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Maul, G. A.

Publications and source records attributed to Maul, G. A..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Fitting of satellite and in-situ ocean surface temperatures Results for polymode during the winter of 1977-1978

For the period considered, December 1977 through February 1978, bivariate Gaussian discriminant function cloud identification revealed that more than 93 percent of the 8-km resolution GOES infrared pixels were cloud contaminated. Cloud-free in-situ calibration points were distributed in nonrandom groups; this resulted in systematic errors when using least squares techniques. Surfaces and regression lines were least squares fitted between satellite and in-situ data; use was also made of differences and ratios. The best results were achieved with a regression in the form of the infrared radiative transfer equation; but this was no better than + or - 0.9 K. Because of extensive cloudiness, the linear regressions were seldom useful, and temperature ratios with + or - 1.3 K experimental errors best represent the applicability of GEOS data to sea surface temperatures.

Maul, G. A.↗
NASA NTRS1983

Zenith angle effects in multichannel infrared sea surface remote sensing

Several approaches to infrared multichannel sea surface temperature retrievals propose using a universal set of constants. It is shown that the single-channel multiangle technique (i.e., GOES and NOAA) and the multichannel single-angle technique (NOAA-n) are similar concepts with a common derivation from radiative transfer theory. It is also shown that the linear correlation factor between surface temperature minus satellite temperature in one channel versus the difference in satellite temperatures in two channels is not independent of the difference in satellite sensed equivalent blackbody temperature. The 3.7-micron, 11-micron, and 12-micron channels on the NOAA-n AVHRR can be used in combination to compute atmospheric transmissivity and average atmospheric temperature, but a better combination would be substituting three 0.5-micron-wide channels centered on 11.25 micron, 11.75 micron, and 12.25 micron. A triple window multispectral scanner in the 11-12.5 micron region allows determination of diffuse surface reflectance which can bias sea surface temperatures - 0.4 K + or - 0.3 K.

Maul, G. A.↗
NASA NTRS1978

Deep sea tides determination from GEOS-3

GEOS 3 altimeter data in a 5 degree X 5 degree square centered at 30 deg N, 70 deg W were analyzed to evaluate deep sea tide determination from a spacecraft. The signal to noise ratio of known tidal variability to altimeter measurement of sea level above the ellipsoid was 0.1. A sample was obtained in a 5 deg x 5 deg area approximately once every four days. The randomly spaced time series was analyzed using two independent least squares techniques.

Maul, G. A.↗
NASA NTRS1976

An Experiment to Evaluate Skylab Earth Resources Sensors for Detection of the Gulf Stream

The author has identified the following significant results. An experiment to evaluate the Skylab earth resources package for observing ocean currents was performed in the Straits of Florida in January 1974. Data from the S190 photographic facility, S191 spectroradiometer and S192 multispectral scanner, were compared with surface observations. The anticyclonic edge of the Gulf Stream could be identified in the Skylab S190A and B photographs, but the cyclonic edge was obscured by clouds. The aircraft photographs were judged not useful for spectral analysis because vignetting caused the blue/green ratios to be dependent on the position in the photograph. The spectral measurement technique could not identify the anticyclonic front, but mass of Florida Bay water which was in the process of flowing into the Straits could be identified and classified. Monte Carlo simulations of the visible spectrum showed that the aerosol concentration could be estimated and a correction technique was devised.

Maul, G. A.↗
NASA NTRS1975

On the use of the earth resources technology satellite /LANDSAT-1/ in optical oceanography

Observations of the Gulf Stream System in the Gulf of Mexico were obtained in synchronization with LANDSAT-1. Computer enhanced images, which are necessary to extract useful oceanic information, show that the current can be observed by color (diffuse radiance) or sea state (specular radiance) effects associated with the cyclonic boundary even in the absence of a surface thermal signature. The color effect relates to the spectral variations in the optical properties of the water and its suspended particles, and is studied by radiative transfer theory. Significant oceanic parameters identified are: the probability of forward scattering, and the ratio of scattering to total attenuation. Several spectra of upwelling diffuse light are computed as a function of the concentration of particles and yellow substance.

Maul, G. A.↗
NASA NTRS1974

Satellite photography of eddies in the gulf loop current

Cyclonic ocean eddies, approximately 12 to 32 kilometers in diameter, have been photographed in the eastern Gulf of Mexico by SKYLAB. Apparently caused by horizon velocity shear, these features are associated with the Gulf Loop Current, whose position was known a fortnight before and after the observation. The eddies were discovered in sunlight-enhanced patterns of streamlines on the surface, and appear to be embedded in the flow.

Maul, G. A.↗