[1] Enhancement of cloud droplet number concentration by anthropogenic aerosols has previously been demonstrated by in-situ measurements, but there remains large uncertainty in the resultant enhancement of cloud optical depth and reflectivity. Detection of this effect is made difficult by the large inherent variability in cloud liquid water path (LWP); the dominant influence of LWP on optical depth and albedo masks any aerosol influences. Here we use ground-based remote sensing of cloud optical depth (t c ) by narrowband radiometry and LWP by microwave radiometry to determine the dependence of optical depth on LWP, thereby permitting examination of aerosol influence; the method is limited to complete overcast conditions with single layer clouds, as determined mainly by millimeter wave cloud radar. Measurements in north central Oklahoma on 13 different days in the year 2000 show wide variation in LWP and optical depth on any given day, but with near linear proportionality between the two quantities; variance in LWP accounts as much as 97% of the variance in optical depth on individual days and for about 63% of the variance in optical depth for the whole data set. The slope of optical depth vs. LWP is inversely proportional to the effective radius of cloud droplets (r e ); event-average cloud droplet effective radius ranged from 5.6 ± 0.1 to 12.3 ± 0.6 mm (average ± uncertainty in the mean). This effective radius is negatively correlated with aerosol light scattering coefficient at the surface as expected for the aerosol indirect effect; the weak correlation (R 2 = 0.24) might be due in part to vertically decoupled structure of aerosol particle concentration and possible meteorological influence such as vertical wind shear. Cloud albedo and radiative forcing for a given LWP are highly sensitive to effective radius; for solar zenith angle 60°and typical LWP of 100 g m À2 , as effective radius decreases from 10.2 to 5.8 mm determined on different days, the resultant decrease in calculated net shortwave irradiance at the top of the atmosphere (Twomey forcing) is about 50 W m

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[1] Liquid water path (LWP) variability at scales ranging from roughly 200 m to 20 km in continental boundary layer clouds is investigated using ground-based remote sensing at the Oklahoma site of the Atmospheric Radiation Measurement (ARM) program. Twelve episodes from the years of 1999 to 2001 are selected corresponding to conditions of overcast, liquid water single-layered cloud. In contrast to previous studies of marine boundary layer clouds, variability in cloud-top height in these clouds is comparable to that of cloud base, and most continental clouds appear to be subadiabatic. In agreement with previous studies of marine boundary layer clouds, variations in LWP are well related to the variations in cloud thickness. LWP variability exhibits significantly negative correlation with the static stability of the inversion near cloud top; larger cloud variability is associated with less stable inversions. A previously developed parameterization of LWP variability is extended to account for the differing conditions of continental clouds. The relationship between fluctuations in LWP and cloud thickness suggests that cloud parameterizations treating variations in LWP at these scales should include the effects of subgrid-scale fluctuations in cloud thickness. One such treatment is proposed within the context of a statistical cloud scheme.

Abstract.[Purpose] The purpose of this study was to evaluate the effects of push-up plus exercise with visual biofeedback on the activity of the shoulder stabilizer muscles in individuals with winged scapula.[Subjects] This study was conducted with two groups: a visual biofeedback push-up plus exercise group (n=6) and a control push-up plus exercise group (n=6).[Methods] Muscular activity of the shoulder stabilizer muscles of both groups were measured by electromyogram (EMG), both before and after the exercise.[Results] The control group showed a significant difference pre-and post-exercise in the activity of the serratus anterior muscle during elbow extension, but differences in other muscles were insignificant. The visual feedback group showed significant differences pre-and post-exercise in activity of the upper and lower trapezius during elbow extension, in the serratus anterior muscle during elbow flexion and extension and scapula protraction, and in the pectoralis major muscle during elbow flexion.[Conclusion] Providing visual biofeedback during push-up plus exercise made the exercise more effective for winged scapula.

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