Originally published in our November 2023 newsletter (Issue 22)
TC’s research at PNNL centers on improving urban representation in land models and examining extreme events over coastal cities in the COMPASS-GLM and ICoM projects. Overall, TC aims to improve discourse around uncertainties when detecting urban climate signals using models and observations. His broader goal is to provide a framework for developing urban representations for other ESMs and to generate global datasets that will be useful to the urban climate community at large.
TC is an Earth Scientist in the Earth System Modeling group at the Pacific Northwest National Laboratory (PNNL) with interest in atmosphere-biosphere interactions at various scales. Before joining PNNL, TC finished his PhD from Yale University on developing a surface-energy budget perspective on aerosolclimate interactions. He has also led and contributed to multiple studies on urban climate impacts across scales, which have been follow-ups to his master’s dissertation research on the urban heat island (UHI) effect. TC is interested in the role of big data, machine learning, and urban informatics to better understand cities and their complexities. He often uses the Google Earth Engine (GEE) cloud computing platform for satellite remote sensing and geospatial analysis and was one of 26 inaugural GEE Developer Experts in the world.
During his time at Yale, TC developed a new algorithm to estimate surface UHI (SUHI), which led to the most comprehensive publicly available SUHI intensity dataset, covering almost 10,000 urban areas, and including annual, seasonal, monthly, and diurnal patterns1. He has also worked extensively on combining satellite estimates of the urban environment with socioeconomic data to examine within-city environmental disparities2–4. However, he has also been concerned about common misuses of SUHI and satellite-derived land surface temperature (LST) when discussing policy and public health. LST is, at best, a crude proxy for overall patterns of urban heat distributions, but this temperature is not what urban residents generally feel. He has been recently focusing on better quantifying the decoupling between urban heat stress and LST. He has examined this decoupling using various methods to provide multiple lines of evidence and ensure the robustness of the patterns. He used crowdsourced data over Europe to show that LST is a poor proxy for daytime heat stress across scales. More recently, he used numerical model simulations to show that disparities in moist heat stress in US cities, although pervasive, are much lower in magnitude than what you might infer from LST6.
At PNNL, he is contributing to the COMPASS-GLM and ICoM projects. His role in these projects is to improve urban representation in land models and examine extreme events over coastal cities. For example, he has been examining the sensitivity of coastal impacts on outdoor heat stress to various model configurations and complexities. Overall, he wants to improve discussions around uncertainties when detecting urban climate signals using models and observations. TC received the 2023 U.S. Department of Energy (DOE) early career award to improve the representation of urban areas in DOE’s Earth system model (ESM). Beyond providing a framework for developing urban representations for other ESMs, this project will generate global datasets that will be useful to the broader urban climate community.
Highlighted Articles:
T. Chakraborty and X. Lee, “A simplified urban-extent algorithm to characterize surface urban heat islands on a global scale and examine vegetation control on their spatiotemporal variability,” International Journal of Applied Earth Observation and Geoinformation, vol. 74, pp. 269–280, Feb. 2019, doi: 10.1016/j.jag.2018.09.015.
T. Chakraborty, A. Hsu, D. Manya, and G. Sheriff, “Disproportionately higher exposure to urban heat in lower-income neighborhoods: a multi-city perspective,” Environ. Res. Lett., vol. 14, no. 10, p. 105003, Sep. 2019, doi: 10.1088/1748-9326/ab3b99.
T. Chakraborty, A. Hsu, D. Manya, and G. Sheriff, “A spatially explicit surface urban heat island database for the United States: Characterization, uncertainties, and possible applications,” ISPRS Journal of Photogrammetry and Remote Sensing, vol. 168, pp. 74–88, Oct. 2020, doi: 10.1016/j.isprsjprs.2020.07.021.
T. Chakraborty, T. Biswas, L. S. Campbell, B. Franklin, S. S. Parker, and M. Tukman, “Feasibility of Afforestation as an Equitable NatureBased Solution in Urban Areas,” Sustainable Cities and Society, p. 103826, 2022, doi: 10.1016/j.scs.2022.103826.
T. Chakraborty, Z. S. Venter, Y. Qian, and X. Lee, “Lower urban humidity moderates outdoor heat stress,” AGU Advances, vol. 3, no. 5, p. e2022AV000729, 2022, doi: 10.1029/2022AV00072. T. Chakraborty, A. J. Newman, Y. Qian, A. Hsu, and G. Sheriff, “Residential segregation and outdoor urban moist heat stress disparities in the United States,” One Earth, vol. 6, no. 6, pp. 738–750, 2023, doi: 10.1016/j.oneear.2023.05.016.