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This paper provides a detailed description of the atmospheric conditions characterizing the high Himalayas, thanks to continuous observations begun in March 2006 at the Nepal Climate Observatory-Pyramid (NCO-P) located at 5079 m a.s.l. on the southern foothills of Mt. Everest, in the framework of ABC-UNEP and SHARE-Ev-K2-CNR projects. The work presents a characterization of meteorological conditions and air-mass circulation at NCO-P during the first two years of activity. The mean values of atmospheric pressure, temperature and wind speed recorded at the site were: 551 hPa, −3.0 °C, 4.7 m s−1, respectively. The highest seasonal values of temperature (1.7 °C) and relative humidity (94%) were registered during the monsoon season, which was also characterized by thick clouds, present in about 80% of the afternoon hours, and by a frequency of cloud-free sky of less than 10%. The lowest temperature and relative humidity seasonal values were registered during winter, −6.3 °C and 22%, respectively, the season being characterised by mainly cloud-free sky conditions and rare thick clouds. The summer monsoon influenced rain precipitation (seasonal mean: 237 mm), while wind was dominated by flows from the bottom of the valley (S–SW) and upper mountain (N–NE). The atmospheric composition at NCO-P has been studied thanks to measurements of black carbon (BC), aerosol scattering coefficient, PM1, coarse particles and ozone. The annual behaviour of the measured parameters shows the highest seasonal values during the pre-monsoon (BC: 316.9 ng m−3, PM1: 3.9 μg m−3, scattering coefficient: 11.9 Mm−1, coarse particles: 0.37 cm−3 and O3: 60.9 ppbv), while the lowest concentrations occurred during the monsoon (BC: 49.6 ng m−3, PM1: 0.6 μg m−3, scattering coefficient: 2.2 Mm−1, and O3: 38.9 ppbv) and, for coarse particles, during the post-monsoon (0.07 cm−3. At NCO-P, the synoptic-scale circulation regimes present three principal contributions: Westerly, South-Westerly and Regional, as shown by the analysis of in-situ meteorological parameters and 5-day LAGRANTO back-trajectories. The influence of the brown cloud (AOD>0.4) extending over Indo–Gangetic Plains up to the Himalayan foothills has been evaluated by analysing the in-situ concentrations of the ABC constituents. This analysis revealed that brown cloud hot spots mainly influence the South Himalayas during the pre-monsoon, in the presence of very high levels of atmospheric compounds (BC: 1974.1 ng m−3, PM1: 23.5 μg m−3, scattering coefficient: 57.7 Mm−1, coarse particles: 0.64 cm−3, O3: 69.2 ppbv, respectively). During this season 20% of the days were characterised by a strong brown cloud influence during the afternoon, leading to a 5-fold increased in the BC and PM1 values, in comparison with seasonal means. Our investigations provide clear evidence that, especially during the pre-monsoon, the southern side of the high Himalayan valleys represent a \"direct channel\" able to transport brown cloud pollutants up to 5000 m a.s.l., where the pristine atmospheric composition can be strongly influenced.

This work investigates the variability of ozone (O3), carbon monoxide (CO) and equivalent black carbon (BC) at the Italian Climate Observatory \"O. Vittori\" (ICO-OV), part of the Mt. Cimone global GAW-WMO station (Italy). For this purpose, ICO-OV observations carried out in the period January 2007–June 2009, have been analyzed and correlated with the outputs of the FLEXPART Lagrangian dispersion model to specifically evaluate the influence of biomass burning (BB) and anthropogenic emissions younger than 20 days. During the investigation period, the average O3, CO and BC at ICO-OV were 54 ± 3 ppb, 122 ± 7 ppb and 213 ± 34 ng m−3 (mean ± expanded uncertainty with p < 95%), with clear seasonal cycles characterized by summer maxima and winter minima for O3 and BC and spring maximum and summer minimum for CO. According to FLEXPART outputs, BB impact is maximized during the warm months from July to September but appeared to have a significant contribution to the observed tracers only during specific transport events. We characterised in detail five \"representative\" events with respect to transport scales (i.e. global, regional and local), source regions and O3, CO and BC variations. For these events, very large variability of enhancement ratios O3/CO (from −0.22 to 0.71) and BC/CO (from 2.69 to 29.83 ng m−3 ppb−1) were observed. CO contributions related with anthropogenic emissions (COant) contributed to 17.4% of the mean CO value observed at ICO-OV, with the warm months appearing particularly affected by transport events of air-masses rich in anthropogenic pollution. The proportion of tracer variability that is described by FLEXPART COant peaked to 37% (in May–September) for CO, 19% (in May–September) for O3 and 32% (in January–April) for BC. During May–September, the analysis of the correlation among CO, O3 and BC as a function of the COant indicated that ICO-OV was influenced by air-masses rich in anthropogenic pollution transported from the regional to the global scale. On the other side, CO and O3 were negatively correlated during October–December, when FLEXPART does not show significant presence of recent anthropogenic emissions and only a few observations are characterized by enhanced BC. Such behaviour may be attributed to an ensemble of processes concurrent in enhancing O3 with low CO (upper troposphere/lower stratosphere intrusions) and to O3 titration by NO in polluted air-masses along with lower photochemical activity. An intermediate situation occurs in January–April when CO and O3 were almost uncorrelated and BC enhancements were associated to relatively old (10 days) anthropogenic emissions.

