Microwave radiometric temperatures of terrain
Microwave radiometers to measure radiation temperatures for several types of terrain for application to estimation of surface temperature from observed antenna temperature
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Results for “Surface estimation”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Enzyme activity in terrestrial soil in relation to exploration of the Martian surface Semiannual progress report, 1 Jul. - 31 Dec. 1967
Enzyme behavior in nonclassical systems, surface pH estimation in soils, and enzymatic activities in stored and geologically preserved soils
Mc Laren, A. D.↗
Studies of reaction geometry in oxidation and reduction of the alkaline silver electrode
Two methods of surface area estimations of sintered silver electrodes have given roughness factors of 58 and 81. One method is based on constant current oxidation, the other is based on potentiostatic oxidation. Examination of both wire and sintered silver electrodes via scanning electron microscopy at various stages of oxidation have shown that important structural features are mounds of oxide. In potentiostatic oxidations these appear to form on sites instantaneously nucleated while in constant current oxidations progressive nucleation is indicated.
Butler, E. A.↗
Gravity - Mare Humorum.
Global tracking coverage of the Apollo 15 subsatellite has provided gravity measurements from 50 km altitudes over the entire Humorum basin. An estimate of surface mass points at 2 degree intervals, which best fit the data reveals a mass distribution having a lesser mass excess for the very central area. When two different profiles were fit using a two disk model it was again found for each profile that the smaller central disk decreased the central mass by approximately 30%. The mass distribution per unit area however for the major portion of the mascon is still consistent with the other mascons (Crisium, Nectaris and Serenitatis) of approximately 800-900 kg/sq cm. The surface mass point solution seems to correlate somewhat with the dark areas on Whitaker's IR-UV map.
Sjogren, W. L.↗
Spoked wheels to deploy large surfaces in space-weight estimates for solar arrays
Extensible booms were used to deploy and support solar cell arrays of varying areas. Solar cell array systems were built with one or two booms to deploy and tension a blanket with attached cells and bussing. A segmented and hinged rim supported by spokes joined to a common hub is described. This structure can be compactly packaged and deployed.
Crawford, R. F.↗
A simple method to incorporate water vapor absorption in the 15 microns remote temperature sounding
The water vapor absorption in the 15 micron CO2 band, which can affect the remotely sensed temperatures near the surface, are estimated with the help of an empirical method. This method is based on the differential absorption properties of the water vapor in the 11-13 micron window region and does not require a detailed knowledge of the water vapor profile. With this approach Nimbus 4 IRIS radiance measurements are inverted to obtain temperature profiles. These calculated profiles agree with radiosonde data within about 2 C.
Dallu, G.↗
Estimation of ground temperature from GFCR radiometric signal
A procedure was developed which demonstrates the feasibility of estimating actual surface temperature from the effective brightness temperature which can be conveniently measured by a radiometer from remote sensing platforms. Atmospheric corrections to the effective brightness temperature are computed corresponding to the 'base model' atmosphere and several modifications of this caused by deviations of the various atmospheric or surface parameters from their base model values. Simple analytical relations were established between the deviations of these parameters and the additional temperature corrections required to compensate for them. Effects of simultaneous variation of several parameters also were examined. Use of these analytical relations, instead of radiative transfer calculations, results in tremendous savings in data reduction costs.
Gupia, S. K.↗
Radar scattering laws and wavelength dependence of the lunar surface
Data from Apollo lunar bistatic radar experiments have been processed to give probability density functions for surface slopes. These show best agreement with a Hagfors scattering law, though data having both gaussian and exponential characteristics also exist. Surface roughness estimates range from 4 deg in maria to at least 8 deg in highlands, values which are appropriate to 25 m horizontal scales and which are areal averages over tens of square kilometers. Roughness varies with wavelength, most strongly in maria.
Simpson, R. A.↗
Ultraviolet absorption spectrum of hydrogen peroxide vapor
The ultraviolet absorption cross sections of hydrogen peroxide vapor have been determined over the wavelength range 210 to 350 nm at 296 K. At the longer wavelengths, the gas phase absorptivities are significantly larger than the corresponding values in condensed phase. The atmospheric H2O2 photodissociation rate for overhead sun at the earth's surface is estimated to be about 1.3 x 10 to the -5th/sec.
