# Presentation: 545251

## An Evaluation ofHIRDLS Measurements of Thin Ozone Filaments in the Extra-Tropical NH UTLS during Late-Winter/Early-Spring 

- B. Nardi, V. Yudin, J. Gille, T. Leblanc  & the HIRDLS Team
- WOUDC Investigators: P. von der Gathen (AWI-NA: Ny Aalesund); J. Davies (MSC: Churchill, Kelowna, Eureka, CA); H. De Backer (RMIB: UCCLE, BEL); R. Stubi (MeteoSwiss: Payerne, CHE); F. J. Schmidlin (NASA-WFF: Wallops Island, USA); B. Kois (PIMWM: Legionowo, POL); S. Pavla (CHMI-PR: Praha,CZE), B. Calpini (MeteoSwiss: Nairobi, KEN); F. Posny (Univ.LaReunion); G. Bodeker (NIWA-LAU: Lauder, NZ).
- Aura Science Meeting
- Columbia, MD, Oct 27-30, 2008

## Outline

-  Quality of v4 ozone, improvements over v3
-  Individual lamina profiles compared with sondes & lidar
-  Mean differences:   compare full data set to only isolated lamina cases
-  Examples of measurements intrusions confirmed   by O3-sonde

## V003

_**HIRDLS vs Ozonesonde**_

**V003**

**V004**

- _Payerne, CHE, 46.5°N_

- PP

- VMR

- %

## Mean Differences - [V4] HIRDLS Ozone vs Ozonesondes

- _Mean Differences - [V4] HIRDLS__** **__Ozone vs Ozonesondes_

- 1oS

## Intercontinental Chemical Transport Experiment (INTEX-B)

_**Intercontinental Chemical Transport Experiment **__**(INTEX-B)**_

- AROTAL Data courtesy Tom McGee

## Frequency of ozone lamina [HIRDLS V004]

**Notes:**
The frequency of lamina occurrence as measured with HIRDLS ozone, is determined by counting profiles where the ozone mixing ratio falls below a threshold value at the 100 hPa pressure level. 
The ratio of the number of lamina profiles to the total number of profiles is plotted on Mercator Maps above for each month in 2006.

## Ozone UTLS Lamina:  HIRDLS v4 Ozone vs Ozonesondes

## Mean Difference

- _ALL coincidences_

- _Lamina cases only_

- Subset: 57%

- Subset: 30%

- Subset: 34%

- _Mean Difference_

## ALL Ozone lamina cases

- _ALL Ozone lamina cases_

- RIGHT: The statistical differences in terms of volume mixing ratio (top right), partial pressure (center right) and percent difference (bottom right). A 10% accuracy to pressures of about 200 hPa are indicated.

- Lumped set of all coincident lamina profiles over three years for five stations: Prague, Payerne, UCCLE, Legionowo, and Wallops Island.

- BOTTOM: Scatter plots of all data points [2659H & 247S profiles] in terms of partial pressure (left) and volume mixing ratio (right) are shown.

## O3 Lamina observations 

- Shown is a double layered ozone filament in the NH spring UTLS, extending down to 300 hPa (left). The comparison between an ozonesonde and the closest eight coincident HIRDLS profiles (approximately 300 km, 3 hours), indicates that the vertical features are well captured by HIRDLS (above).

- _O3 Lamina observations _
- _with HIRDLS V004 Ozone_
- _[individual profiles]_

## O3 Lamina observations 

- _O3 Lamina observations _
- _with HIRDLS V004 Ozone_
- _[individual profiles]_

- Shown is a layered ozone filament in the NH spring UTLS, extending down to 250 hPa (left). The comparison between an ozonesonde and the closest eight coincident HIRDLS profiles (approximately 300 km, 3 hours), indicates that the vertical features are well captured by HIRDLS (above).

## O3 Lamina observations 

- _O3 Lamina observations _
- _with HIRDLS V004 Ozone_
- _[individual profiles]_

- Shown is a layered ozone filament in the NH spring UTLS, extending down to 250 hPa (left). The comparison between an ozonesonde and the closest eight coincident HIRDLS profiles (approximately 300 km, 3 hours), indicates that the vertical features are well captured by HIRDLS (above).

## O3 Lamina observations 

- _O3 Lamina observations _
- _with HIRDLS V004 Ozone_
- _[individual profiles]_

- Shown is a layered ozone filament in the NH spring UTLS, extending down to 250 hPa (left). The comparison between an ozonesonde and the closest eight coincident HIRDLS profiles (approximately 300 km, 3 hours), indicates that the vertical features are well captured by HIRDLS (above).

## Summary & Conclusions

- Comparisons of individual HIRDLS O3 profile with ozonesondes confirm that thin O3 layers and large O3 gradients observed by HIRDLS are real;
- Statistical analysis of three years of coincident O3 profiles over multiple ozonesonde sites shows that observations exclusively of lamina cases do not cause an appreciable degradation of the O3-mean-differences.
- Very high correlation exists (r=0.97) between sonde and HIRDLS ozone MR for all profiles containing _strong lamina_ [247 sonde profiles over 5 stations coincident with 2659 HIDLS profiles].
- Therefore measurements of O3 filaments and large O3 gradients in the extra-tropical UTLS are confirmed statistically to be of the same high quality as the larger HIRDLS O3 data set.

## Slide 15

## Frequency of ozone lamina [HIRDLS V004]

## Ozone UTLS Lamina:  HIRDLS v4 Ozone vs  LIDARS

## O3 Lamina observations 

- _O3 Lamina observations _
- _with HIRDLS V004 Ozone_
- _[individual profiles]_

- Shown is a layered ozone filament in the NH spring UTLS, extending down to 250 hPa (left). The comparison between an ozonesonde and the closest eight coincident HIRDLS profiles (approximately 300 km, 3 hours), indicates that the vertical features are well captured by HIRDLS (above).

## O3 Lamina observations 

- _O3 Lamina observations _
- _with HIRDLS V004 Ozone_
- _[individual profiles]_

- Shown is a layered ozone filament in the NH spring UTLS, extending down to 250 hPa (left). The comparison between an ozonesonde and the closest eight coincident HIRDLS profiles (approximately 300 km, 3 hours), indicates that the vertical features are well captured by HIRDLS (above).

## O3 Lamina observations 

- _O3 Lamina observations _
- _with HIRDLS V004 Ozone_
- _[individual profiles]_

- Shown is a layered ozone filament in the NH spring UTLS, extending down to 250 hPa (left). The comparison between an ozonesonde and the closest eight coincident HIRDLS profiles (approximately 300 km, 3 hours), indicates that the vertical features are well captured by HIRDLS (above).