Task Status Updates and Calibration Approaches for MIT Lincoln Laboratory Projects
Explore the progress and methodologies for various tasks including interferometer optimization, calibration approaches, and analysis of small differences between SDR and RDR in projects conducted at MIT Lincoln Laboratory. Detailed completion percentages, objectives, and descriptions are discussed, providing insights into ongoing research and development efforts.
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MIT/LL Cal/Val tasks status Oct 23 2012 Daniel L. Mooney SOUMI NPP SDR Product Review October 23, 2012 MIT Lincoln Laboratory 999999-1 XYZ 3/18/2025
MIT/LL Cal/Val task completion 10/23/2012 Further analysis to complete Task 1 Interferometer Optimization 2 IR Channel Programmable Amplifier Gain Check and Adjustment 3 NEdN performance and trending 4 Monitor correlated noise 5 Responsively stability and Sensitivity Characterization 6 Spatial correlations caused by calibration averaging 7 Spatial integration of CrIS and ATMS 8 ILS correction with structured Earth scenes 9 Monitor short-term and long-term repeatability Completion 90% 100% 100% 50% 70% 100% 30% 20% 20% MIT Lincoln Laboratory 999999-2 XYZ 3/18/2025
MIT/LL Task 1 Interferometer Optimization 90% Task Objective: Evaluate the performance of the interferometer on orbit Description: Review raw earth, ICT less space spectra for systematic gain and phase variation with orbit. Responsivity stability over the orbit. Compare calibration residuals over multiple orbits. Comparisons to final TVAC testing, HK, and Dwell data Possible change to on orbit operation: Scan baffle temperature profile Task work Comparing biases for different calibration algorithms Laser monitoring Ripple sources Status - 90% complete Looking at systematic bias and ripple MIT Lincoln Laboratory 999999-3 XYZ 3/18/2025
Different calibration approaches Current ATBD approach Current Order, v2.20 of SDR Algorithm: calibration S ( ( ) ) S S S S Resampling to User Grid Bandpass Filter Nonlinearity correction ( , ) = -1 F F ES SP R T u SNLcorr EScal ICT spec ICT SP Calibration is done in a shifted wavenumber space and then shifted back with F-1. Working with Exelis on revised calibration proposal below Direct approach Calibration in final wavenumber space S S S ( F FIR gain removal ( ) ) -1 Nonlinearity correction F S S Sraw ( , ) = ES SP R T u EScal ICT spec -1 ICT SP Covert all extended spectra to final wavenumber scale Single F matrix performs all corrections ( FINT, ILS & resampling) Calibration done with final spec wavenumbers MIT Lincoln Laboratory 999999-4 XYZ 3/18/2025
Small differences between SDR and RDR(LLcal) Segregated into corners, edges, and center Gain error with Hamming applied to reduce ringing LW real RDR-SDR at 900 cm-1 GranuleID=NPP000271296803 Beginning Time IET=1725148916984107, UTC Time=2012-09-01 00:01:22.984 0.03 0.02 center 0.01 sides 1 2 3 4 5 6 7 8 9 0 mW/m2-str-cm-1 -0.01 corners -0.02 -0.03 -0.04 -0.05 700 750 800 850 Wavenumber 900 950 1000 1050 1100 MIT Lincoln Laboratory 999999-5 XYZ 3/18/2025
