Diagnosing dust-climate interactions in observations to test Earth System Models

Lead Research Organisation: Imperial College London
Department Name: Dept of Physics

Abstract

"Mineral dust is a key component of the Earth system, scattering and absorbing incoming solar and emitted longwave radiation and modifying the properties of, in particular, ice clouds. Dust deposited to the ocean is a source of iron, stimulating the biological pump and influencing air-sea carbon exchange. Similarly, deposited dust constitutes a major source of nutrients for the world's rainforests, providing a further link to the carbon cycle.

Despite this, our ability to predict dust emission, amount and impact in a changing world is poor. A recent study comparing the output of climate models used in the IPCC 5th Assessment Report concludes that "there is no reason to assume that the projections of dust emission and concentration for the 21st century have any validity." Given the multi-faceted role that dust plays within the Earth System there is an urgent need to improve this situation. Among other goals, the UK's next generation Earth system model, UKESM1, seeks to do just this. In this model, dust emissions respond to vegetation cover, wind speed and soil moisture. The relationships used for each of these interactions are based on an understanding of the underlying physics and on empirical relationships derived from observations, but there is a lack of evidence as to the realism of the emergent relationships at the regional scale. The overall goal of this project is thus to evaluate UKESM1 performance at these scales using Earth Observation (EO) data, contributing to an improved representation of dust processes in future UKESM model versions.

In this project you will use state of the art EO data to diagnose relationships between dust activity and selected climate variables at the regional scale, assessing the impact of observational uncertainties on any dependencies that are seen. You will then use the new understanding of these relationships to test UKESM1, comparing the regional-scale relationships seen in the EO data and model output, and investigating any discrepancies to understand their cause. This work will strongly complement broader European-wide efforts to improve the representation of dust in ESMs. Although primarily based within the Physics department at Imperial, you will spend time at the Met Office through the course of the project, working directly with UKESM1 developers.

Publications

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