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  • Author or Editor: Valery U. Zavorotny x
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Andre V. Smirnov and Valery U. Zavorotny

Abstract

Radar returns from the sea surface can be represented as the sum of two contributions from Bragg scattering and from individual breaking events. This representation is used to analyze polarimetric radar images of ocean areas obtained at grazing angles 6°<ψ<18° with the airborne Ku-band radar in the New York Bight. All images were obtained for light and moderate winds and can be divided into three types according to texture differences. Images obtained confirm that there are differences between returns for horizontal/horizontal (HH) and vertical/vertical (VV) polarizations for the three types. The first type agrees qualitatively with predictions of the two-scale Bragg model, whereas the other two do not. The second and third types have a significant spike contribution from breaking events at both polarizations. The last type reveals drastic differences between images obtained using HH and VV polarizations. The polarization dissimilarity is a result of a low correlation between the spike clusters in HH-polarized images and the variations of continuous background in VV-polarized images. The role of atmospheric stability in processes responsible for spatial decorrelation of the different scatterers is also examined.

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Christopher S. Ruf, Robert Atlas, Paul S. Chang, Maria Paola Clarizia, James L. Garrison, Scott Gleason, Stephen J. Katzberg, Zorana Jelenak, Joel T. Johnson, Sharanya J. Majumdar, Andrew O’brien, Derek J. Posselt, Aaron J. Ridley, Randall J. Rose, and Valery U. Zavorotny

Abstract

The Cyclone Global Navigation Satellite System (CYGNSS) is a new NASA earth science mission scheduled to be launched in 2016 that focuses on tropical cyclones (TCs) and tropical convection. The mission’s two primary objectives are the measurement of ocean surface wind speed with sufficient temporal resolution to resolve short-time-scale processes such as the rapid intensification phase of TC development and the ability of the surface measurements to penetrate through the extremely high precipitation rates typically encountered in the TC inner core. The mission’s goal is to support significant improvements in our ability to forecast TC track, intensity, and storm surge through better observations and, ultimately, better understanding of inner-core processes. CYGNSS meets its temporal sampling objective by deploying a constellation of eight satellites. Its ability to see through heavy precipitation is enabled by its operation as a bistatic radar using low-frequency GPS signals. The mission will deploy an eight-spacecraft constellation in a low-inclination (35°) circular orbit to maximize coverage and sampling in the tropics. Each CYGNSS spacecraft carries a four-channel radar receiver that measures GPS navigation signals scattered by the ocean surface. The mission will measure inner-core surface winds with high temporal resolution and spatial coverage, under all precipitating conditions, and over the full dynamic range of TC wind speeds.

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