1,121 research outputs found

    How life affects the geochemical cycle of carbon

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    Developing a quantitative understanding of the biogeochemical cycles of carbon as they have worked throughout Earth history on various time scales, how they have been affected by biological evolution, and how changes in the carbon content of ocean and atmosphere may have affected climate and the evolution of life are the goals of the research. Theoretical simulations were developed that can be tuned to reproduce such data as exist and, once tuned, can be used to predict properties that have not yet been observed. This is an ongoing process, in which models and results are refined as new data and interpretations become available and as understanding of the global system improves. Results of the research are described in several papers which were published or submitted for publication. These papers are summarized. Future research plans are presented

    Numerical Studies of the Solar Energetic Particle Transport and Acceleration

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76215/1/AIAA-2005-4928-462.pd

    Effects of Atmospheric Absorption of Incoming Radiation on the Radiation Limit of the Troposphere: Reply

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    In response to a comment on their previous note about the Voigt line profile, here the authors clarify relevant statements and numeric algorithms in the original note

    High resolution Doppler lidar

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    A high resolution lidar system was implemented to measure winds in the lower atmosphere. The wind speed along the line of sight was determined by measuring the Doppler shift of the aerosol backscattered laser signal. The system in its present configuration is stable, and behaves as indicated by theoretical simulations. This system was built to demonstrate the capabilities of the detector system as a prototype for a spaceborne lidar. The detector system investigated consisted of a plane Fabry-Perot etalon, and a 12-ring anode detector. This system is generically similar to the Fabry-Perot interferometer developed for passive wind measurements on board the Dynamics Explorer satellite. That this detector system performs well in a lidar configuration was demonstrated

    Weak pitch angle scattering of few MV rigidity ions from measurements of anisotropies in the distribution function of interstellar pickup H +

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95477/1/grl8632.pd

    A Microwave Radiance Assimilation Study for a Tundra Snowpack

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    Recent studies have begun exploring the assimilation of microwave radiances for the modeling and retrieval of snow properties. At a point scale, and for short durations (i week), radiance assimilation (RA) results are encouraging. However, in order to determine how practical RA might be for snow retrievals when applied over longer durations, larger spatial scales, and/or different snow types, we must expand the scope of the tests. In this paper we use coincident microwave radiance measurements and station data from a tundra site on the North Slope of Alaska. The field data are from the 3rd Radio-brightness Energy Balance Experiment (REBEX-3) carried out in 1994-95 by the University of Michigan. This dataset will provide a test of RA over months instead of one week, and for a very different type of snow than previous snow RA studies. We will address the following questions: flow well can a snowpack physical model (SM), forced with local weather, match measured conditions for a tundra snowpack?; How well can a microwave emission model, driven by the snowpack model, match measured microwave brightnesses for a tundra snowpack?; How well does RA increase or decrease the fidelity of estimates of snow depth and temperatures for a tundra snowpack

    Medsat: A satellite system for surveillance of tropical vector‐borne diseases

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    In this paper, the authors describe the need for, and preliminary student design of, a research satellite system (Medsat) devoted to the surveillance of environmental and epidemiological factors that influence the patterns and dynamics of tropical vector‐borne diseases.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87321/2/318_1.pd
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