Blowing snow and sea ice surfaces as a source of polar sea salt aerosol (BLOWSEA)

Lead Research Organisation: NERC British Antarctic Survey
Department Name: Science Programmes

Abstract

Small particles (known as aerosol) in the atmosphere play several critical roles. They affect the transmission of sunlight to the underlying surface; they affect the formation of clouds, and they host and enhance important chemical reactions. When they are deposited on ice they leave a record of past conditions that can be accessed by drilling ice cores. The most significant aerosol component over marine areas is sea salt aerosol. Over most of the world's oceans this is created by bubble bursting in sea spray. However there is strong evidence that another source of sea salt aerosol is important in the polar regions, and that this ultimately derives from the surface of sea ice. The existence of this source forms the basis for a proposed method using ice core data for determining changes in sea ice extent over long time periods. Additionally sea salt aerosol, along with salty sea ice surfaces, is the host for the production of halogen compounds which seem to play a key role in the oxidation chemistry of the polar regions. It is therefore important to understand the sources of polar sea salt aerosol and therefore to be able to predict how they may vary with, and feedback to, climate.

It was recently proposed that the main source of this polar sea salt aerosol was the sublimation of salty blowing snow. The idea is that snow on sea ice has a significant salinity. When this salty snow is mobilised into blowing snow, sublimation from the (top of) the blowing snow layer will allow the formation of sea salt aerosol above the blowing snow layer, that can remain airborne after the blowing snow has ceased. First calculations suggested that this would provide a strong source of aerosol (greater than that from open ocean processes over an equivalent area). It was proposed that this would have a strong influence on polar halogen chemistry and a noticeable influence on halogens at lower latitudes. However, this was based on estimates of the relevant parameters as there were no data about aerosol production from this source, and almost no data about blowing snow over sea ice in general.

Here we propose to take advantage of a very rare opportunity to penetrate the Antarctic sea ice zone during winter, as we have been allocated spaces on an unusual winter cruise into the sea ice zone on the German icebreaker Polarstern. During this cruise, we will be able to confirm that the blowing snow sea ice source exists, and make measurements that will provide a soundly-based parameterisation of the source. This will be done by making measurements of the snow on sea ice, of the blowing snow itself, and of aerosol above the blowing snow, as well as before and after such episodes. Measurements will include salinity, chemistry (looking at the amount of bromine present in each medium), and for blowing snow and aerosol, the amounts and size distributions.

By combining our data with meteorological data, and by comparing them to satellite observations that have recently attempted to identify blowing snow episodes, we will be able to make estimates of the spatial and temporal distribution of sea salt aerosol from this source over the entire Antarctic sea ice zone. This will allow us to assess the importance of this source of sea salt (and of halogens) compared to others that have been proposed. We will then use existing models to assess how important such a source is to sea salt deposition in Antarctica, allowing us to determine how sea salt in ice cores is related to sea ice extent. This opens the possibility of turning a qualitative sea ice proxy into a quantitative one. Models will also be used to re-assess the importance of this source for halogen chemistry in the polar regions and globally.

In summary this proposal will provide the first targeted measurements of the parameters needed to assess the importance of blowing snow sublimation as a source of sea salt, and to quantify its most relevant impacts.

Planned Impact

The main immediate beneficiaries of our research are academic ones. Our data will benefit process understanding and quantitative estimates in several fields. We have identified in particular:

* Atmospheric scientists studying sea salt aerosol globally, including its direct and indirect radiative effects
* Cryosphere/atmosphere scientists studying boundary layer processes, blowing snow, and its impact on mass balance
* Ice core scientists developing proxies from sea salt
* Atmospheric chemists studying the role of halogens in oxidation chemistry

Beyond this, because one major aim is to develop a quantitative sea ice extent proxy from sea salt in ice cores, we also identify a community of:

* Sea ice scientists, starting with the palaeo-sea ice community, and through their integrated findings, the sea ice modelling and prediction community.

