6e. Update on NOAA-20 Ozone Mapping and Profiler Suite (OMPS) L. Flynn (NOAA) and NOAA-20 NOAA and NASA OMPS EDR and SDR Teams GSICS Annual Research Meeting, UV Subgroup, 21st March 2018

Disclaimer "The contents of this presentation are mine personally and do not necessarily reflect any position of the US Government or the National Oceanic and Atmospheric Administration."

Outline Instrument Performance Ozone Product Performance Solar Wavelength Geolocation Summary for other characteristics Ozone Product Performance Ozone profile products Total column ozone products Web resources (monitoring, document and data) Summary and Conclusions

Initial solar data are good and stable N20 NP N20 NM Slide from Glen Jaross NASA Comparisons to prelaunch synthetic proxy data. Residual variations w.r.t. Reference Solar are comparable for SNPP and N20 NOAA-20 lacks radiometric adjustments, esp. in dichroic region, and corrections for solar activity

Shifts detected by using first solar calibration Shifts detected by using first solar calibration. Wavelength shifts affect performance if not corrected in ground processing: NM shift = -0.165 nm (+ intra-orbital variations); NP shift = +0.150 nm NM sun-normalized radiance comparison: N20 measured and modeled Measured – modeled difference before shift correction Measured – modeled difference after 0.03 nm radiance shift of solar to match Earth radiance Key retrieval wavelengths Results from Colin Seftor SSAI Spectral structure translates to ozone retrieval errors

Small along-track geolocation error within requirements High contrast scenes in Bolivia and Persian Gulf both suggest ~ 0.2 deg. along-track pointing error. Such errors are not important for key OMPS ozone products (0.8 deg. requirement). An adjustment could be introduced via the instrument mounting matrix. Salar de Uyuni, 15 Jan., 2018 (SNPP VIIRS image overlayed with pink OMPS image)

Other OMPS performance PLTs Science Trending Dark current degradation in family with S-NPP OMPS. Linearity fluctuations comparable to S-NPP OMPS. Noise Characterization Measured noise matches modeled noise. Sample Table Optimization No buffer overflows occur when the sampling assumes 2.2x compression efficiency. OMPS has a candidate sample table for future High Resolution measurements – 140 cross-track FOVs every 2.5S. Baseline solar measurement and goniometry verification Utilizes eight solar sequences, each at a non-nominal yaw angle Solar data from orb 1009 indicates no error at Az = 26.9°. Not as good as verifying at 29° as originally planned. Slide from Glen Jaross NASA

Summary of Findings for Ozone Profile EDR NOAA-20 OMPS Nadir Profiler / V8Pro EDR EOF analysis of measurements shows good SNRs. Outliers are larger by linear factors in FOV size not square root factors. EDRs show good results for this stage of maturity. Output error for Profile Error Code 8 cases (Excessively large initial residual – Flag is correctly set). Code fix will be delivered to NDE with Provisional Table updates. Code error in cross-track macropixel computation; fix expected at IDPS in July 2018. New OMPS Nadir Profile sample table needed to match OMPS Nadir Mapper FOV. Radiation in the South Atlantic Anomaly has a large effect on radiances for 50x50km^2 FOVs, some just outside of geographic flagged region Outliers are linear not square root in reduction with increasing pixel aggregation. New field-angle-map, wavelength scales and solar tables provided by SDR Team. Some cases of negative radiances found in the auroral oval . Dichroic effects on wavelength/bandpass and on calibration from +0.15-nm shift not yet accounted for in SDR calibration tables or EDR adjustments. Possible overcorrection for stray light (not shown).

South Atlantic Anomaly

Summary of Findings for Total Ozone EDR NOAA-20 OMPS Nadir Mapper / V8TOz EDR EOF analysis of measurements shows good SNRs, similar intra-orbit wavelength shift and expected patterns. EDRs show good results for this stage of maturity. EDRs tested at STAR for low and medium FOV granules: 35x5  35x15  103x15. Stray light – need to check measurements in the overlap region from 300 nm to 310 nm with NP. 16-image granule SDR Processing error due to variable processing times; Code fix tested at STAR. Mismatch in current Medium to Low SDR FOV Cross-track aggregation. New tables have been prepared. Team needs 8-day averages with corrected SDRs to compute cross-track bias statistics and validate versus S-NPP.

