# Jiachen Lu: Integrating the Urban Climate and Energy Model (UCLEM) into ACCESS-AM3 via CABLE: Model Description and Global Evaluation

**URL:** https://forum.access-hive.org.au/t/jiachen-lu-integrating-the-urban-climate-and-energy-model-uclem-into-access-am3-via-cable-model-description-and-global-evaluation/6834
**Category:** ESM/Land/CMIP7 Workshop Abstracts 2026
**Created:** [20 August 2026 05:31 UTC](https://forum.access-hive.org.au/t/jiachen-lu-integrating-the-urban-climate-and-energy-model-uclem-into-access-am3-via-cable-model-description-and-global-evaluation/6834 "2026-08-20T05:31:24Z")
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### Author: ![lachlanswhyborn](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/lachlanswhyborn/32/1837_2.png) [@lachlanswhyborn](https://forum.access-hive.org.au/u/lachlanswhyborn)
#### Post date: [20 August 2026 05:31 UTC](https://forum.access-hive.org.au/t/jiachen-lu-integrating-the-urban-climate-and-energy-model-uclem-into-access-am3-via-cable-model-description-and-global-evaluation/6834/1 "2026-08-20T05:31:24Z")

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Jiachen Lu: Integrating the Urban Climate and Energy Model (UCLEM) into ACCESS-AM3 via CABLE: Model Description and Global Evaluation

Urban areas alter the surface energy balance through impervious materials, complex geometry, anthropogenic heat emissions, and reduced vegetation, creating distinct thermal, radiative, and hydrological processes that require explicit representation in Earth system models. We describe the integration of the Urban Climate and Energy Balance Model (UCLEM) into ACCESS-AM3 via the CABLE land surface model.

UCLEM represents urban surfaces as a single-layer urban canopy comprising seven built facets together with in-canyon and rooftop vegetation. It solves coupled radiation, turbulent flux, heat conduction, hydrology, snow, and anthropogenic heat processes for each facet. Within CABLE’s explicit–implicit time-stepping framework, UCLEM is called twice per atmospheric timestep. A diagnostic call provides direct-beam and diffuse urban albedo to the Unified Model (UM) radiation scheme, while a prognostic call advances the urban canopy state and returns urban-tile sensible and latent heat fluxes, radiative and screen-level temperatures, storage heat flux, roughness length, and drag coefficient, replacing the corresponding CABLE values for urban tiles.

Meteorological forcing from the UM atmosphere is supplied to the urban tile, where a new Monin–Obukhov Similarity Theory (MOST) profile-scaling routine extrapolates temperature, humidity, and wind from the lowest model level to canyon-top and roof-top heights with stability corrections. The implementation is fully integrated with UM operational infrastructure, including configuration through a dedicated namelist, diagnostics via the STASH framework, and restart capability through persistence of internal temperatures, hydrological stores, and snow states in UM dump files.

Two global simulations demonstrate the implementation. A 20-year simulation at ~135 km resolution (N96) produces realistic spatial patterns of urban temperatures, energy fluxes, and anthropogenic heat emissions, with good agreement against observations from 20 urban flux towers. A 2-year simulation at ~25 km resolution (N512) resolves individual cities and reproduces key urban phenomena, including the urban heat island effect.