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  • Author or Editor: William G. Pichel x
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Frank M. Monaldo
,
Xiaofeng Li
,
William G. Pichel
, and
Christopher R. Jackson

Spaceborne synthetic aperture radar (SAR) imagery can make high-resolution (≤500 m) ocean wind speed measurements. The authors anticipate reprocessing the full decade and a half of Radarsat-1 SAR imagery and generating a SAR wind speed archive. These data will be of use for studies of coastal atmospheric phenomena and assessment of offshore wind power potential. To illustrate the potential of this latter application, they review the ability of SARs to measure wind speed, discuss an approach for using SARs to create wind speed climatologies useful for wind power resource assessments, and consider issues concerning the applicably of such data for these assessments.

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Xiaofeng Li
,
Jun A. Zhang
,
Xiaofeng Yang
,
William G. Pichel
,
Mark DeMaria
,
David Long
, and
Ziwei Li

In 2008, the Canadian Space Agency sponsored the Radarsat Hurricane Applications Project (RHAP), for researching new developments in the application of Radarsat-1 synthetic aperture radar (SAR) data and innovative mapping approaches to better understand the dynamics of tropical cyclone genesis, morphology, and movement. Although tropical cyclones can be detected by many remote sensors, SAR can yield high-resolution (subkilometer) and low-level storm information that cannot be seen below the clouds by other sensors. In addition to the wind field and tropical cyclone eye information, structures associated with atmospheric processes can also be detected by SAR. We have acquired 161 Radarsat-1 SAR images through RHAP between 2001 and 2007. Among these, 73 images show clear tropical cyclone eye structure. In addition, we also acquired 10 images from the European Space Agency's Envisat SAR between 2004 and 2010. Both Atlantic hurricanes and Pacific typhoons are included.

In this study, we analyze these 83 (73 Radarsat-1 and 10 Envisat) images with tropical cyclone eye information along with ancillary tropical cyclone intensity information from the archive to generate tropical cyclone morphology statistics. Histograms of wave-number asymmetry and intensity are presented. The statistics show that when the storm has higher intensity, the tropical cyclone eye tends to become more symmetric, and the area of the tropical cyclone eye, defined by the minimum wind area, tends to be smaller. Examples of finescale structures within the tropical cyclone (i.e., eye/eyewall mesovortices, arc clouds, double eyewalls, and abnormally high wind or rain within eyes) are presented and discussed.

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