Urban-Climate System Linkages and NASA Involvement in the Houston
Environmental Aerosol Thunderstorm (HEAT) Project

 

Abstract

Urbanization is one of the extreme cases of land use change. Although currently only 1.2% of the land is considered urban, the spatial coverage and density of cities are expected to rapidly increase in the near future. It is estimated that by the year 2025, 60% of the world's population will live in cities (UNFP, 1999). Though urban areas are local in scale, human activity in urban environments has impacts at local, to global scale by changing atmospheric composition; impacting components of the water cycle; and modifying the carbon cycle and ecosystems. However, our understanding of urbanization on the total Earth-climate system is incomplete. Better understanding of how the Earth's atmosphere-ocean-land-biosphere components interact as a coupled system and the influence of the urban environment on this climate system is critical.

Several issues or questions raised in the U,S. Climate Change Science Program echo the aforementioned statement about the urban environment-climate system linkage: A few examples include:

a. How are land-use and land-cover are linked to climate and weather?
b. How do climate variability and change affect land use and land cover, and what are the potential
    feedbacks of changes in land use and land cover to climate?
c. How do the primary and secondary pollutants from the world's megacities and large-scale, non-urban
    emissions (e.g., agriculture, ecosystems, etc.) contribute to global atmospheric composition?
d. How are estimates of atmospheric composition and related processes to be used in assessments of the
    vulnerability of ecosystems to urban growth and long-range chemical transport?
e. Research on the climatic effects of temperature on air quality, particularly in urban heat islands and other
    regional settings, and the potential health consequences.

Additionally, the U.S. Weather Research Program (Dabberdt et al. 2000) stated that there is a substantial need for more observational and modeling work to improve basic understanding of weather and climate impacts in the urban zone. This is particularly important since local-scale anthropogenic changes in weather and climate have a proportionally larger impact on the global population when they are associated with increases in population density.

A comprehensive assessment of the role of urban environment on weather, climate, global water cycle, global carbon cycle, ecosystems, and atmospheric composition has not been a primary focus of past efforts. We propose a comprehensive program to address the co-relationship between urbanization and its impact on the Earth system components using NASA's unique satellite-based and ground-based remote sensing and numerical modeling resources. This program will leverage interagency and university resources during the Houston Environmental Aerosol Thunderstorm Project (HEAT) planned for the summer of 2005 (http://www.met.tamu.edu/ciams/heat/). The primary goals of HEAT are to examine the local to regional effects of the urban environment on (1) atmospheric composition and chemistry, (2) cloud microphysical-precipitation-lightning processes, and (3) boundary layer and coastal zone interface processes. Though focused on the Houston region, the characterization and understanding of urban-climate system processes and linkages will translate to the broader context that NASA is well suited to address.

A team of NASA research and instrument scientists, modelers, and applications stakeholders have crafted a program that seeks to leverage this unique opportunity while addressing key research questions related to ESE, but highly synergistic with HEAT objectives. The proposed effort is not motivated by a desire to "jump on the next field campaign train." Instead, this effort is a carefully conceived program to address key science and societal question about urban environments, which are emerging rapidly as a key topic in climate change/system assessment and prediction (e.g. recent sessions at the 2003 AGU meeting, 2004 AMS meeting, and numerous others in 2004 and 2005). The proposed work is aligned closely with key ESE research strategy questions:

a. How are global precipitation and the cycling of water changing? (Variability)
b. What changes are occurring in land cover and land use, and what are the causes? (Forcing)
c. What trends in atmospheric constituents and solar radiation are driving global climate? (Forcing)
d. How is the Earth's surface being transformed and how can such information be used to predict future changes? (Forcing)
e. What are effects of clouds and surface hydrologic processes on Earth's climate? (Response)
f. What are the effects of regional pollution on the global atmosphere, and the effects of global chemical and climate changes on regional air quality? (Response)
g. How are variations in local weather, precipitation, and water resources related to global climate variation? (Consequences)
h. What are the consequences of land cover and land use change for the sustainability of ecosystems and economic productivity? (Consequences)
i. What are the consequences of climate and sea level changes and increased human activities on coastal regions? (Consequences)
j. How can weather forecast duration and reliability be improved by new space-based observations, data assimilation, and modeling? (Prediction)

Furthermore the proposed activity is aligned with ESE Applications Program efforts to enable organizations in the public and private sectors to routinely deliver and use Earth science information that saves lives, improves the quality of life, and saves resources through improved decision making.. The Urban-climate system linkages proposal is aligned with Air Quality, Coastal Management, Disaster Management, Public Health and Water Management applications of national priority identified by NASA. It also addresses key cross-cutting topics in the NASA ESE Applications program like Community Growth. Additionally, the proposing team has work to establish stakeholders with decision support tools that could benefit from the infusion of NASA observations, models, and expertise.

The proposal is a self-contained but modular effort involving an array of NASA-affiliated personnel and assets. The proposal is
drafted to be considered as a whole; however, the modularity provides flexibility to fund components of the effort if they are viewed as
more vital to the NASA mission or more cost-effective. Each module of the proposal discusses its specific science objectives, resource
needs, and budget. The proposal is structured in the following manner:

HEAT Overview
Observations of the Urban Earth System Components and Validation of Observing Systems
Coupled Modeling of Urban Earth System Components
Benchmarking NASA-HEAT measurements and results in Application Communities