Investigation into the importance of aerosols from blowing snow for accurate predictions of Arctic climate change

Location: University of Exeter, Streatham Campus, Exeter EX4 4QJ

This project is one of a number that are in competition for funding from the NERC Great Western Four+ Doctoral Training Partnership (GW4+ DTP). The GW4+ DTP consists of the Great Western Four alliance of the University of Bath, University of Bristol, Cardiff University and the University of Exeter plus five Research Organisation partners: British Antarctic Survey, British Geological Survey, Centre for Ecology and Hydrology, the Natural History Museum and Plymouth Marine Laboratory. The partnership aims to provide a broad training in earth and environmental sciences, designed to train tomorrow’s leaders in earth and environmental science.

For further details about the programme please see http://nercgw4plus.ac.uk/

Project details

Reducing current uncertainties associated with model estimates of future climate is hampered by our understanding of the impact aerosol particles have on the radiative budget via their interactions with clouds (Carslaw et al., 2013). The Arctic environment is particularly sensitive to perturbations of the radiative budget.

During the last century the temperature increase in the Arctic has been observed to be twice the global average. This “Arctic amplification” is not fully understood, but it likely relates to the complex feedbacks surrounding sea ice, clouds and aerosols. Sea salt aerosols (SSA) play an important role in cloud formation and are generated both directly from the ocean into the atmosphere by bursting bubbles; blowing snow above sea ice (Fig. 2B) and frost flowers (Fig. 2B), (Huang and Jaeglé, 2017). It is important to constrain the relative contribution of SSA from the sea ice to the Arctic in climate models as this is a dominant air-mass transport pathway (Fig. 1).

Project Aims and Methods

A unique set of campaign measurements of blowing snow from the N-ICE 2015 ice drift expedition have been used by the British Antarctic Survey (BAS) to develop a parameterisation describing the production of SSA from the sea ice (BAS, paper in preparation). This will be implemented in UKESM1: a state-of-the-art Earth system model (ESM) developed by the Met Office and used to investigate the importance of this aerosol source for Arctic aerosol-cloud-climate interactions.

A novel Lagrangian trajectory framework for evaluating GCMs has been developed (Fig 1). This provides a step-change in our ability to confront climate models with aerosol observations by allowing us to use aerosol source-receptor relationships from observations (Tunved et al., 2013) as a metric for stringent evaluation of aerosol processes in climate models.

The student will apply this new parameterisation and Lagrangian evaluation strategy to evaluate and improve understanding of the processes underpinning simulation of snow blowing aerosols and their impact on climate by:

1.) Implementation of parameterisation to describe emission of SSA from blowing snow into UKESM1.

2.) Evaluation of simulated Arctic aerosol properties before/after (1) against measurements.

3.) Investigation of the impact of aerosols originating from blowing snow on the climate system by applying a Lagrangian trajectory analysis to UKESM1.

4.) Investigation of interactions between SSA, clouds and sea ice extent on model estimates of future climate change.
We envisage a high degree of flexibility for the student to lead the direction of investigation in (4).

Training

In addition to the DTP, the student will receive:
1) Training courses on running the UKESM1 (UK Met Office).
2) Training on measurements of blowing snow from the British Antarctic Survey.
2) Training on observations from Arctic Zeppelin station and Oden Icebreaker (ACES, Stockholm Uni.).
3) Opportunity to attend specialised Arctic workshops (ESTICC/CRAICC).
4) Training on using Hysplit/NAME atmospheric trajectory models
5) Training on using CIS data analysis software: (University of Oxford).
On the job training at the Met Office in supercomputing. The candidate will be further supported by Haywood/Partridge established group of PhD/PDRAs working with the supervisors. International conferences (e.g. EGU, Vienna) and international workshops are expected to be attended.