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A physically based bare-surface soil moisture inversion technique for application with passive microwave satellite measurements, including the Advanced Microwave-Scanning Radiometer--Earth Observing System, Special Sensor Microwave/Imager, Scanning Multichannel Microwave Radiometer, and Tropical Rainfall Measuring Mission Microwave Imager, was developed in this paper. The inversion technique is based on the concept of a simple parameterized surface emission model, the [Q.sub.p] model, which was developed using advanced integral equation model simulations of microwave emission. Through evaluation of the relationship between roughness parameters [Q.sub.p] at different polarizations, it was found that they could be described by a linear function. Using this relationship and the surface emissivities measured from two polarizations, the effect of the surface roughness is cancelled out. In other words, this approach consisted in adding different weights on the v and h polarization measurements so as to minimize the surface roughness effects. This method leads to a dual-polarization inversion technique for the estimation of the surface dielectric properties directly from the emissivity measurements. For validation, we compared the soil moisture estimates, derived from ground radiometer measurements at C- to Ka-band obtained from the Institute National de Recherches Agronomiques' field experimental data in 1993 and the Beltsville Agricultural Research Center's field experimental data at C- and X-band obtained in 1979-1982, with the field in situ soil moisture measurements. The accuracies [root-mean-square error (rmse)] are higher than 4% for the available experimental data at the incidence angles of 50[degrees] and 60[degrees]. The newly developed inversion technique should be very useful in monitoring global soil moisture properties using the currently available satellite instruments that commonly have incidence angles between 50[degrees] and 55[degrees]. Index Terms--Inversion technique, passive microwave, roughness, soil moisture.

This paper presents the effects of rain on the performance of a Ka-band local multipoint distribution system (LMDS) in Taiwan. The rain distribution statistics, from 2-yr measurements with 1-min temporal resolution and 12-yr measurements with a 1-h temporal resolutions, were analyzed. The rain-attenuation model that takes local rain effects is established statistically. These statistical data are used to analyze the performance of the LMDS in terms of its signal-to-interference (S/I) ratio, bit-error rate (BER), and channel capacity at various service distances. From the analysis, it is found that the light rain events induce better S/I for cellular network service, because other base transceiver station (BTS) interference signals around the main BTS are likely to be blocked by rain. The probability that below the nominal value of the channel capacity, when there is rain fading without cellular interference, meets a margin of BER = [10.sup.-6] in a 6-kin cell using quaternary phase-shift keying (QPSK) modulation. However, when the cellular interference is presented, the effective BTS service distance greatly shrinks to 2-3 km. In summary, in a cellular network environment, as the cell coverage radius is reduced, the effective BTS service range will be correspondingly compressed, suggesting that the cellular interference is even more serious than the rain attenuation itself. Index Terms--Ka-band, local multipoint distribution system (LMDS) system, rain fading.

This paper presents a model of microwave emissions from rough surfaces. We derive a more complete expression of the single-scattering terms in the integral equation method (IEM) surface scattering model. The complementary components for the scattered fields are rederived, based on the removal of a simplifying assumption in the spectral representation of Green's function. In addition, new but compact expressions for the complementary field coefficients can be obtained after quite lengthy mathematical manipulations. Three-dimensional Monte Carlo simulations of surface emission from Gaussian rough surfaces were used to examine the validity of the model. The results based on the new version (advanced IEM) indicate that significant improvements for emissivity prediction may be obtained for a wide range of roughness scales, in particular in the intermediate roughness regions. It is also shown that the original IEM produces larger errors that lead to tens of Kelvins in brightness temperature, which are unacceptable for passive remote sensing. Index Terms--Microwave emissions, moment method simulation, rough surfaces, scattering model.

ABSTRACT Twenty-five volatile organic compounds (VOCs) up to [C.sub.10] were measured using Carbotrap multibed thermal adsorption tubes during the morning and afternoon rush hours on four different days in all [...]

Soil moisture is an important parameter for hydrological and climatic investigations. Future satellite missions with L-band passive microwave radiometers will significantly increase the capability of monitoring earth's soil moisture globally. Understanding the effects of surface roughness on microwave emission and developing quantitative bare-surface soil moisture retrieval algorithms is one of the essential components in many applications of geophysical properties in the complex earth terrain by microwave remote sensing. In this study, we explore the use of the integral equation model (IEM) for modeling microwave emission. This model was validated using a three-dimensional Monte Carlo model. The results indicate that the IEM model can be used to simulate the surface emission quite well for a wide range of surface roughness conditions with high confidence. Several important characteristics of the effects of surface roughness on radiometer emission signals at L-band 1.4 GHz that have not been adequately addressed in the current semiempirical surface effective reflectivity models are demonstrated by using IEM-simulated data. Using an IEM-simulated database for a wide range of surface soil moisture and roughness properties, we developed a parameterized surface effective reflectivity model with three typically used correlation functions and an inversion model that puts different weights on the polarization measurements to minimize surface roughness effects and to estimate the surface dielectric properties directly from dual-polarization measurements. The inversion technique was validated with four years (1979-1982) of ground microwave radiometer experiment data over several bare-surface test sites at Beltsville, MD. The accuracies in random-mean-square error are within or about 3% for incidence angles from 20[degrees] to 50[degrees]. Index Terms--L-band radiometer, soil moisture, surface emission.

ABSTRACT Airflow and pollutant dispersion in a cross-harbor traffic tunnel were experimentally and numerically studied. Concentrations of the gaseous pollutants CO, [NO.sub.x], and total hydrocarbons (THC) at three axial locations [...]