No abstract

Simultaneous microwave radar and spectral radiometric data were collected over Lake Erie during March 1978. A theoretical development is presented which interprets the data collected at nadir in terms of changes in the ice thickness and the electromagnetic attenuation coefficient. The theory also addresses the failure of the spectral radiometer to determine ice thickness through observations of quarter wavelength excursions in the reflectivity. Radar data collected off‐nadir showed a substantially different behavior compared to that collected near nadir. This difference is attributed to a change in propagation characteristics from quasi‐specular return from the ice‐water interface to scattering from the rough air‐ice interface.

The surface area above submarine springs of fresh water exhibit temperatures and salinities lower than the surrounding sea waters. A multifrequency radiometer system which earlier demonstrated an accuracy of IøC and 1%o in remotely detecting the surface temperature and salinities, respectively, was used to detect submarine freshwater springs. The first mission on February 4, 1978, consisted of overflight measurements over three fourths of the coastal areas around the island of Puerto Rico. During the second mission on February 6, 1978, special attention was directed to the northwest portion of Puerto Rico where several submarine springs had been reported. The previously reported spring locations correlated well with the locations detected by the radiometers. After separating the surface runoffs such as rivers, lagoons, marshes, and bays, 44 submarine freshwater springs were identified which indicates that the submarine freshwater outflow locations are more numerous around the island than had earlier been estimated. The majority of the submarine springs are located at the northwest and southeast portion of the Puerto Rican coastline. The success of detecting the same submarine springs during both missions at the northwest portion of the island was 39%. INTRODUCTION At the second Caribbean Geological Conference January1959 [Arnow and Bogart, 1960] it was pointed out that the 'rapid economic growth of Puerto Rico involves an increasing demand for fresh water for municipal, industrial and agricultural use' and a program of water resource investigation was to supply a basis for the solution of future water problems. The basic hydrologic equation [Arnow and Bogart, 1960] (the precipitation is equal the sum of the stream runoffs, of the freshwater submarine discharges, of the change of water storage, and of the evapotranspiration) may provide the basis for a closed system such as Puerto Rico island. All equation elements can be determined with the necessary accuracy for the evapotranspiration solution except the amount of freshwater submarine discharges. The School of Engineering of Puerto Rico University, Mayaguez, conducted extensive investigations in May, June, andJuly 1971 to the northwest coast of Puerto Rico as reported [Percious, 1972] with aerial photography, visible and infrared, and with trailing conductivity probes from a vessel, and with diving teams to find submarine freshwater discharges. The investigators succeeded in locating several springs at the north: west coast. However the investigations were very time consuming and tedious. The visible and infrared photography could in most cases not distinguish between submarine groundwater discharges and submerged geological features. The vessel had problems with towing the conductivity probes close enough to the coastline because of submerged reefs and heavy surf. The diving teams were successful in determining discharge velocity and volume after the freshwater spring had been located. The surface areas above submarine springs of fresh water ß exhibit temperatu...

A microwave stepped frequency radiometer operating from 4.5 to 7.2 gigahertz has been designed, fabricated and fli?ht tested in an airborne remote sensing mission by NASA Langley Research Center. This paper describes the design of this precision microwave Dicke-switched noise feedback radiometer, calibration techniques and presents typical results from remote sensing mission employing this radiometer. SUMMARY --

No abstract