# Presentation: 284399

## AURA Validation 2005Ozone Profile PotentialL. Flynn and T. Beck

## Outline

- MLS and SBUV/2 Ozone Profile Comparisons
- Format and matchup criteria
- Average profile differences
- Layers versus latitude
- Forward Model Projections for OMI UV1
- Mg II Index from OMI UV1

## Products MLS and SBUV

- MLS ozone profiles are converted from PPMV to ozone layer amounts.  Layer amounts are preferable in this study so that the profiles may be run through TOMRAD.   The layer pressures are the same as used in V8SBUV( 21 layers).
- The MLS data is screened for precision, quality, and status flags.  The pressures compared lie within the range of 251 hPa to 0.1 hPa.

## SBUV and MLS matchup

- Matchups were found within a 40 day time period going from June 1 to July 10 2005.
- The matchup criteria was: geographical distance less than 50 km (less than 20 km at very high latitudes) and the measurement time differences less than 1.5 hours.
- Only NOAA-16 SBUV/2 V8 profiles are used (N17 and N18 to follow).

## MLS-SBUV/2 % Difference

## MLS-SBUV 60S to 60N

## Zonal Means: MLS  versus N16 and N17 SBUV/2

- Zonal means in Layer DU were computed for three days at 4 pressure layers.
- Next pages shows Jan. 1, 2005. This is an interesting date because NOAA 17 is not showing  a radiance anomaly.

| 100 hPa to 30 hPa
30 hPa to 10 hPA 
10 hPa to 1 hPa
1 hPa to 0.1 hPa |
| --- |

## Latitude Dependence 30-100 hPa

## Latitude Dependence 10-30 hPa

## Latitude Dependence 1-10 hPa

## Latitude Dependence 0.1-1.0 hPa

## Using MLS and SBUV for OMI UV1 Radiance Comparison

- Assume the stratosphere is mostly smooth in the daytime tropics.
- We located an orbit that had an excellent coincidence with NOAA16-SBUV on April 22, 2005.
- From roughly 8.5 N to 10 N latitude, there appears to be no major cloud decks, aerosol contamination or sea glint.  There is some cloud contamination, but it is mostly clear.
- We take an averaged V8sbuv NOAA 16 ozone profile and a nearby MLS temperature profile for input to TOMRAD.    For an OMI scan, the geometry of the detector is input to TOMRAD( satva, sza, solaz).   When clouds are present the independent pixel approximation is used to get LER weighted radiances.  The cloud fraction for UV1 pixel is averaged from the UV2 cloud fraction value as determined by OMTO3.   The cloud height information is the V8 climatological value.
- A very simple bandpass model is used( 0.45 nm, triangular, 15 sub-channels).  The slit averaged TOA radiance is obtained for 30 cross-track positions and 159 channels.

## Simulated OMI radiances 

- The solar used in the slit average is formed from that day’s solar by aggregating each L1BIRR pixel in a flat sorted array with an approximate average spacing of 0.01 nm.  A 0.1nm boxcar is convoluted to obtain a much smoother version.
- A smooth solar is used to separate the effects of noise in the irradiance from the radiance.
- The output of the RT model is a sun normalized radiance field that can be compared to the measured radiance at the same geometry. The measured radiance also is normalized by the smoothed UV1 solar signal.
- The resulting structure in the difference of the measured and simulated radiance.
- We did not use the latest, greatest OMI data.

## N-value Differences between OMI UV1 scan #750, orbit 4101 

**N-value Differences between OMI UV1 scan #750, orbit 4101 **
**and Forward Model Radiances**

**Notes:**
The large bump in the middle is the location of the cluster of Bad pixels at about 295 nm.

## Cross-track Section of Previous Surface

**Notes:**
nv_diff_270_310 has 6 rows plotted as a function of wavelength from 270 to 310
nv_diff_270_305 is identical except the max. wavelength is 305 nm, under the theory that since at this low SZA , the SBUV n16 had an ilongchan of 303 nm, the 308 channel is not used, which results in a poor fit for 305nm to 310 nm.

## Mg II index from OMI and SBUV

- Mg II index computed for the time period of Dec. 2, 2004 to Sept. 15, 2005,
- There were 288 days where both NOAA-16 and OMI Mg II data were available.
- The correlation was 0.986.
- The OMI Mg II has greater dynamic range. This results from OMI’s UV1 having a smaller bandpass than SBUV.  In order to see how the index might differ for a wider band, we recomputed the index using irradiances that were convolved with an approximately 1.0 nm wide boxcar function. The resulting time series had a very similar range and offset as the NOAA 16 does.
- The un-flagged data in the range 274 nm to 286 nm are used for most rows which allows for 930 channels within this band. The average spacing in wavelength is  0.013 nm.

## Mg II Index for OMI since 2 Dec. 2004