Role Of Clouds In Houston's Urban Heat Island And Extreme Heat

Studying and simulating Houston-Galveston metropolitan area Heat Index and the Urban Heat Island effect requires special attention and considerations to moist processes. During the extreme warm season, the afternoon sea breeze phenomenon provides a natural air conditioning to the city's residents, and facilitates the redistribution of pollutants, moisture, and heat. Of note is that humidity makes a significant difference between the actual surface temperature and the Heat Index. Understanding the modeling uncertainties in the prediction of extreme heat is a standing scientific and operational challenge. Daytime satellite-based cloud climatology products show that the Houston urban area favors the formation of boundary layer clouds during the summertime. Neglecting the role of aerosols, we hypothesize that urban-induced clouds can have a significant net surface cooling effect impacting extreme heat indicators. To address this hypothesis, we developed cloud-resolving simulation focused over the urban environment to assess the impact of non-precipitation clouds during low wind speed conditions. Results show that an all sky simulation tends to improve model performance by simulating colder surface temperatures relative to the clear sky simulations. We conclude that our all sky simulation is related to more clouds developing over the Houston area than in the rural area, with spatial patterns that resemble those from cloud climatology products. This presentation uses observed products and the outlined cutting-edge high-resolution modeling to better characterize the UHI and the Heat Index for forecasting and planning times scales.