Infrared continuum water vapor absorption coefficients derived from satellite data.

In a recent paper W. B. Grant ["Water Vapor Absorption Coefficients in the 8-13-microm Spectral Region: a Critical Review," Appl. Opt. 29, 451-462 (1990)] reviewed experimental measurements of the water vapor continuum absorption coefficients in the 8-13-microm spectral region. In comparing three different groundbased techniques he concluded that the absorption coefficients used in the HITRAN and LOWTRAN-7 codes are in reasonable agreement with the measurements. These coefficients are approximately 20% lower than those used in the LOWTRAN-6 code. A fourth method of experimentally determining the water vapor absorption coefficients is described which suggests an opposite result. A comparison between sets of satellite measured infrared radiances and ship measurements of sea surface temperature using a model of infrared transmission through the atmosphere gives coefficients that are 20-40% larger than those used in LOWTRAN-6. Agreement between the four different measurement techniques is only posible if a much stronger negative temperature dependence of the continuum absorption coefficients is adopted. This results in significant increases in the coefficients at temperatures below 270 K.

Infectious bovine keratoconjunctivitis: seasonal variation in cultural, biochemical and immunoreactive properties of Moraxella bovis isolated from the eyes of cattle.

The eyes of 20 young cattle were examined over an 18 month period in which 12 members of the group contracted infectious bovine keratoconjunctivitis (IBK). On each of 23 occasions cultural, biochemical and immunoreactive properties of up to 6 isolates of Moraxella bovis derived from each eye were determined. Relationships between the clinical response of eyes, phenotypic properties of M. bovis and annual variations in the level of solar ultraviolet radiation of 280 to 320 nm wavelength were examined. M. bovis was isolated from all IBK-affected and some unaffected eyes less than one month after the maximum annual level of the mean weekly UV radiation (2,840 mWh.m-2 X nm-1) was recorded. A high proportion of M. bovis from IBK lesions were simultaneously active in haemolysis, agar corrosion, gelatin liquefaction and litmus milk peptonisation. Some of these characteristics showed marked dissociation despite consistent reactivity in the fluorescent antibody test, which had a sensitivity and specificity of 95%. Fall in the mean weekly level of UV radiation below 1,438 mWh X m-2 X nm-1 in autumn was accompanied by healing of ulcers, persistent scar formation and a decline in the number of M. bovis isolated from affected eyes. A slower decline in the number of M. bovis isolated from apparently healthy eyes occurred in the winter and occasional fresh IBK lesions occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential-absorption lidar measurements in the oxygen A band using a ruby lidar and stimulated Raman scattering.

Stimulated Raman scattering has been used to convert the output wavelength of a ruby-laser radar (lambda = 6943 A) into the oxygen A band near 7660 A. The system has been used to measure the energy backscattered from the lower atmosphere at both 6943 and 7658 A. Smith and Platt [NOAA Technical Memorandum, NESS 89 (1977)] have shown that such differential-absorption lidar measurements can be used to give both pressure height profiles and vertical temperature profiles. Some correlation between pressure height and oxygen absorption has been found, but greater transmitted energies and better frequency stability at the converted wavelength are required before an operational system can be implemented.

Instrumentation for remote sensing solar radiation from light aircraft.

The paper outlines the instrumentation needed to study, from a light aircraft, the solar radiation reflected by ground surfaces and the incoming solar radiation. A global shortwave radiometer was mounted on the roof of the aircraft and a specially designed mount was used to support a downward pointing 70-mm aerial camera, a downward pointing narrow-beam pyranometer, and, sometimes, a downward pointing global shortwave pyranometer. Calibration factors were determined for the three pyranometers by comparison with a standard Angstrom compensation pyrheliometer. Results have indicated trends in the albedos of major plant communities and have shown that the calculated albedo values vary according to whether the downward pointing instrument is narrow-beam or global. Comparisons were also made with albedos measured on the ground.