E. Palipane and co-authors, in a recent GRL paper, use the ECMWF IFS global AGCM run at 16km resolution to assess the benefit of resolving sub-synoptic to mesoscale processes on annular mode (AM) variability. The model run at this resolution was found to be more skilful, particularly in terms of the variance of AMs, the intrinsic e-folding time scales of the AMs, as well as the downward influence from the stratosphere to the troposphere in the AMs. The full abstract can be found 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.

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.

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.

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.

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.

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.

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.

G. Kirgis and co-authors recently published a paper in ACP regarding the interannual variability of stratospheric ozone at Mauna Loa, Hawaii, and Table Mountain, California. They used a multi-linear regression analysis on monthly mean lidar and satellite profile data between 20-45km from the volcanically quiescent period of January 1995 to April 2011. Results were consistent with recent model simulations indicating changes in tropical upwelling. They found a net increase and sign of ozone recovery after 2005. 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.