EM models for evaluating rain perturbation on the NRCS of the sea surface observed near nadir

Abstract

Abstract:The authors address the problem of evaluating the normalised radar cross section gURCS) of the sea surface perturbed by the joint effect of rain and wind, when observed close to nadir. They present a model, based on the full wave theory, for evaluating such an NRCS when varying polarisation, frequency and incidence angle (not far from nadir) for different values of wind velocity and of the root mean square height of the corrugation induced by rainfall. Some comparisons are made with the integral equation model results in the case of rain-induced corrugation alone. The two models are found to be in good agreement. In addition, partial comparisons made with experimental data suggest that the proposed model is well grounded and exploitable for application. It is indeed expected that the model can be exploited to improve precipitation measurements over the sea through spaceborne rain radar and to improve wind measurements using scatterometers in the presence of rain.

Numerical study on SAR-based rogue wave detection part two: Rogue wave detection

“…Since NRCS perturbation can also be effected by rainfall, wave breaking, wind speed and other parameters [6,8] , the efficiency and validity of this detection method remains to be compared with remotely sensed experimental observations. However the physical principles discussed in our numerical calculations are generally applicable.…”

“…In this work, the approach proposed in part one [6] is used to simulate SAR images, and then a criterion function is constructed based on these images. It's believed that this work is able to shed light on the progress of SAR-based rogue wave remote sensing.…”

Spaceborne rainfall Doppler radar measurements: correction of errors induced by pointing uncertainties

“…Figure 2 plots σ 0 against w for four values of R for a nadir-looking radar at 14 GHz. These resulted were generated using a Full Wave Model (FWM) 9 in which the sea surface is characterized by the wind spectrum 10 and by the ring waves generated by the raindrops. Note that at nadir, σ 0 at 20 mm/hr rain is almost 1 dB below that for a clear ocean).…”

<title>Model-based approach for rainfall rate retrieval over the sea surface through rain radar</title>

“…Introducing this relationship in Eq. (3), the ratio P(r) / P ('iv ) gives, after simple manipulations: k(r) exp Jk(s)ds =w0(r) (6) where 1//3 A P(r)•r2cr5C3 wo(r) The rainfall rate profile R(r) can then be obtained from k(r) by means of a frequency-dependent relationship of the kind R(r) = Ak(r)B. Eq. (8) shows that the estimate of k(r) provided by the kZS is not sensitive to the characteristics of precipitation at ranges less than r. In particular, if r refers to a radar cell below the melting layer, no assumption about its structure is needed a priori when using the kZS algorithm.…”