CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions....
-
Upload
lucinda-stafford -
Category
Documents
-
view
219 -
download
0
Transcript of CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions....
CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.
• ITT INDUSTRIES • AER • BOMEM • BALL • DRS
EDR Algorithms for the Cross-track Infrared Sounder
Xu LiuAtmospheric Environmental research, Inc.
131 HartwellAve, Lexington, Ma 02421
Contact: [email protected]
and
Ronald J. Glumb, Christopher E. Lietzke and Joseph P. PredinaITT Industries, ITT Aerospace/Communications,
1919 West Cook Road, P.O. Box 3700, Fort Wayne, IN 46801, USA
Contact: [email protected]
CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.
• ITT INDUSTRIES • AER • BOMEM • BALL • DRS
2
CrIMSS EDR Products
ATMS
SpacecraftNavigation
Space Segment(Generate RDRs)
Ground Calibration(Generate SDRs)
CrISIR S
cen
esM
icro
wav
e S
cen
es
ATMS
CrIS IR (9 FOVs)
First Guess Profile
CMIS
Mer
ge
SD
Rs
MicrowaveRetrieval
Produce ATMS SDRs
Produce CrIS SDRs
Produce CMIS SDRs
S/C
Sto
re a
nd
Fo
rwar
d
Calibrated and Geolocated Radiances
Ground Science Algorithms(Generate EDRs)
Produce CMIS EDR
High AltitudeTemperature
Mic
row
ave
Sce
nes
CrIS Hardware & Software
Other NPOESS ElementsCrIMSS
EDR Products
SceneClassification
Infrared and MicrowaveRetrieval
CrIS EDR Algorithm
ps (NWP)
Surface Map
Climateology(first guess)
CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.
• ITT INDUSTRIES • AER • BOMEM • BALL • DRS
3
AMSU/MHS Channels Used(ATMS to replace AMSU/MHS)
CrIS EDR Algorithm
Chan #
Central Freq.(GHz)
Side Band (GHz)
Bandwidth (MHz)
Channel Function
0 270 Water Vapor Burden 1 2
23.800 31.400 0 180 Surface Temperature
3 50.300 0 180 Surface Temperature 4 52.800 0 400 Surface Temperature 5 53.596 0.115 170 Tropospheric Temp. 6 54.400 0 400 Tropospheric Temp. 7 54.940 0 400 Tropospheric Temp. 8 55.500 0 330 Tropospheric Temp. 9 57.290 0 330 Stratospheric Temp.
10 57.290 0.217 78 Stratospheric Temp. 11 57.290 0.322 0.048 36 Stratospheric Temp. 12 57.290 0.322 0.022 16 Stratospheric Temp. 13 57.290 0.322 0.010 8 Stratospheric Temp. 14 57.290 0.322 0.0045 3 Stratospheric Temp. 15 89.000 0 6000 Cloud Top and Snow 16 89.000 0.9 1000 Precipitation 17 150.000 0.9 1000 Water Vapor 18 183.310 1 500 Water Vapor 19 183.310 3 1000 Water Vapor 20 183.310 7 2000 Water Vapor
CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.
• ITT INDUSTRIES • AER • BOMEM • BALL • DRS
4
CrIS Channels Used
• Channels Excluded During MW/IR Retrieval– Ozone Band from 950 cm-1 to 1095 cm-1– Trace gas channels– Low information content channels (channel selection)
– Good results using only 400, 300 and 150 channels
• Special High Information Content Channels Used– 709.5 cm-1 to 746 cm-1 for cloud parameter estimation and
Principle Component Analysis (PCA) for estimating number of cloud formations
– 2190 cm-1 to 2250 cm-1 for cloud parameter estimation
Band Frequency Range Resolution (1/2L) # Channels LWIR 650-1095 cm-1 0.625 cm-1 713 MWIR 1210-1750 cm-1 1.25 cm-1 433 SWIR 2155-2550 cm-1 2.5 cm-1 159
Total 1305
CrIS EDR Algorithm
CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.
• ITT INDUSTRIES • AER • BOMEM • BALL • DRS
5
Fast Forward Model
• Optimal Spectral Sampling (OSS)– Developed at Atmospheric Environmental Research (AER)– Fast and accurate (validated against Line-by-line models)– Can model non-localized Instrument Line Shape (ILS)– Computes Jacobian efficiently– Accurate treatment of reflective radiation from surface– Both MW and IR versions developed
CrIS EDR Algorithm
Benchmarked against AIRS fast forward model in 1999………OSS > 20 times fasterOSS > 40 times faster when including Jacobians
Only 20% Speed Penalty when Modeling sinc vs. Blackman-Harris Instrument ILS
CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.
• ITT INDUSTRIES • AER • BOMEM • BALL • DRS
6
Retrieval Methodology (Rogers, 1976)
)(1
1 aiiioyTixi
Tixai xxKyySKSKKSxx
aiiioyTixiy
Tiai xxKyySKSKSKxx
1111
1
CrIS EDR Algorithm
Observed Radiance
Calculated Radiance
Matrix of Partial Derivatives of yi With Respect to x
Retrieved Variable
Error Covariance Matrix of Background Error Covariance
Matrix of Measurement
Background Temp/moisture/
Emissivity/Reflectivity/
etc.
EOF Form Used
GeneralForm Used
EOF Form Has Much Smaller Dimension & Is
Modified to Handle Nonlinear Case
CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.
• ITT INDUSTRIES • AER • BOMEM • BALL • DRS
7
Retrieved Parameters
Parameter # of elementsTemperature 20 EOFsWater vapor 10 EOFs
Ozone 1 (column correction)*Other trace gases Column correction onlySkin Temperature 1
MW Surface Emissivity 5 EOFsMW Cloud Liquid Water 1MW Cloud Top Pressure 1
IR Surface Emissivity 6 hinge pointsIR Surface Reflectivity 6 hinge points
CrIS EDR Algorithm
CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.
• ITT INDUSTRIES • AER • BOMEM • BALL • DRS
8
CrIMSS Retrieval Process (1 of 6)
• Initialization– Load instrument specifications (AMSU, MHS, CrIS
frequencies, Noise, etc.)– Load climatoligical atmospheric data base– Load surface background data base (Mean profiles, error
covariance matrices)– Load OSS parameters (Optical depth tables)– Load solar spectrum– Load topography & land/ocean mask
CrIS EDR Algorithm
Fast Forward Model Parameters Indexed Every 10 Degree of Temperature
GTOPO30 Digital Elevation Map, land/ocean mask
Used for First Guess
CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.
• ITT INDUSTRIES • AER • BOMEM • BALL • DRS
9
CrIMSS Retrieval Process (2 of 6)
• Preprocessing– Test for precipitation– Compute surface pressure from NWP data– Test for surface type
• Land• Ocean• Ice• Snow• Coast: ocean/land• Coast: ice/snow
– Choose Background by Surface type & mix with emissivity information
CrIS EDR Algorithm
Land/ocean maps & MW Brightness Temperature tests @ 31, 50, 89 & 23 GHz
MW Land Emissivity per Grody model (Grody, 1988)
MW Ocean Emissivity per Wilheit model (Wilheit, 1979)
Interpolated in Time and Space
CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.
• ITT INDUSTRIES • AER • BOMEM • BALL • DRS
10
CrIMSS Retrieval Process (3 of 6)
• Microwave Only Retrieval– Average radiances from 9 MHS
FOVs– Execute OSS fast forward model
based upon climatology first guess
– Perform inversion & update first guess profile
– Calculate new radiances using OSS
– Test for convergence– Continue iteration if convergence
criteria not met
CrIS EDR Algorithm
CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.
• ITT INDUSTRIES • AER • BOMEM • BALL • DRS
11
CrIMSS Retrieval Process (4 of 6)CrIS EDR Algorithm
• Scene Classification– Purpose
• Maximize # of good retrievals within a field of regard (FOR)
• Optimize an FOV clustering strategy for treatment of clouds and use of cloud clearing algorithm
– Method• Form matrix of 9 FOVs by 62 IR
channels in the spectral region from 709 to 748 cm-1
• Analyze for up to 9 principle components
• Determine number of cloud formations present from PCA analysis & 2 statistical tests
• Cluster minimum number of FOVs needed to perform cloud clearing
3 2 1
6 5 4
9 8 7
3 principle components indicating 2 cloud
formations
Example of PCA Analysis
CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.
