Dr. Zhihua, Assistant Professor with the ASU’s School of Sustainable Engineering & the Built Environment joins the NCE as the Co-Director for Climate Systems Research.

Dr. Zhihua Wang completed his Ph.D. study in the Environmental Engineering and Water Research (EEWR) program at Princeton University. He obtained his B.Eng and M.Eng degrees in Civil and Environmental Engineering at Nanyang Technological University (Singapore) in 2002 and 2004, respectively.

Dr. Wang’s primary research interest is on the urban environment under the changing climate, including land-atmosphere interactions, subsurface heat/water transport, urban heat island effect and the long-term sustainability of cities. Zhihua’s research focuses on both field measurement and numerical modeling to investigate the urban flow dynamics and the surface/subsurface transport of energy and water. The field measurement aims to study the urban-rural difference in terms of the land-atmospheric interaction and ecohydrological systems, and to assess the effect of urban development and land use change in the Sonoran desert. Furthermore, Zhihua is involved in the development of multi-scale multi-physics numerical modeling as a powerful tool to tackle urban environmental problems, ranging from local (~10-100 m) to neighborhood (~1 km) to mesoscales (~100 km). The integrated model also embraces a variety of physical components including: building energy (HVAC) systems, boundary-layer physics, heat and mass transfer and the mesoscale atmospheric dynamics.

Zhihua is an active member of the American Meteorological Society (AMS), American Physical Society (APS), American Geophysical Union (AGU) and International Association for Urban Climate (IAUC). As a passionate and highly-motivated researcher, he has been highly productive and published more than 20 peer-reviewed papers in high impact journals and conference proceedings.

Work on Urban Heat Island (UHI)
Zhihua has investigated the effect of different surface covers, including the engineered concrete and asphalt pavements, gravel roofs and urban lawns, on the surface temperature and heat budget distributions by coupling the heat transfer analysis with the urban hydrological modeling. Advanced stochastic simulations have also been performed to characterize the inherent uncertainty in the parameter space associated with commonly used state-of-art numerical urban models, such as Weather Research and Forecasting (WRF) developed by the National Center of Atmospheric Research (NCAR). Preliminary study shows that these surface exchange schemes, when coupled to the building energy model and atmospheric dynamics, will yield promising results and enhance the understanding on the mechanism and possible mitigation strategies of the UHI effect, thus will have profound impact on the long term sustainability of urban development.

Recently, the NCE completed a study for the Asphalt Pavement Alliance (APA) on asphalt pavement temperature effects on overall Urban Heat Island (UHI) with focus on characterizing porous asphalt mixtures. A paper summarizing the study was presented at the Transportation Research Board meeting in January 2012. Excerpts of the study are presented as follows. Please contact the NCE to obtain a copy of the report or paper.

Rapid urbanization requires an increase in pavement surface area, which contributes to UHI due to unfavorable heat retention properties. In recent years, the use of alternate pavement designs has become more common in attempt to mitigate environmental impacts of urbanization. Specifically, use of porous pavements is gaining popularity in the paving industry due to attractive storm water mitigation and friction properties. However, little information is available regarding thermal behavior of these materials.

This study explored the extent to which porous asphalt pavement influenced pavement temperatures and investigated the impact on UHI by considering the diurnal temperature cycle. A one-dimensional pavement temperature model developed at ASU was used to model surface temperatures of porous asphalt, dense graded asphalt and Portland cement concrete pavements.

Several scenarios were considered to include variations in pavement thickness, structure and albedo. In addition, thermal conductivity testing was performed on porous asphalt mixtures to obtain values for current and future analysis.

In general, porous asphalt exhibited higher daytime surface temperatures of the three pavement types because of the reduced thermal energy transfer from the surface to subsurface layers. In comparison, porous asphalt showed the lowest nighttime temperatures when compared to other materials with similar or higher albedo. This trend can be attributed to the unique insulating properties of this material due to a high air void content. As anticipated, the outcome of this study indicated that pavements impact on UHI is a complex problem and needs to consider important interaction between influencing factors such as pavement thickness, structure, material type, and albedo.

The Asphalt Pavement Alliance (APA) is one of the founding industry members and supporters of the NCE since its inception back in 2006. The NCE and APA have successfully collaborated on various research activities in the areas of sustainable asphalt paving materials and the Urban Heat Island (UHI) effect. Many of these research initiatives have direct correlation to research interests and pavement solutions currently offered by the APA. The NCE looks forward to continue working with the APA to develop more sustainable solutions and serve the growing pavement market with Green initiatives.

The NCE appreciates the continued support of the APA, and look forward to a fruitful and beneficial relationship to both organizations.

Recently, the NCE completed a study for the APA on asphalt pavement temperature effects on overall UHI with focus on characterizing porous asphalt mixtures. A paper summarizing the study was presented at the Transportation Research Board meeting in January 2012. Please contact the NCE to obtain a copy of the report or paper.

http://chainreactionkids.org/stories-paving-the-way-to-a-cooler-future

The NCE welcomes Dr. Krishna P. Biligiri as the new Assistant Director to help provide leadership and direction to the center’s research activities.