The aim of learning about palaeo sea ice is to improve (confidence in) models of sea ice and therefore predictions. This in turn would lead to benefits to those who need to access the ice-covered areas of the polar regions, with obvious economic (shipping, resources, insurance) and geopolitical implications. However, our more fundamental science will not go this far down the impact pathway, and we consider our main responsibility in ensuring impact to be
* ensuring that our findings are incorporated into the latest UK Earth System models (via the Cambridge team's role in UKCA, and via scientific conference presentations and publication)
* ensuring that our construction of a sea salt ice core sea ice proxy is validated by the palaeo sea ice community and that the results of using the proxy are disseminated to the wider sea ice community; this will be done through activities around the IGBP-PAGES Sea Ice Proxy working Group, which PI Wolff co-chairs.

Finally, we as scientists have a role in making science exciting and accessible to the public and to students. Like many projects in the Antarctic, this project has considerable potential as an exemplar of how science is done and how exciting it can be. BAS and the PI's group have a strong record of public outreach to get exciting science across, and they will use their usual channels (which include many public lectures by the PI, visits to BAS by groups such as the Cambridge Programme for Industry, visits to schools and web material). Because the cruise is led by AWI, we will follow their lead on the overall outreach from the cruise (not available at the time of writing the proposal), but we will work this experiment and project into BAS's usual NC/KE-funded activities.

Publications

10 25 50
 
Description The research cruise for BLOWSEA has been completed, and the requisite measurements successfully made. Samples have been analysed, and, together with in situ measurements, have been used to develop improved numerical model parameterisations. The results from the BLOWSEA winter cruise are consistent with the idea that blowing snow is an important source of sea salt aerosol to the Antarctic atmosphere. Modelling calculations using the newly-tested parameterisation suggests that blowing snow on sea ice is a significant source of sub micron aerosol. These particles can act as cloud condensation nuclei, thus signalling a potential impact on cloud formation, with consequent influence on radiative balance. The aim is to look specifically at this impact in a follow-up project.
Exploitation Route The data will be used to improve parameterisations in numerical models to assess the contribution made by Antarctic blowing snow to sea salt aerosol.
The improved parameterisations will be used in a range of studies, and introduced into various 3D models. In particular, the potential role of sea salt aerosol as cloud condensation nuclei is a major finding that needs to be fully explored in future studies.
Sectors Education,Environment

 
Description Non-academic impacts thus far have stemmed from outreach activities within this grant, such as the BLOWSEA web pages.
First Year Of Impact 2014
Sector Education
 
Description BAS Innovation Voucher Scheme
Amount £5,000 (GBP)
Organisation British Antarctic Survey 
Sector Academic/University
Country United Kingdom
Start 12/2015 
End 04/2016
 
Description International Opportunities fund (IOF)
Amount £39,874 (GBP)
Funding ID NE/M005852/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 10/2014 
End 08/2015
 
Description Sea Salt Aerosol above Arctic Sea Ice - sources, processes and climate impacts (MOSAiC Jan2018 scheme)
Amount £394,000 (GBP)
Funding ID NE/S00257X/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 04/2019 
End 03/2022
 
Description UK-Canada Arctic Partnership: 2018 Bursaries Programme
Amount £20,000 (GBP)
Organisation Department for Business, Energy & Industrial Strategy 
Sector Public
Country United Kingdom
Start 03/2018 
End 07/2018
 
Title New model parameterisation for sea salt aerosol production fro blowing snow 
Description A new parameterisation to model production of sea salt aerosol from blowing snow in the sea ice zone was developed and tested against field observations. 
Type Of Material Improvements to research infrastructure 
Year Produced 2016 
Provided To Others? Yes  
Impact Two research papers, one submitted and one nearly ready 
 
Title BLOWSEA field data 
Description A suite of measurements made within the Antarctic sea ice zone of: i) snow salinity profiles; ii) size spectrum, salinity, and ionic composition of blowing snow layers over sea ice; iii) size spectrum and ionic composition of sea salt aerosol above blowing snow events; iv) meteorological conditions. 
Type Of Material Database/Collection of data 
Year Produced 2014 
Provided To Others? Yes  
Impact Improved parameterisations for Antarctic blowing snow that are currently being assessed within numerical atmospheric chemistry model. 
 
