Investigating the impacts of anthropogenic heat over East China with a global variable-resolution model

Anthropogenic heat (AH) is an important urban forcing that affects atmospheric pro- cesses from local to regional scales. However, its multiscale impacts are difficult to quantify using conventional global and regional models. In this study, we conduct simulations for four months in 2022 using the integrated Atmospheric Model Across Scales (iAMAS), a global variable-resolution model that couples urban, regional, and large-scale processes within a unified framework, with grid spacing refined from 50 km globally to 3 km over East China. AH is applied as additional surface heat flux over urban areas in East China. Two AH parameterizations are implemented: a spatially uniform scheme (UniAH) and a gridded dataset (GrdAH). Their atmospheric multiscale effects are evaluated by comparing the two AH simulations with a baseline simulation without AH and validating the results against surface station observations in East China. Both AH experiments increase near-surface temperature and boundary layer height, with stronger winter responses, while GrdAH more accurately reproduces observed 2-m temperature and 10-m wind speed. At the urban scale, AH reduces the underestimation of the urban heat island and enhances upward motion. AH-induced thermal perturbations modulate low-level jet and influence upper air circu- lation, then alters convergence-divergence patterns. Their interactions with background circulation extend precipitation responses far beyond urban areas. These findings highlight the multiscale impacts of AH and the value of variable-resolution modeling for simulating urban forcing and its atmospheric feedbacks.