1. Page 1 CO2 distribution in stratosphere from MIPAS Bianca Maria Dinelli Istituto di Scienze dell'Atmosfera e del Clima CNR (Italy) Massimo Carlotti Enzo Papandrea Dip.to di Chimica Fisica e Inorganica Università di Bologna (Italy) Fabrizio Niro

2. Page 2 CO2 distribution in stratosphere from MIPAS CO 2 is commonly used to derive Temperature and Pressure in the stratosphere. Lack of measurements of vertical distribution in the stratosphere. Can MIPAS provide information about CO 2 in stratosphere?

3. Page 3 CO2 distribution in stratosphere from MIPAS GMTR has been upgraded with: CO 2 line-mixing modeling, Target-dependent retrieval grid. MWs have been selected for simultaneous p, T, CO 2 retrieval with MWMAKE.

4. Page 4 CO2 distribution in stratosphere from MIPAS

5. Page 5 CO2 distribution in stratosphere from MIPAS O3O3

6. Page 6 CO2 distribution in stratosphere from MIPAS Ozone and water give the main contributions to systematic error. MW selection for p, T, H 2 O, O 3 and CO 2 retrieval not successful. RETRIEVAL STRATEGY 1.GMTR of p, T, H 2 O, O 3 2.GMTR of p, T, CO 2 using H 2 O and O 3 from step 1. Check on consistency of p, T retrieved in the two steps

7. Page 7 CO2 distribution in stratosphere from MIPAS Temperature from p, T, H2O, O3 and from p, T, CO2

8. Page 8 CO2 distribution in stratosphere from MIPAS The entire full resolution mission has been processed. To reduce ESDs the vertical retrieval grid of CO 2 has been degraded to 6 km steps. The resulting precision of individual CO 2 profiles is similar to other VMR targets. Averaging is needed to eliminate the too big random component of the error. Monthly averages over 10 deg latitude bins. Results above 60 km and below 12 km not shown because affected by extrapolation errors

9. Page 9 CO2 distribution in stratosphere from MIPAS July 02Sept. 02Jan. 03July 03March 03

10. Page 10 CO2 distribution in stratosphere from MIPAS Conclusions  The random error of the averaged VMRs is negligible  The systematic component still remains significant: 3 - 8%.  For internal comparison the effect of systematic errors that affect the CO 2 fields in the same direction (i.e. spectroscopic errors) can be neglected.  No correlation found with the retrieved temperature and pressure

11. Page 11 CO2 distribution in stratosphere from MIPAS Conclusions  The observed altitude and time variations need to be explained.  The low CO 2 VMR at high altitudes is consistent with its destruction by photo dissociation.  Not clear the origin of the low values consistently found at ~36 km (3.6 hPa )  However the magnitude of the systematic errors prevents absolute conclusions (i.e. age of stratospheric air)