Abstract
Effects of nonlinearity on theairflow past an urban heat island and precipitationchange downwind, are investigated analytically in thecontext of the weakly nonlinear response of a stablystratified uniform flow to specified heating. Theheating structure is assumed to be bell-shaped in thehorizontal and exponentially decreasing with height.The forcing to the first-order equation exhibitscooling in the concentrated low-level heating region.The linear solution component shows upward motiondownstream as suggested by many previous studies. Theweakly nonlinear solution component shows downward orupward motion downstream depending on the heatingdepth. It is proposed that when the heating depth islarge, but still within a valid range of theperturbation expansion, the linear and weaklynonlinear effects constructively work together toproduce enhanced upward motion on the downstream side,not far from the heating centre. This explains toa greater extent the precipitation enhancement downstream ofthe heat island than is possible from the linear effect alone. Itis also proposed that when the heating depth is small,the linear and weakly nonlinear effects destructivelywork together to reduce upward motion on thedownstream side, not far from the heating centre. Thisexplains to a greater extent the lack of precipitation enhancementdownstream than is possible from the linear effect alone.
Similar content being viewed by others
References
Baik, J.-J.: 1992, 'Response of a Stably Stratified Atmosphere to Low-LevelHeating-An Application to the Heat Island Problem', J. Appl. Meteorol. 31, 291–303.
Baik, J.-J. and Chun, H.-Y.: 1996, 'Effects of Nonlinearity on the Atmospheric Flow Response to Low-Level Heating in a Uniform Flow', J. Atmos. Sci. 53, 1856–1869.
Booker, J. R. and Bretherton, F. P.: 1967, 'The Critical Layer for Internal Gravity Waves in a Shear Flow', J. Fluid Mech. 27, 513–539.
Changnon, S. A., Shealy, B. T., and Scott, R. W.: 1991, 'Precipitation Changes in Fall,Winter, and Spring Caused by St. Louis', J. Appl. Meteorol. 30, 126–134.
Chun, H.-Y. and Baik, J.-J.: 1994, 'Weakly Nonlinear Response of a Stably Stratified Atmosphere to Diabatic Forcing in a Uniform Flow', J. Atmos. Sci. 51, 3109–3121.
Lin, Y.-L. and Chun, H.-Y.: 1991, 'Effects of Diabatic Cooling in a Shear Flow with a Critical Level', J. Atmos. Sci. 48, 2476–2491.
Lin, Y.-L. and Smith, R. B.: 1986, 'Transient Dynamics of Airflow near a Local Heat Source', J. Atmos. Sci. 43, 40–49.
Oke, T. R.: 1973, 'City Size and the Urban Heat Island', Atmos. Environ. 7, 769–779.
Olfe, D. B. and Lee, R. L.: 1971, 'Linearized Calculations of Urban Heat Island Convection Effects', J. Atmos. Sci. 28, 1374–1388.
Pielke, R. A.: 1984, Mesoscale Meteorological Modeling, Academic Press, 612 pp.
Smith, R. B. and Lin, Y.-L.: 1982, 'The Addition of Heat to a Stratified Airstream with Application to the Dynamics of Orographic Rain', Quart. J. Roy. Meteorol. Soc. 108, 353–378.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
BAIK, JJ., CHUN, HY. A DYNAMICAL MODEL FOR URBAN HEAT ISLANDS. Boundary-Layer Meteorology 83, 463–477 (1997). https://doi.org/10.1023/A:1000346229951
Issue Date:
DOI: https://doi.org/10.1023/A:1000346229951