Importance of radiative transfer processes in urban climate models: A study based on the PALM model system 6.0

0531794 - ÚI 2023 RIV DE eng J - Journal Article
Salim, M. - Schubert, S. - Resler, Jaroslav - Krč, Pavel - Maronga, B. - Kanani-Sühring, F. - Sühring, M. - Schneider, Ch.
Importance of radiative transfer processes in urban climate models: A study based on the PALM model system 6.0.
Geoscientific Model Development. Roč. 15, č. 1 (2022), s. 145-171. ISSN 1991-959X. E-ISSN 1991-9603
R&D Projects: GA KHP(CZ) UH0383; GA TA ČR(CZ) TO01000219
Institutional support: RVO:67985807
Keywords : radiative transfer * radiation interactions * radiation in urban canopy * RTM
OECD category: Meteorology and atmospheric sciences
Impact factor: 5.1, year: 2022
Method of publishing: Open access
https://dx.doi.org/10.5194/gmd-15-145-2022

Including radiative transfer processes within the urban canopy layer into microscale urban climate models (UCMs) is essential to obtain realistic model results. These processes include the interaction of buildings and vegetation with shortwave and longwave radiation, thermal emission, and radiation reflections. They contribute differently to the radiation budget of urban surfaces. Each process requires different computational resources and physical data for the urban elements. This study investigates how much detail modellers should include to parameterise radiative transfer in microscale building resolving UCMs. To that end, we introduce a stepwise parameterization method to the PALM model system 6.0 to quantify individually the effects of the main radiative transfer processes on the radiation budget and on the flow field. We quantify numerical simulations of both simple and realistic urban configurations to identify the radiative transfer processes which have major effects on the radiation budget, such as surface and vegetation interaction with short wave and long wave radiation, and those which have minor effects, such as multiple reflections. The study also shows that radiative transfer processes within the canopy layer implicitly affect the incoming radiation since the radiative transfer model is coupled to the radiation model. The flow field changes considerably in response to the radiative transfer processes included in the model. The study highlights those processes which are essentially needed to assure acceptable quality of the flow field. Omitting any of these processes may lead to high uncertainties in the model results.
Permanent Link: http://hdl.handle.net/11104/0310410

Scientific data in ASEP :
Sensitivity Analysis of the PALM Model System 6.0 in the Urban Environment