In this contribution, we provide an overview of the EMM (Earth and Mars Research Network) research infrastructure, outlining its main components and the potential scientific products that can be derived through its use. The presentation delves into selected aspects in greater detail, particularly where they resonate with the multiple scientific and technological challenges associated with the FORUM mission.

MIPAS is a Fourier Transform spectrometer that measured the atmospheric limb emission spectra in the middle infrared on board the ENVISAT satellite. These measurements allowed the global monitoring of the three-dimensional (latitude, longitude and altitude) distribution of temperature and of the concentrations of many species, during both day and night, for 10 years, from July 2002 to April 2012. MIPAS measurements allowed to study the atmosphere from the upper troposphere to the stratosphere and above, up to the thermosphere. The interest in these measurements goes beyond the end of the mission, as they can be used in long time series of data to determine changes in atmospheric composition and in our planet's climate. Furthermore, if the Changing-Atmosphere Infra-Red Tomography Explorer (CAIRT) mission, one of four candidates for Earth Explorer 11, will be selected, MIPAS data will constitute a benchmark for these measurements. CAIRT exploits indeed the heritage of MIPAS on ENVISAT, but allows to measure the composition of the atmosphere with unprecedented three-dimensional resolution being the first imaging Fourier Transform spectrometer sounding the limb of the atmosphere from space. For the last reanalysis of the whole MIPAS mission, a significant effort was made by the MIPAS Quality Working Group, supported by ESA, to improve both L1 [1] and L2 processors, as well as spectroscopy and Level 2 Initial Guess profiles [2], with the objectives of obtaining L2 products with increased accuracy, better temporal stability, and a larger number of retrieved species. The main improvements of L1 processor were related to the radiometric calibration and pointing. With these new processors a MIPAS full mission reprocessing has been recently performed ([1] and [3]). The quality of this final operational data set has been assessed with comprehensive validation studies including comparisons to ground-based in-situ and balloon-borne measurements. The dataset containing the new version 8 of both L1 and L2 products and covering the entire MIPAS operational lifetime period (2002-2012) is available at ESA Earth Online web site.This paper will focus on the lessons learnt, on the quality of the reprocessed data, on the remaining problems, and on further improvements that could improve the quality of both MIPAS L1 and L2 datasets.[1] Kleinert et al. Kleinert, A., Birk, M., Perron, G., and Wagner, G.: Level 1b error budget for MIPAS on ENVISAT, Atmos. Meas. Tech., 11, 5657-5672,https://doi.org/10.5194/amt-11-5657-2018, 2018 [2] Raspollini, P., Arnone, E., Barbara, F., Bianchini, M., Carli, B., Ceccherini, S., Chipperfield, M. P., Dehn, A., Della Fera, S., Dinelli, B. M., Dudhia, A., Flaud, J.-M., Gai, M., Kiefer, M., López-Puertas, M., Moore, D. P., Piro, A., Remedios, J. J., Ridolfi, M., Sembhi, H., Sgheri, L., and Zoppetti, N.: Level 2 processor and auxiliary data for ESA Version 8 final full mission analysis of MIPAS measurements on ENVISAT, Atmos. Meas. Tech. Discuss. [preprint], https://doi.org/10.5194/amt-2021-235, in review, 2021. [3] Dinelli, B. M., Raspollini, P., Gai, M., Sgheri, L., Ridolfi, M., Ceccherini, S., Barbara, F., Zoppetti, N., Castelli, E., Papandrea, E., Pettinari, P., Dehn, A., Dudhia, A., Kiefer, M., Piro, A., Flaud, J.-M., Lopez-Puertas, M., Moore, D., Remedios, J., and Bianchini, M.: The ESA MIPAS/ENVISAT Level2-v8 dataset: 10 years of measurements retrieved with ORM v8.22, Atmos. Meas. Tech. Discuss. [preprint], https://doi.org/10.5194/amt-2021-215, accepted, 2021.

