Ghassem R. Asrar

Learn More
The state of knowledge and outstanding challenges and opportunities in global water cycle observations, research and modeling are briefly reviewed to set the stage for the reasons behind the new thrusts promoted by the World Climate Research Programme (WCRP) as Grand Challenges to be addressed on a 5-to 10-year time frame. Those focused on water are led by(More)
The covariability of temperature (T), precipitation (P) and radiation (R) is an important aspect in understanding the climate influence on crop yields. Here, we analyze county-level corn and soybean yields and observed climate for the period 1983-2012 to understand how growing-season (June, July and August) mean T, P and R influence crop yields jointly and(More)
BACKGROUND Efforts in global heath need to deal not only with current challenges, but also to anticipate new scenarios, which sometimes unfold at lightning speed. Predictive modeling is frequently used to assist planning, but outcomes depend heavily on a subset of critical assumptions, which are mostly hampered by our limited knowledge about the many(More)
The net primary productivity (NPP) is commonly used for understanding the dynamics of terrestrial ecosystems and their role in carbon cycle. We used a combination of the most recent NDVI and model-based NPP estimates (from five models of the TRENDY project) for the period 1982–2012, to study the role of terrestrial ecosystems in carbon cycle under the(More)
Carbon cycling in inland waters has been identified as an important, but poorly constrained component of the global carbon cycle. In this study, we compile and analyze particulate organic carbon (POC) concentration data from 1145 U.S. Geological Survey (USGS) gauge stations to investigate the spatial variability and environmental controls of POC(More)
I take this opportunity to acknowledge the contributions of The Global Energy and Water Cycle Experiment (GEWEX), the Coordinated Enhanced Observing Period, which is now part of the Coordinated Energy and water cycle Observations Project (CEOP), and other affiliated research projects towards advancing our knowledge of water and energy cycle processes(More)
Land models are valuable tools to understand the dynamics of global carbon (C) cycle. Various models have been developed and used for predictions of future C dynamics but uncertainties still exist. Diagnosing the models' behaviors in terms of structures can help to narrow down the uncertainties in prediction of C dynamics. In this study three widely used(More)
The influence of urbanization on vegetation phenology is gaining considerable attention due to its implications for human health, cycling of carbon and other nutrients in Earth system. In this study, we examined the relationship between change in vegetation phenology and urban size, an indicator of urbanization, for the conterminous United States. We(More)
  • 1