A recent ACP article by M.C. Parrondo and co-authors looked at 13 years of ozone soundings taken at the Antarctic Belgrano II station. These observations, taken inside the polar vortex when chemical ozone depletion occurs, are particularly valuable during the winter period, when satellite and ground-based observations based on solar radiation are lacking. The decrease of total ozone in spring was found to strongly depend on meteorological conditions, with greatest depletion occurring during coldest years (up to 59%) and considerably less occurring in warmer years (22%). In addition, they found that about 11% of total ozone loss in the layer where maximum depletion occurs takes place before the sun returns and occurs rather as a result of transport of low latitude air masses into the region, indicative of mixing inside the vortex. Comparison with observations from the South Pole station suggest that ozone loss rates at Belgrano are up to 25% lower than at the South Pole. The full abstract can be found here.

F. Moore and co-authors propose a cost effective stratospheric trace gas measurement program using balloon-based sondes and AirCore sampler techniques as a means to monitor the strength of the Brewer Dobson circulation. This BAMS paper outlines a program that would consist of regular trace gas profile measurements taken at several latitudes, making use of relatively low cost AirCore and sonde techniques. Find the full abstract here.

T.D. Thronberry and co-authors use a chemical ionization mass spectrometer (CIMS) instrument to measure low water vapour mixing ratios in the upper troposphere/lower stratosphere (UTLS). The instrument performed well during 7 different flights, measuring water vapour mixing ratios as low as 3.5ppm near the tropopause. Measurement uncertainty was estimated between 9-11%. Find the full abstract here.

A recent paper in Climate Dynamics by Paula L.M. Gonzalez and co-authors focuses on understanding the regional precipitation trends in South Eastern South America (SESA). Using 6 different climate models they show that the impact of ozone depletion on SESA precipitation has been as large as, or possibly even larger than, the impact of increasing greenhouse gas concentrations over the period 1960-1999. Find the full abstract here.

A recent ACP paper by B. Hassler and co-authors compares three vertically-resolved ozone data sets, the data set of Randel and Wu (2007), Cionni et al., (2011) and Bodeker et al., (2013). All three data sets represent multiple-linear regression fits to vertically resolved ozone observations and cover at least the period from 1979-2005. They find that the main differences among the data sets result from the underlying regression models used, which use different observations and include different basis functions. Climatologies, trends and calculated stratospheric ozone radiative forcing are compared between the three data sets as well. Find the full abstract here.

K.A. Tereszchuk and co-authors present a new PAN (peroxyacetyl nitrate) data product from the ACE-FTS satellite in a recent ACP paper. The estimated detection limit is 5pptv while the total systematic error contribution to the retrieval is approximately 16%. Comparison between the ACE-FTS product and measurements from the MIPAS instrument demonstrate good agreement, differing by no more than 70pptv. The data are used to produce zonal mean distributions of seasonal averages from 5-20km, with a strong seasonality being observed in the UTLS. Find the full abstract here.

T. Trickl and co-authors have just published an ACP paper looking at 35 years of stratospheric aerosol measurements taken at Garmisch-Partenkirchen, Germany. They focused largely on the volcanically quiescent period of 1995-2006 to investigate the processes maintaining a residual lower stratospheric aerosol layer. Their results indicate that the influence of air traffic on stratospheric aerosol loading is small and that although single, large forest-fire events could be noticed, overall biomass burning also seems to have a limited impact on the stratospheric background aerosol. Post 2008 they observed an increase in backscatter coefficients largely due to mid-sized (explosivity index 4) volcanic eruptions, most of which occurred in the mid-latitudes. Find the full abstract here.

A model study using GEOSCCM by M.M. Hurwitz and colleagues published in ACPD looked at the influence of an internally-generated QBO on modelled stratospheric climate and ozone. They found that the inclusion of the QBO slows the meridional circulation, thus increasing the mean stratospheric age-of-air. This, in addition to changes in stratospheric temperature, were found to affect the ozone, methane and nitrous oxide distributions. The modelled QBO also enhanced polar stratospheric variability in winter. Differences between simulations with and without a QBO show a bias toward the westerly phase of the QBO, and resultant polar stratospheric cooling, strengthening of the polar stratospheric jet and a small decrease in Arctic lower stratospheric ozone. Find the full abstract here.

In a recent Journal of Geophysical Research paper, S.M. Päivärinta and colleagues investigated the effects of solar proton events (SPEs) and sudden stratospheric warmings (SSWs) on odd nitrogen and ozone in the polar middle atmosphere using observations from ACE-FTS, MLS/Aura and SABER/TIMED. Considering three different winters, 2005 (with an SPE), 2009 (with an SSW), and 2012 (with SPEs and SSW), they found that NOx increases after both SPEs and SSWs by up to a factor of 25 between 40-90km. As a result of the enhanced NOx concentrations, strong ozone depletion occurred. Find the full abstract here.

In their recent ACPD article, A.Y. Park and co-authors take a statistical look at Umkehr ozone profiles at Boulder, USA, and Arosa, Switzerland. Using principal component analysis and a number basis functions they found that they could accurately capture fine variations in the time evolutions of ozone profiles. At Boulder, strongly declining trends from 2003-2011 at altitudes of 64-32hPa were found, indicating that stratospheric ozone over this region is not yet fully recovering. Find the full abstract here.