Representation of polar lows in numerical weather prediction models

Moreno Ibáñez, M. (2026) Representation of polar lows in numerical weather prediction models. PhD thesis, University of Reading. doi: 10.48683/1926.00129917

Abstract/Summary

Polar lows (PLs) are relatively small and intense maritime cyclones that develop at high latitudes, typically during marine cold air outbreaks. Their representation in numerical weather prediction models is challenging due to their small size, rapid development and short lifetime, as well as the sparseness of conventional observations at high latitudes. PLs can impact the ocean circulation, so the atmospheric horizontal resolution of climate models needs to be high enough to capture them. The overarching goal of this thesis by published works is to analyse how PLs are represented in models with horizontal grid spacings ranging from coarse (50 km) to fine (2.5 km); it is composed of seven published outputs: two literature reviews, three research articles, and two datasets. The literature reviews provide an overview of our knowledge of PLs and research gaps. The first research study uses the Weather Research and Forecasting Model to analyse how the representation of PLs varies with typical climate model resolutions. On reducing the grid spacing from 50 to 25 km, PLs become more frequent, smaller, and more intense. However, a further reduction to 12.5 km does not lead to substantial differences. In the second and third research articles, the Canadian Regional Climate Model is used at convection-permitting resolution to conduct a PL case study. The model represents the observed PL reasonably well and provides details of its structure; however, its skill strongly depends on initial conditions. Consistent with previous studies, moist baroclinic instability plays an essential role in PL development. Key implications of this work are: Firstly, this thesis shows that increasing the atmospheric model horizontal resolution does not necessarily lead to an improvement in the representation of PLs. Secondly, the research objective (weather vs climate studies) and the quality of the initial conditions will affect the potential benefits of enhanced atmospheric model horizontal resolution.

Item Type	Thesis (PhD)
URI	https://centaur.reading.ac.uk/id/eprint/129917
Identification Number/DOI	10.48683/1926.00129917
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
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