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Evaluation of a single-layer urban energy balance model using measured energy fluxes by scaled outdoor experiments in humid subtropical climate.

Evaluation of a single-layer urban energy balance model using measured energy fluxes by scaled outdoor experiments in humid subtropical climate.

Authors :
Hang, Jian
Zeng, Liyue
Li, Xianxiang
Wang, Dongyang
Source :
Building & Environment; Apr2024, Vol. 254, pN.PAG-N.PAG, 1p
Publication Year :
2024

Abstract

Urban energy balance models can simulate the localized climate and fluxes in urban areas. They are often evaluated using real urban site observations. However, uncertainties in anthropogenic emission, geometry and materials can hinder interpretation. These uncertainties can be eliminated by scaled outdoor models. We assess the performance of a single-layer urban canopy model (SLUCM) offline in predicting surface energy balance (SEB) fluxes within a street canyon-like urban configuration using field measurements from a scaled outdoor setup in Guangzhou, China. We utilize observations of SEB fluxes and surface temperature from a homogenous scaled urban site characterized by street canyons. The scaled observations in June–December 2020 in a dense urban environment with a height-to-width ratio (H/W) of 2 are employed to assess seasonal variations in model performance. Additionally, the December data from two distinct urban scenarios (H/W = 2(2020) and 0.5(2019)) are utilized to compare model performance in deep and shallow street canyon settings. Results show that Q S (R <superscript>2</superscript> = ∼0.47, RMSE = ∼46.0) is the most challenging to predict, followed by Q H (R <superscript>2</superscript> = ∼0.92, RMSE = ∼65.5), Q* (R <superscript>2</superscript> = ∼0.99, RMSE = ∼39.5), L ↑(R <superscript>2</superscript> = ∼0.95, RMSE = ∼33.7), and K ↑(R <superscript>2</superscript> = ∼0.99, RMSE = ∼6.2). SLUCM faces difficulties simulating L↑ particularly during nighttime and cloudy conditions. It also tends to underestimate daytime net radiation (Q *), especially during hot, humid months. Moreover, H/W ratio slightly affects SLUCM's performance in simulating SEB fluxes under dry cool conditions denser urban settings (H/W = 2) show better model performance in K↑, Q H , and Q S but worse performance in L↑ and Q*. • ●SEB components evaluated across different seasons and skies for H/W = 2 and 0.5. • Q S is hardest to predict (R <superscript>2</superscript> = ∼0.47, RMSE = ∼46.0), followed by Q H , Q* , L ↑, K ↑. • SLUCM predicts SEB components better on cool dry days than on hot humid days. • SLUCM predicts SEB components better on clear days than cloudy days. • In cool, dry conditions SLUCM performs better for H/W = 2 case for K ↑, Q H , and Q S. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
03601323
Volume :
254
Database :
Supplemental Index
Journal :
Building & Environment
Publication Type :
Academic Journal
Accession number :
176247108
Full Text :
https://doi.org/10.1016/j.buildenv.2024.111364