# Presentation: 183537

## Origin of the January-Mach 2004 strong NO2 enhancement in the northern polar stratosphere using MIPAS and GOMOS data  Jean-Baptiste RENARD, Pierre-Louis BLELLY, Quentin BOURGEOIS, Florence GOUTAIL                                            LPCE-CNRS, Orléans, France            Service d’Aéronomie, Verrières le Buisson, France

## 

- NO2 enhancements are sometimes observed in the middle stratosphere during polar winter, due to strong solar flares (protons flux)
- October-November 2003 event in Artic:

- GOMOS nighttime data (ppbv), Hauchecorne et al., JGR, 2005

****

##    Persistence of this Arctic NO2 enhancement in Spring 2004 observed by many satellite instruments

   Origin of the persistence is unknown

   Gaps in polar latitudes coverage using solar occultation instruments (e.g. SAGE)

   Necessity of nighttime measurements

-    Origin of the persistence is unknown
-    Gaps in polar latitudes coverage using solar occultation instruments (e.g. SAGE)
-    Necessity of nighttime measurements

## Two instruments onboard ENVISAT:

-     GOMOS : star occultation method – UV visible
-     MIPAS : Infra red limb sounder
- Validation by UV-visible
- balloon-borne instrument
- SALOMON (Moon occultation)

- SALOMON gondola

##   March 2004: comparison between MIPAS,
  GOMOS and SALOMON

Detection of the NO2 
enhancement above 40 km

Uncertainties on MIPAS 
absolute values: 
 - poor vertical resolution 
   above 40 km
 - overestimation of 
   concentrations by a factor 2

-   GOMOS and SALOMON
- Detection of the NO2
- enhancement above 40 km
- Uncertainties on MIPAS
- absolute values:
-  - poor vertical resolution
-    above 40 km
-  - overestimation of
-    concentrations by a factor 2

## No peak for NO2 in the MIPAS data at southern polar latitudes in January – April 2004

- January-February 2004 data

## GOMOS data for January-April 2004 not yet available (except sparse data at the beginning of March 2004)

MIPAS data must be used cautiously

Nevertheless, the analysis of the NO2 persistence can be conducted ...

- MIPAS data must be used cautiously
- Nevertheless, the analysis of the NO2 persistence can be conducted ...

## Two NO2 enhancements in the October 2003 - April 2004 period

- Downward transport in the stratosphere of 250±50 m per day

## Second enhancement stronger than the first one, and at higher altitude

## Different nature and origin
for the two NO2 enhancements

	 No major solar flare in January 2004 !

- for the two NO2 enhancements
- 	 No major solar flare in January 2004 !

## Starting date of the second enhancement: 
23 January 2004 

- 23 January 2004

- Ground-based measurements of NO2 columns by the spectrometer SAOZ

-   ****

## Solar coronal mass ejection on 20 Jan. 2004 (01:00 UT)

Effect on Earth magnetosphere on 22 Jan. (01h40 UT), and magnetic storm

      SAMPEX satellite data

- Effect on Earth magnetosphere on 22 Jan. (01h40 UT), and magnetic storm
-       SAMPEX satellite data

## No proton detection

Detection of electrons with energies of few 100 keV in the auroral regions (North and South)

Such electrons can penetrate in the atmosphere down to altitude of 60-70 km

Nighttime chemistry in the lower mesosphere
 NOx  production only in the Arctic

- Detection of electrons with energies of few 100 keV in the auroral regions (North and South)
- Such electrons can penetrate in the atmosphere down to altitude of 60-70 km
- Nighttime chemistry in the lower mesosphere
-  NOx  production only in the Arctic

## October – November event :

Stronger solar event, but smaller NO2 production !

- Stronger solar event, but s**maller NO****2**** production !**

## Conclusion

- Detection of large amount of NO2 in the lower mesosphere produced by auroral electrons
- Need of GOMOS data at the beginning of 2004 (level 2 and 1b) in order to better document the event
- The retrieval of NO2 could be better accurate with GOMOS than with MIPAS
- Search of the frequency of such event