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...ling from the surface. This results in a depression of brightness temperatures 4088 VOLUME 13J O U R N A L O F C L I M A T E in areas where significant optical depths of ice hydrometeors are present (=-=Spencer 1986-=-); at 85-GHz emission from rain is minimized, leaving signatures from ice hydrometeors. The use of polarization corrected temperature (PCT; Spencer et al. 1989) allows the removal of surface polarizat...

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...e, AL 35805. E-mail: Daniel.Cecil@msfc.nasa.gov MARCH 2005 C E C I L E T A L . 543 © 2005 American Meteorological Society MWR2876 (e.g., brightness temperature) by exploiting simultaneous measurements of other characteristics (e.g., radar reflectivity profiles and lightning flash rates). The large, comprehensive database enables bulk quantification of relationships between these characteristics, which have previously been examined using idealized models (Vivekanandan et al. 1990, 1991; SkofronickJackson and Wang 2000) and/or much smaller sets of storms from particular regions (Shackford 1960; Spencer 1986; Spencer et al. 1989; Dye et al. 1989; Mohr et al. 1996; Toracinta et al. 1996, 2002; Nesbitt et al. 2000; Carey and Rutledge 2000; Petersen and Rutledge 2001; Cecil and Zipser 2002). Many of the relationships presented here are consistent with those reported in previous studies, but the size of this database and the unique combination of radar, radiometer, and lightning sensor allow some analyses (e.g., probability of lightning as a function of brightness temperature or reflectivity) that would otherwise be less comprehensive or even impossible. Emphasis is placed on the most vigorous and/or...

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...re 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 et al. (1991), Vivekanandan e...

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...n the system. In any given storm, these values may not be coincident. However, based on theory (Wilheit et al. 1982; Mugnai et al. 1990; Adler et al. 1991; Vivekanandan et al. 1991) and observations (=-=Spencer 1986-=-; Hakkarinen and Adler 1988; Rutledge and MacGorman 1988; Heymsfield and Fulton 1988, 1994; Fulton and Heymsfield 1991; Keighton et al. 1991; Toracinta et al. 1996; Mohr et al. 1996; Petersen et al. 1...

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... At 37 GHz, the mean residual polarization is 3.3 K; at 85.5 GHz it increases to a mean of 7.6 K, with a few instances as large as 15 K. In a few very rare cases, a negative polarization difference of up to 2 K is observed at 85.5 GHz. No negative polarizations are observed at the lower frequencies; indeed, a positive difference of approximately 1 K probably represents a hard lower bound on the 37-GHz polarization difference. In the bottom row of scatterplots, the vertical and horizontal polarizations are plotted against each other for each frequency. The interpretation of these plots follows Spencer (1986), Spencer et al. (1989), and Petty (1994a). At 19.35 GHz, the dominant source of brightness temperature variability lies in the more or less linDECEMBER 2001 2109P E T T Y FIG. 4. Observed SSM/I brightness temperatures from widespread, moderate-to-heavy tropical rainfall: (a)–(c) vertically polarized brightness temperatures vs T22V 2 T19V; (d)–(f ) polarization differences TV 2 TH vs T22V 2 T19V; (g)–(i) TV vs TH (diagonal line indicates polarization difference of zero). From left to right, columns present results for 19.35, 37, and 85.5 GHz, respectively. In all panels, solid lines represent ...

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...ed instruments such as the Electrically Scanning Microwave Radiometer (ESMR) aboard the Nimbus-5 satellite [91] and the Scanning Multichannel Microwave Radiometer (SMMR) aboard the Nimbus-7 satellite =-=[79]-=-. Some recent and ongoing attempts have involved the Tropical Rainfall Measurement Mission (TRMM) coordinated by the U.S. National Aeronautics and Space Administration (NASA) and the National Space De...

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...for inversion algorithms used to estimate precipitation from passive microwave radiometer measurements has been addressed in a number of studies (e.g., Kummerow et al. 1996; Kummerow and Giglio 1994; =-=Spencer 1986-=-; Harris and Foufoula-Georgiou 2001) and is generally referred to as the beam-filling problem. In essence, simulated precipitating cloud fields are used together with radiative transfer schemes to sim...

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...e of the non-linear relation between T b and hydrometeor concentrations. In essence, this is known as the beam-filling problem [e.g., Kummerow, 1998; Kummerow et al., 1996; Kummerow and Giglio, 1994; =-=Spencer, 1986-=-], which is largely a problem of non-linear averaging of precipitation. With respect to our objective of examining the effect of subgrid variability on T b,sim estimates, our concern is that if the mo...