An investigation of channeled wind events in Southeast Alaska using synthetic aperture radar

A recent compositing study at NWS Forecast Office Juneau identified areas where satellite synthetic aperture radar (SAR) wind speed data consistently revealed enhanced channeled wind events for specific synoptic scale meteorological situations. However, due to the wind direction dependence on SAR wind speed retrieval, and inherent wind direction ambiguity within the channels, the actual values of wind speed for the events is uncertain. The current research focuses on two such areas in Southeast Alaska's inside waters. Those areas: (1) show a tendency for enhanced channeled wind under specific synoptic conditions; (2) are within quick sailing range of a nearby harbor; and (3) potentially provide new insight into complex channeled wind events. During the fall of 2006 and spring of 2007, for each study area, local boat operators were on-call for field programs aimed at collecting in situ wind vector observations coincident with satellite SAR overpasses during channeled wind events. The current research presents preliminary results from the field programs. The complete in situ and SAR wind speed comparison data set is employed to determine the accuracy of SAR-derived winds under various synoptic situations (i.e., develop an error climatology) and to assess the impact of improved input wind directions in these critical locations. It is expected that the results may be employed for more general use across other inside water areas. It is also expected that this information will contribute to an improved understanding of the wind behavior in complex inside water channels and, thus, will ultimately lead to improved graphical marine forecast and warnings products.