WRF-UACM Multilayer Urban Canopy Model Description

The WRF–Urban Asymmetric Convective Model (UACM), developed by Dr. Utkarsh Prakash Bhautmage and colleagues, is a multilayer urban canopy parameterization within the WRF framework designed to improve the representation of urban meteorology, boundary-layer processes, and fog prediction, while remaining computationally efficient compared to more complex urban schemes. Its first major application was in Hong Kong, a dense high-rise coastal megacity, where UACM successfully captured strong urban heat island intensity, intricate wind flows within urban canyons, and the coupling between urban morphology and coastal boundary-layer dynamics. Building on this, the model was applied in Delhi (India), where it significantly enhanced the simulation of radiation fog events by incorporating updated land-use and high-resolution morphological datasets. UACM improved near-surface wind, temperature, and humidity forecasts, reduced cold biases, better captured nocturnal urban heat island patterns, and advanced fog onset predictions by several hours compared with baseline WRF schemes. Importantly, UACM has now been operationalized for winter fog forecasting at Indira Gandhi International (IGI) Airport in Delhi, where it is used every year during the fog season, and its outputs are made publicly available through the Ministry of Earth Sciences, Govt. of India Winter Fog Experiment (WIFEX) portal (link). Furthermore, UACM is currently being implemented over the Mumbai region (India) to improve extreme rainfall prediction, extending its applicability from fog and urban heat island studies to high-impact precipitation forecasting. Together, these efforts highlight UACM’s versatility for both research and operational forecasting across diverse urban environments worldwide. For queries on implementing the WRF-UACM model, contact Dr. Utkarsh P. Bhautmage (upbhautmage@connect.ust.hk OR yukimicky7@gmail.com).