Cava et al. (2025) Energy Partitioning and Air Temperature Anomalies Above Urban Surfaces: A High-Resolution PALM-4U Study

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: Atmosphere
• Year: 2025
• Date: 2025-12-12
• Authors: Daniela Cava, Luca Mortarini, Tony Christian Landi, Oxana Drofa, Giorgio Veratti, Edoardo Fiorillo, Umberto Giostra, Daiane de Vargas Brondani
• DOI: 10.3390/atmos16121401

Research Groups

Not explicitly stated in the provided text, but the study involves advanced atmospheric modeling and urban meteorology research, likely from institutions associated with the development and application of the MOLOCH and PALM-4U models, potentially in Bologna, Italy.

Short Summary

This study applies a coupled atmospheric model (MOLOCH and PALM-4U) to Bologna during a summer 2023 heatwave to quantify meter-scale thermal variability and energy exchanges within the urban canopy. It reveals pronounced diurnal and vertical atmospheric dynamics and distinct surface-dependent thermal contrasts, highlighting the roles of asphalt/roofs as heat sources/reservoirs and vegetation as a cooling mechanism.

Objective

• To quantify the physical processes governing near-surface thermal variability and fine-scale energy exchanges within the Urban Canopy Layer and Roughness Sublayer in densely built urban areas during heatwaves.

Study Configuration

• Spatial Scale: Meter-scale atmospheric dynamics at 2 m horizontal resolution, resolving the Urban Canopy Layer and Roughness Sublayer.
• Temporal Scale: A summer 2023 heatwave.

Methodology and Data

• Models used: Coupled MOLOCH and PALM model system 6.0 (PALM-4U).
• Data sources: In situ meteorological observations and Landsat-8 Land Surface Temperature (LST) data for validation.

Main Results

• The coupled model configuration showed improved agreement with observations for air temperature and wind speed compared to standalone mesoscale simulations.
• Pronounced diurnal and vertical variability of wind speed, turbulent kinetic energy, and friction velocity were observed, with maxima occurring between two and three times the median building height (hc).
• Asphalt and roofs act as strong daytime heat sources (Bowen ratio βasphalt ≈ 4.8) and nocturnal heat reservoirs at pedestrian level (z ≈ 0.07 hc).
• Vegetation sustains daytime latent heat fluxes (βvegetation ≈ 0.6÷0.8) and contributes to cooler surface and near-surface air (Temperature anomaly of surface ΔTs ≈ −9 °C and air ΔTair ≈ −0.3 °C).
• Thermal anomalies decay with increasing height, vanishing above approximately 2.5 times the median building height (z ≈ 2.5 hc) due to turbulent mixing.

Contributions

• Provides novel insights into fine-scale energy exchanges and atmospheric dynamics driving intra-urban thermal heterogeneity during heatwaves using a high-resolution coupled model system.
• Offers quantitative understanding of surface-dependent thermal contrasts and their vertical extent, supporting the development of climate-resilient urban design strategies.
• Validates the performance of the coupled MOLOCH and PALM-4U system for resolving meter-scale urban atmospheric processes.

Funding

Not explicitly stated in the provided text.

Citation

@article{Cava2025Energy,
  author = {Cava, Daniela and Mortarini, Luca and Landi, Tony Christian and Drofa, Oxana and Veratti, Giorgio and Fiorillo, Edoardo and Giostra, Umberto and Brondani, Daiane de Vargas},
  title = {Energy Partitioning and Air Temperature Anomalies Above Urban Surfaces: A High-Resolution PALM-4U Study},
  journal = {Atmosphere},
  year = {2025},
  doi = {10.3390/atmos16121401},
  url = {https://doi.org/10.3390/atmos16121401}
}