The lower stratosphere: interactions with the tropospheric chemistry/climate system
Lead Research Organisation:
University of Leeds
Department Name: School of Earth and Environment
Abstract
It is now well established that the atmospheric system is highly copled and that changes in one location can have a significant impact elsewhere. For example, changes in stratospheric ozone can have an important consequence for surface UV. The lower stratosphere is especially important. Itis a region where there have been recent changes in the concentrations of aerosol and ozone which are now known to have influenced surface climate and tropospheric composition although the details of the interactions are not fully resolved. We expect that composition in this region will cahnge in the future, for example, in response to changes in the abundance of greenhouse gases or ozone-deplting substances. It is important to assess the future impact on the climate system of aqny changes in lower startospheric composition. This is the major objective of our proposal and will be achieved by using a chemistry/climate model that the partners have helped to develop. We will use the UKCA model, based on the latest Met Office climate model, into which we have added detailed descriptins of atmospheric chemistry and aerosol. We will use the model to explore the processes involved in recent past changes (e.g. after the major eruption of Mt Pinatubo which injected a large amount of sulphur into the stratosphere leading to enhanced stratospheric aerosol and subsequent changes in surface temperature). We will also use the model to consider a range of scenarios as ozone 'recovers' in response to the Montreal Protocol. The model will be used to explore the scientific implications of geoengineering solutions recently proposed to mitigate the impact of greenhouse gas induced climate change.
Publications
Braesicke P
(2010)
Might dimming the sun change atmospheric ENSO teleconnections as we know them?
in Atmospheric Science Letters
Dhomse S
(2014)
Aerosol microphysics simulations of the Mt.~Pinatubo eruption with the UM-UKCA composition-climate model
in Atmospheric Chemistry and Physics
Gillett N
(2011)
Attribution of observed changes in stratospheric ozone and temperature
in Atmospheric Chemistry and Physics
Malavelle FF
(2017)
Strong constraints on aerosol-cloud interactions from volcanic eruptions.
in Nature
Morgenstern O
(2010)
Review of the formulation of present-generation stratospheric chemistry-climate models and associated external forcings
in Journal of Geophysical Research: Atmospheres
Strahan S
(2011)
Using transport diagnostics to understand chemistry climate model ozone simulations
in Journal of Geophysical Research
Telford P
(2010)
Effects of climate-induced changes in isoprene emissions after the eruption of Mount Pinatubo
in Atmospheric Chemistry and Physics
Description | A global model of stratospheric aerosol microphysics has been created as part of the UK Earth System Model. We have found that the observed dimming of the sun (radiative forcing) caused by the 1991 Pinatubo eruption can be explained with just half the emission of sulphur dioxide commonly quoted. The reason is that our new model resolves the size of the stratospheric aerosol particles in a more realistic way, which increases the efficiency with which they scatter solar radiation. If our results are borne out by other models, it would imply that sulphur emitted from the volcano is twice as effective at forcing climate than previously thought. |
Exploitation Route | This project has created a new version of the HadGEM/UKESM model including interactive stratospheric aerosol. The model can be used to study impacts of volcanic eruptions on climate as well as geoengineering. |
Sectors | Environment |
URL | http://gassp.org.uk |