Office of Biological and Environmental Research Weekly Report

September 15, 2008

Evolution of Clouds in the Tropical West Pacific – Fair Weather Clouds Lead to Stormy Days Ahead. Scientists in the DOE Atmospheric Radiation Measurement (ARM) Program used ground-based radars that penetrate through clouds to provide a more accurate picture of tropical clouds. They found that satellites underestimate cloud heights, especially when multiple cloud layers are present. By combining the satellite and ground-based data, the investigators determined how clouds change as the weather varies from fair and dry to humid and rainy conditions over 30-60 day periods. The ARM radars showed that the low and mid-level clouds that populate the sky under fair weather gradually give way to higher clouds over 1-2 weeks, supporting the theory that the shallow clouds slowly moisten the atmosphere and pave the way for stormy weather to break out later. Climate models simulate this transition poorly, suggesting that this new data can help improve the models’ representation of clouds and their effect on weather and climate.

Reference: Chen, Y., and A.D. Del Genio, 2008: Evaluation of tropical cloud regimes in observations and a general circulation model. Climate Dynamics, doi:10.1007/s00382-008-0386-6

Media Interest: No

Contact: Kiran Alapaty, SC-23.1, (301) 903-3175

Berkeley Scientist Elected Home Secretary of the National Academy of Engineering.

Dr. Thomas F. Budinger of the Lawrence Berkeley National Laboratory has been elected the Home Secretary of the National Academy of Engineering (NAE). Responsibilities of this position include oversight and policy development for the membership, requiring engagement of the twelve sections of the NAE in technical activities, and for reports that analyze engineering and science issues facing the U.S. Dr Budinger's conducted medical imaging research for many years with support from the DOE Office of Biological and Environmental Research. While serving in this capacity in Washington, DC, Dr. Budinger will continue research at the Berkeley Lab and some teaching activities as a professor at the University of California, Berkeley.

Media Interest: None

Contact: Prem Srivastava, SC-23.2, (301) 903-4071

New Modeling Approach Integrates Geochemical Processes into Field-Scale Simulation of Uranium Mobility in Groundwater at the Hanford Site. Uranium is a persistent groundwater contaminant at many DOE sites due to its adsorption onto mineral surfaces and/or precipitation of various uranium minerals within subsurface materials. These molecular-scale processes often exert a profound influence on uranium mobility at the field scale. One challenge in simulating uranium transport in the subsurface is the difficulty in coupling these molecular-scale geochemical processes controlling uranium concentrations with groundwater transport processes that occur at the field-scale. Researchers at PNNL have developed a modeling approach that incorporates these two types of information derived from laboratory and field experiments. The approach couples molecular-scale, laboratory-derived characterization of uranium geochemical properties with field-scale descriptions of transport processes obtained from tracer experiments. The new approach will be tested as part of the DOE-funded Integrated Field-Scale Subsurface Research Challenge (IFC) site at the Hanford 300 Area (http://ifchanford.pnl.gov/).

Citation: Liu, C. Zachara, JM, Qafoku, NP, Wang, Z. (2008), Scale-dependent desorption of uranium from contaminated subsurface sediments. Wat. Resour. Res. vol. 44 (W08413), doi:10.1029/2007WR006478.

Media Interest: No

Contact: Robert T. Anderson, SC 23.1, (301) 903-5549

New, Surprising Insights into Potential Effects of Ozone Pollution on Forest Growth. Fossil fuel use is causing an increase in the concentrations of both carbon dioxide and ozone in the atmosphere. The increasing carbon dioxide concentration is expected to stimulate tree growth, while available data indicate that increasing ozone can counteract the beneficial effects of increasing carbon dioxide on tree growth. Recently published measurements from the longest running field experiment exposing trees to elevated carbon dioxide and ozone, research sponsored by DOE, surprisingly indicate that the combination of elevated carbon dioxide and ozone stimulated root growth in some tree communities. The scientists conducting the research suggested that the death of ozone-sensitive trees followed by increased growth of ozone-tolerant trees made possible by access to space and soil nutrients that would have been used by ozone-sensitive trees might be the explanation for the increased root growth. But whatever the mechanism might be, these new results indicate a possible long term response to increasing concentrations of carbon dioxide and ozone that is not generally considered in assessments of potential effects of the changing composition of the atmosphere on forest tree growth.

Media Interest: Possibly

Contact: Jeffrey S. Amthor, SC-23.1, (301) 903-2507