Estimates of Spaceborne Precipitation Radar Pulsewidth and Beamwidth Using Sea Surface Echo Data

Calibration of the Dual-Frequency Precipitation Radar Onboard the Global Precipitation Measurement Core Observatory

“…|K | 2 in (1) is set to 0.9255 for Ku-band and 0.8989 for Ka-band by using the permittivity of water at 10 • C [19]. For τ , we evaluated DPR's pulse waveforms measured by the ARC after launch and by the sea surface echo at the nadir incidence [20]; as a result, we consequently adopted the parameters obtained from the FEPT. We can determine the magnitudes of P t G t and P r /G r by measuring the power of the transmitted/received electromagnetic signals between the spaceborne radar (PR or DPR) and the ARC.…”

“…The biases at incidence angle larger than ±11 • are caused by the PR's sparse range sampling intervals that underestimate σ 0 . The PR oversamples the Earth's surface echoes with a 125-m interval when the incidence angle is less than ±11 • , while it samples only with a 250-m interval at large incidence angles and misses the surface echo peak [16], [20], thereby resulting in the underestimation of σ 0 in the outer regions. In contrast to the PR, the DPR oversamples the Earth's surface echoes in all angles so that no discontinuity is expected.…”

“…As a result, θ a and θ c were estimated to be 0.692 • and 0.708 • . For the pulsewidth, the DPR-ARC measured the pulse waveform of the PR, and the pulse-like response of the PR was reconstructed from sea surface echo data [20]. From those results, τ was obtained to be 1.40 μs for the A-side and 1.45 μs for the B-side system.…”

“…We can conclude that θ a and θ c adopted in the DPR products in V5 have no trend and are reliable. It is worth noting that Kanemaru et al[20] estimated θ c from sea surface echoes at oblique incidence angles. Their results agree very well with our results within 0.006 • .…”

A Feasibility Study on Wide Swath Observation by Spaceborne Precipitation Radar

“…However, depending on the state of the earth's surface in the grating direction, it is undeniable that grating lobe clutter may occur even at these scan angles. The relationship between measured NCRS (σ 0 m ) and the received signal power at the surface (P r,s ) is expressed by Kanemaru et al [26] as…”