Modeling the performance of direct-detection Doppler lidar systems including cloud and solar background variability.

Previous modeling of the performance of spaceborne direct-detection Doppler lidar systems assumed extremely idealized atmospheric models. Here we develop a technique for modeling the performance of these systems in a more realistic atmosphere, based on actual airborne lidar observations. The resulting atmospheric model contains cloud and aerosol variability that is absent in other simulations of spaceborne Doppler lidar instruments. To produce a realistic simulation of daytime performance, we include solar radiance values that are based on actual measurements and are allowed to vary as the viewing scene changes. Simulations are performed for two types of direct-detection Doppler lidar system: the double-edge and the multichannel techniques. Both systems were optimized to measure winds from Rayleigh backscatter at 355 nm. Simulations show that the measurement uncertainty during daytime is degraded by only approximately 10-20% compared with nighttime performance, provided that a proper solar filter is included in the instrument design.

Effects of gender, ethnicity and place of residence on nutrient intake among elderly residents of southwestern Louisiana.

The purpose of this study was to examine the joint effects of gender, ethnicity, seasonal variations and place of residence on nutrient intake among elderly residents of Southwestern Louisiana. Three hundred and fifty-one elderly subjects volunteered and completed all four interviews evenly spaced throughout the year. Multiple analysis of covariance and hierarchal log linear regression were used to examine the joint effects of the independent variables on nutrient intake of eight nutrients; calories, protein, iron, calcium, vitamin C, vitamin A, riboflavin and thiamin. There were differences between males and females for the intake of calories, protein, iron and vitamin C. Over time, there were differences between rural and urban subjects. Rural subjects showed greater seasonal variability than urban subjects. In addition, the three ethnic groups showed different patterns of seasonal variability. When the nutrient intake data were dichotomized at 68% of the Recommended Dietary Allowances, we found that Blacks were more likely to report values below 68% of the RDA than were either Caucasian group. Also, males were more likely to report values below 68% of the RDA than were females. This study illustrates the need for assessing the effects of multiple factors on nutrient intakes. It also shows that there can be significant differences even between nominally similar ethnic groups. With the increased nutritional risk that the elderly face, further research is needed to clarify and extend these results.

Initial Analysis of OSTA-1 Ocean Color Experiment Imagery.

Ocean images were obtained at three widely separated locations on the earth as part of NASA's ocean color experiment. Digital computer enhancement and band-ratioing techniques were applied to radiometrically corrected spectral data to emphasize patterns of chlorophyll distribution and, in one case, of bottom topography. The chlorophyll pattern in the Yellow Sea between China and Korea was evident in a scene produced from shuttle orbit 24. The effects of the discharge from the Yangtze and other rivers were also observed. Two scenes from orbits 30 and 32 revealed the movement of patches of plankton in the Gulf of Cádiz. Geometric corrections of these images permitted ocean current velocities in the vicinity to be deduced. The variability in water depth over the Grand Bahama Bank was estimated by using the blue-green channel of the instrument. The very clear water conditions in the area caused bottom-reflected sunlight to produce a sensor signal that was inversely related to the depth of the water.