Seminar by Johannes Feddema on Sep 30, 2015

Join us for our opening event featuring a presentation by Johannes Feddema on Sept 30, 2015 at the University Club (Wild Rose room).

Title: “Modeling Urban Systems in an Earth System Model”

When assessing the impacts of climate change on society, it is important to consider that over half the world population now lives in some form of urban center and that the impacts of climate change must consider the specific responses of urban climates within the context of global climate change.  It is well documented that urban systems experience significantly different climates compared to their surrounding landscapes; most often referred to as the “urban heat island effect.”  Therefore, to better assess the impact of climate change on humans, it is important to incorporate urban climate effects in climate simulations and climate impact studies.  However, the material make-up, design, and density of urban areas are important factors that affect climate outcomes associated with urban areas.  Outcomes from such urban characteristics include changes in albedo, urban heat island intensity, diurnal temperature range etc.  Thus urban systems may respond differently to large scale climate change compared to surrounding landscapes.

This paper will provide a brief overview of the implementation of an urban canyon type model in the National Center for Atmospheric Research (U.S.A) Community Earth System Model (CESM).  Recognizing that urban areas can be very heterogeneous in their design and use of construction materials, we will illustrate how we compiled a dataset to represent these heterogeneous properties for 33 regions globally.  We then illustrate how this dataset influences urban climate simulations at global scales by contrasting these simulations to a fixed set of properties for a particular location in Vancouver, CA.  For example, using more realistic urban properties generally decreases heat islands of urban areas in tropical regions, and increases urban heat islands in higher latitudes.  Similarly we can evaluate the differential impacts of urban areas depending on their surrounding climate types (dry, moist, hot or cold).  A final component of the talk will consider how future use of materials and urban design might impact urban climate properties in the future.  We propose several alternative scenarios generally associated with IPCC future Representative Concentration Pathways (RCPs).  We will present datasets to represent these future urban conditions, and show the potential impacts on global urban heat island characteristics.