The observations acquired during the full mission of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument, aboard the European Space Agency Environmental Satellite (Envisat), have been analysed with version 8.22 of the Optimised Retrieval Model (ORM), originally developed as the scientific prototype of the ESA level-2 processor for MIPAS observations. The results of the analyses have been included into the MI- PAS level-2 version 8 (level2-v8) database containing atmospheric fields of pressure, temperature, and volume mixing ratio (VMR) of MIPAS main targets H2 O, O3 , HNO3 , CH4 , N2 O, and NO2 , along with the minor gases CFC- 11, ClONO2 , N2 O5 , CFC-12, COF2 , CCl4 , CF4 , HCFC-22, C2 H2 , CH3 Cl, COCl2 , C2 H6 , OCS, and HDO. The database covers all the measurements acquired by MIPAS in the nominal measurement mode of the full resolution (FR) part of the mission (from July 2002 to March 2004) and all the observation modes of the optimised resolution (OR) part (from January 2005 to April 2012). The number of species included in the MIPAS level2-v8 dataset makes it of particular importance for the studies of stratospheric chemistry. The database is considered by ESA the final release of the MIPAS level-2 products.The ORM algorithm is operated at the vertical grid coincident to the tangent altitudes of the observations or to a subset of them, spanning (in the nominal mode) the alti- tude range from 6 to 68km in the FR phase and from 6 to 70 km in the OR period. In the latitude domain, FR profiles are spaced by about 4.7o, while the OR profiles are spaced by about 3.7o. For each retrieved species, the auxiliary data and the retrieval choices are described. Each product is characterised in terms of the retrieval error, spatial resolution, and "useful" vertical range in both phases of the MIPAS mission. These depend on the characteristics of the measurements (spectral and vertical resolution of the measurements), the retrieval choices (number of spectral points in- cluded in the analyses, number of altitudes included in the vertical retrieval grid), and the information content of the measurements for each trace species. For temperature, water vapour, ozone, and nitric acid, the number of degrees of freedom is significantly larger in the OR phase than in the FR one, mainly due to the finer vertical measurement grid. In the FR phase, some trace species are characterised by a smaller retrieval error with respect to the OR phase, mainly due to the larger number of spectral points used in the analyses, along with the reduced vertical resolution. The way of handling possible caveats (negative VMR, vertical grid representation) is discussed. The quality of the retrieved profiles is assessed through four criteria, two providing information on the successful convergence of the retrieval iterations, one on the capability of the retrieval to reproduce the measurements, and one on the presence of outliers. An easy way to identify and filter the problematic profiles with the informa- tion contained in the output files is provided. MIPAS level2- v8 data are available to the scientific community through the ESA portal (https://doi.org/10.5270/EN1-c8hgqx4).

MIPAS is a Fourier Transform spectrometer that measured the atmospheric limb emission spectra in the middle infrared on board the ENVISAT satellite. These measurements allowed the global monitoring of the three-dimensional (latitude, longitude and altitude) distribution of concentrations of many species, during both day and night, for 10 years, from July 2002 to April 2012. Being a limb sounding instrument, the focus of MIPAS measurements was the study of the atmosphere from the upper troposphere to the stratosphere and above, up to the mesosphere. The interest in these measurements goes beyond the end of the mission, as they can be used in long time series of data to determine changes in our planet's climate. To this purpose, it is therefore important to continue improving their quality. The quality of MIPAS L2 products depends on the quality of the L1 products, on the L2 model accuracy, on the quality of auxiliary data, particularly on spectroscopic data. For the last reanalysis of the whole MIPAS mission, a significant effort was made by the MIPAS Quality Working Group, supported by ESA, to improve both L1 and L2 processors, as well as spectroscopy, with the objectives of obtaining L2 products with increased accuracy, better temporal stability, and a larger number of retrieved species. Here we present the full mission dataset, including vertical profiles of 21 trace species plus temperature, obtained by applying the latest version of ESA L2 processor (ORM V8) to the MIPAS L1 data obtained with version 8 of the L1 processor. The impact of the improvements of both L1 and L2 processors on the quality of the L2 products is presented, as well as results of the validation against independent correlative measurements.

