Science Update: Chemical ionization mass spectrometry measurements of low-ppm mixing ratios of water vapour in the UTLS

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.

Science Update: Cost effective trace gas measurements for long term monitoring of stratospheric circulation

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.

Science Update: Influence of an internally-generated QBO on stratospheric climate and chemistry

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.

Science Update: 35 years of stratospheric aerosol measurements at Garmisch-Partenkirchen

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.