# Presentation: 827816

## NOAA-18 SBUV/2 

**OV & A&E **
**RESULTS**
**L. Flynn**

## 15 OV SBUV/2 tests completed

**NOAA-18 SBUV/2 OV and A&E**

- 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

**Notes:**
 Additional Tests(Done for NOAA-17 SBUV/2) 
            Test_SBUVA01            Range 3 Cathode 
                    Make measurements from the Cathode for Range 3. 
                    Compare Cathode and Anode measurements for Range 3. Look at IRR 2/3. 
X          Test_SBUVA02          SO2 Measurements  (No more)                     Do not repeat for NOAA-N 
            Test_SBUVA03            EP TOMS Measurements 
                    Use the 12 discrete measurements to make two passes through the six EP TOMS wavelengths. 
                    Allow comparison of SBUV/2 and TOMS by using the same wavelengths in the Version 8 retrievals 
            Test_SBUVA04            CCR/Monochromator Comparison 
                    Take measurements at 380 nm with the monochromator. 
                    Obtain a baseline for comparison of the PMT and the photometer. 
            Test_SBUVA05            Out-of-Band Response 
                    Change test to measure in earth view in position mode at shorter wavelengths. 
                    Compare monochromator variations to photometer variations to estimate OOBR. 
Additional Tests (New for NOAA-N SBUV/2) 
            Test_SBUVA06            Backup Grating Encoder 
                    Make LampCal and continuous scan or Mg II solar measurements with the backup Grating Position Encoder. 
                    Obtain baseline for relative wavelength scale performance. 
            Test_SBUVA07            Backup Diffuser Position 
                    Make position mode solar with backup encoder for diffuser position. 
                    Obtain baseline for relative position performance. 
            Test_SBUVA08            8 second Range 3 noise 
                    Examine position mode solar data to check for this NOAA-16 SBUV/2 problem. 
                    If present, test alternate wavelength orders. 
            Test_SBUVA09            Noisy Range 1 
                    Examine nightside Range 1 offset to check for this NOAA-16 SBUV/2 problem. 
Trending. In addition to the planned trending for 
                    Electronics calibration vs. time (discrete) (IRR 2/3 and offsets) 
                    Radiometric dark current level vs. time (discrete) (See SBUVA09.) 
                    Diffuser reflectance vs. time (discrete) 
               we should also trend the following 
                    Mg II Index 
                    Range 3 Anode/Cathode (See SBUVA01.) 
                    Photometer/Monochromator performance (See SBUVA04.) 
                    Throughput and solar diffuser signal for evidence of 
                            dichroic outgassing as seen for NOAA-17 SBUV/2 
                            (See last currently planned trend item as well.) 

## 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

**Notes:**
Emil, 
       There seems to be some confusion about the additional OV tests for NOAA-N SBUV/2. There were five additional tests performed for the NOAA-17 SBUV/2, and we are dropping one of them. I have had the enclosed discussions with Jim Mentall and Matt  DeLand since February when I provided the first draft of these and the new tests. I also sent you a copy of the presentation Shobha Kondragunta gave last week on September 13. Four of the new test for NOAA-N SBUV/2 are related to previous SBUV/2 TOARs. I would be happy to go into even more detail on the usefulness of and expected information from these tests than was provided in the presentation material. I would further note that two of the new tests are engineering check-out/baseline tests on backup components. 
       Larry Flynn, Co-Chair Ozone Products Oversight Panel 

