The Urban-PLUMBER multi-site model evaluation project: Phase 2 initial results

We present results from Phase 2 of the Urban-PLUMBER project, where we assess the ability to represent the surface energy balance across 30 land surface models at 20 sites, ranging from highly urbanised to highly vegetated. Our findings broadly support those of Phase 1, that community efforts have led to better representation of sensible and latent heat fluxes. However, at sites with higher impervious fractions (i.e. areas with little vegetation or bare soil), urbanised models tend to underestimate, and non-urbanised models overestimate the magnitude of observed latent heat fluxes, with urbanised models performing better overall. We find the performance of models without urban representation diverges at approximately 30% impervious fraction.

Our comparison with simple empirically based benchmark models indicates capacity for improvement in longwave radiation and momentum flux representation. Through this benchmarking methodology, we find this study’s group of models perform better than those in the original PLUMBER projects, which tested non-urban land surface models at non-urban sites.

The Urban-PLUMBER project has involved more than 60 contributing scientists, including those providing flux tower and meteorological data, undertaking simulations, developing models and evaluation methods. This presentation focuses on the modelling results for Phase 2. The observational forcing and benchmark data will be openly available, providing tools for future model development and modeller training.