Short circuit of water vapor and polluted air to the global stratosphere by convective transport over the Tibetan Plateau.

During boreal summer, much of the water vapor and CO entering the global tropical stratosphere is transported over the Asian monsoon/Tibetan Plateau (TP) region. Studies have suggested that most of this transport is carried out either by tropical convection over the South Asian monsoon region or by extratropical convection over southern China. By using measurements from the newly available National Aeronautics and Space Administration Aura Microwave Limb Sounder, along with observations from the Aqua and Tropical Rainfall-Measuring Mission satellites, we establish that the TP provides the main pathway for cross-tropopause transport in this region.

Interhemispheric Differences in Polar Stratospheric HNO3, H2O, CIO, and O3.

Simultaneous global measurements of nitric acid (HNO(3)), water (H(2)O), chlorine monoxide (CIO), and ozone (O(3)) in the stratosphere have been obtained over complete annual cycles in both hemispheres by the Microwave Limb Sounder on the Upper Atmosphere Research Satellite. A sizeable decrease in gas-phase HNO(3) was evident in the lower stratospheric vortex over Antarctica by early June 1992, followed by a significant reduction in gas-phase H(2)O after mid-July. By mid-August, near the time of peak CIO, abundances of gas-phase HNO(3) and H(2)O were extremely low.

Attenuation of monochromatic X-rays by normal and abnormal breast tissues.

Rationale And Objectives: A prior study indicated that differences in the x-ray linear attenuation coefficients of cancerous and normal breast tissues tend to increase as the energy of the incident beam decreases. The authors investigated x-ray energies down to 20 keV. In the current study, the linear attenuation coefficients for normal and selected cancerous breast tissues within the energy range of 14 to 18 keV were determined.

Current Status of the VU MFEL Compton X-Ray Program.

The Vanderbilt University medical FEL (free electron laser) Compton x-ray program is close to being operational. The FEL modifications necessary for this new capability are near completion. The transport and detection systems for electron and IR beams have been designed, delivered, and tested.

Near-monochromatic X-ray beams produced by the free electron laser and Compton backscatter.

The intense photon output of a free electron laser may be made to collide with its own high energy electron beam to create nearly monochromatic x-rays using Compton backscatter techniques. These x-rays can be used for imaging and non-imaging diagnostic and therapeutic experiments. The initial configuration of the Vanderbilt Medical Free Electron Laser (Sierra Laser Systems, Sunnyvale, CA) produces intense x-rays up to 17.

Chlorine monoxide radical, ozone, and hydrogen peroxide: stratospheric measurements by microwave limb sounding.

Profiles of stratospheric ozone and chlorine monoxide radical (C1O) have been obtained from balloon measurements of atmospheric limb thermal emission at millimeter wavelengths. The C1O measurements, important for assessing the predicted depletion of stratospheric ozone by chlorine from industrial sources, are in close agreement with present theory, The predicted decrease of C1O at sunset was measured. A tentative value for the stratospheric abundance of hydrogen peroxide was also determined.

Microwave radiometric measurements of sea surface temperature from the seasat satellite: first results.

Initial results from the Seasat scanning multichannel microwave radiometer indicate that the sea surface temperature can be measured with a root-mean-square sensitivity of 1.2 degrees C or better. The first microwave map of sea surface temperature for the entire Pacific has been produced.

Microwave spectroscopic imagery of the Earth.

The microwave spectrometer on the Nimbus 6 satellite has produced the first microwave spectral images of the earth. It has yielded global maps of (i) atmospheric temperature profiles, (ii) the distributions of water vapor and liquid water over ocean, and (iii) the coverage and type of ice and snow. The method has potential for operational synoptic monitoring.

Microwave measurement of mesospheric carbon monoxide.

Ground-based observation of atmospheric absorption of solar radiation at a wavelength of 2.6 millimeters has provided the first measurement of mesospheric carbon monoxide. The measurement agrees with photochemical predictions of a carbon monoxide source in the lower thermosphere due to dissociation of carbon dioxide by solar radiation, and has implications for the magnitude of vertical transport in the mesosphere.

Venus: microwave detection of carbon monoxide.

The 115-gigahertz microwave line of carbon monoxide has been detected in the spectrum of Venus. The measurement proves that the carbon monoxide mixing ratio increases above an altitude of 85 kilometers in the Venus stratosphere and provides quantitative information on carbon monoxide in the altitude region from 80 to 110 kilometers. This altitude region is well above that which has been previously sensed.

Microwave spectrometer on the nimbus 5 satellite: meteorological and geophysical data.

The Nimbus 5 microwave spectrometer has been used to measure thermal radiation in five frequency bands between 22.235 and 58.8 gigahertz, and has yielded both the temperature profile and, over ocean, the vapor and liquid water content of the terrestrial atmosphere, even in overcast conditions.

Water vapor: observations of galactic sources.

We measured the emission of water vapor at a wavelength of 1.35 centimeters from nine sources with the 120-foot (36.5-meter) Haystack antenna.