Work package M4: Surface energy Budget

Contact information

Principal investigators: ​Dr. Björn Maronga , ​Prof. Dr. Günter Groß

Staff: ​M.Sc. Robert von Tils

Institution: Institute of Meteorology and Climatology (​http://www.muk.uni-hannover.de/), Leibniz Universität Hannover (​https://www.uni-hannover.de/)

Goals of WP-M4

The local temperature within a complex urban environment is determined by the specific site parameters as well as by the atmospheric conditions. In a surface energy budget model, these factors for soil, vegetation and atmosphere are combined, resulting in a specific surface temperature for a small urban area patch. Since surface temperature is a key element for urban climate, particular attention must be paid to the proper calculation for very different surfaces and soil properties. In this work package, a consistent surface energy budget model will be provided for the <new model> model that is suitable to calculate surface temperatures for bare soils, the wide variety of green surfaces, water bodies, and building façades. Within the framework of these investigations to calculate urban surface temperatures, special focus must be given on specific urban surfaces and undergrounds/substrates like lawns and ecoplasters (lawn paving blocks), paved roads and places, crashed rocks and gravel, trees including shadow, building design elements like green roof or green façade, and water bodies of variable depth.

Work program

WP-M4.1: Surface temperatures for mainly sealed surfaces

In a first step, the energy budget for mainly sealed surfaces will be developed and implemented in <new model>. For paved roads and places the heat transfer into or out of the soil is the dominant part of the surface energy budget. Evapotranspiration and the latent heat flux are hence very small because of the limited interaction with soil water and water availability. In a sensitivity study the most important soil parameters have to be identified in order to specify the minimum input data standards and the necessary degree of accuracy. The subroutine will be tested against available observations for surfaces with different degree of sealing.

WP-M4.2: Surface temperatures for mainly green and blue surfaces

Urban green and water bodies offer a significant potential to moderate the urban heat island, especially during summer. Specific energy budgets for the wide variety of green infrastructures will be developed including lawns, trees, green roofs and green walls. Also water areas are effective measures to limit high temperatures in an urban surrounding. Energy budgets for water bodies of variable size and depth are necessary to estimate the interactions with atmospheric temperatures. The most sensitive parameters must be identified and their depth of accuracy needs to be specified. The quality of the developed subroutine will be tested against observations. A model description, interpretation aids and presentation of the importance of different input parameter will be provided.

WP-M4.3: Application of the surface energy budget model

The developed surface budget model, which includes specific urban surfaces, will be used to calculate surface temperatures for selected observation periods in the demo cities (from Module B/ 3DO project). The results are used to identify characteristic deficiencies of the model, and the required corrections to the appropriate part of the budget model, is necessary. Also specific surfaces within the demo cities with great relevance for the local climate will be identified and the budget model will be complemented.