Observations of Local Scale Perturbations Resulting from Urban Environments

Current operational forecasting, in general, frequently ignores the local perturbations caused by urban environments. Although predictions have consistently improved with time, there are many aspects in which models are still lacking, such as local effects of topography, vegetation, and land use. There have been many suggestions for improving surface parameterizations and now with the available computing power, and model resolution becoming more and more refined, the possibility of cities being parameterized is a reality. In order to more completely understand the effects of an urban environment, this study deployed several Vaisala WXTs around the perimeter of West Lafayette and Lafayette, IN to consistently monitor and record data synchronously every five minutes for a time period of two weeks. Data was also received from fixed Mobile Automated Weather Station (MAWS) and Automated Surface Observation System (ASOS) located around the perimeter at neighboring helipads, hospitals, and airports. Theoretical advection was calculated from the observations and compared to data collected at the intermediate fixed observation stations throughout the cities. Potential temperature was used in calculations to negate heating and cooling caused by rising and sinking of the air parcels due to the area's variable terrain. Deviations were expected, even in near proximity readings. Our study will show how urban environments can cause local scale weather perturbations and downstream deviations on the larger scale. By understanding how a city (in general) diverts the wind flow and precipitation, atmospheric scientists will be able to use this information to improve parameterization schemes for higher resolution models.