LW (RDR-SDR) in-band vs. SDR in-band for granule NPP000271296803 LW SDR at 900 cm-1 GranuleID=NPP000271296803 Beginning Time IET=1725148916984107, UTC Time=2012-09-01 00:01:22.984 LW SDR at 900 cm-1 GranuleID=NPP000271296803 Beginning Time IET=1725148916984107, UTC Time=2012-09-01 00:01:22.984 110 0.04 LW 800-970 cm-1 in-band average 100 0.03 90 0.02 center 80 SDR-RDR (mW/m2-str-cm-1) SDR-RDR (mW/m2-str-cm-1) 0.01 70 sides 60 0 50 -0.01 40 corners -0.02 30 -0.03 20 -0.04 10 0 10 20 30 40 50 60 70 80 90 650 700 750 800 850 900 950 1000 1050 1100 in band SDR (mW/m2-str-cm-1) Wavenumber (cm-1) center sides corners 0.999790; 1.000180; 0.999970; RDR gain to remove tilts MIT Lincoln Laboratory 999999-6 XYZ 3/18/2025
Difference between LW IDPS and LL calibrated spectra with Hamming with Hamming without Hamming LW real TRDR-TSDR at 900 cm-1 GranuleID=NPP000271297123 Beginning Time IET=1725148948984107, UTC Time=2012-09-01 00:01:54.984 SW real TRDR-TSDR at 900 cm-1 GranuleID=NPP000271297123 Beginning Time IET=1725148948984107, UTC Time=2012-09-01 00:01:22.984 100 40 80 30 60 20 40 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 10 20 dT (mK) dT (mK) 0 0 -20 -10 -40 -20 -60 -30 -80 -100 -40 650 700 750 800 850 Wavenumber 900 950 1000 1050 1100 650 700 750 800 850 Wavenumber 900 950 1000 1050 Large ringing difference center sides corners 0.999790; 1.000180; 0.999970; Fixed gain applied to RDR(LLcal) results MIT Lincoln Laboratory 999999-7 XYZ 3/18/2025
SW (RDR-SDR) in-band vs. SDR in-band for granule NPP000271296803 SW SDR at 900 cm-1 GranuleID=NPP000271297123 Beginning Time IET=1725148948984107, UTC Time=2012-09-01 00:01:54.984 SW SDR at 900 cm-1 GranuleID=NPP000271297123 Beginning Time IET=1725148948984107, UTC Time=2012-09-01 00:01:54.984 -4 6x 10 2 SW 2155-2180 cm-1 in-band average 1.8 5 1.6 4 center 1.4 3 SDR-RDR (mW/m2-str-cm-1) SDR-RDR (mW/m2-str-cm-1) 1.2 2 sides 1 1 corners 0.8 0 0.6 -1 0.4 -2 0.2 -3 0 2150 2200 2250 2300 2350 2400 2450 2500 2550 -4 0 0.1 0.2 0.3 0.4 0.5 0.6 Wavenumber (cm-1) in band SDR (mW/m2-str-cm-1) center sides corners 1.00060; 1.00025 1 RDR gain to remove tilts MIT Lincoln Laboratory 999999-8 XYZ 3/18/2025
Difference between SW IDPS and LL calibrated spectra with Hamming without Hamming LW real TRDR-TSDR at 900 cm-1 GranuleID=NPP000271301923 Beginning Time IET=1725149428984106, UTC Time=2012-09-01 00:09:22.984 SW real TRDR-TSDR at 900 cm-1 GranuleID=NPP000271297763 Beginning Time IET=1725149012984106, UTC Time=2012-09-01 00:02:26.984 40 4 3 30 2 20 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 10 dT (mK) dT (mK) 0 0 -1 -10 -2 -20 -3 -30 -4 2200 2250 2300 2350 2400 2450 2500 2550 -40 2150 2200 2250 2300 2350 2400 2450 2500 2550 Wavenumber Wavenumber Large ringing difference center sides corners 1.00060; 1.00025 1 Fixed gain applied to LLcal results MIT Lincoln Laboratory 999999-9 XYZ 3/18/2025
MW (RDR-SDR) in-band vs. SDR in-band for granule NPP000271296803 MW SDR at 900 cm-1 GranuleID=NPP000271297443 Beginning Time IET=1725148980984106, UTC Time=2012-09-01 00:02:26.984 MW SDR at 900 cm-1 GranuleID=NPP000271296803 Beginning Time IET=1725148916984107, UTC Time=2012-09-01 00:01:22.984 0.01 45 MW 1225-1395 cm-1 in-band average 0.008 40 0.006 35 0.004 30 SDR-RDR (mW/m2-str-cm-1) 1 2 3 4 5 6 7 8 9 SDR-RDR (mW/m2-str-cm-1) 0.002 25 0 20 -0.002 15 -0.004 10 -0.006 5 -0.008 0 -0.01 1200 1300 1400 1500 1600 1700 1800 0 5 10 15 Wavenumber (cm-1) in band SDR (mW/m2-str-cm-1) Curvature on FOVs 3, 7 and, 8 is a nonlinear difference center sides corners 1.00045 1.0002 1 Fixed gain applied to LLcal results MIT Lincoln Laboratory 999999-10 XYZ 3/18/2025
