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Observing the development of upwelling on the northeast coast of Africa by measuring ocean surface emission with infrared radiometers on Nimbus satellites is reported. Using the temperature of the ocean as telemetered by the satellite, the biological potential of an area is estimated, and consequently the highest potential for fisheries.
Evaluation of observations of surface temperature and salinity along the western edge of the Gulf Stream made from a ship and of concurrent temperature observations obtained by instrumented aircraft at six altitudes. The major feature along a five-kilometer line normal to the Stream's edge is a temperature gradient of about 0.75 C/kilometer within which are embedded two abrupt temperature increases of about 1.5 C. Temperature variations were compensated by salinity variations, yielding nearly constant density through the frontal zone; a sharp lateral current shear was associated with the thermohaline mixing region between the steps. The attenuation of surface temperature measured by the airborne radiometer was compared with a theoretical model. The analysis supports the view that a two-part correction technique is required: one part for bulk-skin temperature differences, and another for atmospheric attenuation of sea surface emission due to the mass and temperature of interfering gases.
Determination of the effective temperatures of the satellites by means of broad-band observations made at Mauna Kea in 1971. The temperatures of the Galilean satellites are in fair agreement with observations at shorter wavelengths and with theory. The 20-micron flux of Titan is nearly an order of magnitude lower than expected, suggesting either low surface emissivity or high atmospheric opacity between 18 and 25 micron. Hydrogen could produce the required opacity, but the abundance needed is large.
An integral method which has previously been applied to the hypersonic blunt body thermal problem is improved and extended to obtain downstream flux predictions and to improve stagnation predictions. To account for the effect of downstream conditions propagated upstream through the subsonic shock layer region, the normal momentum equation is solved simultaneously with the other governing conservation equations. The effects of viscosity, conduction, dissociation and ionization, nongray radiation, surface emissivity, and ablation are included. Illustrative results are presented for body models of hemispheres and a continuous curvature body which closely approximates a hemispherically blunted wide angle (60 half angle) cone. The atmospheric models are air and a 50% Co2-50% N mixture at low densities, which should be representative of the Martian or Venusian atmospheres.
The effects of the magnetic field and superfluidity on the cooling of neutron stars during the stage when they can be observed as pulsars are considered. A neutron-star model with a stellar mass of 1.07 solar mass, a radius of 12.33 km, and a central energy density of 7.39 x 10 to the 14th power gauss/cu cm was chosen. It appears that during the earlier periods while the star cools by neutrino emission, surface temperatures are somewhat higher at a given age in the presence of stronger magnetic fields. An interesting result is that most pulsars may be very cold.
Basic quantum detection and estimation theory, applications to optics, photon counting, and filtering theory are studied. Recent work on the restoration of degraded optical images received at photoelectrically emissive surfaces is also reported, the data used by the method are the numbers of electrons ejected from various parts of the surface.
The Nimbus 5 microwave spectrometer has been used to measure thermal radiation in five frequency bands between 22.235 and 58.8 gigahertz, and has yielded both the temperature profile and, over ocean, the vapor and liquid water content of the terrestrial atmosphere, even in overcast conditions. Information has also been obtained on geophysical parameters that affect the surface emissivity, such as ice type, sea roughness, and snow cover. The experiment demonstrates the considerable potential of passive microwave sensing of meteorological and geophysical parameters.
Interferometric observations of Mercury at 3.71 cm are used to determine the dielectric constant of the subsurface material at a depth of 50 cm to be 2.4 plus or minus 0.3. The surface emissivity in the radio range is determined by the value of the dielectric constant which is thus necessary in order to interpret the thermal properties of the regolith. New integrated-disk data at 6- and 18-cm wavelengths are found to be consistent with a regolith of particulate geological material in which radiative transfer of heat is important. The results are very similar to the lunar case where regolith density, dielectric constant, and loss tangent are observed to increase smoothly with depth in the subsurface.
Atmospheric radiation was measured as a function of wavelength, position, angle, and time. Radiation was determined by temperature, cloud (aerosol), composition, and surface emissivity measurements. The theory of radiative transfer is reviewed, along with retrieval methods. Instruments onboard space probes for infrared remote sounding of planetary atmospheres are also described.
A steady state, collisionless flow analysis was made of the density distribution within a hemisphere-disc system due to independent, uniformly distributed internal gas sources. The model was used to estimate the density within a molecular shield, deployed from the shuttle orbiter, which contained internal experiments having a prescribed gas source. Contour plots of the density distribution within the system were presented for disc-to-hemisphere radius ratios of .1, .3, .5, .7, and for disc-to-hemisphere surface emission flux density ratios of .01, 1, 100. The hemisphere-disc system was compared to the empty hemisphere, and it was found that if the disc emission flux density was the same as the hemisphere and the disc radius was not greater than 1/3 of the hemisphere radius, the increase in density at the center of the hemisphere-disc system was less than 50%.
