Urban Climatology
Weather station (right) and net radiometer (left) on the green garden rooftop of City Hall in an urban canyon of downtown Chicago: The sensors allowed evaluating the energy balance of a surface surrounded by manmade structures that altered the solar and terrestrial radiation fields, air flow and evaporative cooling. [Work conducted as part of the Ph.D. research of Timothy Barzyk.]
Longwave terrestrial radiation received in an urban canyon (solid line) compared with radiation from an unobstructed sky (dashed line): Thermal emission from the warm walls of tall structures helps to maintain overnight temperatures higher than would otherwise be the case. [Work conducted as part of the Ph.D. research of Timothy Barzyk.]
Elevated surface temperatures (red) associated with Chicago's urban "heat island" effect.
A new direction, that currently dominates research in the area of atmospheric radiation and energetics, focuses on the energetics of urban microclimates. Ongoing research involves acquiring and analyzing data for solar and terrestrial radiation and meteorological variables obtained in a variety of urban environments. The combination of this dataset with a statistics-based energy balance model of the urban surface allows inferring information about the flux of sensible heat, thermal conduction in the surface layer, and evaporative cooling. Recent measurements conducted near the base of an urban canyon in downtown Chicago provide insight into the formation and character of the urban heat island. In the urban center, the heat island is largely a nighttime phenomenon where thermal emission from the vertical faces of high-rise buildings and inefficient sensible heat transport lead to nocturnal urban surface temperatures warmer than would exist otherwise. The results have implications for improving the energy efficiency of heavily urbanized areas.
Much of the motivation of this research is public policy, i.e., how do modern settlement systems interact with environmental constraints that settlement infrastructure creates? This research is done in collaboration with colleagues at the Harris School for Public Policy Studies.
View of the urban canyon from the green garden rooftop of Chicago's City Hall: Looking North (right), looking South (left).
Research Group
Radhika Khosla (graduate student)
Previous students:
Elizabeth Weatherhead
Guyong Wen
Yixiang Liao
Zheng Qu
Shelby Winiecki
Carynelisa Erlick
Timothy Barzyk
Collaborators from other institutions
Jeffrey S. Gaffney (University of Arkansas, formerly Argonne National Lab)
Nancy A. Marley (University of Arkansas)
Germar Bernhard (Biospherical Instruments, Inc.)