A Kalman-filter based inverse emission estimation method for long-lived trace gases is presented for use in conjunction with a Lagrangian particle dispersion model like FLEXPART. The sequential nature of the approach allows tracing slow seasonal and interannual changes rather than estimating a single period-mean emission field. Other important features include the estimation of a slowly varying concentration background at each measurement station, the possibility to constrain the solution to non-negative emissions, the quantification of uncertainties, the consideration of temporal correlations in the residuals, and the applicability to potentially large inversion problems. The method is first demonstrated for a set of synthetic observations created from a prescribed emission field with different levels of (correlated) noise, which closely mimics true observations. It is then applied to real observations of the three halocarbons HFC-125, HFC-152a and HCFC-141b at the remote research stations Jungfraujoch and Mace Head for the quantification of emissions in Western European countries from 2006 to 2010. Estimated HFC-125 emissions are mostly consistent with national totals reported to UNFCCC in the framework of the Kyoto Protocol and show a generally increasing trend over the considered period. Results for HFC-152a are much more variable with estimated emissions being both higher and lower than reported emissions in different countries. The highest emissions of the order of 700–800 Mg yr−1 are estimated for Italy, which so far does not report HFC-152a emissions. Emissions of HCFC-141b show a continuing strong decrease as expected due to its controls in developed countries under the Montreal Protocol. Emissions from France, however, were still rather large, in the range of 700–1000 Mg yr−1 in the years 2006 and 2007 but strongly declined thereafter.

High frequency, in situ observations from 11 globally distributed sites for the period 1994–2014 and archived air measurements dating from 1978 onward have been used to determine the global growth rate of 1,1-difluoroethane (HFC-152a, CH3CHF2). These observations have been combined with a range of atmospheric transport models to derive global emission estimates in a top-down approach. HFC-152a is a greenhouse gas with a short atmospheric lifetime of about 1.5 years. Since it does not contain chlorine or bromine, HFC-152a makes no direct contribution to the destruction of stratospheric ozone and is therefore used as a substitute for the ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). The concentration of HFC-152a has grown substantially since the first direct measurements in 1994, reaching a maximum annual global growth rate of 0.84 ± 0.05 ppt yr−1 in 2006, implying a substantial increase in emissions up to 2006. However, since 2007, the annual rate of growth has slowed to 0.38 ± 0.04 ppt yr−1 in 2010 with a further decline to an annual average rate of growth in 2013–2014 of −0.06 ± 0.05 ppt yr−1. The annual average Northern Hemisphere (NH) mole fraction in 1994 was 1.2 ppt rising to an annual average mole fraction of 10.1 ppt in 2014. Average annual mole fractions in the Southern Hemisphere (SH) in 1998 and 2014 were 0.84 and 4.5 ppt, respectively. We estimate global emissions of HFC-152a have risen from 7.3 ± 5.6 Gg yr−1 in 1994 to a maximum of 54.4 ± 17.1 Gg yr−1 in 2011, declining to 52.5 ± 20.1 Gg yr−1 in 2014 or 7.2 ± 2.8 Tg-CO2 eq yr−1. Analysis of mole fraction enhancements above regional background atmospheric levels suggests substantial emissions from North America, Asia, and Europe. Global HFC emissions (so called “bottom up” emissions) reported by the United Nations Framework Convention on Climate Change (UNFCCC) are based on cumulative national emission data reported to the UNFCCC, which in turn are based on national consumption data. There appears to be a significant underestimate ( >  20 Gg) of “bottom-up” reported emissions of HFC-152a, possibly arising from largely underestimated USA emissions and undeclared Asian emissions.

