Extreme wind conditions observed by satellite synthetic aperture radar in the North West Pacific

Cross-Polarized Synthetic Aperture Radar: A New Potential Measurement Technique for Hurricanes

“…Some studies using scatterometer data have shown that for wind speeds above 30 m s -1 and rain rates exceeding 15 mm h -1 , the error in the winds can be more than 10 m s -1 (Yang et al 2004). Moreover, the influence of heavy rain on the C-band ocean backscatter has been estimated from an existing radiative transfer model (Reppucci et al 2008). It was shown that the NRCS attenuation can be more than −1 dB for rain rates of 30 mm h -1 , and even larger damping-up to −2 dBfor rain rates of 50 mm h -1 .…”

“…SAR wind speed retrieval accuracy is affected by errors in estimated wind directions. In general, there are three approaches that have been developed to obtain wind directions: 1) use wind-induced streaks visible in the SAR image to infer the wind direction (Gerling 1986;Vachon and Dobson 1996;Horstmann et al 2005;Reppucci et al 2010), 2) acquire wind directions from an operational weather prediction system (Monaldo et al 2001), and 3) obtain wind directions from scatterometer measurements (Xu et al 2010). However, there are some limitations to acquiring the wind directions from these methods.…”

“…By comparison, C-band SAR can penetrate cloud and rainbands, to some extent, and therefore uniquely monitor hurricanes from space, with wide swaths and high resolution (Friedman and Li 2000;Katsaros et al 2002). In recent years, much attention has focused on the retrieval of hurricane winds from C-band RADARSAT-1 and Environmental Satellite (Envisat) Advanced Synthetic Aperture Radar (ASAR) images (Horstmann et al 2005;Shen et al 2006;Reppucci et al 2010). Studies show that CMOD5 provides better estimates than those from CMOD4 for hurricane-forced winds (Horstmann et al 2005).…”

Wind and wave observations off the south Pacific Coast of Mexico using TerraSAR-X imagery

“…While values of are given for each pixel on the image annotation file, the azimuth direction f was derived by visual observation of wind streaks and other distinct patterns directly on the image quicklooks; according to Reppucci et al (2008), they tend to align fairly well with the direction of the wind. In their paper, these authors present a flow chart depicting the steps followed to calculate the wind speed using the CMOD5 GMF.…”

“…Assessments of the wind field and the sea state over large areas of the open ocean have been performed through the analysis of space-borne SAR under calm-weather conditions (Vesecky and Stewart 1982, Beal et al 1983, Vachon and Dobson 1996 and extreme-weather conditions (Katsaros et al 2002, Horstmann et al 2006, Li et al 2008, Reppucci et al 2008, with promising results. SAR image analyses have delivered detailed information on the spatial variability of winds and waves in coastal areas (Johannessen et al 1996, Ocampo-Torres 2001, Ocampo-Torres et al 2007, Díaz Méndez et al 2008.…”