Difference between LW IDPS and LL calibrated spectra with Hamming with Hamming without Hamming MW real TRDR-TSDR at 900 cm-1 GranuleID=NPP000271299043 Beginning Time IET=1725149140984106, UTC Time=2012-09-01 00:05:06.984 LW real TRDR-TSDR at 900 cm-1 GranuleID=NPP000271297123 Beginning Time IET=1725148948984107, UTC Time=2012-09-01 00:01:54.984 40 100 80 30 60 20 40 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 10 20 dT (mK) dT (mK) 0 0 -20 -10 -40 -20 -60 -30 -80 -40 -100 1250 1300 1350 1400 1450 Wavenumber 1500 1550 1600 1650 1700 1750 1200 1300 1400 1500 1600 1700 1800 Wavenumber Large ringing difference center sides corners 1.00045 1.0002 1 Fixed gain applied to LLcal results MIT Lincoln Laboratory 999999-11 XYZ 3/18/2025
Comparisons of results Large ringing in differences almost completely removed with Hamming filter Small gain differences in the results Cain adjusted results differ by less than +/- 1 mK in LW and SW band, and +/- 5 mK for the MW band MW band shows nonlinear difference for band 3, 7, and 8 All differences have large ripple which is most likely due to delta function approximation in CMO MIT Lincoln Laboratory 999999-12 XYZ 3/18/2025
Delta function approx error summary How good is the approximation? N 0 ( ) ( * ) ( ) Sinq xR z Sinq y z dz Sinq xR y The answer is not too good. The errors occur across the band and are ripples The mean errors over an ensemble of x and y LW MW 1.00000 1.E-14 SW Same resulution R=1 delta approx errors Real resulution ratios R Max delta approx errors 1.00000 1.E-14 1.001977 1.020532 0.003 1.00000 1.E-14 1.00507 0.006 0.015 Actual transformation from extended FOV to on axis ray is a summation of many integrals with different R= uspec/ ua MIT Lincoln Laboratory 999999-13 XYZ 3/18/2025
LW band delta function approximation error for R NOT 1 N 0 ( ) ( * ) ( ) Sinq xR z Sinq y z dz Sinq xR y MIT Lincoln Laboratory 999999-14 XYZ 3/18/2025
Small orbital dependent variation in metrology laser wavelength Metrology laser variation from default 1.5462608 microns Start time = 2012-09-01 00:00:17.367 1 Delta lambda in ppm 0.5 0 -0.5 -1 0 5 10 15 20 25 30 Days Metrology aser ppm power spectrum 30 25 period=0.99677 days power spectrum 20 15 10 5 0 0 0.2 0.4 0.6 0.8 frequency (day-1) 1 1.2 1.4 1.6 1.8 MIT Lincoln Laboratory 999999-15 XYZ 3/18/2025
MIT/LL Task 2 IR Channel Amplifier Gain 100% Task Objective: Determine the overall gain in the interferogram Task Description: Review all parameters needed for the overall gain in the interferogram including - temperature variation, amplifier gain, decimation filter, a1, Vinst and laser diode temperature variation, ZPD peak over orbit Task work: Tracked parameters over multiple orbits Covered by other members Status 100% complete MIT Lincoln Laboratory 999999-16 XYZ 3/18/2025
MIT/LL Task 3 100% NEDN performance and trending Task Objective: Characterize the CrIS NEDN and trend over multiple orbits Task Description: Estimate the NEDN for ICT and over multiple orbits Evaluate noise sources for ICT and space looks Process HDF5 RDR data to independently access the noise Task work: NEDN every hour Status - 100% complete No significant change in instrument noise over 4 months MIT Lincoln Laboratory 999999-17 XYZ 3/18/2025
Find the maximum NEDN in the spectral range as a % of the specification NEDN estimated every hour Monitor maximum in: LW: 665 to 1095 cm-1 MW: full band SW full band MIT Lincoln Laboratory 999999-18 XYZ 3/18/2025