TOAR-435 - NOAA-16 SBUV INCREASED DATA DROPOUTS - November 15, 2003 Range-1 Noise (10/12/2004)
  The ozone profile data from the NOAA-16 SBUV/2 began showing increased data dropouts in early November, 2003. The percentage of daily scans flagged for bad quality peaked at approximately 25% on November 15, 2003. The profile data appeared to recover for a while in December but then started to exhibit the same data dropout behavior in mid-to-late December, 2003. The bad profiles were distributed globally and were not confined to any particular region over the globe. There was an intense solar activity in the month of November, but examination of sweep-mode solar data revealed no correlation to the rejected profile data. Examination of the product shows that the profiles that were flagged had large final residues at the two shortest wavelengths whose radiances are measured in range 1. Associated with this behavior is an increased noise in the photo multiplier tube range 1 offset measurement.
  All available data, including a special test performed on October 21, 2004, have been examined without being able to identify a root cause. Additionally, the standard deviation of the Range 1 noise has returned to nominal values negating the possibility of further tests. My personal view is that the scanner on either AMSU-A2 or AMSU-B in June of 2002 became noisier and eventually swamped the (NOAA-16) SBUV microphonics filter. Six months later the scanner slowly returned to quieter operation, and the SBUV standard deviations returned to nominal values. Since there is no clear root cause for this anomaly, I recommend that this TOAR be moved to inactive.
TOAR-426 - NOAA-16 SBUV SOLAR IRRADIANCE MEASUREMENTS - May 5, 2003
  During April and May, 2003, the NOAA-16 SBUV/3 solar irradiance measurements were consistently about 1.5 per cent higher than previous data. The increase was observed at all wavelengths. It is believed that these elevated irradiance values represent occasions when the NOAA-16 solar diffuser deployed to an incorrect position.
  On June 16, 2003, the NOAA-16 diffuser encoder was switched from primary to backup. At the time of the switch, the diffuser position and solar irradiance values showed the same anomalous readings that originally caused the switch to be implemented. However, on  June 19, the diffuser started getting to the correct position, and solar irradiance data was back within specifications.
TOAR-412-NOAA-16 SBUV/2 RANGE 3 MEASUREMENT ANOMALY - March 1, 2002
The SBUV/2 instrument on board NOAA-16 has been experiencing erratic behavior in its range 3 measurements from the cathode of the Photo Multiplier Tube (PMT).  The errors associated with this behavior increased during March and June of 2002 and produced 1% errors in the total column ozone retrievals.  The errors show an 8-second periodic behavior for range 3 measurements with the first two  2-second measurements in an 8-second interval relatively unaffected and the second two 2-second measurements showing increased  offset and noise bias and variability.
  A closure was submitted for this TOAR.  The electronic circuit in which the noise arises is the Cathode Current Monitor.  The most likely cause of the noise in the Range 3 signal is EMI due to the AMSU 8 second sync pulse effecting the Cathode Current Monitor. Further research into the cause of the 8-second noise is not likely to produce any useful information.  No corrective action for future spacecraft is required, since all instruments in which Range 3 science data comes from the anode have been launched.  The proposed work-around to this anomaly involves reordering the SBUV/2 wavelength sequence.  Wavelengths that produce few or no Range 3 values are swapped into the 8-second period.  Implementation of this work-around will take place after the ozone hole season  has concluded, sometime in late winter or early spring. 

