Assessing the impact of urban land conversion and regional surface climate and its socio-economic consequence in Western North Africa

Urbanization represents a small areal fraction of global land transformation; however, it occupies earth’s most fertile and productive lands, and its ecological impact is significant and long lasting on the landscape. Over the last few decades, urban expansion has been rapid and significant, especially in developing countries where the population is becoming increasingly urban and where changing land rights and ownership have led to expansion of suburban areas. Morocco, a developing country in Northwest Africa, is emblematic of these trends. Research on the specific physical processes associated with urbanization is needed to assess the impact of urban land conversion on local and regional surface climate and its impact on society. This research will help us understand the interactions between urban landscapes and surface climate and the relationships between urban land use and societies, and will provide managers and policymakers a knowledge platform to consider in urban planning. Urban land conversion affects surface climate through four mechanisms: reduction of transpiration from a reduction in vegetation fraction; a reduction in water infiltration capacity and consequent increase in surface runoff; the alteration of surface albedo through choice of building material and color; and the modification of surface roughness and consequent impacts on surface heat and moisture convergence. The proposed research will use satellite data and models to address a core theme of this solicitation, namely that urban expansion has been rapid and significant over the last few decades, as populations in developing countries become increasingly urban. Specifically, the study comprises four major tasks: First, we will use moderate-resolution optical imagery (Landsat, Sentinel-2) to map urbanization through time for the densely populated and rapidly urbanizing cities of Morocco. Specifically, we will generate maps for 10 large cities for two time periods -- 2008 and 2018 -- where data are available and where the urban signature is remotely measurable on the landscape. These products will serve as baseline boundary conditions for the modeling tasks. Second, we will run land surface models available through the NASA Land Information System (LIS) offline over the selected cities to assess the diurnal variation of the land surface temperature (LST) and evaluate the interactions between LST variability, city characteristics, and ambient climate. This modeling work will show which urban characteristics and related landscape arrangements are best for mitigating the UHI in cities with different climate settings. Third, we will use the fully coupled Weather Research and Forecasting (WRF) model to investigate the Urban Archipelago Effect (UAE) at a regional level over a group of relatively large cities along Morocco’s Atlantic coast and assess the effect of the surface UHI on rainfall patterns. A key novelty of this research will be to explore the aggregate effects of an urban chain’ generated by a series of large cities on regional climate. Finally, we will parameterize the urban-induced land cover and land use changes and their environmental effects to investigate building energy demand as calculated in the Global Change Analysis Model (GCAM).