NEDN for September 1- 4 2012 by the hour as % of upper limit MaxLW NEDN as % of Specification 665 to 1095 cm-1 1 2 3 4 5 6 7 8 9 100 % of spec 80 60 40 0 5 10 15 20 25 30 35 40 45 50 Hours 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 MaxMW NEDN as % of Specification 1210 to 1750 cm-1 250 200 % of spec 150 100 50 0 5 10 15 20 25 30 35 40 45 50 Hours MaxSW NEDN as % of Specification 2155 to 2550 cm-1 100 % of spec 80 60 40 0 5 10 15 20 25 30 35 40 45 50 Hours MIT Lincoln Laboratory 999999-19 XYZ 3/18/2025
MIT/LL 4 50% Monitor Correlated Noise Task Objective: Assess correlation in real and imaginary noise Task Description: Determine correlation matrix for spectral channels for different time scales PCA analysis for single FOV Cross correlation in the ICT noise for different FOVs Task work: Code modified for covariance estimation over 1 hour periods Status 50% Spot tests over months show uncorrelated spectral noise MIT Lincoln Laboratory 999999-20 XYZ 3/18/2025
MIT/LL 5 70% Responsivity Stability Task Objective: Monitor complex responsively over multiple orbits Task Description: Correlate with BATC environmental test results Correlate with instrument temperature over orbits Task work: Z=(Earth-SP)/(ICT-SP) and responsivity for small data sets Responsivity for single orbits Status: 70% Spikes in phase at terminator for calibrated spectra MIT Lincoln Laboratory 999999-21 XYZ 3/18/2025
LW variation in responsibility magnitude with orbit shows small periodic change change in phase (mrad) change in magnitude (%) Effects due to temperature changes in thin films in CrIS No significant effect calibrated data with two point calibration MIT Lincoln Laboratory 999999-22 XYZ 3/18/2025
LW small residual phase variations in calibrated radiance produce most errors below 0.03 % 2 2 R R r = + i r Radiance phase error at 900 cm-1 scale; err=1.e-4 = 6.4 mK 40 20 Phase error (mrad) 0 -20 -40 0 500 1000 1500 2000 2500 3000 3500 4000 Mirror rotations 25 20 Radiance error (mK) 15 10 5 0 0 500 1000 1500 2000 2500 3000 3500 4000 Mirror rotations 433 out of 2712965 above 6.4mK (0.03%) Tobin (UW) showed spikes coincident with terminator MIT Lincoln Laboratory 999999-23 XYZ 3/18/2025
MIT/LL 6 100% Spatial correlation and calibration averaging Task Objective: Estimate responsivity spatial correlation over multiple granules (~240 seconds) caused by calibration averaging Description: Determine relative temporal noise contributions of ICT and SP and Earth for clear ocean scenes Determine the correlation in responsivity for clear ocean scenes Task work: None staff shortage resolved will catch up quickly Status 0% Running calibrations with variable length cal averages MIT Lincoln Laboratory 999999-24 XYZ 3/18/2025
Correlated responsivity due to 30 point calibration average Time power spectrum % change in responsivity f=1/(240 sec) Correlation length MIT Lincoln Laboratory 999999-25 XYZ 3/18/2025
MIT/LL 7 30% Spatial integration of CrIS and ATMS Task Objective: Preliminary checks of the registration of CrIS and ATMS as prerequisite for Backus-Gilbert Task Description: Use geographical edges and gradients to compare output from ATMS and CrIS, map model, ascending/descending orbit differences Use double difference methods to correlate variation Task work: Validated geolocation and timing Status: 30% Optimal geolocation of CrIS and ATMS Initial runs made using ADL 4.0 for Crimss EDR MIT Lincoln Laboratory 999999-26 XYZ 3/18/2025
