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Curran, R. J.

Publications and source records attributed to Curran, R. J..

36 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

The effect of ground hydrology on climate sensitivity to solar constant variations

A zonally averaged climate model is used to investigate the effects of different evaporation parameterizations on climate sensitivity to solar constant variations. The model is based on the annual mean zonally averaged hemispheric climate model of Ohring and Adler (1978), with some modifications on the heating parameterizations. The dynamic model utilizes the two-level quasi-geostrophic potential vorticity equations. The heating processes are related to solar radiation, long-wave radiation, convection, evaporation, latent heat release, and ocean transport. Evaporation parameterization has been improved by using a nonlinear formulation in which the Bowen ratio is determined by the vertical gradients of water vapor and temperature near the earth's surface.

Chow, S.-H.↗
NASA NTRS1976

Effects of the atmosphere on remote sensing

The interaction between electromagnetic radiation and the earth's atmosphere is considered, taking into account windows in the electromagnetic spectrum, solar and terrestrial radiation, physical properties of the atmosphere, and clouds. The characteristics of upwelling radiation in the visible wavelengths are discussed along with infrared radiation and microwaves. Attention is given to radiant emittance, radiance, contrast, effects of atmospheric turbulence, ocean color, and questions concerning the classification of surface features with the aid of computers.

Fraser, R. S.↗
NASA NTRS1975

The application of satellite data in the determination of ocean temperatures and cloud characteristics and statistics

The author has identified the following significant results. The major shortcoming of the data was the loss of the infrared radiances from the S191 spectrometer. The cloud thermodynamic phase determination procedure was derived and tested with the data collected by the S192 multispectral scanner. Results of the test indicate a large fraction of the data could be classified thermodynamically. An added bonus was the inclusion of snow in the classification approach. The conclusion to be drawn from this portion of the effort is that in most cases considered ice clouds, liquid water droplet clouds, and snow fields can be spectroscopically separated to a high degree of accuracy.

Curran, R. J.↗
NASA NTRS1974

The detection of dust storms over land and water with satellite visible and infrared measurements

The position of a large area of dust was successfully located over the Sahara Desert and off the west coast of Africa with infrared measurements from the Temperature Humidity Infrared Radiometer (THIR) and visible information from the Image Dissector Camera System (IDCS) on Nimbus 4 between 20 and 25 April 1970. Over land, near midday, the dust areas were associated with lower equivalent blackbody temperatures (TBB's) than in the surrounding areas due to the mixing of the dust with the cooler air just above the surface. Near midnight dust areas appeared to be located where the TBB's were higher than the surrounding regions. The TBB contrast was insufficient for dust detection over the ocean, but the contrast in the visible was great enough to track the movement of the dust for several days off the African west coast. Measurements from the THIR 6.5-7.2 micron channel were useful for detecting the presence of cirrus clouds which could have caused a misinterpretation of the 10.5-12.5 micron TBB's.

Shenk, W. E.↗
NASA NTRS1973

Mars - Mariner 9 spectroscopic evidence for H2O ice clouds

Spectral features observed with the Mariner 9 interferometer spectrometer are identified as those of H2O ice. The measured spectra are compared with theoretical calculations for the transfer of radiation through clouds of ice particles with variations in size distribution and integrated cloud mass. Comparisons with an observed spectrum from the Tharsis Ridge region indicate H2O ice clouds composed of particles with a mean radius of 2.0 microns and an integrated cloud mass of .00005 g/sq cm.

Curran, R. J.↗
NASA NTRS1973

A multi-spectral method for estimating cirrus cloud top heights

A two-channel method has been developed to estimate the altitude of cirrus clouds over ocean areas with an expected altitude error less than or equal to plus or minus 50 mb. Reflected radiation is used to estimate cirrus emissivity in the 10- to 11-micron spectral interval. The cirrus altitude is determined from the emissivity estimate, a registered 10- to 11-micron measurement, and a vertical temperature profile. Nimbus 3 medium-resolution infrared radiometer measurements were used to establish the relationship between reflectance and 11-micron cirrus emissivity.

Shenk, W. E.↗
NASA NTRS1973

Mars: Mariner 9 spectroscopic evidence for H2O ice clouds

Spectral features observed with the Mariner 9 Interferometer Spectrometer are identified as those of water ice. Measured spectra are compared with theoretical calulations for the transfer of radiation through clouds of ice particles with variations in size distribution and integrated cloud mass. Comparisons with an observed spectrum from the Tharsis Ridge region indicate water ice clouds composed of particles with mean radius 2.0 microns and integrated cloud mass 0.00005 g/sq cm.

