NOAA-18 SBUV/2 OV & A&E RESULTS L. Flynn

1. NOAA-18 SBUV/2 OV & A&E RESULTS L. Flynn

2. NOAA-18 SBUV/2 OV and A&E • 15 OV SBUV/2 tests completed • Some additional tests performed for A&E • Instrument characterization and calibration provided to operations by SSAI (GSFC Code 613) • Earliest ACF data delivery yet • Earth view data taken almost from the start is available for reprocessing

3. NOAA-18 SBUV/2 OV and A&E • Additional tests were not included in formal OV • Five tests were in OV for NOAA-17 SBUV/2 • Additional tests to characterize stray light • Specification for stray light is inadequate • Position mode and day-time diffuser deployment • Not all tests performed (not considered OV) • TOARs closed/inactive before launch (CDR) • No need seen to add OV tests in these areas • SBUV/2 did not take advantage of AMSU off/on • Regular solar measurements not started earlier • Regular operational schedule implementation delayed

4. Additional Tests Recommended Test_SBUVA01 Range 3 Cathode Test_SBUVA02 SO2 (Discontinue) Test_SBUVA03 EP/TOMS Measurements (For NASA) Test_SBUVA04 CCR/Monochromator Test_SBUVA05 OOBR (Analysis of Earth position mode) Test_SBUVA06 Backup Grating Encoder Baseline Test_SBUVA07 Backup Diffuser Position Baseline Test_SBUVA08 8-second Range 3 noise (from SBUVA01) Test_SBUVA09 Noisy Range 1 (Analysis) Test_SBUVA10 OOBR (Earth view Mg II and other features) Test_SBUVA11 Compare to NOAA-16 SBUV/2 (Analysis) Test_SBUVA12 Compare to EOS Aura OMI (Analysis) Test_SBUVA13 Deploy solar diffuser on day side (earth-shine) TRENDING Throughput/Solar for evidence of dichroic outgassing as seen with NOAA-17 SBUV/2. Start weekly solar measurements sooner. Range 3 Anode/Cathode. Repeat SBUVA01. Mg II Index. Start sooner, take in Earth view Photometer/Monochromator performance. Repeat SBUVA04 over instrument lifetime.

5. Parameters & Tables from NOAA-17 A&E Report TABLE 15.1 Ozone Processing Calibration Data for NOAA-17 SBUV/2 Quantity Location Wavelength Calibration Ebert Coefficients Table 6.1 p. 29 Standard Ozone Wavelengths Table 6.8 p. 32 Radiance Calibration Constants Table 12.3 p. 86 Irradiance Calibration Constants Table 12.2 p. 86 Electronic Offsets Table 5.1 p. 17 Non-linearity Corrections Table 10.1 p. 62 PMT Temperature Correction Table 8.1 p. 47 Inter-range Ratio IRR12 p. 53 Inter-range Ratio IRR23A (anode mode) p. 53 Inter-range Ratio IRR23C (cathode mode) Table 9.1 p. 53 Table 9.2 p. 54 Goniometric Correction Table 7.1 p. 40 Table 7.2 p. 40 Table 7.3 p. 41 Day-1 Solar Irradiances Table 13.1 p. 91 Total Ozone Pair Adjustment Factors Table 14.1 p. 94 Stray light characterization was delivered later, separately.

6. NOAA-18 Day-1 Solar Irradiance Channel Wavelength Irrad_new Diff 1 251.97 39.03 -9.4% 2 273.64 169.15 -12.7% 3 283.10 307.87 -7.1% 4 287.67 316.23 -7.1% 5 292.30 516.84 -5.9% 6 297.58 506.99 -5.1% 7 301.97 428.52 -5.6% 8 305.84 553.92 -6.6% 9 312.61 659.57 -4.4% 10 317.54 764.59 -4.5% 11 331.25 977.00 -1.6% 12 339.86 1019.89 -2.3% CCR 378.62 1204.65 -7.6%

7. NOAA-18 Initial Parameters Adjustments 1. Day -1 Irradiance adjustments are on the preceding slide.. 2. Anode IRR23. On-orbit inter-range ratio for Range 3 anode data (IRR23A) is significantly lower than the pre-launch value. The value derived from on-orbit data is IRR23A = 92.459 a change of -7.5% from the pre-launch value. 3. Range 2 Non-Linearity. There was an error in the pre-launch non-linearity correction for high Range 2 signals (>45,000 counts). A simple additional linear correction is given by CF = CI/(1.0+(6.46933e-07*(CI-45000))) for CI > 45000 4. Ozone tables and wavelengths. The pre-launch wavelength calibration needs to be adjusted by approximately 0.9 grating positions. This requires revision of the total ozone tables and wavelength scale values. 5. Time-Dependent ACF. Range 3 cathode measurements in early June and early July indicate a PMT sensitivity change of approximately -1% during that time. Since regular solar measurements are not yet available, a linear extrapolation of these measurements was used to produce a time-dependent ACF with identical values at all wavelengths for SSAI ozone processing. This is important for profile ozone. Note that the rate of PMT change derived from IRR23C data typically slows after the first few months of operation.

9. Comparison of equatorial zonal mean Ozone profiles for SBUV/2 instruments NOAA-18 Blue NOAA-17 Green NOAA-16 Red 18-17 Blue 18-16 Green 17-16 Red

10. NOAA-18 SBUV/2 Monitoring

11. Backup

12. 1. Day -1 Irradiance. The initial NOAA-18 solar irradiance measurements are low relative to reference data, with differences ranging from 2-4% at long wavelengths to 8-10% at short wavelengths. Diffuser reflectivity tests show no significant change from pre-launch values, so we believe that the radiometric calibration has changed. The simplest correction for ozone processing at this time is to provide new "Day 1" irradiance values processed with the pre-launch calibration constants, so that observed albedo values are consistent with the albedo calibration. At a later date, SSAI will supply revised calibration constants for both radiance and irradiance data as a long-term solution. This is the procedure that was used for NOAA-17 SBUV/2, and will yield the same albedo calibration for NOAA-18 as our initial fix. The revised "Day 1" irradiance values and the difference from current data are listed below. 2. Anode IRR23. The on-orbit inter-range ratio for Range 3 anode data (IRR23A) is significantly lower than the pre-launch value supplied by SSAI. Our recommended value derived from on-orbit data is IRR23A = 92.459 a change of -7.5% from the pre-launch value. 3. Range 2 Non-Linearity. SSAI identified an error in the pre-launch non-linearity correction for high Range 2 signals (45,000 counts), and derived a linear adjustment. The maximum albedo correction for ozone processing is approximately -0.9% at 55,000 counts Range 2 (higher signals are processed in Range 3). The corresponding impact on profile ozone could be up to 1.0-1.5%, depending on wavelength. A simple statement to apply this correction is: C_true = C_NL2/(1.0+(6.46933e-07*(C_NL2-45,000))) where C_NL2 = Range 2 counts after using pre-launch non-linearity correction C_NL2 45,000 counts C_true = Corrected Range 2 counts 4. Ozone Tables. On-orbit measurements suggest that the pre-launch wavelength calibration supplied by SSAI needs to be adjusted by approximately 0.9 grating positions. We have generated revised tables for the SSAI ozone processing code in order to have a more accurate Ring effect correction. This adjustment changes total ozone values by a few DU to as much as 4-5 DU in some cases. Huang can provide you with these tables. Please note that we have not updated wavelength scale values at this time, only the tables. 5. Time-Dependent ACF. Range 3 cathode measurements in early June and early July indicate a PMT sensitivity change of approximately -1% during that time. Since regular solar measurements are not yet available, a linear extrapolation of these measurements was used to produce a time-dependent ACF with identical values at all wavelengths for SSAI ozone processing. The corresponding data set can be supplied by Huang. This term has only a small effect on total ozone through the calculated reflectivity, and is more important for profile ozone. Note that the rate of PMT change derived from IRR23C data typically slows after the first few months of operation.

13. NOAA-17 Report on Additional OV and A&E • Out-of-band response • Ball measurements • Ozone impact • Correction • Special measurements • SO2 • EPTOMS • Photometer • OMPS Mapper (TBD) • Operational schedule • Sweep mode 1/day per week (1/6 coverage) • Solar diffuser in conjunction with NOAA-16 SBUV/2 • Mg II Index 2/day • Range 3