Description BLOWSEA collaboration with Cambridge 
Organisation University of Cambridge
Department Department of Chemistry
Country United Kingdom 
Sector Academic/University 
PI Contribution Provided new parameterisations to be used in numerical modelling calculations.
Collaborator Contribution Run numerical models to assess the new parameterisations.
Impact Model runs that are currently being analysed/interpreted ahead of publication.
Start Year 2015
 
Description BLOWSEA collaboration with Leeds 
Organisation University of Leeds
Department School of Earth and Environment
Country United Kingdom 
Sector Academic/University 
PI Contribution BAS scientists ran Leeds instrumentation during the BLOWSEA cruise.
Collaborator Contribution Leeds partners provided the instrumentation and helped with data work-up and interpretation.
Impact Dataset from the field measurements that are currently being interpreted ahead of publication.
Start Year 2012
 
Description BLOWSEA collaboration with SAMS 
Organisation Scottish Association For Marine Science
Country United Kingdom 
Sector Charity/Non Profit 
PI Contribution Providing measurements generated during the BLOWSEA campaign for joint analysis/interpretation.
Collaborator Contribution Expertise in interpretation of the field data.
Impact The increased understanding contributed to further successful grant application. Papers arising from this collaboration are in progress.
Start Year 2012
 
Description Collaboration with Prof. Kouichi Nishimura (Nagoya University / Japan) 
Organisation Nagoya University
Department Graduate School of Environmental Studies
Country Japan 
Sector Academic/University 
PI Contribution The BAS team deployed a snow particle counter owned by Prof. Nishimura during the ABSCISSA field phase on the N-ICE2015 sea ice cruise. Measurements of snow particle concentration and size distribution above sea ice were carried out, followed by data processing, conference presentations and publications (in preparation) with collaborator Prof. Nishimura as co-author.
Collaborator Contribution Prof. Nishimura and his team provided a snow particle counter (SPC) on loan to the BAS team, carried out instrument calibration prior to the N-IC2015 field season and provided the expertise needed to process and interpret the data.
Impact M.M. Frey, S. Norris, I.M. Brooks, K. Nishimura, A.E. Jones, Arctic Sea Salt Aerosol from Blowing Snow and Sea Ice Surfaces - a Missing Natural Source in Winter, Conference Abstract No. A23I-05, AGU Fall Meeting San Francisco, 2015. M.M. Frey, S. Norris, I.M. Brooks, K. Nishimura, A.E. Jones, Arctic Sea-Ice-Zone Blowing Snow - Contribution to Sea Salt Aerosol (ABSCISSA), oral presentation at N-ICE2015 workshop, Malangen Brygge / Norway, 17-19 Nov 2015. M.M. Frey, S. Norris, I.M. Brooks, K. Nishimura, P.A. Anderson, S. Palm, A.E. Jones, E.W. Wolff, Sea Salt Aerosol from Blowing Snow and Sea Ice Surfaces - a Missing Natural Source in Winter, invited seminar at Grad. School of Environmental Studies, Nagoya University, Japan, 29 Jun 2016.
Start Year 2014
 