• ITT INDUSTRIES • AER • BOMEM • BALL • DRS
12
CrIMSS Retrieval Process (5 of 6)
C C flag
C a lcula te C C Radiance
Perform Phys ica l Invers ion
Update geophys ica l param etersC a lcula te new Radiance
A ll C lus tersProcessed?
Q ua li ty C ontrol
T rue
Yes
C a lcula te C lear Radiance es tim ate from M W Retr ieva l or NW P Profi le
C onvergence? M ax Ite ra tions?
A verage F O V 's w ith inc lus te r
Yes
F a lse
No
NextC lus ter
No
CrIS EDR Algorithm
• Combined MW/IR Retrieval– Uses MW retrieval as first
guess (profiles, surface, cloud parameters)
– Modified Maximum Likelihood Method for nonlinear retrieval
– Dynamically adjust channel weights to improve convergence and stability
– Cloud clearing parameter estimated each iteration
– FOVs averaged above 80 mbar– Test for convergence– Continue iterations if
convergence criteria not met
CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.
• ITT INDUSTRIES • AER • BOMEM • BALL • DRS
13
CrIMSS Retrieval Process (6 of 6)
• Quality Control– If normalized 2 > 1.0 for
the retrieval, then retrieval is not reported
– If MW radiances after MW/IR retrieval differ by more than 3 K from observed radiances, then entire retrieval rejected
– If MW retrieval and MW/IR retrieval differ by more than 3 K, then the MW/IR retrieval is rejected
– If difference between cloud cleared CrIMSS radiances and VIIRS cloud free radiance is greater than 2 k, then retrieval is suspect
CrIS EDR Algorithm
nchanN
nchan
i i
obseri
retri
1
22 )(
R e t r i e v e d B r i g h t n e s s T e m p e r a t u r e i n
i t h C h a n n e l
N u m b e r o f S p e c t r a l C h a n n e l s ( o r s u p e r c h a n n e l s )
U s e d i n R e t r i e v a l
O b s e r v e d B r i g h t n e s s T e m p e r a t u r e i n
i t h C h a n n e l
S t o p I f• < 0 . 7• < 1 0 % c h a n g e b e t w e e n i t e r a t i o n s• # i t e r a t i o n s = 4
N o i s e V a r i a n c e f o r i t h C h a n n e l
nlev
IRMWTMWTnlev
iii
1
2))/()((
M i c r o w a v e R e t r i e v e d B r i g h t n e s s
T e m p e r a t u r e @ L e v e l i
C o m b i n e d M i c r o w a v e / I RR e t r i e v e d B r i g h t n e s s
T e m p e r a t u r e @ L e v e l i
N u m b e r o f R e t r i e v e d L e v e l s B e l o w 3 k m A l t i t u d e
I f > 3 K R e j e c t
M W / I R R e t r i e v a l
CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.
• ITT INDUSTRIES • AER • BOMEM • BALL • DRS
14
Performance for Various Levels of Channel SelectionCrIS EDR Algorithm
CrIS Use or disclosure of data contained on this sheet is subject to NPOESS Program restrictions.
• ITT INDUSTRIES • AER • BOMEM • BALL • DRS
15
CrIMSS Projected Performance
0
5
10
15
20
25
30
0.0 0.5 1.0
Retrieved Pressure Accuracy (%)
Alt
itu
de
(k
m)
1
10
100
10000 0.5 1 1.5
Retrieved Temperature Error (K, rms)
Alt
itu
de
(m
ba
r)
100
1000
Retrieved Moisture Error (%, rms)
500Alt
itu
de
(m
ba
r)
0 5 10 15 20 25
“Threshold”Performance
CrIS EDR Algorithm
Based on Global Average