16-Image Granule Errors Cross-Track Bias

Raytheon-devised Cross-granule retrieval fix for 16-Image RDRs tested at STAR by SDR Team

Provisional Delivery to NDE planned for May Planned code, script and table changes at NDE Dynamic SDR sizing adjustment for NM SDRs in codes, not control scripts Improved handling of end of orbit, end of day, and duplicate granules Fix for Profile Error Code 8 output EDR content for V8Pro Check FOV alignment accuracy for NM and NP within code. New adjustment tables for V8TOz and V8Pro Requires access to SDRs with better sample tables Requires access to SDRs with better stray light corrections Test data processing to confirm LFSO2 is ready for smaller FOV V8TOz EDRs from NOAA-20

Web Resources Additional information is available in the OMPS V8TOz and V8Pro algorithm theoretical basis documents (ATBDs) and the SDR and EDR maturity review briefings, which can be accessed at: https://www.star.nesdis.noaa.gov/jpss/Docs.php and https://www.star.nesdis.noaa.gov/jpss/AlgorithmMaturity.php Provisional NOAA-20 OMPS SDR near-real-time status and performance monitoring web page will become available by using the following websites: https://www.star.nesdis.noaa.gov/icvs/status_J01_OMPS_NP.php https://www.star.nesdis.noaa.gov/icvs/status_J01_OMPS_NM.php Pre-operational NOAA-20 OMPS EDR near-real-time status and performance monitoring web pages will become available at the following websites: Archive https://www.class.ncdc.noaa.gov/saa/products/search?datatype_family=JPSS_OZONE Operations http://www.ospo.noaa.gov/http://www.ospo.noaa.gov/Products/atmosphere/index.html Long-term https://www.star.nesdis.noaa.gov/smcd/spb/OMPSDemo/proOMPSbeta.php Daily maps https://www.star.nesdis.noaa.gov/jpss/EDRs/products_ozone.php Activity https://ozoneaq.gsfc.nasa.gov/omps/n20/activity

Summary & Conclusions The NOAA-20 OMPS Ozone EDR and BUFR products are ready for users to examine with proper formatting and reasonable content. Deficiencies in the OMPS SDRs are known, and the SDR Team has paths forward to improve the products. Minor code and script changes will be provided to NDE for the V8Pro, V8TOz and LFSO2 codes. Final adjustments for the EDR products will be developed using off- line STAR SDR processing. Product quality will improve as SDR Team adjustments and corrections enter the IDPS processing system.

Backup Provisional Review Presentations…

NOAA-20 OMPS Instrument Performance G. Jaross & OMPS SOC 20 February 2018

Agenda Performance issues requiring attention Ground-to-orbit wavelength shifts Pixel selection in flight tables Performance anomalies NOT requiring attention Sensor degradation shortward of 265 nm FOD on detector Along-track geolocation Pixel saturation Summary of 8 performance PLTs All but one completed successfully No indication of goniometry errors – no repeat of yaw maneuvers Open Issues (further analysis needed) readout structure during NP solar cal.

NM solar wavelength registration remains a challenge – as on SNPP N20 NM Wavelengths during solar measurements POS 1 POS 4 POS 7 POS 2 POS 6 POS 5 POS 3 Problem: NM solar data collected when wavelengths changing at greatest rate 3-orbit solar sequence used on NPP OMPS smears out wavelength registration for each of the 7 diffuser positions 1-orbit solar used on N20 yields more precise registration at each position Recommendation: Base the N20 NM baseline wavelength registration on 1-orbit solar data 3-orbit sequence 1 2 3 4 5 6 7 1-orbit sequence

Pixel selection leads to poor radiometry NM Total Ozone Measurements Edge-of-swath error caused by radiance error in marginal pixel Data gaps caused by ground processing error Radiance error exists in edge pixels Edge pixels are not needed for full global coverage Solution: remove unnecessary edge pixels from telemetered data (long-term), remove edge pixels in ground processing (interim).

