Project A2-1:Land-Atmosphere-Hydrosphere Interactions in Urban Terrain

Elie Bou-Zeid, PhD – Principal Investigator

Princeton University
Civil and Environmental Engineering

Claire Welty, PhD – Co-Principal Investigator

University of Maryland, Baltimore County
Chemical, Biochemical and Environmental Engineering


The overarching aim of the project is to build the next-generation urban hydro-climatological simulation platform that will combine the state of the science in atmospheric, urban surface, and groundwater models.A2-1 Urban Layer

Specifically, we will couple the Weather Research and Forecasting (WRF) atmospheric model with the ParFlow subsurface flow model. At the urban interface of these two domains, we will implement and further develop an Urban Canopy Model (UCM) that captures the wide range of radiative, thermodynamic, fluid dynamic, and hydrologic processes operating in urban terrain.

The new simulation platform will have capabilities that are not available in any current model. Specifically, we aim to use the new model to assess:

  • Water demand and cooling impact of canyon trees
  • Total urban water demand and how it is modulated by weather
  • Influence of surface-groundwater coupling and decoupling on the urban microclimate
  • Complex water-climate-energy repercussions of green infrastructure systems (urban irrigation, rainwater tanks, biofiltration systems, green roofs, etc.)
  • Thermal comfort in the urban outdoor space.

These applications will help us better understand urban sustainability under historic extreme events (e.g., heat waves, floods, droughts) and present conditions. Furthermore, the modeling advances will also be transferred to other teams who are focusing on the impact of future extreme events, and how the cities of the future can reduce their resource use and improve their resilience and sustainability.


The project will require current and past land use data and data for urban water and energy consumption.



The data will be used as input to the simulations, and to develop mitigation scenarios.

A2-1: Coupled Model

The model consists of three coupled elements:A2-1 updated model

  1. Weather Research and Forecasting (WRF) atmospheric model
  2. ParFlow subsurface flow model
  3. Advanced Urban Canopy Model (UCM) for the urban surface (interface between atmosphere and subsurface)

These are highly complex models that require extensive computing and skill to execute. Thus they will be shared only within the scientific community.

However, based on these models’ outputs, we could consider the development of simplified interactive tools that can help decision makers understand the benefits and consequences of certain actions and mitigation scenarios we have assessed in our work.

Journal Articles

Bradshaw, J., Bou-Zeid, E, and Harris, R.H. (2016) “Greenhouse gas mitigation benefits and cost-effectiveness of weatherization treatments for low-income, American, urban housing stocks”, Energy and Buildings, 128,911-920, DOI: 10.1016/j.enbuild.2016.07.020.

El-Samra R. , Bou-Zeid E., El-Fadel M. “To What Extent Does High Resolution Dynamical Downscaling Improve the  Representation of Climatic Extremes over an Orographically Complex Terrain?”, Theoretical and Applied Climatology, online, DOI 10.1007/s00704-017-2273-8 Status = Published; Acknowledgment of Federal Support = Yes; Peer Reviewed = Yes.

El-Samra R., Bou-Zeid E., El-Fadel M. (2018) “What Model Resolution is required in Climatological Downscaling over Complex Terrain?”, Atmospheric Research, 203, 68–82, DOI:10.1016/j.atmosres.2017.11.030. Status = Published, Acknowledgement of Federal Support = Yes, Peer Reviewed = Yes

Kuehni, S.M., Bou-Zeid E., Webb C., Shokri N. (2016), “Roof cooling by direct evaporation from a porous roof layer”, Energy and Buildings, 127, 512-528, DOI: 10.1016/j.enbuild.2016.06.019.

Li Q., Bou-Zeid E., Anderson W., Grimmond S., Hultmark M. (2016) “Quality and Reliability of LES of Convective Scalar Transfer at High Reynolds Numbers”, International Journal of Heat and Mass Transfer, 102, 959–970.  Status = Published; Acknowledgment of Federal Support = Yes; Peer Reviewed = Yes.

Li Q, Wang ZH (2017) Large-eddy simulation of the impact of urban trees on momentum and heat fluxes, Agricultural and Forest Meteorology, Status = Published; Acknowledgment of Federal Support = Yes; Peer Reviewed = Yes.

Llaguno-Munitxa M., Bou-Zeid E., Hultmark M. (2017) “The influence of building geometry on street canyon air flow: validation of large eddy simulations against wind tunnel experiments”, Journal of Wind Engineering & Industrial Aerodynamics, 165, 115-130. Status = Published; Acknowledgment of Federal Support = Yes; Peer Reviewed = Yes.

Malings C., Pozzi M., Klima K., Bergés M., Bou-Zeid E., Ramamurthy P. (2017) “Surface Heat Assessment for Developed Environments: Probabilistic Urban Temperature Modeling”, Computers, Environment and Urban Systems, 66, 53-64, DOI: 10.1016/j.compenvurbsys.2017.07.006. Status = Published; Acknowledgment of Federal Support = Yes; Peer Reviewed = Yes.

Ramamurthy, P., & Bou‐Zeid, E. (2016). Heatwaves and Urban Heat Islands: A Comparative Analysis of Multiple Cities Using a High‐Resolution Numerical Model. Journal of Geophysical Research: Atmospheres. Status = Published; Acknowledgment of Federal Support = Yes; Peer Reviewed = Yes.

Ryu, Y.-H., J. A. Smith, M. L. Baeck and E. Bou-Zeid, The influence of land-surface heterogeneities on heavy convective rainfall in the Baltimore-Washington metropolitan area, Monthly Weather Review, 144, 553–573, 2016. Status = published. Acknowledgement = yes. Peer-reviewed =yes.