MIT/LL 8 20% ILS correction with structured earth scenes Task Objective: Evaluate the expected error in SDR data due to ILS correction for structured scene Task Description: Use VIIRS images to evaluate the radiance distribution in the scene and the error relative to the uniform scene Compare the variability in the estimated error with other errors Autocorrelation of the spectrum Status: 20% MIT Lincoln Laboratory 999999-27 XYZ 3/18/2025
MIT/LL 9 20% Monitor long term repeatability Task Objective: Monitor long term repeatability for systematic bias and drifts using large ensemble averages. Task Description: Clear ocean scenes with high confidence low structure atmospheric conditions suitable for large averages Monitor radiometric differences between calibrated Earth scene radiances and data from AIRS, IASI, ECMWF, SNO for systematic differences Status: 20% Examined results against LBL for clear ocean areas Excessive averaging required to get noise down Completed RDR calibration for golden days MIT Lincoln Laboratory 999999-28 XYZ 3/18/2025
Backup MIT Lincoln Laboratory 999999-29 XYZ 3/18/2025
Why does it work? Starting with the direct calibration ( ) -1 ( ) F F S B SP S S L k B E , , L k ( ) L ( ) k ( ) = = -1 F ICT S S B E , B SP , ( ) ( ) E ICT -1 -1 F S B ICT S , B SP S B ICT , B SP , , The F operator has two functions Removes distortion in structured spectra Shifts spectra The ICT and Space spectra are fortunately unstructured and only shifted and the ratio is presumed to be the same under F which results in ATBD algorithm, ( ) ( ) S B SP S F L k B E , , L k ( ) ( F S ) = -1 -1 F F ICT S L B E , B SP , ( ) ( ) E ICT B ICT S , B SP S B ICT S , B SP shifted S , , MIT Lincoln Laboratory 999999-30 XYZ 3/18/2025
Direct calibration Exist well defined Matrices A and B that model the measurement process such that the: ( ) G ( ) + = A S k gS S On axis ray raw spectrum A bk 0 S k ( ) ( ) + = B G gS S Extended FOV raw spectrum B bk 0 On axis ray calibrated spectra S A SP S S A E , , N k ( ) N ( ) = k E ICT S A ICT , A SP , Calibrated CrIS spectrum uses F matrix ( ) ' ' -1 -1 -1 -1 + A F B F = AB (B*B') , F = BA where 1 2 ( ) -1 F F S S S A SP S S B E , , A E , , N k ( ) N ( ) ( ) B SP S = = k N k ( ) E ICT ICT -1 S S B ICT , B SP , A ICT , A SP , -1 here implies pseudo inverse MIT Lincoln Laboratory 999999-31 XYZ 3/18/2025
ATBD calibration Presume that the measured spectrum can be written in terms of the on-axis ray spectrum as before = F S S B A Rather than applying F-1 to get to the on-axis spectrum calibration is attempted with the raw extended FOV spectra ( ) S B SP S S B E , , L k ( ) L ( ) = -1 F F k ( ) E ICT S B ICT , B SP , The presumption is that the ratio of measured spectra remains unchanged under F transformation MIT Lincoln Laboratory 999999-32 XYZ 3/18/2025
Ringing of impulse response to single wavenumber The minimum ripple relative to the peak is (N+1)/2 bins from the peak 0 10 Sinq(z,N) Sinc min/max 0.001157 -29.3651 0.001894 -27.2263 0.005000 -23.0102 db LW MW SW db -1 10 -2 10 0 20 40 wavenumber 60 80 100 z Unavoidable ripple far from the peak as high a 0.5% peak for SW band for a single channel MIT Lincoln Laboratory 999999-33 XYZ 3/18/2025
LW band delta function approximation error for R=1 is essentially zero N 0 ( ) ( * ) ( ) Sinq xR z Sinq y z dz Sinq xR y MIT Lincoln Laboratory 999999-34 XYZ 3/18/2025