Riporta i principali risultati ottenuti nell'ambito del progetto: "Support to MIPAS Level 2 processor Verification and Validation - Phase F", Contratto ESA 4000112093/14/I-LG, cioe' la messa a punto del codice ORM_V8 da utilizzare per la rianalisi di livello 2 dell'intera missione di MIPAS/ENVISAT, il dataset processato, i test di verifica e di validazione dei prodotti di Livello 2 generati.

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a limb-viewing infrared Fourier transform spectrometer that operated from 2002 to 2012 onboard the ENVISAT satellite. The analysis of MIPAS measurements allows to study the temporal evolution of numerous species of interest for the study of the ozone in the stratosphere, pollutants and many green-house gases. The objective of the MIPAS Quality Working Group is to improve the quality of the MIPAS products through a fruitful collaboration among spectroscopists, Level 1, Level 2, and validation teams. A large effort has recently led to implement significant improvements in both ESA Level 1 and Level 2 processors, as well as in spectroscopic database and in some absorption cross-sections in order to improve the quality of the products. In addition to the products already present in the V7 dataset (temperature and the VMR of H2O, O3, HNO3, CH4, N2O, NO2, CFC-11, CFC-12, N2O5, ClONO2, HCFC-22, COF2, CF4, HCN and CCl4), the VMR of six additional species (OCS, CH3Cl, HDO, C2H2, C2H6, COCl2) will be provided in V8 dataset. In order to evaluate the impact of the changes in the products before full mission reprocessing, the analysis of the performances of the products of the modified L1 and L2 processors, as well as the auxiliary data, has been performed on a Diagnostic DataSet (DDS). The orbits of the DDS have been chosen in coincidence with correlative measurements for performing also a preliminary assessment of the accuracy of the products and to evaluate possible changes in the drift. With respect to V7 products, main improvements consist in a reduction of the temperature bias in the first part of the mission, a reduction of the discontinuities in CH4 and N2O time series due to daily gain upgrade, a better filtering of clouds and a better handling of horizontal inhomogeneities.The results of the assessment of the quality of MIPAS measurements will be shown, as well as the study of the temporal evolution and variability of all species. We will also investigate the spatial, seasonal, and interannual variations in the distribution of these species.

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) is a limb-viewing infrared Fourier transform spectrometer that operated from 2002 to 2012 onboard the ENVISAT satellite. The maintenance and the upgrade of both L1 and L2 ESA processors are accomplished by the Quality Working Group, where a fruitful collaboration among Level 1, Level 2 and validation teams can be exploited. Recently both ESA L1 and L2 processors have been updated, as well as the spectroscopic database and some absorption cross-sections. In addition to the products already present in the current release (V7) of ESA MIPAS data (temperature and the VMR of H2O, O3, HNO3, CH4, N2O, NO2, CFC-11, CFC-12, N2O5, ClONO2, HCFC-22, COF2, CF4, HCN and CCl4), the VMR of six additional species (OCS, CH3Cl, HDO, C2H2, C2H6, COCl2) will be provided in V8 dataset. In preparation of V8 full mission reprocessing, three Diagnostic Datasets have been generated to check the performances of all L1, L2 processors and the new auxiliary data.The analysis of these Diagnostic Datasets and the comparison with previous full mission dataset V7 will be used to perform a first assessment of the quality of the new V8 products. In the paper special focus will be given to the new species.

MIPAS on ENVISAT performed almost continuous and global measurements of atmospheric temperature and composition from June 2002 to April 2012. These data are very useful for understanding atmosphere climatology from the upper troposphere to the mesosphere, including trends in composition and variability, as a reference for middle atmosphere ozone and general circulation as well as improvement of tropospheric composition retrievals. The ESA Level 2 processor, based on the Optimized Retrieval Model (ORM), originally designed for the Near Real Time analysis and developed by an European Consortium led by IFAC, is currently improved and used for the reanalysis of the full MIPAS mission. The maintenance and the upgrade of the ESA processor are made in the frame of the MIPAS Quality Working Group, where a fruitful collaboration among Level 1, Level 2 and validation teams is exploited. This collaboration is essential to improve the accuracy of the products and their characterization. This paper is meant to describe the most recent upgrades in the MIPAS processor, in particular the full mission was recently reprocessed with L1 V7 and L2 V7 processors, containing significant improvements with respect to previous version 6, and further improvements are in preparation, that will be collected in version 8 of the ESA processor. The improvements include both L1 and L2 processors, as well as the auxiliary data. In the L1 processor the correction of the instrumental drift caused by the ageing of the detectors has been implemented in order to reduce the non negligible systematic error in the trend estimation. Furthermore, the measured daily gain instead of the weekly gain is now used for the radiometric calibration that allows to better take account for the discontinuities in the gain that occasionally occur in MIPAS band B. Improvements in the L2 processor include a different approach for retrieving atmospheric continuum, the use of an a posteriori regularization with altitude dependent constraint, a better approach for handling interfering species, a reduced bias in CFC-11, the handling of horizontal inhomogeneities and the use of ECMWF altitude/pressure relation to determine more accurate altitudes. Improvements in the auxiliary data consist in the use of microwindows with larger information content, an improved spectroscopic database and diurnally varying climatological dataset. Furthermore, additional species are provided in the new processors, leading to a total of 22 retrieved species by the L2 version 8 processor. Each of these changes has a different impact on the Level 2 products. The individual contributions, as well as the cumulative effects, will be evaluated with a comparison with previous versions of MIPAS products and corresponding results of validation. Improvements in the trend determination will also be evaluated, as well as the quality of the new retrieved species.

MIPAS on ENVISAT performed almost continuous measurements of atmospheric composition for approximately 10 years, from June 2002 to April 2012. ESA processor, based on the algorithm ORM (Optimized Retrieval Model), originally designed for the Near Real Time analysis and developed by an European Consortium led by IFAC, is currently used for the reanalysis of the full MIPAS mission. The maintenance and the upgrade of the ESA processor are made in the frame of the Quality Working Group, where a fruitful collaboration among Level 1, Level 2 and validation teams can be exploited. This collaboration is essential to pursue improvements in the accuracy of the products and their characterization. This paper is meant to describe the most recent upgrades in the ESA processor performed to improve the quality of ESA products. In particular, the full mission was recently reprocessed with L1 V7 and L2 V7 processors, containing significant improvements with respect to previous version V6, and further improvements are in preparation, that will be collected in version 8 of the ESA processor. Improvements involve both L1 and L2 processors, as well as the auxiliary data. Improvements in the L1 processor consist in a correction of the instrumental drift, improved spike detection algorithm and new Instrument Line Shape, as well as the use of measured daily gain instead of weekly gain. Improvements in the L2 processor include a different approach for retrieving atmospheric continuum, the use of an a posteriori regularization with altitude dependent constraint, a better approach for handling interfering species, a reduced bias in CFC-11, the handling of horizontal inhomogeneities and the use of ECMWF altitude/pressure relation for determining more accurate altitudes. Improvements in the auxiliary data consist in the use of microwindows with larger information content, new spectroscopic database and diurnally varying climatological dataset. Furthermore, with each new version additional species are provided, leading to 20 the number of retrieved species by the L2 V8 processor. Improvements in the V7 products will be revised on the light of the results of the validation with correlative measurements, and, by comparing the first new L2 V8 products with the L2 V7 ones, a preliminary assessment of the performance of the new V8 processor will be performed.

