Urban modeling over Houston in support of SIMMER

Extreme heat is a leading cause of weather-related human mortality in the United States. As global warming patterns continue, researchers anticipate increases in the severity, frequency and duration of extreme heat events, especially in the southern and western U.S. Many cities in these regions may have amplified vulnerability due to their rapidly evolving socioeconomic fabric (for example, growing elderly populations). This raises a series of questions about the increased health risks of urban residents to extreme heat, and about effective means of mitigation and adaptation in present and future climates. We will introduce a NASA-funded project aimed at addressing these questions via the System for Integrated Modeling of Metropolitan Extreme Heat Risk (SIMMER). Through SIMMER, we hope to advance methodology for assessing current and future urban vulnerabilities from the heat waves through the refinement and integration of physical and social science models, and to build local capacity for heat hazard mitigation and climate change adaptation in the public health sector. We will also present results from a series of sensitivity studies over Houston and surrounding area employing a recently-implemented multi-layer urban canopy model (UCM) within the Noah Land Surface Model. The UCM has multiple layers in the atmosphere to explicitly resolve the effects of buildings, and has an indoor-outdoor exchange model that directly interacts with the atmospheric boundary layer. The goal of this work, which supports the physical science component of SIMMER, is to characterize the ill-defined and uncertain parameter space, including building characteristics and spatial organization, in the new multi-layer UCM for Houston, and to assess whether and how this parameter space is sensitive to the choice of urban morphology datasets. Results focus on the seasonal and inter-annual range of both the modeled urban heat island effect and the magnitude of surface energy components and temperatures.