MIPAS-2D water database and its validation B.M. Dinelli ISAC-CNR – Bologna – Italy With the help of E. Arnone, E. Castelli - ISAC M.Carlotti, L. Magnani, E. Papandrea DCFI – University of Bologna - Italy M. Prevedelli, M. Ridolfi DF- University of Bologna – Italy A. Burini, S.Casadio SERCO - Italy

MIPAS/ENVISAT MIPAS measurements have been mainly acquired using two different spectral and geographical resolutions: Full Resolution mission (FR) From June 2002 to March 2004 Spectral resolution 0.025 cm-1 ~72 scans per orbit on 17 views ranging from 6 to 68 km Optimized Resolution mission (OR) From January 2005 to April 2012 Spectral resolution 0.0625 ~92 scans per orbit on 27 limb views ranging from 3 to 70 km MIPAS measurements are directly processed by ESA in two stages Interferograms are converted in calibrated and geolocated spectra (level1b data) Spectra are analysed to obtain vertical distributions of p,T and VMRs of several key species: H2O, O3, HNO3, CH4, N2O, NO2, etc. (level 2 data) ESA level 2 data are obtained with the ORM algorithm (retrieval on tangent points, horizontal atmospheric gradients neglected)

FR OR ∆Lat = ~4.6o ∆Lat = ~3.7o Constant altitudes along the orbits Variable altitudes along the orbit ~72 scans ~94 scans 17 altitudes 27 altitudes 0.025 cm-1 0.0625 cm-1 ∆Lat = ~4.6o ∆Lat = ~3.7o OR FR

GMTR retrieval system The GMTR code (Carlotti et al., Appl. Opt., 45, 716-727, 2006) has been developed to analyse MIPAS observations The main characteristics of GMTR are: The horizontal inhomogeneities of the atmosphere are properly modelled using a 2-D discretization of the atmosphere. Observations of a full orbit can be simultaneously analyzed The (2-D) retrieval grid is fully independent from the measurement grid. Target species can be retrieved simultaneously (Multi-Target-Retrieval) in order to suppress the systematic error due to spectral interferences.

GMTR retrieval system The 2-D FM internal to the GMTR code can be used to study the effects of horizontal gradient in 1-D analysis The data retrieved with GMTR are not affected by the error due to neglecting temperature horizontal gradients (Kiefer et al., AMT,3 1487-1507, 2010)

MIPAS2D database The GMTR code has been applied to the full MIPAS mission and the MIPAS2D database has been developed (Dinelli at al., AMT,3, 355-374, 2010) Retrievals have been performed using Optimal Estimation Cloudy spectra have been removed from the analysis The database is public and can be downloaded following the instructions given in the web sites: http://www.isac.cnr.it/~rss/mipas2d.htm http://www.mbf.fci.unibo.it/mipas2d.html The database containes 2-D fields of: p, T, H2O, O3, HNO3, CH4, N2O, NO2 for the full mission CFC-11, CFC-12, N2O5, COF2, ClONO2 (minor species) are also present Because of their correlations P,T, H2O, O3 have been jointly retrieved The other targets are retrieved singularly in cascade. 2-D Averaging Kernels available upon request

MIPAS2D database The data have been retrieved on a fixed vertical grid (17 altitudes) From 6 to 42 km at 3 km steps + 47, 52, 60, 68 Two types of horizontal grids for both the FR and OR mission GRD - fixed at 5 degrees latitudinal steps NOM – at the average latitude of each MIPAS scan The GRD retrieval grid makes the spatial resolution of both FR and OR products homogeneous Level 1b data processed with IPF V5.X Originally the analysis was performed with two different sets of MWs (target dependent) one for the FR mission and one for the OR mission FR mission has been analysed also with the OR MWs For this analysis the spectral resolution of MIPAS spectra has been artificially degraded to the OR Most MIPAS observation modes analysed (NOM - UTLS - MA)

H2O time-series 15N-15S

Time series of month-pressure distributions of water vapor anomalies in the vertical range 50 to 5 hPa (15N-15S)

Zonal mean of water distribution from 2002 to 2010

Validation We have started to validate the version 2 of MIPAS2D We are currently using data from other satellite instruments (MLS, ACE) Coincidence criteria: Time mismatch 60 min Distance < 500 km

Water MIPAS2D vs ACE South Pole

MIPAS2D vs MLS South Pole

North Polar region

Mid-Lat North

South Polar region

Comparison with ACE and MLS January South Pole Mid-Lat South Mid-Lat North North Pole

Comparison of Temperature with MLS and ACE South Pole Mid-Lat South Mid-Lat North North Pole

Conclusions We have analysed all the measurements in the observation modes NOM UTLS and MA of MIPAS for the whole mission (July 2002 to April 2012). The 2D fields of pressure, temperature and VMR of H2O, O3 have been obtained on a fixed altitude grid at two horizontal grids: fixed at 5 deg steps or at the scan geolocation, for the whole mission. The analysis has been performed with the GMTR system that enables the tomographic retrieval of MIPAS data taking properly into account the horizontal inhomogeneities of the atmosphere. The resulting database is available to end users and can be dowloaded following the instructions contained into the web sites: http://www.mbf.fci.unibo.it/mipas2d.html and http://www.isac.cnr.it/~rss/mipas2d.htm The database includes results for the FR mission analysed with the same set of MWs of the OR 2-D Averaging Kernels can be distributed upon request

Conclusions Validation with satellite data (ACE and MLS) shows a positive bias of about 5% from 200 to 1 hPa wrt both instruments Above and below higher differences are present Consistent behavior in all latitude bands Comparison of the temperature profiles (retrieved simultaneously) with ACE and MLS doesn’t show the same behavior therefore no correlations We are currently working to reduce the differences by changing the set of analysed MWs