MODIS detected surface urban heat islands and sinks: Global locations and controls

• We characterize and map surface urban heat islands and sinks globally for 2010.
• Alteration of thermal inertia patterns is implicated in the creation of heat islands and sinks.
• Urban area, vegetation and development are within-city controls of urban heat islands and sinks.

Urbanization is a global problem with emergent properties. The difference in temperature between urban and rural surfaces is one such property that affects health, energy consumption budgets, regional planning and climate. We used remotely sensed datasets and gridded population to estimate the magnitude of thermal differentials (urban heat islands and/or sinks), the timing of heat differential events, and the controlling variables. The global scope of the study provides a consistent analytical environment that enables identification of the key factors that contribute to deleterious heat differentials. We propose new indices of thermal differential and use them to show particular prevalence of heat islands and sinks in arid regions. A variable ranking analysis indicates that development intensity, vegetation amount and the size of the urban metropolis are the most important urban variables to predict heat differentials. Population was of lesser importance in this study. Urban structure indices were also ranked lower, though a different measurement scale qualifies this conclusion. The results support the paradigm of compact development and incorporation of vegetation to the urban infrastructure.