tasks performed at star
DESCRIPTION
SNO CrIS Validation. CRTM Validation. - PowerPoint PPT PresentationTRANSCRIPT
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Metop-B Bias Metop-B Std
Channel
Erro
r(K)
Metop-B HIRS instrument On-orbit status and performance
Chengli Qi1 ([email protected]), Changyong Cao2([email protected]), Tiejun Chang3([email protected]), Fuzhong Weng2([email protected]),
1 UMD/ESSIC/CICS ,2 NOAA/NESDIS/STAR, 3 Earth Resource Technology, Inc
Metop-B launched on Sep, 2012, verification of instrument performance is an essential
step before the L1 data distributed operationally. Verification performance including:
BlackBody temperature, channel noises, radiance data assessment, Geo-location evaluation,
ICVS trending, et al. NEdN of all IR channels and NEdA of VIS channel meet specification.
HIRS L1B data are evaluated with CRTM model simulation and NPP/CrIS observation and
reached coincident conclusion, biases are within 1K for all IR channels except ch1 and ch16.
Trend of instruments parameters and NEdN also discussed.
Tasks Performed at STAR
Task Name Description Status1. Blackbody temperature measurement
Verify BB temperature PRT measurement and its variation
Completed
2. Dark current restore Verify the post-launch space view data in a reasonable range
Completed
3. IR channel instrument noise
Compute count standard deviation and convert to NEdN. Calculate dynamic range.
Completed
4. VIS channel instrument noise and dynamic range
Compute count standard deviation and convert to NEdA. Calculate dynamic range.
Completed
5. Calibration slope Verify that post-launch slope is consistent with pre-launch and is stable
Completed
6. Calibration intercept Evaluate the intercept and verify it is in reasonable range.
Completed
7. Measurement assessment by CRTM
Difference between observation and simulation
Completed
8. Inter-sensor comparison Compare HIRS with IASI or CrIS Completed
9. Visible channel measurement assessment
Using desert as reference. Completed
10. Geo-location evaluation Evaluate the geo-location of the images Completed11. Instrument temperature trending and monitoring
Verify the instrument temperature, filter wheel housing temperature
Completed
12. Coherent noise Verify any noise at fixed frequency Completed
13. Stray Light Evaluate the stray light on blackbody Completed
Orbital variation of BB temperature is in reasonable range of 2~3K, temperature variation std between 5 PRTs within 0.006~0.117K.
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mW
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On-orbit
Pre-launch
Specification
0.0000.001
0.0020.0030.004
0.0050.006
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Channel
mW
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sr.c
m-1
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On-orbitPre-launchSpecification
Noise in all 19 infrared channels meet specification except ch14 which is near the specification. On-orbit NEdN for all infrared channels are slightly larger than pre-launch test results.
Instrument performance and temperature trending and monitoring
(http://www.star.nesdis.noaa.gov/icvs/M1/ipm_telemetry_m1_hirx.php)
Metop-B/HIRS ICVS system aim to monitoring of important instrument performance and status,
includes NEΔN, slope, blackbody and cold space view counts which can reveal the measurement
quality and calibration accuracy as well as stability. Temperature of instrument components is also
monitored which can reflect the instrument healthy and telemetry status.
Metop-B/HIRS NEdN of long-wave channels 1 to 7 displayed upward trend since launch and channel
5,6,7 NEdN out of specification after Jan, 2013. Also there is an upward trend for filter wheel housing
temperature and filter wheel motor temperature which went up by about 1K and 0.5K respectively . By
comparison, the temperature changes for the filter wheel housing and motor of MetOp-A HIRS are
within 0.2K in the past 4 months.
0 2 4 6 8 10 12 14 16 18 20-1.5
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Metop-A Bias Metop-B Bias Metop-A Std
Metop-B Std
Channel
Erro
r(K)
1) The std error characteristics of HIRS onboard Metop-A and B are very close, std error of Metop-B is slightly less than Metop-A.2) Bias of Metop-A/HIRS are within 0.5K for all 19 infrared channels, that of Metop-B/HIRS are within 1K for all 19 channels except channel 1 and 16 that are with bias of out of 1.5K.
CRTM ValidationSNO CrIS Validation
The error characteristics for two Methods agreed , bias of channel 1 is about 2K, bias of channel 16 is about 1.5K for SNO method and 2.5K for model Validation, and within 1K for all other channels.
AzenithSolarBzenithSolarAzenithSensorBzenithSensorA
B
A
B qpRR
________ ''
1.184 0.00238 0.009542A
B
'p 'q
Solar zenith B>A
Solar zenith B<A
After Solar zenith angle correction
Model from AVHRR Team
Visible channel measurement assessment
Resync noise observed in the ch1 period monitor data
Noise pattern similar to prelaunch test results.
Analysis of BB radiance versus detector output delta count(count minus mean space count) shows smooth variation curse, verified no obvious stray light.
Using Blackbody view orbit data (19 Oct, 09:56Z) to analyse stray light, channel delta counts changed consistently with BB temperature, verified there is no evident signal of stray light.
NEdN
A
B
RR
A
B
: Ch20 Albedo ratio of Metop-B to A : Ch20 Albedo ratio of Metop-B to A after
Correction of solar and sensor zenith angle