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Comparison between SAR streaks and AVHRR spatial and temporal evolution of cloud streets to derive rolls aspect ratio maps and PBL depth

Elena Arabini(1) and Marc Chiacchio(2)

(1) Prof. Inst., v. Confalonieri 54, 41100 Modena, Italy
(2) IACETH, Universit├Ątstrasse 16, CH-8092 Z├╝rich, Switzerland


Combination of spaceborne synthetic aperture radar (SAR) and advanced very high resolution radiometer (AVHRR) images are used to investigate the planetary roll vortex and cloud street formation in order to derive rolls aspect ratio and produce maps analysing sub-images of the given data. Finally, the planetary boundary layer (PBL) depth will be estimated. As case studies two midlatitudes ERS-1 SAR images, acquired on 30 March 2000 offshore Genoa gulf, are presented. Evidence of the occurrence of the characteristic streaks due to the presence of roll vortices are analysed under different stability and wind intensity conditions not far from the coast. In correspondence of the two SAR images two AVHRR images (respectively acquired two hours before and after the corresponding SAR images) are analysed. The visible and infrared AVHRR images show the spatial and temporal evolution of the evident streak formations and give indication of how streets are spaced. By applying Fourier analysis to proper SAR subimages, the rolls horizontal wavelength is measured while from the AVHRR images the cloud top height is calculated and the rolls height derived. By matching the time and scale resolution of the satellite data and properly sub-sampling the images, 6 Km resolution rolls aspect ratio maps are produced and the PBL depth estimated. The obtained results are supported by in situ data provided by buoy ODAS Italia 1, located in the north Tyrrhenian sea.


Workshop poster

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry