Category Archives: News

Science Update: Identification of downward propagation of Artic stratospheric climate change over recent decades

In a new Journal of Climate study, D.J. Ivy and co-authors examine changes in Arctic climate since 1979, focusing on the decadal scale. They show that dynamically quiescent years, with no major sudden stratospheric warmings, are marked by a strengthening of the Arctic polar vortex over the past 30 years. Associated changes, such as decreases in temperatures and ozone, propagate downwards into the lowermost Arctic stratosphere during late winter and early spring. This strengthening of the Arctic vortex appears to occur at higher altitudes than in the Antarctic and does not propagate as low into the troposphere, rather the signal remains confined to the uppermost troposphere. The full abstract can be found here.

Thank you for your contribution to the SPARC General Assembly

The 5th SPARC General Assembly has been a great success and most memorable event. Find information how to stay involved!

Dear GA participant,

On behalf of the SPARC Co-chairs Joan Alexander and Greg Bodeker, the local and scientific organising committees, as well
as the SPARC Office, we would like to warmly thank you for contributing to the great success of the 5th SPARC General Assembly held from 12-17 January 2014 in
Queenstown, New Zealand. The many excellent talks and posters presented at the conference as well as the lively discussions, learning opportunities, and great
fun we enjoyed together made this event most memorable!

We take this opportunity to once again welcome you to connect with ongoing and future SPARC activities and to inform you about the many ways you can stay in
touch with the rest of the community.

* We have uploaded all talks and abstracts to the conference website as well as a selection of photos:
http://www.aparc-climate.org/meetings/general-assembly-2014/
* Those of you interested in subscribing to the biannual SPARC newsletter should
subscribe right away – the January 2014 issue is due in the next week: http://www.aparc-climate.org/publications/newsletter/
* The news section and the
calendar on the SPARC website will keep you up to date: http://www.aparc-climate.org/news/news/ ; http://www.aparc-climate.org/meetings/ .

Please also keep us informed about events and activities in your region/country that might be of interest to the wider SPARC community.

With warm regards,

The SPARC Office

Science Update: Multi-model estimates of atmospheric lifetimes of long-lived ozone depleting substances: Present and future

A new JGR article by M. Chipperfield and co-authors highlights some of the modelling work that was done as part of the SPARC ‘Lifetimes of stratospheric ozone-depleting substances, their replacements, and related species’ Report (SPARC report no. 6). They diagnosed the lifetimes of long-lived source gases removed in the stratosphere using six 3D and one 2D model, which all used the same standard photochemical data. They investigate the effect of different lifetime definitions and find that different methods agree very well within the same model. Larger differences in lifetimes are calculated by different models, the main causes of which are variation in the simulated rates of ascent and horizontal mixing in the tropical mid-lower stratosphere. For 2100 conditions, the model circulation speeds generally increase, but a thicker ozone layer due to recovery and climate change reduces photolysis rates. These effects compensate so the net impact on modelled lifetimes is small. The abstract can be found here.

Science Update: Sensitivity of Northern Hemispheric winter warming patterns to ozone climatology

In a new JGR article, S. Muthers and co-authors investigate the impact of different ozone climatologies on the dynamic response to large tropical eruptions. Ensemble sensitivity experiments with a coupled ocean-atmosphere model are perturbed with a single Tambora-like eruption. They find that larger meridional gradients in lower stratospheric ozone favour the coupling of zonal wind anomalies between the stratosphere and troposphere after the eruption. Associated sea level pressure, temperature, and precipitation patterns are more pronounced and the Northern Hemisphere winter warming is significant. Results also indicate that there is a non-linear response of the dynamics to the ozone and volcanic forcings. The full abstract can be found here.

Science Update: Evaluation of UTLS hygrometer accuracy during the NASA MACPEX mission

A.W. Rollins and co-authors present new work comparing hygrometer measurements in the UTLS in a new JGR article. Disagreements between instruments at the low mixing ratios (<10ppm) typical of this region have caused uncertainties in the description of the physical processes controlling dehydration in the tropical tropopause layer and how water vapour enters the stratosphere, as well as hindering validation of satellite retrievals. Several hygrometers were flown simultaneously during the MACPEX campaign to allow for a full intercomparison of instruments. Differences between instruments were reduced compared to some other previous campaigns, but remain non-negligible (on the order of 20% or 0.8ppm). They suggest that unrecognised errors in the quantification of instrumental background for some or all of the hygrometeors are a likely cause for these differences. Until these errors are better understood, the measurement uncertainty will continue to limit our understanding of dehydration in the tropical tropopause layer and cirrus microphysical processes. The full abstract can be found here.

