Characterizing the Effects of Intra-Urban Land Cover Heterogeneity on Convective Precipitation in Houston, Texas

Urbanization profoundly impacts local meteorology and precipitation processes, as urban landscapes modify heat, moisture, and momentum fluxes in the boundary layer. For example, past modeling studies have revealed that urban areas can enhance rainfall by over 30% through mechanisms such as increased moisture convergence and the urban heat island effect. In addition, the coastal environment has unique mechanisms that control the distribution of convective precipitation, such as sea breeze. However, long-duration, observational analyses utilizing high-resolution meteorological measurements of deep convection in coastal urban environments are lacking, which limits our process-level understanding of these modeled relationships. In particular, knowledge gaps remain regarding how intra-urban variabilites in building densities and configurations influence the initiation, intensity, distribution, and trajectory of summertime convective rainfall, as prior works have not examined linkages between distinct local climate zones and convective storm characteristics. We address these knowledge gaps by utilizing radar observations, remote sensing, and geospatial analysis to systematically investigate how specific local climate zones linked to urbanization and coastal processes affect convective storm characteristics and rainfall patterns in Houston, Texas. We utilize observations from the KHGX NEXRAD Level-II data for the Houston area for the summer periods of 1994–2022 to track convective cells and analyze their relationship with both rainfall occurrence and intensity. The rainfall data are extracted from the KHGX NEXRAD Level-III data, and the data are quality-controlled to exclude stratiform rainfall. We also categorize the local climate zones of the urban area into 17 distinct zones through unsupervised clustering of Landsat 8 satellite data. The intent is to understand how different urban configurations impact convective cell initiation and duration and rainfall occurrence, and the degree to which the urban area impacts the rainfall rate in the nearby suburban and rural areas, as well as distance from the coastline. Finally, we examine how different urban configurations between 2020 and 2022 impact downstream propagation of radar-derived precipitation features, hypothesizing links to urban-induced changes in aerosol composition and loading. The findings will reveal nuanced insights into urban–convection interactions, elucidating the causal pathways fundamental to projected increases in extreme rainfall associated with urban areas globally.