Curran, R. J.↗
NASA NTRS1973

Biomass in the upwelling areas along the northwest coast of Africa as viewed with ERTS-1

Light penetration in water is affected by plankton, algae, and dissolved and suspended matter. As a consequence, the composition of backscattered light from below the air-sea interface is determined by the nature of the constituents in the water column. In contrast to the absorption spectrum of chemically pure chlorophyll in solution, algae suspensions absorb and scatter light more uniformly throughout the visible part of the electromagnetic spectrum. Because of their spectral absorption and scattering properties plankton concentration can be estimated by measuring the spectral backscattered radiance over water. Experiments using this approach were performed in upwelling regions along the northwest coast of Africa.

Szekielda, K.↗
NASA NTRS1973

Oceanic turbidity and chlorophyll as inferred from ERTS-1 observations

Spectral signatures of phytoplankton and other obscuring effects are considered in order to determine how to best use satellite data. The results of this study were then used to analyze the spectral data obtained from the ERTS-1 multispectral scanner (MSS). The analyzed satellite data were finally compared with surface ship measurements of chlorophyll concentration. It was found that the effects of water turbidity on the multispectral imagery can be discriminated by rationing the two shortest wavelength channels so that the effect of phytoplankton is enhanced.

Curran, R. J.↗
NASA NTRS1973

Cloud emissivity

Infrared interferometric spectra obtained by Nimbus-4 instrumentation are analyzed for the spectral properties of cloud brightness temperatures as a function of wave number. It is shown that cloud-top altitude determination can be corrected for emissions from lower levels in the cloud if an estimate can be made of the particle density. Brightness temperature in the 700 to 950 wave number region can be used to estimate cloud number density.

Curran, R. J.↗
NASA NTRS1972

Atmospheric and surface properties of Mars obtained by infrared spectroscopy on Mariner 9

During the eleven month operational lifetime of Mariner 9, the infrared spectroscopy experiment obtained data over a large portion of Mars. Recently obtained spectra indicate that strong seasonal variations in the water vapor distribution over both polar regions occurred. The wettest atmospheric conditions observed so far contain 20 to 30 precipitable microns of water over the north polar cap during northern spring. A low resolution pressure map is presented which covers that portion of the planet between latitudes -60 deg and +25 deg. A more detailed study of the Coprates canyon indicates that at its lowest point the canyon floor must be at least 5 km below the rim. Applications of tidal theory to temperature fields derived from the spectra indicate diurnal surface pressure fluctuations of as much as 12 percent during the great dust storm of 1971-72. Qualitative arguments based on radiative transfer calculations for model dust clouds composed of spherical quartz particles suggest that particle radii during the storm were of the order of a few microns.

Conrath, B.↗
NASA NTRS1972

Ocean color determination through a scattering atmosphere

Measurements made of the surface level albedo for ocean water containing various concentrations of phytoplankton indicate a strong correlation between wavelength dependent albedo ratios and phytoplankton chlorophyll concentration. To sense surface level albedo ratios from space platforms it is necessary to correct for the scattering and absorption properties of the atmosphere for the wavelengths in question. Atmospheric scattering models were constructed to calculate corrections at two wavelengths, 0.46 and 0.54 millimicrons. Assuming a natural background uncertainty in the aerosol optical depth of 0.1, it is found that the chlorophyll concentration may be determined to within one standard deviation of from 0.5 to 2.5 milligrams per cubic meter. By remotely sensing the aerosol optical depth to a greater accuracy it appears feasible to detect chlorophyll concentrations to uncertainty approaching 0.1 milligram per cubic meter.

Curran, R. J.↗
NASA NTRS1972

Radiometric ocean color surveys through a scattering atmosphere

A series of aircraft flights has been initiated to measure the spectral reflectance of ocean waters containing various concentrations of chlorophyll. The results of both the theoretical and experimental investigations indicate that satellite-borne radiometers can sense ocean color. However, the accuracy to which the chlorophyll concentration can be measured appears to be 0.1 to 0.4 mg/cu m depending upon solar zenith angles. These accuracies are less than desired by many of the oceanographers and an effort is being made to improve the quality of the chlorophyll concentration determination. Further measurements will be made in areas with higher chlorophyll concentration in order to better understand the relationship between chlorophyll concentration and ocean color. Also the effects of high water turbidity will be investigated.

Curran, R. J.↗
NASA NTRS1972

Variation of cloud emissivity in the infrared.

The spectral radiative properties of solid and liquid H2O particles in the thermal infrared are examined. The study of these properties is aimed at an explanation of the spectral features associated with certain clouds pointed out by Hanel et al. (1972) in an analysis of the results of the Nimbus 4 infrared spectroscopy experiment.

Curran, R. J.↗