P1.1 Use of Synthetic Aperture Radar in the Fine-scale Analysis of Synoptic- Scale Fronts at Sea
نویسندگان
چکیده
Fine-scale surface analysis of synoptic-scale weather systems is a challenging undertaking in the best of circumstances, but has proven particularly difficult at sea because of the paucity of in situ observations (Bosart 2003; Young et al. 1997). Remote sensing has taken a lead role in mitigating this problem. The success of remote sensing in this respect depends on the nature of the phenomena being analyzed, the quantity being measured by the remote sensor, and the ratio of the scales of interest to the spatial resolution of the remote sensor. For example, lower tropospheric streamline analysis via visible or infrared cloud track-winds would be problematic under cirrus overcast while a microwave scatterometer would face no such difficulty. Synthetic aperture radar (SAR) offers particularly intriguing opportunities for improving the accuracy and resolution of marine surface analyses because of its ability to sense the ocean surface footprints of atmospheric processes, regardless of daylight and cloud conditions, and its order 10 m to 100 m spatial resolution (Sikora et al. 2004). Thus, SAR opens the possibility of conducting fine-scale surface analysis of marine weather systems, as Friedman et al. (2001) first demonstrated using polar mesoscale cyclones. Here, we will focus on the use of SAR in the fine-scale analysis of synoptic-scale fronts, including the mesoscale and microscale substructure of the fronts. For clarity and compactness, we will invoke the scale nomenclature of Orlanski (1975). Therein, the spatial range of the macroscale is divided into α (i.e., planetary, 10,000 to 40,000 km) and β (i.e. synoptic, 2000 to 10,000 km). The mesoscale is divided into α (200 to 2000 km), β (20 to 200 km), and γ (2 to 20 km) and the microscale into α (200 to 2000 m), β (20 to 200 m), and γ (2 to 20 m). Of these, current spaceborne SAR instruments can fully observe only meso-β, meso-γ, and micro-α phenomena. 1.1 Basics of Synthetic Aperture Radar
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