10 Aug 2023
 | 10 Aug 2023
Status: this preprint is open for discussion.

A clustering approach to reduce computational expense in land surface models: a case study using JULES vn5.9

Elizabeth Cooper, Rich Ellis, Eleanor Blyth, and Simon Dadson

Abstract. Land surface models such as JULES (the Joint UK Land Environment Simulator) are usually run on a regular, rectilinear grid, resulting in gridded outputs for variables such as soil moisture and water fluxes. Here we investigate a method of clustering grid cells with similar characteristics together in JULES. Clustering grid cells has the potential to reduce computational expense as well as providing an alternative to tiling approaches for capturing sub-grid heterogeneity. In this study, we cluster grid cells exclusively in the land surface part of modelling, i.e., separate from river routing. We compare gridded and clustered soil moisture outputs from JULES with measurements from the UK Centre for Ecology and Hydrology (UKCEH) COSMOS-UK network and show that the clustering approach can model soil moisture well while reducing computational expense. However, soil moisture results are dependent on the characteristics used to create the clusters. We investigate the effect of using clusters on predicted river flows, and compare routed JULES outputs with NRFA gauge data in the catchment. We show that less expensive JULES clustered outputs give similar river flow results to standard gridded outputs when routed at the grid resolution, and are able to match observed river flow better than gridded outputs when routed at higher resolution.

Elizabeth Cooper et al.

Status: open (until 16 Oct 2023)

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Elizabeth Cooper et al.

Elizabeth Cooper et al.


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Short summary
We have tested a different way of simulating soil moisture and river flow. Instead of dividing the land up into over 10,000 squares to run our numerical model, we cluster the land into fewer, irregular areas with similar landscape characteristics. We show that different ways of clustering the landscape produce different patterns of soil moisture. We also show that with this method we can we match observations as well as our usual gridded approach for ten times less computational resource.