Revised Sample Table needs testing and approval N20 OMPS NM Radiance Sensitivity Current sample tables include pixels with little or no photon sensitivity NM has been tested with a revised sample table that chops 10 pixels off either edge. More than enough for full equatorial coverage.

Interim NM Sample Table at 17x17 km2 Sinabung Eruption 19 Feb., 2018 Demonstrates current instrument operations Small spatial mismatch with NP SNPP OMPS 50 x 50 km2 N20 OMPS 17 x 17 km2 Courtesy of Colin Seftor http://ozoneaq.gsfc.nasa.gov

No evidence of continued NP degradation after launch Albedo Calibration accuracy Waiver 472-CCR-17-1378 NP Solar Flux compared to Reference Measured solar irradiance changes include sensor, diffuser, and solar flux changes Some evidence of the degradation seen before launch NP Sun-normalized radiance compared to Model Sun-normalized radiances include only diffuser reflectivity changes No evidence the diffuser has degraded Observed pre-launch change

No effect of detector FOD observed in science data No need to take action until a radiometric error is found Initial post-launch LED aliveness test Xtrack Position Time Unbinned Antarctic signals spectral index 80 Xtrack Position Position 5 Position 6 Orbit 696 solar irradiance Wavelength Xtrack Position

Small NP solar signal errors A Single NP Solar Image NP CCD Signal Levels 10 – 20 count error in smear- corrected NP solar signals Caused by timing pattern issue – when is charge integrated in the CCD readout Currently investigating other NP image types. DN

Small along-track geolocation error within requirements Salar de Uyuni, 15 Jan., 2018 (SNPP VIIRS image overlayed with pink OMPS image) High contrast scenes in Bolivia and Persian Gulf both suggest ~ 0.2 deg. error. Such errors are not important for key OMPS ozone products (0.8 deg. requirement) An adjustment could be introduced via the instrument mounting matrix

Small number of pixel saturations is acceptable OMPS geolocation data was used for the analysis Comprised of unbinned, no co-added data at 44 wavelengths Wavelength with highest sensitivity (329.6 nm) was included Search for instances where signal overflowed the 14 bit register (ie, > 214-1) Results indicate that 4 NM wavelengths saturate, 0.1% of pixels at 329 nm As expected, percentage mirrors mean signal levels Small number of NP saturations is consistent with transient events

Data compression leads to granularization issue Difference between CCSDS time and Image time RDR granules formed from CCSDS time stamp in packet header Relationship between CCSDS time and image time affected by on-board data compression Depending on granule boundaries, a granule can receive 14, 15, or 16 images. SDR is only sized for 15 images max. Recommendation: Re-size SDR to handle more images per granule Time Difference (ms) Image Number in granule

Other OMPS performance PLTs Science Trending Dark current degradation in family with SNPP Linearity fluctuations comparable to SNPP Noise Characterization Measured noise matches modeled noise Sample Table Optimization No buffer overflows occur when the sampling assumes 2.2x compression OMPS has a candidate sample table for any future High Resolution measurements Baseline solar measurement and goniometry verification Utilizes 8 solar sequences, each at a non-nominal yaw angle Sign error led to incorrect yaw maneuver angles Instead of repeating, we will collect annual Reference at new 18.9 deg. Solar data from orb 1009 (see 28 Jan. data on Slide 8) indicates no error at Az = 26.9 deg. Not as good as verifying at 29 deg. as originally planned.

Summary Other than new flight tables, no changes needed to operations Sample table update to NM and possibly NP needed to repair edge-of-swath problem Use Medium rather than Low resolution timing pattern to reduce error in interim pending table load approval New Ground LUTs needed to correct wavelength shifts This is expected work; i.e. business as usual Initial wavelength LUTs are available Intra-orbital corrections use same code introduced for SNPP OMPS Additional errors do not require correction but are recommended 0.2 deg. along-track pointing adjustment Introduce more stringent saturation flags