# Presentation: 664217

## AURA VALIDATION WORKSHOP September 21-23 2005Ground Based Microwave Ozone Radiometer Measurements Compared with MLS and Other Instruments at Two NDSC SitesAlan Parrish, Ian BoydLucien Froidevaux, Rob Koopman, Stuart McDermid, Daan Swart, Kaley Walker

## NDSC MICROWAVE OZONE RADIOMETERS AT MAUNA LOA AND LAUDER: MEASUREMENT CHARACTERISTICS

**SITES:   MAUNA LOA, HAWAII  (19.5********N., 204.4********E.), SINCE JULY, 1995.**
**                     ****LAUDER, NEW ZEALAND  (45.0********S., 169.7********E), SINCE NOV*****,*****1992.**
**A LIST OF PUBLICATIONS THAT DESCRIBE THE EXPERIMENT, OZONE RETRIEVAL, ERROR ANALYSIS, AND RESULTS FROM BLIND INTERCOMPARISON CAMPAIGNS IS AVAILABLE AS A HANDOUT.**
**4 PROFILES ARE GENERATED EACH DAY IN GOOD WEATHER.**
**EXPECTED PRECISION:  4-5% 56-0.3 hPa (~20-57 KM), 7% AT 0.1 hPa (~64 KM).**
**EXPECTED ACCURACY:  6-9% 56-0.3 hPa (~20-57 KM), 11% AT 0.1 hPa. **
**VERTICAL RESOLUTION:  6-10 KM, 56-0.8 hPa, (~20-50 KM), 13 KM AT 0.1 hPa.**
**FOR THIS PRESENTATION, ALL***** *****DATA HAVE BEEN INTERPOLATED ONTO THE MLS STANDARD PRESSURE GRID FROM 46 TO 0.04 hPa.**

**August 2004 to August 2005**
**Blue lines from nighttime observations; red from daytime.**
**MLS observations have been convolved with microwave averaging kernels.**
**Error bars: 1 sigma uncertainty limits for the average differences are shown. **
**Criteria for Convolved Profiles ±1.0o Lat, ±3.0o Long, ±12 hrs, MLS Error 50%**
**Number of Comparisons:**
**	****Mauna Loa: 58/63 (Day/Night)**
**	****Lauder: 75/66 (Day/Night)**
**MLS and microwave mostly agree to within 5% from 46 to 0.3 hPa.**
**Microwave retrieval is primary cause of the oscillatory nature of difference profiles, particularly around 10 hPa. **
**No evidence for latitude dependence in MLS measurements; results are similar at both sites.**

**Notes:**
Replace Lauder slide with current one

## MLS-Microwave Comparisons
August 2004 to August 2005
Dashed lines show results using convolved MLS data, as in previous slide.
Added solid lines: MLS data compared directly to microwave without convolution.
To average down noise at top of profiles, coincidence criteria have been relaxed to  ±2.5o Lat, ±8.0o Long, ±12 hrs. with no MLS error limit.  >200 comparisons.
Effects of relatively low microwave resolution are not important up to ~0.3 hPa; differences using original and convolved profiles are very similar.
Significant sharp gradients occur at 0.2 hPa and above; these must be in the MLS data.
At night, MLS and microwave agree within 12% at 0.1 hPa, and within 25% at 0.04 hPa.
During the day, differences increase to ~25% around 0.1-0.15 hPa.
Daytime ozone levels small, increasing percentage errors for given absolute errors.  

**August 2004 to August 2005**
**Dashed lines show results using convolved MLS data, as in previous slide.**
**Added solid lines: MLS data compared directly to microwave without convolution.**
**To average down noise at top of profiles, coincidence criteria have been relaxed to  ±2.5o Lat, ±8.0o Long, ±12 hrs. with no MLS error limit.  >200 comparisons.**
**Effects of relatively low microwave resolution are not important up to ~0.3 hPa; differences using original and convolved profiles are very similar.**
**Significant sharp gradients occur at 0.2 hPa and above; these must be in the MLS data.**
**At night, MLS and microwave agree within 12% at 0.1 hPa, and within 25% at 0.04 hPa.**
**During the day, differences increase to ~25% around 0.1-0.15 hPa.**
**Daytime ozone levels small, increasing percentage errors for given absolute errors.  **

## Validation of Nighttime Measurements

**MLS, blue; MIPAS red; GOMOS, green; LIDAR, purple.**
**MIPAS, GOMOS data from an earlier period, ~2002-2004.**
**Consistency of three profiles suggests microwave is underestimating ozone by ~10-15% at 0.1 hPa.**
**MLS data mostly consistent with MIPAS and GOMOS within ~5% from 46-0.15 hPa, and also to the top of the lidar profile.**

## Validation of Daytime Measurements

**MLS-MWR shown in blue; MIPAS-MWR in red.**
**MLS and MIPAS are again consistent, except at 0.1 hPa at Lauder.**
**Interpretation of the discrepancy at Lauder at 0.1 hPa would be complicated by the time difference between the MLS and MIPAS comparisons.**
**MLS-MWR difference at 0.1 hPa appears to be slightly larger during the day.**

**Notes:**
ACE data should be in a separate slide.

## Errors shown may be underestimated due to limited number of coincidences in data we presently have.
ACE-Microwave differences within ~5% from 15-2 hPa at both sites, and within ~15% from 46-0.7 hPa.

**ACE-Microwave differences within ~5% from 15-2 hPa at both sites, and within ~15% from 46-0.7 hPa.**

**ACE v2.2-Microwave Comparisons**

## CONCLUSIONS

**MLS AND MICROWAVE DATA GENERALLY AGREE TO WITHIN 5% FROM 46-0.3 hPa, AND WITHIN 12% TO 0.1 hPa AT NIGHT, OR 25% DURING THE DAY AT MAUNA LOA AND LAUDER.**
**AT ~0.1 hPa, MICROWAVE DATA APPEARS TO BE BIASED LOW, AS MLS, GOMOS, AND MIPAS DIFFERENCES WITH MICROWAVE ARE GENERALLY CONSISTENT.**
**WE SEE NO EVIDENCE FOR ANY SUBTANTIAL ABSOLUTE ERRORS IN MLS MEASUREMENTS FROM 46-0.1 hPa.**
**PRELIMINARY RESULTS FOR ACE: GOOD AGREEMENT WITH MICROWAVE BETWEEN ~15-2 hPa; ACE APPEARS TO OVERESTIMATE OZONE ABOVE THIS RANGE AND UNDERESTIMATE IT BELOW. **