Results of an experimental search for new macroscopic forces with Yukawa range between 5 and 500 microns are presented. The experiment uses 1 kHz mechanical oscillators as test masses with a stiff conducting shield between them to suppress backgrounds. No signal is observed above the instrumental thermal noise after 22 hours of integration time. These results provide the strongest limits to date between 10 and 100 microns, improve on previous limits by as much as three orders of magnitude, and rule out half of the remaining parameter space for predictions of string-inspired models with low-energy supersymmetry breaking. New forces of four times gravitational strength or greater are excluded at the 95% confidence level for interaction ranges between 200 and 500 microns.

The Advanced Very High Resolution Radiometer (AVHRR) on the NOAA 7 satellite acquires 1‐km spatial resolution data in “split window” channels at 10.8 and 11.9 μm. Data from these spectral channels may be used to estimate surface temperature and the atmospheric correction to radiation from the earth's surface. Analysis of a data set from July 1981 shows that (1) there is satisfactory agreement between the equation resulting from radiative transfer theory and the atmospheric correction algorithm as obtained by analysis of an area of incipient cloud street formation; (2) agreement is also satisfactory between this algorithm and the statistically derived NOAA algorithm used to obtain sea surface temperatures from the satellite data (However, the comparison assumes the NOAA algorithm is valid outside its range of derivation.); (3) in areas of cloud street formation, variations of atmospheric moisture produce radiance temperature differences of order 2–3°C, which if neglected would cause errors in the derivation of surface thermal characteristics. This meteorological variation over distances of 5–10 km would not be inferred from conventional radiosonde measurements or from lower‐resolution satellite soundings.

Several methods have been used to estimate regional scale evapotranspiration from satellite thermal infrared measurements. These procedures assume knowledge of surface properties such as sur face roughness, albedo, vegetation characteristics, etc. In many areas of the earth these parameters are not accurately known due to the rap idity of change of vegetation, lack of adequate geographical data bases, and the low spatial resolution of satellite data which results in multiple surface types corresponding to each satellite measurement. In this pa per, an estimate of evapotranspiration is developed by relating varia tions of satellite-derived surface temperature to a vegetation index computed from satellite visible and ncar infrared data. The method requires independent estimates of evapotranspiration for a completely vegetated area and for a non vegetated area, although such areas need not appear in the satellite data. A regional estimate of evapotranspi ration is derived despite the lack of precise estimates for individual satellite measurements. The method requires spatial variability in the satellite data: it does not apply in uniform areas. In addition, a prop ertv is identified which permits discrimination of cirrus clouds from ar;as of varying soil moisture. A data bank of surface characteristics should be developed to support description of surface processes at large scal es.

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