Science Update: NOx variability in the polar middle atmosphere from October 2003 to March 2004

In a recent ACPD article, M. Sinnhuber and co-authors use MIPAS observations to investigate the impact of energetic particle precipitation on the NOx budget in the stratosphere and lower mesosphere during a period of high solar and geomagnetic activity (October 2003-March 2004). They show that in the winter hemisphere the indirect effect of auroral electron precipitation due to downwelling of upper mesospheric/lower thermospheric air exceeds the direct impact of a very large solar proton event by nearly one order of magnitude. Although a direct effect of electron precipitation on NOx cannot be ruled out, it is lower than 3ppb from 40-56km altitude, and lower than 6ppb from 56-70km altitude. The full abstract can be found here.

Science Update: Climate system response to stratospheric ozone depletion and recovery

In a new review article, M. Previdi and L.M. Polvani, present an overview of current knowledge of the climate response to stratospheric ozone depletion and its projected recovery. Compared to greenhouse gases the radiative forcing of the observed stratospheric ozone loss is small, but despite this, significant changes in the Southern Hemisphere climate system have been observed. This has largely been seen in a shift of the tropospheric mid-latitude jet, and associated changes in tropospheric and surface temperatures, clouds, cloud radiative effects, and precipitation at both middle and low latitudes. Uncertainty, however, remains around the impact of ozone loss on sea-ice. In future, ozone recovery will figure prominently in climate change. The full abstract can be found here.

Science update: Harmonized dataset of ozone profiles from satellite measurements

V.F. Sofieva and co-authors present a new, merged ozone profile dataset based on limb and occultation measurements from several satellites (GOMOS, MIPS, SCIAMACHY, OSIRIS, SMR, and ACE-FTS). The data from each instrument are screened by the instrument teams, and provided altitude and temperature profiles are used to convert between number density and mixing ratio on a pressure or altitude grid. Tables of biases between each pair of instruments for each month are provided, as are bias uncertainties. The dataset provides high-resolution data for the 2001-2012 period in netcdf format and can be found at: http://www.esa-ozone-cci.org/?q=node/161. The full abstract can be found here.

Science update: Diurnal variability of stratospheric ozone measured at Mauna Loa

In a recent ACPD article, A. Parrish and co-authors use microwave observations from the Mauna Loa NDACC station to investigate the diurnal variation of stratospheric ozone. They compare these microwave observations with satellite measurements from Aura-MLS, UARS-MLS, SMILES and SBUV/2, as well as with output from the GEOSCCM chemistry climate model. The measurements agree with the model to better than 1.5% in most cases except the morning-night differences, which are significantly higher in the observations (2-3% from ~39-43km). The full abstract can be found here.

SPARC community meets in Queenstown, New Zealand

Today, a total of 300 scientists is gathering at the opening of the Fifth SPARC General Assembly in Queenstown, New Zealand.

This 6-day conference takes place approximately every five years attracting atmospheric and climate physicists and chemists, climate modellers, water cycle and cloud specialists and other experts from across the world. A traditional Maori welcome dance opened the conference followed by a warm welcome by Prof. Jim Metson, Chief Science Advisor at New Zealand’s Ministry of Business, Innovation and Employment.

In his address SPARC co-chair and conference convener Greg Bodeker welcomed the growing community, which is increasingly focusing on the troposphere as well as the stratosphere. In particular he welcomed the new delegates to these "family reunions", saying that "here it is where we share our latest research results and our passion for what we do. SPARC is a vibrant organisation and the value that you can derive from SPARC will, in a large part, be determined by your contribution to SPARC. So have a good week. Talk a lot. Have fun. Learn a lot. You can sleep next week."

The dense programme is organised around plenary sessions with invited lectures, poster sessions with one-minute pitches to introduce presenters and their research topics, and a series of side events. Some 80 early-career and developing country scientists sponsored by partners to the conference are attending the assembly. Sponsors include: the World Climate Research Programme; the World Meteorological Organisation and its research programmes WIGOS, GAW, and WWRP; the US National Science Foundation; the Asia-Pacific Network for Global Change Research; the Canadian Space Agency; NIWA; the Australian Research Council’s Center of Excellence for Climate System Science; ESA; Antarctica New Zealand; the Committee on Space Research COSPAR; Bodeker Scientific; TOF Werk; Aerodyne Research Inc.; Macquarie University; University of Otago; and the sponsors of the SPARC International Project Office including the Swiss Federal Institute of Technology Zurich; the Federal Office for the Environment, and the Federal Office of Meteorology and Climatology.

Find the SPARC General Assembly website.