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...s the observed brightness temperature FIG. 1. Fraction of precipitation features with lightning as a function of the precipitation feature’s minimum 85-GHz PCT. by scattering the upwelling radiation (=-=Wu and Weinman 1984-=-; Wilheit 1986; Spencer 1986; Spencer et al. 1989). For this study, it is necessary to consider additional influences on 85-GHz brightness temperature. Cloud– radiation model databases such as Adler e...

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...is and many other studies of convective systems, scattering of upwelling radiation is primarily due to precipitation-sized ice hydrometeors present above the emitting rain layer (Wilheit et al. 1982; =-=Wu and Weinman 1984-=-; Spencer et al. 1989). The resulting reduction of the observed brightness temperatures, termed the ice scattering signatures, is a function of the particle size distribution, bulk density, number con...

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...zed case depicted in Fig. 1, the polarization difference at a given frequency may not vanish as the rain cloud becomes optically thick. Rather, scattering by both rain drops and ice particles viewed at an oblique angle can give rise to modest residual polarization differences. Differences of up to 2–3 K may be explained by spherical particles alone (Liu and Simmer 1996); observed differences of up to 10 K or more that are frequently observed in stratiform rain clouds (Spencer et al. 1989; Heymsfield and Fulton 1994) may depend on the presence of preferentially oriented nonspherical particles (Wu and Weinman 1984; Turk and Vivekanandan 1995; Evans and Stephens 1995b). Note that the ideal response of SSM/I to rainfall as depicted in Fig. 1 assumes that the field of view (FOV) is completely filled with rain of uniform intensity. Given the coarse resolution of the SSM/I (see above), this assumption is difficult to satisfy in practice. The radiative consequences of rain-cloud inhomogeneity within the FOV can be broken down into three components: 1) the effects of averaging a nonlinear function of surface rain rate (e.g., the TB–R relationships in Fig. 1) over the two-dimensional FOV—this is the classic ‘‘...

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...and recursively for th-order polynomials. In many applications the truncation of this Legendre series to the first order (i.e., ), also called Eddington’s approximation [40], is quite effective [30], =-=[31]-=-. The average scattering phase function then becomes (9) being the weights and given by and with , by definition, the asymmetry factor of the scattering phase function [15]. It is worth mentioning tha...

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...ty of the height of ice clouds, vertically non-uniform cirrus clouds, liquidswater clouds, or atmospheric variability. Thus, the results were not accurate.sObservational studies (Wilheit et al. 1982; =-=Wu and Weinman 1984-=-; Hakkarinen andsAdler 1988; Spencer et al. 1989; Adler et al. 1990; Liu and Curry 1998; Bennartz andsBauer 2003) have shown that the brightness temperature near 85 GHz is stronglysdepressed due to th...

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...iativestransfer models which have been used for liquid and iceshydrometeor profile retrievals in terms of accuracy andscomputation efficiency.sSolutions to the Eddington secondorder approximation [1],=-=[2]-=- with and without δ-scaling [3],sthe Neumann iterative method [4],[5] and the Monte Carlos(MC) method [3] are compared at frequencies of 89, 118,s150, 183.3+/-1, 183.3+/-7, 220, 340 GHz at nadir and a...

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...or even their lack, especially in rainy clouds. The modeling approach is generally more versatile, even though it requires a thorough insight into the electromagnetic interaction between the microwave radiation and the scattering medium [21], [22]. Moreover, a modeling approach needs to produce synthetic data in agreement with available measured ones in order to yield unbiased estimates [18]. The radiative transfer theory has been the most used approach so far to account for the multiple scattering and the vertical inhomogeneity of the atmosphere in the presence of hydrometeor scattering [21]–[23]. The objective of this work is to investigate the potentiality of ground-based microwave radiometry for rainy-cloud param0196-2892/02$17.00 © 2002 IEEE MARZANO et al.: GROUND-BASED MULTIFREQUENCY MICROWAVE RADIOMETRY 743 eter retrieval by optimizing frequency sets and retrieval algorithms best suited for observing both stratiform and convective precipitation. Inversion algorithms for ground-based retrieval of precipitation parameters are developed, adopting a model-based approach. Vertical profiles of stratiform and convective precipitation are generated by means of a microphysically-consiste...

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...6033 has a sufficiently narrow beam width, then the second term of Eq. (2) can be approximated by the analogous term in Eq. (1b), as in the case of radar and laser sources. In the same perspective, once the radiance field is computed from Eqs. (1) at a given position, the received power of an antenna (or detector) with a directive gain G can be derived from10,13 Wr 2 4 0 2 1 1 G(, ; , ) I(, , )dd, (3) where is the e.m. wavelength in the medium. The zenith opacity at height z can be related to the volumetric extinction coefficient kez as follows: 0 z ke(z)dz, (4) where is allowed to vary in the range 0, s because s is the total optical depth (see Fig. 10). The irradiance F Wm2 Hz1 at a given is related to radiance through the following integral relationship: F↓() 0 2 0 1 I(, , )dd, F↑() 0 2 0 1 I(, , )dd, (5) where F↓ and F↑ represent the downward and upward fluxes, and from now on we assume as a positive quantity (i.e., |cos |) so that can be used to designate the upwelling direction. The diffuse upward and downward flux densities, then, are given by Eqs. (5), integrating from 0 and 1 with respect...