MIPAS on ENVISAT performed almost continuously measurements of the atmospheric composition for almost 10 years, from June 2002 to April 2012. These ten years cover a period when the first effect of the dismiss of the emission of the CFCs after the Montreal protocol ratification in 1987can be measured. Even if ten years constitute a short period to derive trends, it has been proven that useful information on time variation of atmospheric constituents can be derived from the analysis of these measurements. However, previous versions of MIPAS on ENVISAT dataset were characterized by an instrumental drift due to the fact that some detectors used by MIPAS were affected by non-linearities, which change with time due to the ageing of the detectors and this was cause of a non negligible systematic error in the trend estimation. The new full mission reprocessed dataset V7 that will be released very soon uses L1 files where the impact of the ageing of the detectors on non-linearities has been corrected. Furthermore, also the L2 processor has been upgraded with new functionalities improving the performances of the processor. We present the results of study of trends derived from the analysis of the new MIPAS V7 products on several MIPAS target species including ozone depleting species, like CFC-11, CFC-12, CCl4 and HCFC-22.

In this paper we analyze the performance of the three MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) observation modes that sound the Upper-Troposphere/Lower-Stratosphere (UT/LS) region. The two-dimensional (2-D) tomographic retrieval approach is assumed to derive the atmospheric field of geophysical parameters. For each observation mode we have calculated the 2-D distribution of the information load quantifier relative to the main MIPAS targets. The performance of the observation modes has been evaluated in terms of strength and spatial coverage of the information-load distribution along the full orbit. The indications of the information-load analysis has been validated with simulated retrievals based on the observational parameters of real orbits. In the simulation studies we have assessed the precision and the spatial (both horizontal and vertical) resolution of the retrieval products. The performance of the three observation modes has been compared for the MIPAS main products in both the UT/LS and the extended altitude range. This study shows that the two observation modes that were specifically designed for the UT/LS region are actually competitive with the third one, designed for the whole stratosphere, up to altitudes that far exceed the UT/LS. In the UT/LS the performance of the two specific observation modes is comparable even if the best performance in terms of horizontal resolution is provided by the observation mode that was excluded by the European Space Agency (ESA) from the current MIPAS duty cycle. This paper reports the first application of the information-load analysis and highlights the worthiness of this approach to make qualitative considerations about retrieval potential and selection of retrieval grid.

We present a multi-year database of atmospheric fields of the upper troposphere, stratosphere and lower mesosphere retrieved from satellite measurements adopting a 2-dimensional tomographic approach. The full mission of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument, on board the European Space Agency ENVISAT satellite, is analyzed with the Geofit Multi-Target Retrieval (GMTR) system to obtain the MIPAS2D database with atmospheric fields of pressure, temperature and volume mixing ratio of MIPAS main targets H2O, O3, HNO3, CH4, N2O, and NO2. The database covers both the MIPAS nominal observation mode measured at Full Resolution (FR) from July 2002 to March 2004 and the nominal observation mode of the new configuration, measured at Optimized Resolution (OR) and introduced in 2005. Further to the main targets, minor species N2O5, ClONO2, COF2, CFC-11, and CFC-12 for the FR mission only have been included in MIPAS2D to enhance its applicability in studies of stratospheric chemistry. The database is continuously updated with the analysis of the ongoing measurements that are planned to last until the end of 2013 and extended to other targets. The GMTR algorithm is operated on a fixed vertical grid coincident with the tangent altitudes of the FR nominal mode, spanning the altitude range from 6 to 68 km. In the horizontal domain, FR measurements are retrieved on both the observational grid and an equispaced 5 latitudinal-degrees grid which is made possible by the 2-dimensional retrieval algorithm. The analysis of MIPAS OR observations is operated on the same altitude-latitude fixed retrieval grid used for the FR measurements. This choice provides a database with a homogeneous altitude and latitude grid, over the whole globe, covering to date about seven years of measurements. The equispaced latitude grid provides a new and convenient layout for the much needed synergetic studies of data from various instrumental and modeling sources. MIPAS2D is available to the scientific community through the two web sites http://www.mbf.fci.unibo.it/mipas2d.html, and http://www.isac.cnr.it/~rss/mipas2d.htm