In a new GRL article, A. Scaife and co-authors examine the predictability of the Quasi-Biennial Oscillation (QBO) in initialised climate forecasts extending out to lead times of years using coupled ocean-atmosphere models with internally generated QBOs. They demonstrate the predictability of the QBO extending out to more than three years, with correlation scores exceeding 0.7 at a lead-time of 12 months. Predictability could be further improved through better initialisation and more realistic representation of the QBO, although this may depend on the realism of the gravity wave parameterisation used. They also show that predictability is lowest in winter and that skilful prediction of the QBO does not guarantee predictability of the extra-tropical winter teleconnection so important for surface winter climate prediction. The full abstract can be found here.

Abstract submission and application for financial support now close on 28 February. The MOZAIC-IAGOS Scientific Symposium on Atmospheric Composition Observation by Commercial Aircraft will take place in Toulouse, France, 12-15 May 2014.

Find website.

M. Ern and co-authors present a new study in JGR using satellite observations to improve the representation of the quasi-biennial oscillation (QBO) in models. This improvement requires a better understanding of the driving of the QBO by atmospheric waves, which remains highly uncertain because of the small horizontal scales involved and because no direct estimation based on global observations yet exists. They derive gravity wave momentum fluxes from temperature observations form the HIRDLS and SABER satellite instruments, and show that waves with wavelengths <10km interact most strongly with the QBO. They estimate gravity wave drag and compare this to the missing drag in the tropical momentum budget of ERA-Interim. During eastward wind shear the observations agree well with ERA-Interim, however, during westward wind shear the observations are two times lower than ERA-Interim. This possibly suggests that uncertainties in the ERA-Interim advection terms remain. They find that the tropical gravity waves are strongly intermittent and thus may play in important role in terms of QBO formation. This may have important implications for gravity wave parameterisation in models. The full abstract can be found here.

The second Chemistry Climate Model Initiative (CCMI) Meeting will be held in Lancaster, UK from 20-22 May 2014.

CCMI is a joint project of IGAC and SPARC with the aim to investigate and understand the historical and projected evolution of stratospheric and tropospheric composition and chemistry, including the links between those domains, and the feedbacks with the physical climate.

We are currently compiling already submitted abstracts, and we are expecting to announce our programme in the next week or so. In the meantime, we continue to invite abstract submissions on a broad range of topics related to chemistry-climate interactions, including from modellers, measurement scientists and data analysts.
More details, including registration can be found on the meeting website: http://www.lancaster.ac.uk/ccmi2014

FINANCIAL SUPPORT

Limited financial support is available to support attendance, with a preference for early career scientists and those coming from developing nations and countries in transition. Please see: http://www.lancaster.ac.uk/ccmi2014/support/

KEY DATES – ***PLEASE NOTE UPDATED DEADLINES***

Financial support deadline: 28th February 2014 (including abstract submission)

Abstract submission: 14th March 2014

Registration deadline: 1st April 2014

In addition, rooms in the meeting hotel can only be block booked for a limited time, so early accommodation booking is advised.

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.

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

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.

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.

In a recent ACPD article, M. Sinnhuber and co-authors use MIPAS observations to investigate the impact of energetic particle precipitation on the NO_x 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 NO_x 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.

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.