Since the introduction of human assisted reproduction, oocyte cryopreservation has been regarded as an attractive option to capitalize the reproductive potential of surplus oocytes and preserve female fertility. However, for two decades the endeavor to store oocytes has been limited by the not yet optimized methodologies, with the consequence of poor clinical outcome or of uncertain reproducibility. Vitrification has been developed as the promising technology of cryopreservation even if slow freezing remains a suitable choice. Nevertheless, the insufficiency of clinical and correlated multidisciplinary data is still stirring controversy on the impact of this technique on oocyte integrity. Morphological studies may actually provide a great insight in this debate. Phase contrast microscopy and other light microscopy techniques, including cytochemistry, provided substantial morphofunctional data on cryopreserved oocyte, but are unable to unraveling fine structural changes. The ultrastructural damage is one of the most adverse events associated with cryopreservation, as an effect of cryo-protectant toxicity, ice crystal formation and osmotic stress. Surprisingly, transmission electron microscopy has attracted only limited attention in the field of cryopreservation. In this review, the subcellular structure of human mature oocytes following vitrification is discussed at the light of most relevant ultrastructural studies.

Methyl chloroform (MCF) is a man-made chlorinated solvent contributing to the destruction of stratospheric ozone and is controlled under the \"Montreal Protocol on Substances that Deplete the Ozone Layer\" and its amendments, which called for its phase-out in 1996 in developed countries and 2015 in developing countries. Long-term, high-frequency observations of MCF carried out at three European sites show a constant decline in the background mixing ratios of MCF. However, we observe persistent non-negligible mixing ratio enhancements of MCF in pollution episodes, suggesting unexpectedly high ongoing emissions in Europe. In order to identify the source regions and to give an estimate of the magnitude of such emissions, we have used a Bayesian inversion method and a point source analysis, based on high-frequency long-term observations at the three European sites. The inversion identified southeastern France (SEF) as a region with enhanced MCF emissions. This estimate was confirmed by the point source analysis. We performed this analysis using an 11-year data set, from January 2002 to December 2012. Overall, emissions estimated for the European study domain decreased nearly exponentially from 1.1 Gg yr−1 in 2002 to 0.32 Gg yr−1 in 2012, of which the estimated emissions from the SEF region accounted for 0.49 Gg yr−1 in 2002 and 0.20 Gg yr−1 in 2012. The European estimates are a significant fraction of the total semi-hemisphere (30–90° N) emissions, contributing a minimum of 9.8% in 2004 and a maximum of 33.7% in 2011, of which on average 50% are from the SEF region. On the global scale, the SEF region is thus responsible for a minimum of 2.6% (in 2003) and a maximum of 10.3% (in 2009) of the global MCF emissions.

HCFC-22 (CHClF2, chlorodifluoromethane) is an ozone-depleting substance (ODS) as well as a significant greenhouse gas (GHG). HCFC-22 has been used widely as a refrigerant fluid in cooling and air-conditioning equipment since the 1960s, and it has also served as a traditional substitute for some chlorofluorocarbons (CFCs) controlled under the Montreal Protocol. A low frequency record on tropospheric HCFC-22 since the late 1970s is available from measurements of the Southern Hemisphere Cape Grim Air Archive (CGAA) and a few Northern Hemisphere air samples (mostly from Trinidad Head) using the Advanced Global Atmospheric Gases Experiment (AGAGE) instrumentation and calibrations. Since the 1990s high-frequency, high-precision, in situ HCFC-22 measurements have been collected at these AGAGE stations. Since 1992, the Global Monitoring Division of the National Oceanic and Atmospheric Administration/Earth System Research Laboratory (NOAA/ESRL) has also collected flasks on a weekly basis from remote sites across the globe and analyzed them for a suite of halocarbons including HCFC-22. Additionally, since 2006 flasks have been collected approximately daily at a number of tower sites across the US and analyzed for halocarbons and other gases at NOAA. All results show an increase in the atmospheric mole fractions of HCFC-22, and recent data show a growth rate of approximately 4% per year, resulting in an increase in the background atmospheric mole fraction by a factor of 1.7 from 1995 to 2009. Using data on HCFC-22 consumption submitted to the United Nations Environment Programme (UNEP), as well as existing bottom-up emission estimates, we first create globally-gridded a priori HCFC-22 emissions over the 15 yr since 1995. We then use the three-dimensional chemical transport model, Model for Ozone and Related Chemical Tracers version 4 (MOZART v4), and a Bayesian inverse method to estimate global as well as regional annual emissions. Our inversion indicates that the global HCFC-22 emissions have an increasing trend between 1995 and 2009. We further find a surge in HCFC-22 emissions between 2005 and 2009 from developing countries in Asia – the largest emitting region including China and India. Globally, substantial emissions continue despite production and consumption being phased out in developed countries currently.

