Sea Surface Wind Measurement by Airborne Weather Radar Scanning in a Wide-Size Sector

Abstract

Abstract:We suggest a conceptual approach for measuring the near-surface wind vector over water using the airborne weather radar, in addition to its standard meteorological and navigation applications. The airborne weather radar operates in the ground-mapping mode in the range of high to medium incidence angles as a scatterometer. Using the aircraft rectilinear flight over the water surface, measuring the geometry and the geophysical model function, we show that the wind vector can be successfully recovered from the azimuth normalized radar cross-section data obtained from a scanning sector of up to˘100˝. The efficiency and accuracy of the proposed wind vector measurement algorithms are supported by computer simulations indicating their potential as a powerful tool for the wind field reconstruction. Some limitations and recommendations of the suggested approach are further discussed.

On Sea Ice/Water Discrimination by Airborne Weather Radar

“…In case of the ice covered surface, the "measured" NRSCs have been generated using a Rayleigh Power (Exponential) distribution and integrated over 330 samples for each azimuthal direction in the sector of up to ±100° relative to the aircraft course with the azimuthal step of 10°. Next, to find the water GMF approximation, the wind speed and the up-wind direction, best fits to the "measured" NRSCs have been found by solving the system of N = 19 equations for "measured" NRSCs (7). Further, best fits of the ice GMF to the "measured" NRSCs are found and the sea ice/water discrimination is performed according to (1).…”

“…In marked contrast, the AWRs are free of the above limitations. In contrast to the spaceborne scatterometer geometries, the AWR wide-sector scanning geometry allows observation of the area of interest from significantly different azimuthal directions (up to ±100° relative to the aircraft course ), providing the NRCS measurements from many azimuthal directions at the same incidence angle, leading to an unambiguous retrieval of the wind vector [7]- [9].…”

Optimization of Airborne Antenna Geometry for Ocean Surface Scatterometric Measurements

“…In earlier considerations, the use of different antenna configurations has been considered, including both fixed-and rotating antenna systems, with or without horizontal stabilization, with measurements performed during either circular or rectilinear flight [4][5][6][7][8][9][10][11][12][13][14][15][16]. While our previous research largely focused on the possibility of using various existing onboard equipment for overall cost reduction [17][18][19][20], no systematic comparison of both the accuracy and performance of the measurement algorithms for different antenna configurations has been done.…”

“…As our earlier experience indicates, azimuthally diverse NRCS measurements are the best option for scatterometric measurements [17][18][19][20]. That is why wind scatterometers often have either single-beam rotating antennas or multi-beam fixed antenna geometries.…”

Sea Wind Measurement by Doppler Navigation System with X-Configured Beams in Rectilinear Flight

“…This disadvantage can be resolved by use of the modified conventional navigation instruments of aircraft in a scatterometer mode. Recently, such approach has been considered for airborne weather radar application for wind estimation over water at circular and rectilinear flights [28,29]. In general, rectilinear flight measurements can be performed considerably faster and easier to handle.…”