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This paper explains the research process carried out for the development and manufacture of the planetary protection cover for carrying out the electromagnetic compatibility (EMC) tests of the an-isotropic magneto-resistance (AMR) sensor of the ExoMars 2020 mission. This mission has strict bioburden requirements. The electromagnetic properties of several materials have been analyzed in order to study their transmission coefficient and the innovation of this project is the use of fused deposition modeling (FDM) technology as manufacturing method. Additive manufacturing is presented as a promising technology in the field of radiofrequency since it can use a wide range of polymeric materials (thermoplastics) with low transmission coefficient. Observing the electromagnetic (EM) characterization results, it was decided to manufacture a protective cover using FDM technology, because it allows control over the grounding of the instrument and facilitates the integration, cleaning and protection against impacts during the manipulation, with great versatility and low cost. Finally, the cover has been verified during the acceptance EMC tests of the flight model AMR instrument. This work has received funding from the Ministerio de Econom´ıa, Industria y Competitividad (MEIC) Projects TEC2016-79214-C3-1-R, ESP2015-70184-R and ESP2017- 88930-R. Preprint

Polar stratospheric clouds (PSCs) play an important role in polar ozone depletion, since they are involved in diverse ozone destruction processes (chlorine activation, denitrification). The degree of that ozone reduction is depending on the type of PSCs, and hence on their occurrence. Therefore PSC characterization, mainly focused on PSC-type discrimination, is widely demanded. The backscattering (R) and volume linear depolarization (δV) ratios are the parameters usually used in lidar measurements for PSC detection and identification. In this work, an improved version of the standard NASA/Micro Pulse Lidar (MPL-4), which includes a built-in depolarization detection module, has been used for PSC observations above the coastal Antarctic Belgrano II station (Argentina, 77.9° S 34.6° W, 256 m a.s.l.) since 2009. Examination of the MPL-4 δV feature as a suitable index for PSC-type discrimination is based on the analysis of the two-channel data, i.e., the parallel (p-) and perpendicular (s-) polarized MPL signals. This study focuses on the comparison of coincident δV-profiles as obtained from ground-based MPL-4 measurements during three Antarctic winters with those reported from the space-borne lidar CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) aboard the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) satellite in the same period (83 simultaneous cases are analysed for 2009–2011 austral winter times). Three different approaches are considered for the comparison analysis between both lidar profile data sets in order to test the degree of agreement: the correlation coefficient (CC), as a measure of the relationship between both PSC vertical structures; the mean differences together with their root mean square (RMS) values found between data sets; and the percentage differences (BIAS), parameter also used in profiling comparisons between CALIOP and other ground-based lidar systems. All of them are examined as a function of the CALIPSO ground-track distance from the Belgrano II station. Results represent a relatively good agreement between both ground-based MPL-4 and space-borne CALIOP profiles of the volume linear depolarization ratio δV for PSC events, once the MPL-4 depolarization calibration parameters are applied. Discrepancies between CALIOP and MPL-4 profiles in vertical layering structure are enhanced from 20 km up, likely due to a decrease of the signal-to-noise ratio (SNR) for both lidar systems at those altitudes. Regarding the results obtained from the mean and the percentage differences found between MPL-4 and CALIOP δV profiles, a predominance of negative values is also observed, indicating a generalized underestimation of the MPL-4 depolarization as compared to that reported by CALIOP. However, absolute differences between those δV-profile data sets are no higher than a 10 ± 11% in average. Moreover, the degree of agreement between both lidar δV data sets is slightly dependent on the CALIPSO ground-track overpass distance from the Belgrano II station. That is, small discrepancies are found when CALIPSO ground-track distance is as close as far from the ground-based station. These results would indicate that MPL-4 depolarization observations would reflect relatively well the PSC field that CALIOP can detect at relatively large distances from the ground-based station. As a consequence, PSC properties can be statistically similar, on average, over large volumes, and hence the present weak disagreement found between both the lidar δV data sets can be likely dominated by small spatial PSC inhomogeneities along the CALIPSO separation from the station. This statement is based on the fact that Belgrano II is a station located well inside the stable Antarctic polar vortex, allowing determined thermodynamic conditions leading to a very low variability in the PSC field, and in their properties.

Chemical ozone destruction occurs over both polar regions in local winter–spring. In the Antarctic, essentially complete removal of lower-stratospheric ozone currently results in an ozone hole every year, whereas in the Arctic, ozone loss is highly variable and has until now been much more limited. Here we demonstrate that chemical ozone destruction over the Arctic in early 2011 was—for the first time in the observational record—comparable to that in the Antarctic ozone hole. Unusually long-lasting cold conditions in the Arctic lower stratosphere led to persistent enhancement in ozone-destroying forms of chlorine and to unprecedented ozone loss, which exceeded 80 per cent over 18–20 kilometres altitude. Our results show that Arctic ozone holes are possible even with temperatures much milder than those in the Antarctic. We cannot at present predict when such severe Arctic ozone depletion may be matched or exceeded. Since its emergence in the 1980s, the Antarctic ozone hole, the near-complete loss of lower-stratospheric ozone, has occurred every year. The possibility that a similar effect might occur in the Northern Hemisphere has been debated, but despite considerable variation in ozone levels in the Arctic, they had not reached the extremes seen in the south. Until this year. Observations made in the late winter and early spring of 2011 reveal ozone loss far outside the range previously observed over the Northern Hemisphere, comparable to some Antarctic ozone holes. The formation of the hole was driven by an unusually long cold snap and a high level of ozone-destroying chlorine. Although this effect is dramatic, it is difficult to predict whether similar Arctic ozone holes will develop in future.

