Using Earth Observations to Unravel the Greenland Dark Zone (part of the SENSE Centre for Doctoral Training)
Dr J B Mcquaid
Dr Duncan Quincey
Dr A Kirchgaessner
No more applications being accepted
Competition Funded PhD Project (UK Students Only)
The poles are said to be the barometer of the planet and it is critical we understand the processes which are impacting them at this time. The melting of the Greenland icesheet is estimated to have contributed to 16% of planetary sea level change since the early 1990s. In recent times there has been considerable interest in the south west region of the Greenland Icesheet where there has been quite noticeable darkening which in turn leads to an acceleration of surface melting in this region.
A very recent report from the IMBIE project used satellite data from a 26 year period to conclude that Greenland is losing ice seven times faster than it was in the 1990s. We urgently need to improve our understanding of the multitude of processes which contribute to the melting of the icesheet and subsequent discharge of meltwater into the ocean.
We already know that airborne material being deposited to the surface is a major driver of this darkening, however a major NERC project; Black and Bloom, has recently investigated the different components beyond just this transported material which contribute to the reduction of the surface albedo in this area. The so-called bio-albedo system, which co-exists with the deposited material actually consolidating it, goes through seasonal cycles and as the topmost surface melts in the polar spring revealing these algal colonies once more the accelerated melting is quickly re-established.
The Black and Bloom project has already gathered a wealth of compositional data from field samples. Isotopic analyses have shown that a significant fraction is very local, having recirculated onto the icesheet against the surface katabatic winds, further evidence of the complexity of atmosphere above the icesheet, both closeto the surface as well as in the free troposphere above.
This project will provide the opportunity to undertake a multi-scale analysis combining earth observations alongside an atmospheric dispersion model (FLEXPART) to produce climatologies for the entire Greenland icesheet. In this studentship you will use optical satellite observations to detect the formation of melt ponds local to the dark zone to be tracked though the full annual cycle. This will shed light on how local changes in albedo affect the formation, persistence and ultimately their lifetime, all of which are tied to water runoff from the icesheet.
Existing fine-spatial resolution satellite sensors (e.g. Planet, Sentinel) will provide the opportunity to do this at unprecedented spatial and temporal resolutions and capture the variability often ignored in coarse resolution approaches, as well as test ideas around the potential expansion of this darkening into other zones of the ice sheet. New sensors (e.g. SWOT) may give novel insights into lake water level fluctuations and how they respond to changes in surrounding ice surface characteristics, and historic patterns will be established from the long archive of SPOT and Landsat sensors using commonly applied (e.g. NDWI, spectral unmixing) approaches.
FIELDWORK OPPORTUNITY – There is also the possibility of making ground observations using arrays of time-lapse cameras, to characterise the local-scale evolution (albedo and roughness) of the ice surface, and track the distribution of algal communities as the melt-season progresses. These observations will be coupled with the dispersion modelling to track when and where materials impact this part of the ice sheet. The FLEXPART model will be run using the new ERA5 reanalysis data which provides a new high resolution capability back to 1950, this will allow detailed investigations to be conducted as to changes in circulation patterns over this region and assess the sources of the long range transported materials.
This PhD is part of the NERC and UK Space Agency funded Centre for Doctoral Training "SENSE": the Centre for Satellite Data in Environmental Science. SENSE will train 50 PhD students to tackle cross-disciplinary environmental problems by applying the latest data science techniques to satellite data. All our students will receive extensive training on satellite data and AI/Machine Learning, as well as attending a field course on drones, and residential courses hosted by the Satellite Applications Catapult (Harwell), and ESA (Rome). All students will experience extensive training on professional skills, including spending 3 months on an industry placement. See http://www.eo-cdt.org
This 3 year 9 month long NERC SENSE CDT award will provide tuition fees (£4,500 for 2019/20), tax-free stipend at the UK research council rate (£15,009 for 2019/20), and a research training and support grant to support national and international conference travel. www.eo-cdt.org/apply-now
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