In a new ACPD article, N. Eguchi et al. use the NICAM global non-hydrostatic model to investigate the dynamical coupling between the stratosphere and troposphere in the tropical tropopause layer (TTL) during a stratospheric sudden warming (SSW) in boreal winter. The model reproduced the observed tropical tropospheric changes well, including the enhancement of convective activity following the amplification of planetary waves. They found that deep convective activity was enhanced from 10-20°S and although this upwelling in the TTL was correlated with that occurring in the stratosphere, the TTL temperature tendency was controlled mainly by diabatic heating originating from cloud formation. This suggests that the stratospheric meridional circulation affects cloud formation in the TTL. The full abstract can be found here.

The 13th Quadrennial iCACGP Symposium and 13th IGAC Science Conference to be held on 22-26 September 2014 in Natal, Brazil, extended its deadline for abstract submission and Young Scientist support to 31 March.

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In a new ACPD paper, A. Schanz and co-authors use the WACCM model to study the diurnal ozone cycle in the stratosphere, exploring its underlying photochemical and dynamical processes. The analysis is focused on the middle stratosphere at 5hPa where the simulated ozone diurnal cycle shows a minimum after sunrise and maximum in the late afternoon. They find that this diurnal cycle varies seasonally and spatially, with a maximum amplitude of 15% (0.8ppmv) occurring at the polar circle in summer. They show that the global pattern of the diurnal ozone cycle is governed by the solar zenith angle and sunshine duration. They also find that the synoptic scale variability of the diurnal ozone cycle is often anti-correlated with regional temperature anomalies due to the temperature dependence of the Chapman cycle reactions. Furthermore, at high latitudes increased westerly (easterly) winds cause a decrease (increase) in the sunshine duration of an air parcel leading to a weaker (stronger) diurnal ozone cycle. The full abstract can be found here.

The January 2014 issue of the SPARC newsletter No. 42 is now available with articles on the following topics:

• Report on the 34th Session of the Joint Scientific Committee of the World Climate Research Programme
• The SPARC Activity "Lifetime of halogen source gases"
• IUPAC Task Group on Atmospheric Chemical Kinetic Data Evaluation
• Report on the IGAC/SPOARC Chemistry-Climate Model Initiative (CCMI) 2013 Science Workshop
• Workshop on Research Applications of High Resolution Radiosonde Data
• Report on the 7th Atmospheric Limb Conference
• Report on the Atmospheric Composition and the summer Asian Monsoon (ACAM) Workshop
• 5th SPARC General Assembly: A brief look back

Find CLIVAR Bulletin February 2014 with the following content:

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.

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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.