International Network for QBO Research (QBOnet)

The atmosphere changes on time scales from seconds (or less) through to years. An example of the former are leaves swirling about the ground within a dust-devil, while an example of the latter is the quasibiennial oscillation (QBO) which occurs over the equator high up in the stratosphere. The QBO is seen as a slow meander of winds: from easterly to westerly to easterly over a time scale of about 2.5 years. This 'oscillation' is quite regular and so therefore is predictable out from months through to years. These winds have also been linked with weather events in the high latitude stratosphere during winter, and also with weather regimes in the North Atlantic and Europe. It is this combination of potential predictability and the association with weather which can affect people, businesses and ultimately economies which makes knowing more about these stratospheric winds desirable.

However, it has been difficult to get this phenomenon reproduced in global climate models. We know that to get these winds in models one needs a good deal of (vertical) resolution. Perhaps better than 600-800m vertical resolution is needed. In most GCMs with a QBO this is the case, but why? We also know that there needs to be waves sloshing about, either ones that can be 'seen' in the models, or wave effects which are inferred by parameterisations. Get the right mix of waves and you can get a QBO. Get the wrong mix and you don't. Again we do not know entirely why. Furthermore, we also know convection bubbling up over the tropics and the slow migration of air upwards and out to the poles also has a big impact of resolving the QBO. All of these factors need to be constrained in some way to get a QBO. The trouble is that these factors are invariably different in different climate models. It is for this reason that getting a regular QBO in a climate model is so hard.

This project is interested in exploring the sensitivity of the QBO to changes in resolution, diffusion and physics processes in lots of climate models and in reanalyses (models used with observations). To achieve this, we are seeking to bring together all the main modelling centres around the world and all the main researchers interested in the QBO to explore more robust ways of modelling this phenomena and looking for commonalities and differences in reanalyses. We hope that by doing this, we may get more modelling centres interested and thereby improve the number of models which can reproduce the QBO. We also hope that we can get a better understanding of those impacts seen in the North-Atlantic and around Europe and these may affect our seasonal predictions.

The primary objective of QBOnet is to facilitate major advances in our understanding and modelling of the QBO by galvanizing international collaboration amongst researchers that are actively working on the QBO. Secondary objectives include:

(1) Establish the methods and experiments required to most efficiently compare dominant processes involved in maintaining the QBO in different models and how they are modified by resolution, numerical representation and physics parameterisation.
(2) Facilitate (1) by way of targeted visits by the PI and researchers with project partners and through a 3-4 day Workshop
(3) Setup and promote a shared computing resource for both the QBOi and S-RIP QBO projects on the JASMIN facility

The principal impact of this project will be on operational modelling climate communities, primarily the UK Met Office. Improvements in the model representation of the quasibiennial oscillation (QBO) resulting from the project will be directly implemented into the Met Office seasonal to decadal scale forecast model. Results of the project will also filter through to regional climate modelling, and will help inform international modelling groups on the model configuration for the next Coupled Model Intercomparison Project (CMIP6) of the Intergovernmental Panel on Climate Change (IPCC).

Results from the project will also feed to the WCRP SPARC Project, and in particular the Dynamical Variability (DYNVAR) and Gravity Wave Activities and the Data assimilation Working Group. Another organisation to benefit from QBOnet, would be the JSC/CAS Working Group for Numerical Experimentation (WGNE), whose role is to foster coordinated efforts to improve climate models including experiments, so as to diagnose and resolve model error. The QBOnet workshop to be held in year two will showcase the current state-of-the-art modelling of the QBO, and explore improvements to such modelling.

A dedicated website will be set up for this project, with the intent of providing a central location for the understanding of tropical stratosphere variability on climate, with a specific focus on global climate models. The website will be kept up-to-date in near real-time to inform the general public of current publicised results. The latter will also include a blog, maintained by the Researcher Co-Is.