Naval Postgraduate School

About: Naval Postgraduate School is a education organization based out in Monterey, California, United States. It is known for research contribution in the topics: Tropical cyclone & Nonlinear system. The organization has 5246 authors who have published 11614 publications receiving 298300 citations. The organization is also known as: NPS & U.S. Naval Postgraduate School.

Light propagation through anisotropic turbulence.

Abstract: A wealth of experimental data has shown that atmospheric turbulence can be anisotropic; in this case, a Kolmogorov spectrum does not describe well the atmospheric turbulence statistics. In this paper, we show a quantitative analysis of anisotropic turbulence by using a non-Kolmogorov power spectrum with an anisotropic coefficient. The spectrum we use does not include the inner and outer scales, it is valid only inside the inertial subrange, and it has a power-law slope that can be different from a Kolmogorov one. Using this power spectrum, in the weak turbulence condition, we analyze the impact of the power-law variations α on the long-term beam spread and scintillation index for several anisotropic coefficient values ς. We consider only horizontal propagation across the turbulence cells, assuming circular symmetry is maintained on the orthogonal plane to the propagation direction. We conclude that the anisotropic coefficient influences both the long-term beam spread and the scintillation index by the factor ς2−α.

Modeling recent climate variability in the Arctic Ocean

Abstract: Dramatic changes in the circulation of sea ice andtheupperlayersoftheArcticOceanhavebeenreported during the last decade. Similar variability is modeled using a regional, coupled ice-ocean model. Realistic atmospheric forcingeldsfor1979-93 aretheonlyinterannualsignalpre- scribed in the model. Our results show large-scale changes inseaiceandoceanicconditionswhencomparingresultsfor the late 1970s / early 1980s and the 1990s. We hypothesize thatthesechangesareinresponsetoevenlargerscaleatmo- spheric variability in the Northern Hemisphere that can be denedaseithertheArcticOscillationortheNorthAtlantic Oscillation. Agreement between the direction and scale of change in the model and observations, in the absence of in- terannual forcing from the global ocean thermohaline circu- lation, suggests that the atmospheric variability by itself is sucienttoproducebasin-scalechangesintheArcticOcean and sea ice system.

On the link between ocean biota emissions, aerosol, and maritime clouds: Airborne, ground, and satellite measurements off the coast of California

Abstract: Surface, airborne, and satellite measurements over the eastern Pacific Ocean off the coast of California during the period between 2005 and 2007 are used to explore the relationship between ocean chlorophyll a, aerosol, and marine clouds. Periods of enhanced chlorophyll a and wind speed are coincident with increases in particulate diethylamine and methanesulfonate concentrations. The measurements indicate that amines are a source of secondary organic aerosol in the marine atmosphere. Subsaturated aerosol hygroscopic growth measurements indicate that the organic component during periods of high chlorophyll a and wind speed exhibit considerable water uptake ability. Increased average cloud condensation nucleus (CCN) activity during periods of increased chlorophyll a levels likely results from both size distribution and aerosol composition changes. The available data over the period of measurements indicate that the cloud microphysical response, as represented by either cloud droplet number concentration or cloud droplet effective radius, is likely influenced by a combination of atmospheric dynamics and aerosol perturbations during periods of high chlorophyll a concentrations.