12,853 research outputs found
Linear and nonlinear aspects of the tropical 30-60 day oscillation: A modeling study
The scientific problem focused on study of the tropical 30-60 day oscillation and explanation for this phenomenon is discussed. The following subject areas are covered: the scientific problem (the importance of low frequency oscillations; suggested mechanisms for developing the tropical 30-60 day oscillation); proposed research and its objective; basic approach to research; and results (satellite data analysis and retrieval development; thermodynamic model of the oscillation; the 5-level GCM)
Sensors and methods for weather-independent remote sensing with microwaves
Sensors and methods of radar and microwave radiometry which operate in the millimeter wave range are discussed. The properties of electromagnetic waves are discussed as well as the resolution capacity and measurement accuracy of sensor systems
Microwave Heating of Water, Ice and Saline Solution: Molecular Dynamics Study
In order to study the heating process of water by the microwaves of 2.5-20GHz
frequencies, we have performed molecular dynamics simulations by adopting a
non-polarized water model that have fixed point charges on rigid-body
molecules. All runs are started from the equilibrated states derived from the
I ice with given density and temperature. In the presence of microwaves,
the molecules of liquid water exhibit rotational motion whose average phase is
delayed from the microwave electric field. Microwave energy is transferred to
the kinetic and inter-molecular energies of water, where one third of the
absorbed microwave energy is stored as the latter energy. The water in ice
phase is scarcely heated by microwaves because of the tight hydrogen-bonded
network of water molecules. Addition of small amount of salt to pure water
substantially increases the heating rate because of the weakening by defects in
the water network due to sloshing large-size negative ions.Comment: 21 pages, 13 figure
Remote sensing of tropospheric turbulence using GPS radio occultation
Radio occultation (RO) measurements are sensitive to the small-scale irregularities in the atmosphere. In this study, we present a new technique to estimate tropospheric turbulence strength (namely, scintillation index) by analyzing RO amplitude fluctuations in impact parameter domain. GPS RO observations from the COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) satellites enabled us to calculate global maps of scintillation measures, revealing the seasonal, latitudinal, and longitudinal characteristics of the turbulent troposphere. Such information are both difficult and expensive to obtain especially over the oceans. To verify our approach, simulation experiments using the multiple phase screen (MPS) method were conducted. The results show that scintillation indices inferred from the MPS simulations are in good agreement with scintillation measures estimated from COSMIC observations
NASA/MSFC FY88 Global Scale Atmospheric Processes Research Program Review
Interest in environmental issues and the magnitude of the environmental changes continues. One way to gain more understanding of the atmosphere is to make measurements on a global scale from space. The Earth Observation System is a series of new sensors to measure globally atmospheric parameters. Analysis of satellite data by developing algorithms to interpret the radiance information improves the understanding and also defines requirements for these sensors. One measure of knowledge of the atmosphere lies in the ability to predict its behavior. Use of numerical and experimental models provides a better understanding of these processes. These efforts are described in the context of satellite data analysis and fundamental studies of atmospheric dynamics which examine selected processes important to the global circulation
A Taste of Cosmology
This is the summary of two lectures that aim to give an overview of
cosmology. I will not try to be too rigorous in derivations, nor to give a full
historical overview. The idea is to provide a "taste" of cosmology and some of
the interesting topics it covers. The standard cosmological model is presented
and I highlight the successes of cosmology over the past decade or so. Keys to
the development of the standard cosmological model are observations of the
cosmic microwave background and of large-scale structure, which are introduced.
Inflation and dark energy and the outlook for the future are also discussed.
Slides from the lectures are available from the school website:
physicschool.web.cern.ch/PhysicSchool/CLASHEP/CLASHEP2011/.Comment: 16 pages, contribution to the 2011 CERN-Latin-American School of
High-Energy Physics, Natal, Brazil, 23 March-5 April 2011, edited by C.
Grojean, M. Mulders and M. Spiropul
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