Aerosol-Cloud Coupling And Climate Interactions in the Arctic

Lead Research Organisation: University of York
Department Name: Chemistry

Abstract

The climate of the Arctic is changing faster than that almost anywhere else on Earth, warming at a rate of twice the global average. This warming is accompanied by a rapid melting of the sea ice - 2007 saw a record minimum in summer ice extent, and the years since have seen the 2nd and 3rd lowest summer ice extents on record - and a thinning of the ice that remains from year to year. The strong warming in the Arctic is due to several positive feedback processes, including a sea-ice albedo feedback (warmer conditions melt ice, lowering the average reflectivity of the mixed ice/ocean surface and thus absorbing more solar radiation, leading to increased ice melt and further lowering of the albedo) and several cloud feedbacks. Over most of the globe low clouds act to cool the surface since they reflect sunlight; over the arctic the highly reflective ice surface reduces the significance of cloud reflectivity, and the absorption of infrared radiation by cloud water droplets becomes the dominant effect - this acts to trap heat below cloud, warming the surface.
Although climate models generally show a strong greenhouse warming effect in the Arctic, they also disagree with each other more in the Arctic than anywhere else, producing a wider range of possible future climate conditions. The models also tend not to be able to reproduce current Arctic climate conditions very accurately. This large uncertainty in models of the Arctic climate results primarily from poor representation of physical processes within the models, and some unique and particularly challenging conditions. The largest single source of uncertainty is the representation of clouds. The models use simple representations of cloud properties that were developed from observations in mid latitude or tropical cloud systems - very different conditions from those that exist in the Arctic.

This project will make airborne in situ measurements of cloud microphysical properties, the vertical structure of the boundary layer and aerosol properties, and the fluxes of solar and infra red radiation above, below, and within cloud. It will also measure the production rates and properties of aerosol at the surface and their variability with season and extent of sea ice cover. These measurements will be used, along with a range of numerical models of aerosol and cloud processes, and atmospheric dynamics to evaluate the interactions between sea ice extent, aerosol production and cloud properties. New and improved descriptions of these processes suitable for use within climate models will be developed, tested, and implemented within the MetOffice climate model HadGEM. The ability of the current MetOffice models to reproduce the observed Arctic cloud and boundary layer properties will be tested, and the impact of the new parameterization schemes evaluated.
Finally we will undertake a series of climate simulations to examine how future climate will evolve, and the feedbacks between warming of the Arctic, melting of sea ice, production of aerosol, and the properties of clouds evaluated.

Planned Impact

This study has potentially wide impacts throughout the climate modelling community, both within academia and government agencies. Our collaboration with the Met Office guarantees both that all our results will be available directly to the Met Office and Hadley Centre, and that the necessary expertise with the UM is available to this study. A primary goal of the project is the development and implementation of new/improved parameterizations of aerosol, cloud, and boundary layer processes within the UM.

Improvements to parameterization schemes for boundary layer turbulent processes, low level cloud representation, and cloud radiative properties for large scale models will:

- Improve fidelity of climate predictions - this is essential if an accurate assessment of future climate change is to be achieved. This need is particularly pressing for the Arctic regions due to the rapid rate of observed change, and the expected continuation (perhaps acceleration) of this change, but also impacts on predicted climate for the rest of the world.

- Improved performance of numerical weather prediction for mid-to-high latitude regions (including the UK). The Arctic can seem remote, but there are direct influences on UK weather through advection of Arctic air masses, and indirect influence through changes in the tracks of North Atlantic storms associated with changes to surface pressure field in a warmer Arctic.

Improvements to predictive capabilities in the Arctic have impacts for climate prediction around the world. Reducing uncertainty in climate prediction is essential if policy makers are to be able to implement effective plans for limiting the human impacts of climate change.