Shim, S., Shin, S., Meggers, F., Bou-Zeid, E., & Stone, H. A. (2016). Controlled evaporative cooling on a superhydrophilic surface: building a green wall. In Bulletin of the American Physical Society (Vol. 61–20). Portland, Oregon. Retrieved from  Status = Published; Acknowledgment of Federal Support = No;  Peer Reviewed = Yes

Shokri Kuehni, Salomé M.S. Elie Bou-Zeid, Colin Webb, Nima Shokri (2016). Roof cooling by direct evaporation from a porous layer, Energy and Buildings 127: 521-528, Status = Published; Acknowledgement of Federal Support = Unknown; Peer Reviewed = Yes

Song, J. and Wang, Z.-H.: Evaluating the impact of built environment characteristics on urban boundary layer dynamics using an advanced stochastic approach, Atmos. Chem. Phys., 16, 6285-6301,, 2016.

Song J, Wang ZH (2016), Diurnal changes in in urban boundary layer environment induced by urban greening, Environmental Research Letters, 11: 114018.

Song J, Wang ZH, Wang C (2017), Biospheric and anthropogenic contributors to atmospheric CO2 variability in a residential neighborhood
of Phoenix, Arizona, Journal of Geophysical Research: Atmospheres, 122:3317-3329. Status = Published; Acknowledgment of Federal Support = Yes; Peer Reviewed = Yes.

Sun T, Wang ZH, Oechel W, Grimmond CSB (2017) The analytical objective hysteresis model (AnOHM v1.0): Methodology to determine bulk storage heat flux coefficients, Geoscientific Model Development, 10: 2875-2890,  Status = Published; Acknowledgment of Federal Support = Yes; Peer Reviewed = Yes.

Wang ZH, Fan C, Myint SW, Wang C (2016) Size matters: what are the characteristic source areas for urban planning strategies? PLoS One, 11(11):e0165726. Status = Published; Acknowledgment of Federal Support = Yes; Peer Reviewed = Yes.

Wang C, Wang ZH (2017), Projecting population growth as a dynamic measure of regional urban warming, Sustainable Cities and Society, 32: 357-365.  Status = Published; Acknowledgment of Federal Support = Yes; Peer Reviewed = Yes.

Wang ZH, Li Q (2017), Thermodynamic characterisation of urban nocturnal cooling, Heliyon, 3: e00290. Status = Published; Acknowledgment of Federal Support = Yes; Peer Reviewed = Yes

Wang, W., J. A. Smith, P. Ramamurthy, M. L. Baeck, E. Bou-Zeid and T. M. Scanlon, On the correlation of water vapor and CO2: application to flux partitioning of evaporation, Water Resources Research, 52, 9452–9469, doi:10.1002/ 2015WR018161, 2016. Status = published, Acknowledgement = yes. Peer-reviewed=yes.

Yang J. and Bou-Zeid E. (2018) “Should cities embrace their heat islands as shields from extreme cold?” Journal of Applied Meteorology and Climatology, online first, DOI: 10.1175/JAMC-D-17-0265.1. Status = Published, Acknowledgement of Federal Support = Yes, Peer Reviewed = Yes

Yang J, Wang ZH, Georgescu M, Chen F, Tewari M (2016) “Assessing the impact of enhanced hydrological processes on urban hydrometeorology with application to two cities in contrasting climates”. Journal of Hydrometeorology, 17, 1031-1047, DOI:10.1175/JHM-D-15-0112.1

Zhao, Lei, Oppenheimer M., Qing Z., Baldwin J., Ebi K., Bou-Zeid E.; Guan K., Liu X. (2018) “Interactions between urban heat islands and heat waves”, Environmental Research Letters, 13, 034003, DOI: 10.1088/1748-9326/aa9f73. Status = Published, Acknowledgement of Federal Support = Yes, Peer Reviewed = Yes.

Updated: Sept. 2018


Yang, Jiachuan (2016) “Urban Green Infrastructure: Modeling and Implications to Environmental Sustainability”, PhD Dissertation, Arizona State University, Tempe, AZ.

Li, Qi (2016) “Scalar and Momentum transport over Complex Surfaces”, PhD Dissertation, Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ.

Related Materials

Additional Resources


BouZeid_Elie_ProfileElie Bou-Zeid, PhD – Principal Investigator

Associate Professor
Civil and Environmental Engineering
Princeton University
Voice: (609) 258-5429

Dr. Bou-Zeid’s current research specifically focuses on combining numerical, experimental, and analytical tools to study the basic dynamics of flow and transport in environmental systems. The aim is to study how Environmental Fluid Mechanics relate to problems in climate change, air quality, hydrology, and sustainable development.



Welty_Claire_ProfileClaire Welty, PhD – Co-Principal Investigator

Chemical, Biochemical and Environmental Engineering
University of Maryland, Baltimore County
Voice: (410) 455-1766

Our interest is in developing an end-to-end system of field-deployed sensors and fully coupled groundwater-surface water mathematical models to quantify and predict the urban hydrologic cycle and coupled biogeochemical cycles from neighborhood to regional scales. Our goal is to be able to assimilate sensor data into hydrologic and water quality models in near-real time for predicting flow paths, fluxes and stores of water and chemicals on land surfaces and in the subsurface. We work in collaboration with the NSF Baltimore Ecosystem Study Long-Term Ecological Research Site and the USGS MD-DE-DC Water Science Center. While methods are being developed using place-based research in Baltimore area, the methods are widely applicable to other urban areas.

Zhihua Wang, Assistant Professor

Arizona State University

Jiachuan Yang, Postdoctoral Fellow

Princeton University


Hamidreza Omidvar, Ph.D. student,

Princeton University


Mahdad Talebpour, Ph.D. student

University Maryland, Baltimore county


Chenghao Wang, Ph.D. student

Arizona State University