Description Collaboration with S. Palm (NASA GSFC) 
Organisation National Aeronautics and Space Administration (NASA)
Department Goddard Space Flight Center
Country United States 
Sector Public 
PI Contribution The BAS team carried out ground based observations of blowing snow (BS) above sea ice events in the Weddell Sea during a winter cruise in 2013. The observations are used to validate BS satellite retrievals above Antarctica. The BAS observations include snow particle concentrations and size distribution at two levels, which are provided to test the BS algorithm.
Collaborator Contribution S. Palm & team provided maps of BS occurrence in the Weddell sea based on satellite retrievals. These are being used to upscale the point measurements of sea salt aerosol production made by the BAS team, and therefore to assess the significants and wider impacts of BS as a source for new particles above sea ice.
Impact Conference & workshop presentations: - IGS Sea Ice Conference, Hobart / Australia, March 2014 (oral) - AGU Fall Meeting, San Francisco, December 2014 (poster) - LGGE Halogen Workshop, Grenoble, October 2015 (oral) - N-ICE2015 Workshop, Malangen, November 2015 (oral) - AGU Fall Meeting, San Francisco, December 2015 (oral) - Invited seminar presentation at Nagoya University / Japan (Prof. K. Nishimura), June 2016
Start Year 2013
 
Description Xin Yan collaboration wiht Rachel Rhodes, University of Cambridge 
Organisation University of Cambridge
Department Cambridge Stem Cell Institute
Country United Kingdom 
Sector Multiple 
PI Contribution Xin Yang collaborated with Dr Rachel Rhodes on her project modelling the impact of sea salt aerosol on the ice core record in the Arctic.
Collaborator Contribution Dr Rhodes carried out the modelling experiments and led the paper writing.
Impact Paper submitted to the journal Atmospheric Physics and Chemistry.
Start Year 2016
 
Description Xin collaboration with Dominik Heger, Masaryk University, Brno 
Organisation Masaryk University
Department Department of Chemistry
Country Czech Republic 
Sector Academic/University 
PI Contribution Xin Yang approached the group in Brno with an idea to test using their experimental equipment.
Collaborator Contribution They carried out the experiments in their laboratories, using their specialised techniques.
Impact Publication currently under discussion in the on-line journal Atmospheric Chemistry and Physics Discussions.
Start Year 2015
 
Description Anna invited talk at Edinburgh University 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Postgraduate students
Results and Impact Invitation to give talk at University of Edinburgh as part of their regular seminar series, included presenting material/results from BLOWSEA.
Year(s) Of Engagement Activity 2015
 
Description Anna invited talk at UEA 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Postgraduate students
Results and Impact Gave invited talk at regular seminar series at UEA, including presenting results from BLOWSEA.
Year(s) Of Engagement Activity 2014
 
Description BLOWSEA web pages 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Web pages written to describe the BLOWSEA project.
Year(s) Of Engagement Activity 2014
URL https://www.bas.ac.uk/project/blowing-snow-and-sea-ice/#about
 
Description Digital Explorer 'Arctic Live!' Skype Lesson 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Schools
Results and Impact School lessons during 'Arctic Live Week' organised by London based media company 'Digital Explorer' and delivered via 'Skype in the Classroom'. Each year a total of up to a 100 pupils attended several online 45 minute long lessons. Each lesson comprised a 15 minute lecture on the personal bio of a 'polar researcher' (http://oceans.digitalexplorer.com/events/arctic-live-2017/team/), a description of recent field work experiments in the Arctic and how they help improve our understanding of current climate change at the poles. The lecture was then followed by a 30 minute Q&A session moderated by the respective school teacher. Schools and pupils reported increased interest in the environmental sciences, and specifically into polar research, often with follow-up questions.
Year(s) Of Engagement Activity 2015,2016,2017
URL http://oceans.digitalexplorer.com/events/
 
Description London International Youth Scientific Forum (LIYSF) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Undergraduate students
Results and Impact Since 2016 Dr. M. Frey engages with the London International Youth Scientific Forum, which attracts each year ca 500 students (age 16-20 yr) from all over the world. In 2016 he gave a lecture and led a study day on Polar Research; in 2017 he organised a visit of LIYSF students to the British Antarctic Survey and gave a lecture.
Year(s) Of Engagement Activity 2016,2017
URL http://www.liysf.org.uk
 
Description Markus invited talk to UEA 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Postgraduate students
Results and Impact Invitation to give talk at the University of East Anglia as part of their regular seminar series. Led to useful discussions and networking, with subsequent joint studentship application.
Year(s) Of Engagement Activity 2015