A physical model and computational scheme are developed for generating turbulent surface stress, sensible heat flux and humidity flux from mean velocity, temperature and humidity at some fixed height in the atmospheric surface layer, where conditions at this reference level are presumed known from observations or the evolving state of a numerical atmospheric circulation model. The method is based on coupling the Monin-Obukov surface layer similarity profiles which include buoyant stability effects on mean velocity, temperature and humidity to a force-restore formulation for the evolution of surface soil temperature to yield the local values of shear stress, heat flux and surface temperature. A self-contained formulation is presented including parameterizations for solar and infrared radiant fluxes at the surface. Additional parameters needed to implement the scheme are the thermal heat capacity of the soil per unit surface area, surface aerodynamic roughness, latitude, solar declination, surface albedo, surface emissivity and atmospheric transmissivity to solar radiation.
A steady-state, collisionless flow analysis has been made of the density distribution within a hemisphere-disk system due to independent, uniformly distributed internal gas sources. The model may be used to estimate the density within a molecular shield, deployed from the Shuttle Orbiter, which contains internal experiments having a prescribed gas source. Contour plots of the density distribution within the system are presented for disk-to-hemisphere radius ratios of 0.1, 0.3, 0.5, and 0.7, and for disk-to-hemisphere surface emission flux density ratios of 0.01, 1, and 100. The hemisphere-disk system is compared to the empty hemisphere and it is found that if the disk emission flux density is the same as the hemisphere and the disk radius is not greater than one-third of the hemisphere radius, the increase in density at the center of the hemisphere-disk system is less than 50%.
A radiometer which possesses two channels in the 11 to 13 micrometer window region is discussed. The radiometer is used to estimate the sea surface temperature within an accuracy of 1 C. A mathematical model is presented to show that the accuracy is improved to within 0.3 C with an independent estimate of total precipitable water vapor. A broadband channel in the 18 micrometer water vapor band is introduced in addition to the two former channels to remotely sense the total precipitable water vapor. The effect of the surface emissivity is taken into account in the scheme.
A mathematical model of the heating associated with leakage within the space shuttle orbiter wing elevon cove was used to analyze the aerothermal response of the structure. The analysis was applied to wind tunnel results and to shuttle entry conditions. A parametric study described the mechanism by which the energy of the ingested mass is distributed as a function of the Reynolds number, wall conductivity, surface emissivity, and cove height and length. The rate at which energy was transferred into the cove interior was primarily determined by the combined effects of the convection, wall capacitance, and internal radiation terms. Correlation with wind tunnel results indicated that the cold wall convective heating rates, wall temperature, and gas temperature of the cove were predicted by the analytical model for short exposure times. Predicted transient thermal response of the elevon cove subjected to shuttle entry conditions indicated that the allowable leak area at the cove seal was 20 percent less than that previously indicated by experiment.
The main sources of error in remote sensing of sea surface temperature are discussed. The interfering effects of reflected solar radiation, reflected thermal flux, clouds and haze and atmospheric attenuation are examined. The components of measured sea surface radiances, such as clear column radiance, surface emission, atmospheric emission, reflected thermal downward flux, and reflection of solar flux, are analytically presented. The use of the 3.7 micron region window to obtain the radiance to four percent accuracy is discussed. The advantages to be obtained by the use of narrow bandpass channels are assessed.
A quartz hollow tube cathode was used to determine the operating conditions within a mercury orificed hollow cathode. Insert temperature profiles, cathode current distributions, plasma properties profile, and internal pressure-mass flow rate results are summarized and used in a phenomenological model which qualitatively describes electron emission and plasma production processes taking place within the cathode. By defining an idealized ion production region within which most of the plasma processes are concentrated, this model is expressed analytically as a simple set of equations which relate cathode dimensions and specifiable operating conditions, such as mass flow rate and discharge current, to such important parameters as emission surface temperature and internal plasma properties. Key aspects of the model are examined.
A phenomenological model is developed which provides a qualitative description of the basic physical processes taking place within a mercury orifice hollow cathode. This model can be used to predict, to first order, the important cathode operating parameters such as emission length and insert temperature. By assuming an idealized ion production region within which most of the plasma processes are concentrated, the model can be expressed analytically as a simple set of equations which relate cathode dimensions and specifiable operating conditions, such as mass flow rate and discharge current, to such important parameters as insert temperature and plasma properties. A comparison of theoretical and experimental results shows that, if the excited state energy flux is neglected, the model provides relatively accurate predictions of emission length, emission surface temperature, plasma density, and fraction of discharge current due to volume ionization
A moisture sounding radiometer at millimeter wavelengths has been developed for high altitude measurements onboard NASA's WB-57F aircraft. Three channels about the 183.3 GHz water vapor line permit measurement of the atmospheric water vapor profile. A single window channel at 94 GHz provides correction for clouds over the ocean and for surface emissivity variations over land. The instrument is an imaging radiometer operating under microprocessor control throughout each data flight. The system is contained within two packages integrated into the WB-57F pallet. A ground support system was used to perform a quick-look analysis of the data collected immediately following each flight.