HY Scatterometer

HY Scatterometer (HSCAT) on HY-2D is a Ku-band conically scanning pencil-beam scatterometer for sea-surface wind vector measurement.^[1][2] It uses active microwave radar scatterometry with two conically scanning beams that provide multiple azimuth views of each wind vector cell.^[1][2] The operating frequency falls in Ku band at 13.25 to 13.3 GHz.^[1][2] The geometry provides a 1300 km swath, 25 km standard resolution and 50 km best-quality resolution.^[1] The rotating dish is 1 m and spins at 20 rpm, with HH and VV spot beams at 42 and 49 degrees incidence and fore/aft views in each wind vector cell.^[2] Ku-band wind retrievals are sensitive to rain; moderate and heavy rain can create bogus wind retrievals, so quality-control flags are part of the HY-2D retrieval context.^[2] Comparable Ku-band HSCAT instruments fly on HY-2B and HY-2C, forming a series of similar scatterometers across the HY-2 ocean-dynamics satellites.^[1]