
1.56-1.72
1.92-2.08
5.5-14.3
Target gas
O2
CO2, CH4
CO2
CO2, CH4, O3
Resolution[cm-1]
0.2
0.2
0.2
0.2
Detector
Si
InGaAs
InGaAs
PC-MCT
Obs. Band[mm]
Calibration
Solar Irradiance, Deep Space, Moon,
Diode Laser (1.55 micron, ILS)
Blackbody,
Deep space
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TANSO-CAI Cloud and Aerosol Image
The plume of erupting Grimsvotn volcano in Iceland
May 22, 2011, at 15:09
R=678nm(Band2)
G=870nm(Band3)
B=380nm(Band1)
UV channel of 380nm is
useful for aerosol
detection colored in
yellow.
http://www.gosat.nies.go.jp/eng/related/2011/201105.htm
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TANSO-CAI Specifications
TANSO-CAI is operated together with TANSO-FTS to
- detect aerosol spatial distribution and
- cloud coverage
Band
Observation
Band (nm)
Center
Wavelength (nm)
IFOV
(km)
FOV
(km)
Num. of Pixels
(cross track)
1
372-387
380
0.5
1000
2000
2
667-680
678
0.5
1000
2000
3
866-877
870
0.5
1000
2000
4
1560-1640
1620
1.5
750
500
Onboard calibration:
Lunar calibration (/year), Nighttime observation (/month)
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TANSO operation with FTS and CAI
The GOSAT is in normal operation from April 2009 over 2 years. The CAI observation
swath covers the FTS observation points for cloud screening and aerosol correction.
Target observation
Grid observation
Sunglint observation
FTS observation pattern with CAI browse image on Jun. 5, 2010 in dayside
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GOSAT Data Processing
JAXA ->
Sensor,
Level1,
Calibration
L1A
L1B
L2 (column abundance
obtained by each scan)
L4B
L4A
NIES ->
Level2, 3, 4,
Validation
L3 (spatial and temporal
average of column
abundances)
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GOSAT Mission Schedule
2009
12
1
Jan. 23
Launch
2014
2010
2
3
4
5
6
Initial
Checkout
8
9
10 11
12
1
2
1
2
3 ～
Mission life
Initial
Initial Cal.
function
and Val.
check
Critical
phase
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Normal observation
operation
Extra
Operati
on
～
Level 1 (Observation spectra) to public
Level 2 (SWIR CO2 and CH4 of column averaged
density global distribution) to public
Nov. 2010
Level 3 (SWIR CO2 and CH4 column averaged density global
distribution in monthly mean) to public
May 2011
Level2 (TIR CO2 and CH4 density profile global distribution) to RA PI
mid -2011
Level 4A (CO2 and CH4 flux in 64 global regions)
Level 4B (CO2 and CH4 global distribution by 3D model) to RA PI
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GOSAT L2 and L3 Products
(FTS SWIR XCO2, XCH4, CAI Rmin)
XCO2 Apr 2009
XCO2 Jul 2009
CAI Rmin Jun 2009
XCO2 Oct 2009
XCO2 Jan 2010
XCH4 Apr 2009
XCH4 Jul 2009
XCH4 Oct 2009
XCH4 Jan 2010
CAI Rmin Dec 2009
http://www.gosat.nies.go.jp/index_e.html
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CAI Radiometric Accuracy
Initial calibration without zero-level correction
Land,
Clear-sky
Ocean,
Clear-sky
B1
B2
○
B3
○
B4
○
Ocean,
Cloud
L+9M calibration with zero-level correction
Hawaii
ocean
Land,
Clear-sky
Ocean,
Clear-sky
Ocean,
Cloud
○
B1
○
B2
○
○
○
B3
○
○
○
○
Hawaii
ocean
○
○
B4
B2, B3, B4 calibration
○
○
B1 relative to B3
Results
Vicarious calibrated radiance = slope*(radiance after zero-level correction) + offset
Vicarious calibration coefficient
B2, B3
・Ocean, Cloud
・Land, Clear-sky
・Ocean, Clear-sky
Combined calibration
slope
offset
B1
1.138
0.000
B2
0.946
-1.372
B3
1.033
-0.189
B4
1.144
0.000
Results by CAI calibration team
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CAI Radiometric Sensitivity Trend
at Desert Sites
Comparison with MODIS reflectance
Sahara and Rub Al Khali
desert sites
CAI annual trends Jun.-Dec. at Sahara_6
Annual trend
at 9 sites
Ref2010/Ref2009
Annual change
Band1
Band2
Band3
Band4
mean stdev mean stdev mean stdev mean stdev
0.984 0.028 0.960 0.020 0.988 0.017 0.989 0.014
-1.6%
-4.0%
-1.2%
-1.1%
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FTS-SWIR Radiometric Sensitivity
Trend at Desert Sites
Annual trend
Band 1 degradation is estimated in 2 %. No degradations in Band 2 and 3.
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Vicarious Calibration at Railroad Valley
•
Railroad Valley field
- Nevada/USA
– Base-camp: 38.49703 N;
115.69013 W
– Height : about 1435m
0
path37
path36
10 km
©JAXA
ALOS/AVNIR-2 (R/G/B=3/2/1)
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RRV Field Experiments Deployment
Path 37 33.0deg
from West
25deg
19deg
19.9deg
TOA Spectral radiance
Aerosol Optical
Thickness
Surface
CO2 CH4
BRDF
Surface Spectral
Reflectance
Path 36
from East
Surface and Profile
of Pressure, Temperature,16
Humidity
Summary of Radiometric Calibrations
for FTS-SWIR and CAI in 2010
Vicarious
calibration
(vs. pre-launch
calibration)
June 23-July 4,
2009
June 21-22
2010
June 2009
Solar diffuser
plate (back side) June 2010
(vs. onboard
initial calibration)
Sahara
2009-2010
Days
from the
launch
TANSO-FTS
CAI
B1
B2
B3
B1
B2
B3
B4
160
-11±7%
-3±7%
-4±7%
-17%
+4%
0%
-18%
520
-14±7%
-2±5%
-6±5%
-21%
-4%
-4%
-20%
160
-2.7%
-0.9%
-0.4%
N/A
N/A
N/A
N/A
520
-5.1%
-1.6
-0.5%
N/A
N/A
N/A
N/A
-2%
0%
0%
-1.6%
-4.0%
-1.2%
-1.1%
April-September
June-Sep
RRV: Absolute
Solar diffuser plate: relative (monitoring change with time)
Sahara Data: relative (monitoring change with time)
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IASI-GOSAT Simultaneous Nadir
Overpasses
Spectral range
Spectral resolution
Local time
FOV
Spacing interval
Launch
TANSO-FTS/GOSAT
5.5-14.3 micron
0.2 cm-1
13:00 Descending
10 km
150-270 km
22 Jan. 2009
IASI/METOP-A
3.62-15.5 micron
0.35-0.5 cm-1
09:30 Descending
12 km
65 km
19 Oct. 2006
Time:
+/- 20 min
Location: +/- 50 km
Coincidence is restricted to +/- 80.6 deg.
Match-ups are 65 cases in 3 days.
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FTS-TIR Correction Derived from
IASI SNOs
Deep space obscuration correction rate is estimated from IASI-GOSAT SNOs.
680-720cm-1
720-1000cm-1
1000-1080cm-1
1080-1240cm-1
1240-1350cm-1
• Significant improvement is confirmed in the 15 micron CO2 region.
• Coincidences with IASI are located at high latitude, while AIRS at low-middle latitude.
Collaboration with Univ. Wisconsin
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Conclusions
 GOSAT is normally operated over 2 years and acquires fine
absorption spectra in SWIR to TIR regions with cloud/aerosol imager.
 Radiometric calibration on orbit in 2 years
 MODIS reflectance for absolute radiance of SWIR and CAI
 Inter-comparison attempt with other TIR sensors of IASI
 Vicarious calibration field campaign with in-situ measurements
and aircraft over-flight collaborated with NASA OCO-2 research
 Annual degradation monitoring at uniform desert sites
 On-going activities
 Long-term inter-comparison with IASI and AIRS (collaboration with
CNES and RA PIs)
 Long-term trend monitoring at uniform desert sites
 Continuous operations of lunar calibration and solar diffuser
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