Publications

10 25 50
 
Description 1. Iodine contributes to particle formation in the Arctic
2. There are links between composition of the sea surface microlayer and ice nuclei activity
3. Knowledge of DMS sea-air fluxes in the Arctic
4. Knowledge of isoprene and monoterpene sea-air fluxes in the Arctic
Exploitation Route Studies of CCN and IN in the Arctic environment
Sectors Environment

 
Description Research used as part of schools engagement activities
First Year Of Impact 2013
Sector Education
Impact Types Societal

 
Description Chapter 6 Lead author for 2018 WMO/UNEP Scientific Assessment of Ozone Depletion
Geographic Reach Multiple continents/international 
Policy Influence Type Citation in other policy documents
Impact The 2018 WMO/UNEP Scientific Assessment of Ozone Depletion forms part of the quadrennial assessments of ozone depletion by the Scientific Assessment Panel of the Montreal Protocol. These assessments inform decisions taken by governments for the protection of ozone and climate under the Montreal Protocol.
URL https://ozone.unep.org/science/assessment/sap
 
Description Steering committee member of International Commission on Atmospheric Chemistry and Global Pollution (ICACGP)
Geographic Reach Multiple continents/international 
Policy Influence Type Membership of a guideline committee
 
Title ORC3 and ACCACIA DMS, isoprene, monoterpenes and halocarbon data added to BODC 
Description BODC. Data are still embargoed. 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
Impact Publications 
URL https://www.bodc.ac.uk/resources/inventories/edmed/report/6554/
 
Description Bootham Junior School Science Week workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Science workshop on atmospheric science for Y6 children
Year(s) Of Engagement Activity 2016
 
Description Chair of science panel discussion The Next Big Thing at the Hay Festival in association with the Royal Society 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Around 300 people attended the panel event, which discussed novel and exciting science being carried out across the UK by a range of researchers.

Increased awareness of the excitement and usefulness of science
Year(s) Of Engagement Activity 2014
 
Description Public speaker at Hay Festival - talk on Oceans and Climate 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? Yes
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Around 300 people attended the talk. There were many questions afterwards relating to climate and impacts.

Informing the public on issues relating to climate and impacts. One person emailed me for a book recommendation on the subject.
Year(s) Of Engagement Activity 2014
 
Description RSC Joliot-Curie Conference 2016 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Other audiences
Results and Impact Key-note speaker at the Joliot-Curie Conference on career challenges and key milestones. This is an annual event dedicated to supporting the aspirations of early career researchers, particularly women and those who are underrepresented in academia.

Excellent feedback from the delegates anecdotally (as reported by RSC) and on Twitter
Year(s) Of Engagement Activity 2016
 
Description School Visit (St Pauls Girls School) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Invited talk and visit, including discussions with pupils, at St Paul's Girls School
Year(s) Of Engagement Activity 2017
 
Description Summer School on atmospheric sciences (York) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact 3 day summer school in atmospheric science for secondary school children, with aims to (i) Help children, particularly girls, and their families identify that science and science careers are for people like them, (ii) Show that a scientific career can offer a supportive and flexible working environment as well as being interesting, (iii) Educate in atmospheric science.
Year(s) Of Engagement Activity 2016
 
Description Talk at Science Live: A -level (Birmingham Event) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Schools
Results and Impact around 1000 sixth formers attended this event, which is aimed at informing their University and career choices.
Year(s) Of Engagement Activity 2018
 
Description Talk at Science Live: A -level (Birmingham Event) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact Talk at "Science Live: A -level" (Birmingham Event) - one of three Chemistry events for A-level students, organised by "Science Live". http://www.alevelsciencelive.net/
Year(s) Of Engagement Activity 2018
URL http://www.alevelsciencelive.net/
 
Description Talk at Science Live: A -level (London Event) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact Talk at "Science Live: A -level" (London Event) - one of three Chemistry events for A-level students, organised by "Science Live". http://www.alevelsciencelive.net/
Year(s) Of Engagement Activity 2018
URL http://www.alevelsciencelive.net/