Observations of surface ozone (O3) mixing ratios carried out during two ground-based field campaigns in the Galapagos Islands are reported. The first campaign, Primera Investigacion sobre la Quimica, Evolucion y Reparto de Ozono, was carried out from September 2000 to July 2002. The second study, Climate and HAlogen Reactivity tropicaL EXperiment, was conducted from September 2010 to March 2012. These measurements complement the Southern Hemisphere ADditional OZonesonde observations made with weekly to monthly frequency at Galapagos. In this work, the daily, intraseasonal, seasonal and interannual variability of O3 in the marine boundary layer are described and compared to those observed in other tropical locations. The O3 diurnal cycle shows two regimes: (i) photochemical destruction followed by nighttime recovery in the cold season (July to November) and (ii) daytime advection and photochemical loss followed by nighttime depositional loss associated to windless conditions in the warm season (February to April). Wavelet spectral analysis of the intraseasonal variability of O3 reveals components with periods characteristic of tropical instability waves. The O3 seasonal variation in Galapagos is typical of the Southern Hemisphere, with a maximum in August and a minimum in February–March. Comparison with other measurements in remote tropical ocean locations shows that the change of the surface O3 seasonal cycle across the equator is explained by the position of the Intertropical Convergence Zone and the O3 levels upwind.

This work presents a comparison of aerosol properties measured by in situ and remotesensing instrumentation over an urban background site in Madrid (Spain) in autumn 2010. Aerosol size distribution was characterized at ground level by the combined use of two instruments and also in elevated layers by airborne in situ instrumentation. Simultaneously, vertically resolved lidar profiles provided information about the optical properties of aerosols present in the different layers observed. Backscatter-derived ??ngstr??m exponent, calculated using Mie theory with volume size distribution detected experimentally, yielded values lower than 0.5 near ground level, increasing to over 1.5 in elevated layers. The same trend was observed for values obtained using the lidar system. Size distribution measured at elevated layers indicated that the large exponents observed there are associated with size distribution, with a negligible contribution of coarse particles. The results are compromised by the major uncertainty associated with the backscatter-derived ??ngstr??m exponents, due to the low aerosol load detected in the elevated layers.

Polar Stratospheric Clouds (PSCs) play an important role in polar ozone depletion. In particular ice clouds, type PSC-II, with respect to the type PSC-I (nitric acid clouds) produce the most significant effects. Therefore PSC characterization, mainly focused on PSC-II discrimination is needed. The backscattering (R) and volume linear depolarization (δV) ratios are the parameters usually used in lidar measurements for PSC detection and identification. In this work, an improved version of the standard NASA/Micro Pulse Lidar (MPL-4), which includes a built-in depolarization detection module, has been used for PSC observations above the coastal Antarctic Belgrano II station (Argentina, 77.9° S 34.6° W, 256 m a.s.l.) since 2009. Examination of the MPL-4 δV feature as a suitable index for PSC-type discrimination is based on the analysis of the two-channel data, i.e. the parallel (p-) and perpendicular (s-) polarized MPL signals. This study focuses on the comparison of simultaneous δV-profiles as obtained from ground-based MPL-4 measurements during three Antarctic winters with those reported from the space-borne lidar CALIOP aboard the CALIPSO satellite in the same period (48 simultaneous cases are analysed for 2009–2011 austral winter times). Two different variables are considered for the comparison analysis between both lidar datasets in order to test the degree of agreement: the correlation coefficient (CC) and the percentage difference (BIAS). Results indicate a relatively good correlation between the δV-profiles once MPL-4 depolarization calibration parameters are applied. This correlation is based on the linear fitted height-range of the layered structure, obtaining CC values higher than 0.5 for 54% (26 cases) out of all the analysed cases (48 in total). However, less satisfactory results are found when the BIAS test is used in the comparison procedure to test the degree of agreement between the lidar datasets. A predominance of negative BIAS values are observed showing that the MPL-4 δV values are underestimated with respect to CALIOP data; however, differences between the MPL-4 datasets are no greater than an 11% (absolute value) with respect to CALIOP values. Moreover, the agreement appears to be unexpectedly independent of the CALIPSO ground-track overpass distance from the Belgrano II station. Consequently, differences between the δV datasets are not dominated by spatial inhomogeneity of the PSC field.

International audience; The Arctic polar vortex exhibited widespread regions of low temperatures during the winter of 2005, resulting in significant ozone depletion by chlorine and bromine species. We show that chemical loss of column ozone (ΔO3) and the volume of Arctic vortex air cold enough to support the existence of polar stratospheric clouds (VPSC) both exceed levels found for any other Arctic winter during the past 40 years. Cold conditions and ozone loss in the lowermost Arctic stratosphere (e.g., between potential temperatures of 360 to 400 K) were particularly unusual compared to previous years. Measurements indicate ΔO3 = 121 +/- 20 DU and that ΔO3 versus VPSC lies along an extension of the compact, near linear relation observed for previous Arctic winters. The maximum value of VPSC during five to ten year intervals exhibits a steady, monotonic increase over the past four decades, indicating that the coldest Arctic winters have become significantly colder, and hence are more conducive to ozone depletion by anthropogenic halogens.

Radiosonde temperature profiles from Belgrano (78° S) and other Antarctic stations have been compared with European Centre for Medium-Range Weather Forecasting (ECMWF) and National Centers for Environmental Prediction (NCEP) operational analyses during the winter of 2003. Results show good agreement between radiosondes and NCEP and a bias in the ECMWF model which is height and temperature dependent, being up to 3°C too cold at 80 and 25–30 hPa, and hence resulting in an overestimation of the predicted potential PSC areas. Here we show the results of the comparison and discuss the potential implications that this bias might have on the ozone depletion computed by Chemical Transport Models based on ECMWF temperature fields, after rejecting the possibility of a bias in the sondes at extreme low temperatures.