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Using collocated ESCAT, TRMM PR, and ECMWF data, the effects of rain on the ESCAT wind-only retrieval has been evaluated. For high incidence angle measurements, the additional scattering of rain causes estimated wind speeds to appear higher than expected. It is also noted that the selected directions of the rain-corrupted wind vectors generally point along swath in heavy rain, regardless of the true...
This study concerns the modeling and the design of a monostatic heterodyne pulsed LIDAR. The heart of the system is constituted of a 1.55 mum able to produce high pulse repetition frequency. The aim of this work is to assess its efficiency to perform accurate wind speed measurements in the low atmospheric boundary layer, from a 2-D scanning pattern, in the presence of refractive turbulence. A complete...
Aerosol distribution in the atmosphere is used as a wind-tracer by lidars since it is drifted by the wind and respond to its changes. Two methods are used: the correlation and the Doppler method. This first one is easier and cheaper to implement than the latter. It makes it competitive for retrieving wind speed profiles or estimating wind turbulence. However, its accuracy decreases significantly as...
The SeaWinds sensor was launched onboard two satellite missions. The first was the QuikSCAT mission launched in mid 1999 by NASA, and the second was the ADEOS II mission launched by JAXA in late 2002. SeaWinds operates at a ku-band frequency of 13.4 GHz, and was originally designed to measure the speed and direction of the ocean surface wind vector by relating the normalized radar backscatter measurements...
Simultaneous microwave radar and radiometer observations of the ocean were conducted from aircraft during the ShoWEx'99 experiment. Both radar and radiometer wind dependences show similar signal growth with wind speed increase (except for the radiometer at vertical polarization and a near-Brewster angle). Analysis of the low-wind data shows that wind speed is a poor characteristic of the sea surface...
Ocean surface winds observed by satellite scatterometer (QuikSCAT) and passive microwave (SMM/I) provide valuable information for wind energy applications. In wind energy two long-term aspects on the offshore wind climate is of concern. One is the 20-year average necessary for the estimation of produced wind power during the life-time of a wind turbine (i.e. wind resource assessment); the other is...
Marine dark features in SAR imagery related to oil spills, biogenic look-alikes and low wind areas are analyzed by means of the wavelet polarimetric signature (WASP) tool. The WASP encapsulates in a graph the dependency of the wavelet variance on dyadic scale and polarization state. Experiments on SIR-C/X-SAR C-band data showed the effectiveness of this analysis in characterizing textural features...
Although SeaWinds was not originally designed to observe tropical cyclones, new higher resolution products resolve much of the horizontal structure of these storms. However, these higher resolution products (reported at 2.5 km) are inherently noisier than the standard 25 km products and the high rain rates often associated with hurricanes corrupt the wind estimates. Fortunately, these storms have...
The Hurricane Imaging Radiometer (HIRad) is a new airborne sensor that is currently under development. It is intended to produce wide-swath images of ocean surface wind speed and near surface rain rate in hurricanes conditions. HIRad will extend the scientific capabilities and technologies associated with two previous successful airborne microwave radiometers: the real aperture Stepped Frequency Microwave...
In this paper, we develop a novel geophysical model function (GMF) for the WindSat radiometer relating the vertically (V-pol) and horizontally (H-pol) polarized brightness temperature (TB) to the ocean surface wind field. The brightness temperature data from the 10,18 and 37 GHz channels were used in this analysis. The brightness temperature combination of the form (AV-H) is found to be mostly independent...
The normalized radar cross section (NRCS) of ocean surface is measured from three directions of illumination by an airborne dual-frequency synthetic aperture radar(SAR) with L- and X-band, and the dependency of the NRCS and the polarimetric ratio on the relative wind direction is analyzed. In X-band, the NRCSs in parallel polarizations represent the dependency on the relative wind direction. The NRCS...
The forest damage (fallen trees) by a typhoon or a strong wind is frequently generated in recent years. For example, typhoon SONGDA (2004.09) brought about destructive strong winds to almost western half of Hokkaido. According to a temporary report issued by Japan Meteorological Agency, in Sapporo, 50.2 m/s was recorded as a maximum instantaneous wind speed in the history of observation. This typhoon...
The goal of this contribution is the assessment of the potential of a C-band SAR mission with repeat-pass interval of 12 days - as the intended European satellite system Sentinel-1 - to derive ice surface velocity using SAR interferometry (InSAR) and offset-tracking. For this purpose we investigated ERS-1 SAR data acquired during the ice missions in 1992 and 1994 in 3-day repeat- orbits at Nordaustlandet...
A new empirical algorithm-CWAVE [1] was developed at the German aerospace center (DLR). A global dataset of two years (September 1998 to December 2000) of ERS SAR data was reprocessed to more than one million SAR imagettes. Met ocean parameters like significant ocean wave height (Hs), wind speed (U10) and mean wave period (Tm-10) are derived from the SAR images using the CWAVE algorithm [1]. The results...
A full-Stokes vector model for the microwave emissivity of an anisotropic wind driven ocean surface based on measured satellite data and using a two-scale model for surface emission is being developed for the purpose of assimilation of satellite microwave radiances. The model is based on the Ohio State University two-scale code and tuned to WindSat full-Stokes emissivity data as analyzed by Meissner...
SAR images from the Swedish airborne CARABAS-II and LORA systems have been visually analyzed over simulated wind-thrown forest at both single tree and stand level. In ideal conditions, the results show that LORA is more accurate than CARABAS-II at detecting wind-thrown trees, regardless of tree size and direction of the fallen trees relative to flight heading. Furthermore, the visible single trees...
Wind speed has been retrieved reliably from SSM/I microwave radiometric measurements since 1990 with a precision of better than 2 m/s. However, operational requirements of the National Polar-orbiting Operational Environmental Satellite System (NPOESS) dictate retrieval of the ocean surface wind vector, i.e. both speed and direction. This requires improved understanding and forward modeling of the...
The 'Living Planet Programme' of the European Space Agency (ESA) is gaining momentum. Six Earth Explorer missions are currently being implemented including ADM- Aeolus, ESA's Doppler Wind Lidar (DWL) mission. The Aeolus mission will demonstrate the capability of a space- borne high spectral resolution DWL to accurately measure wind profiles in the troposphere and the lower stratosphere (0- 30 km)...
Geoscience Australia is conducting a series of national risk assessments for a range of natural hazards such as severe winds. The impact of severe wind varies considerably between equivalent structures located at different sites due to local roughness of the upwind terrain, shielding provided by upwind structures and topographic factors. Terrain surface roughness information is a critical spatial...
The Canadian Space Agency's Hurricane Watch program monitors tropical cyclones worldwide and acquires RADARSAT-1 Synthetic Aperture Radar imagery to provide experimental datasets to the scientific research community interested in surface wind field studies. The current HW archives spans from 1999 to 2006 and contain a variety of tropical cyclones from around the world. The images show various storm...
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