## 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.

**Notes:**
Below is my understanding what was agreed to during our telecom today.  Call or email me if you see an error.  Phil
OV additional test way forward plan:
> Test_SBUVA01    Range 3 Cathode
OK
> Test_SBUVA02    SO2  (Discontinue)
Not part of OV
> Test_SBUVA03    EP/TOMS Measurements (For NASA)
Not part of OV
> Test_SBUVA04    CCR/Monochromator
OK - Matt DeLand to define the test
> Test_SBUVA05    OOBR (Analysis of Earth position mode)
OK to add additional wavelengths to a current OV test.  Matt to define these.
> Test_SBUVA06    Backup Grating Encoder Baseline
Not part of the OV
> Test_SBUVA07    Backup Diffuser Position Baseline
Maybe - NASA to consider
> Test_SBUVA08    8-second Range 3 noise (from SBUVA01)
Not part of the OV.  Informal analysis of the first test to be done by Matt. 
If a noise is present, then, it will be investigation though anomaly resolution activities. 
> Test_SBUVA09    Noisy Range 1 (Analysis)
Not part of the OV.  Informal analysis to be done by Matt.  If a noise is present, 
then, it will be investigation though anomaly resolution activities. 
> Test_SBUVA10    OOBR (Earth view Mg II and other features)
OK - Matt to define the test.
> Test_SBUVA11    Compare to NOAA-16 SBUV/2 (Analysis)
Not part of the OV.  Matt to perform the analysis
> Test_SBUVA12    Compare to EOS Aura OMI (Analysis)
Not part of the OV.  Matt to perform the analysis
> TRENDING
> 1. Throughput/Solar for evidence of dichroic outgassing as seen with
>    NOAA-17 SBUV/2. Start weekly solar measurements sooner.
> 2. Range 3 Anode/Cathode. Repeat SBUVA01.
> 3. Mg II Index. Start sooner, take in Earth view
> 4. Photometer/Monochromator performance. Repeat SBUVA04 over instrument lifetime.
TRENDING agreement:    Jim Mental is to determine a method to implement trending items 1 & 2 
during the OV period.  Trending items 3 & 4 are not part of the OV testing period. 

## 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.

## 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%

**Notes:**
Day -1 Irradiance.  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. Day-1 values are on the previous slide.

## 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.

**Notes:**
3. Range 2 Non-Linearity.  There was an error in the pre-launch non-linearity correction for high Range 2 signals (45,000 counts).  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 additional linear correction is given by
             C_true  =  C_NL2/(1.0+(6.46933e-07*(C_NL2-45000)))       where    C_NL2 > 45000
4. Ozone tables and wavelengths.  The pre-launch wavelength calibration 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.

## Slide 8

## Comparison

- of equatorial
- zonal mean
- Ozone profiles
- for SBUV/2
- instruments

- 18-17 Blue
- 18-16 Green
- 17-16 Red

- NOAA-18 Blue
- NOAA-17 Green
- NOAA-16 Red

## NOAA-18 SBUV/2 Monitoring

## Backup

- 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.

**Notes:**
SSAI has completed an initial evaluation of the NOAA-18 SBUV/2 on-orbit calibration.  We have identified a set of changes that significantly improve the quality of the total ozone and profile ozone products.  NOAA-18 total ozone values from SSAI test processing agree with NOAA-16 data to within +-5 DU in Equatorial and mid-latitude zonal averages.  Ozone profiles are produced with almost no error codes, and the V8 layer amounts agree with NOAA-16 data to within +-5%.
The following paragraphs list five NOAA-18 ozone processing changes that have been implemented in the SSAI system.  Items #1 and #2 represent calibration changes of  5-10%, and are critical for the creation of adequate NOAA-18 ozone products. Items #3-5 represent calibration changes at the ~1% level, with varying impacts on the ozone products.  These changes are less urgent if time is a concern, but we do recommend that all changes be implemented in the OOPS system for best results.
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.
    Ch        Wvlnth        Irrad_new    Diff
    1         251.97         39.031       -9.44%
    2         273.64         169.15      -12.69%
    3         283.10         307.87       -7.07%
    4         287.67         316.23       -7.08%
    5         292.30         516.84       -5.88%
    6         297.58         506.99       -5.10%
    7         301.97         428.52       -5.65%
    8         305.84         553.92       -6.60%
    9         312.61         659.57       -4.40%
   10         317.54         764.59       -4.51%
   11         331.25         977.00       -1.60%
   12         339.86        1019.89       -2.27%
   CCR        378.62        1204.65       -7.55%
2.  Anode IRR23.  As discussed previously, 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 now
    IRR23A = 92.459
This represents 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.

## NOAA-17 Report on Additional OV and A&E

**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

**Notes:**
See attached A&E report in PDF.

## Slide 14

## Slide 15

## Slide 16