National emission inventories of ozone‐depleting substances (ODS) play a key role in the control mechanisms of the Montreal Protocol's emission reduction plans. New quasi‐continuous ground‐based atmospheric measurements allow us to estimate China's current emissions of the most effective ODS. This serves as an independent validation of China's ODS consumption data reported to the United Nations Environment Programme (UNEP). Emissions of most first‐generation ODS have declined in recent years, suggesting compliance with the regulations of China's advanced phase‐out program. In contrast the emissions of some second‐generation ODS have increased. Because China is currently one of the largest consumers of first generation ODS, the country's upcoming complete phase‐out will be crucial for the rate of decline of atmospheric ODS hence the eventual recovery of the stratospheric ozone.

The performance of 18 European institutions involved in long-term non-methane hydrocarbon (NMHC) measurements in ambient air within the framework of the Global Atmosphere Watch (GAW) and the European Monitoring and Evaluation Programme (EMEP) was assessed with respect to data quality objectives (DQOs) of ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure Network) and GAW. Compared to previous intercomparison studies the DQOs define a novel approach to assess and ensure a high quality of the measurements. Having already been adopted by GAW, the ACTRIS DQOs are demanding with deviations to a reference value of less than 5 % and a repeatability of better than 2 % for NMHC mole fractions above 0.1 nmol mol−1. The participants of the intercomparison analysed two dry gas mixtures in pressurised cylinders, a 30-component NMHC mixture in nitrogen (NMHC_N2) at approximately 1 nmol mol−1 and a whole air sample (NMHC_air), following a standardised operation procedure including zero- and calibration gas measurements. Furthermore, participants had to report details on their instruments and assess their measurement uncertainties. The NMHCs were analysed either by gas chromatography–flame ionisation detection (GC-FID) or by gas chromatography–mass spectrometry (GC-MS). For the NMHC_N2 measurements, 62 % of the reported values were within the 5 % deviation class corresponding to the ACTRIS DQOs. For NMHC_air, generally more frequent and larger deviations to the assigned values were observed, with 50 % of the reported values within the 5 % deviation class. Important contributors to the poorer performance in NMHC_air compared to NMHC_N2 were a more complex matrix and a larger span of NMHC mole fractions (0.03–2.5 nmol mol−1). The performance of the participating laboratories were affected by the different measurement procedures such as the usage of a two-step vs. a one-step calibration, breakthroughs of C2–C3 hydrocarbons in the focussing trap, blank values in zero-gas measurements (especially for those systems using a Nafion® Dryer), adsorptive losses of aromatic compounds, and insufficient chromatographic separation.

The International Halocarbons in Air Comparison Experiment (IHALACE) was conducted to document relationships between calibration scales among various laboratories that measure atmospheric greenhouse and ozone depleting gases. This study included trace gases such as chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs), as well as nitrous oxide, methane, sulfur hexafluoride, very short-lived halocompounds, and carbonyl sulfide. Many of these gases are present in the unpolluted atmosphere at pmol mol−1 (parts per trillion) or nmol mol−1 (parts per billion) levels. Six stainless steel cylinders containing natural and modified natural air samples were circulated among 19 laboratories. Results from this experiment reveal relatively good agreement (within a few percent) among commonly used calibration scales. Scale relationships for some gases, such as CFC-12 and CCl4, were found to be consistent with those derived from estimates of global mean mole fractions, while others, such as halon-1211 and CH3Br, revealed discrepancies. The transfer of calibration scales among laboratories was problematic in many cases, meaning that measurements tied to a particular scale may not, in fact, be compatible. Large scale transfer errors were observed for CH3CCl3 (10–100%) and CCl4 (2–30%), while much smaller scale transfer errors (< 1%) were observed for halon-1211, HCFC-22, and HCFC-142b. These results reveal substantial improvements in calibration over previous comparisons. However, there is room for improvement in communication and coordination of calibration activities with respect to the measurement of halogenated and related trace gases.