Molina, L. T.↗
Preliminary results of SAR soil moisture experiment, November 1975
The experiment was performed using the Environmental Research Institute of Michigan's (ERIM) dual-frequency and dual-polarization side-looking SAR system on board a C-46 aircraft. For each frequency, horizontally polarized pulses were transmitted and both horizontally and vertically polarized return signals were recorded on the signal film simultaneously. The test sites were located in St. Charles, Missouri; Centralia, Missouri; and Lafayette, Indiana. Each test site was a 4.83 km by 8.05 km (3 mile by 5 mile) rectangular strip of terrain. Concurrent with SAR overflight, ground soil samples of 0-to-2.5 cm and 0-to-15 cm layers were collected for soil moisture estimation. The surface features were also noted. Hard-copy image films and the digital data produced via optical processing of the signal films are analyzed in this report to study the relationship of radar backscatter to the moisture content and the surface roughness. Many difficulties associated with processing and analysis of the SAR imagery are noted. In particular, major uncertainty in the quantitative analysis appeared due to the difficulty of quality reproduction of digital data from the signal films.
Choudhury, B. J.↗
Earth radiation budget measurements from satellites and their interpretation for climate modeling and studies
The annual and seasonal averaged Earth atmosphere radiation budgets derived from the most complete set of satellite observations available are presented. The budgets were derived from a composite of 48 monthly mean radiation budget maps. Annually and seasonally averaged radiation budgets are presented as global averages and zonal averages. The geographic distribution of the various radiation budget quantities is described. The annual cycle of the radiation budget was analyzed and the annual variability of net flux was shown to be largely dominated by the regular semi and annual cycles forced by external Earth-Sun geometry variations. Radiative transfer calculations were compared to the observed budget quantities and surface budgets were additionally computed with particular emphasis on discrepancies that exist between the present computations and previous surface budget estimates.
Vonderhaar, T. H.↗
The role of fallback ejecta in the modification of impact craters
The physical processes responsible for the deposition of fragments of target material ejected from the transient cavity of an impact crater within the crater are discussed and quantities of fallback ejecta deposited in impact craters formed on different planetary surfaces are estimated. Consideration is given to the relative importance of in-flight particle collisions and atmospheric particle deceleration, and a model of the aerodynamic deceleration of fallback ejecta is developed. When applied to Meteor Crater in Arizona, the model predicts 5% of the primary ejecta, with an average fragment size of 1.4 cm, to have fallen back into the crater, in agreement with empirical studies of the crater fallback deposit, thus indicating atmospheric deceleration to be the principal mechanism for fallback deposition on earth. The model also predicts the proportion of primary ejecta to be deposited as fallback to increase with excavation cavity diameter on the earth. Model estimates also suggest that more than half of the primary ejecta from large-scale Venusian cavities should be redeposited as fallback, while relatively small amounts of fallback are expected for lunar and Martian craters.
Settle, M.↗
Atmospheric correction of Nimbus-7 Coastal Zone Color Scanner imagery
The Coastal Zone Color Scanner (CZCS) on Nimbus-7 is a scanning radiometer designed to view the ocean in six spectral bands (centered at 443, 520, 550, 670, 750, and 11,500 nm) for the purpose of estimating sea surface chlorophyll and temperature distributions. In the visible bands, the atmosphere obscures the imagery to the extent that at 443 nm, at most, only 20 percent of the observed radiance originates from beneath the sea surface. Retrieving this subsurface radiance from the imagery is complicated by the highly variable nature of the aerosol's contribution. In this paper, an algorithm for the removal of these atmospheric effects from CZCS imagery is described, a preliminary application of the algorithm to an image with very strong horizontal variations in the aerosol optical thickness is presented, and retrieval of the spatial distribution of the aerosol optical thickness is discussed.
Gordon, H. R.↗
Investigation of Icing Characteristics of Typical Light Airplane Engine Induction Systems
The icing characteristics of two typical light-airplane engine induction systems were investigated using the carburetors and manifolds of engines in the horsepower ranges from 65 to 85 and 165 to 185. The smaller system consisted of a float-type carburetor with an unheated manifold and the larger system consisted of a single-barrel pressure-type carburetor with an oil-jacketed manifold. Carburetor-air temperature and humidity limits of visible and serious Icing were determined for various engine power conditions. Several.methods of achieving ice-free induction systems are discussed along with estimates of surface heating requirements of the various induct ion-system components. A study was also made of the icing characteristics of a typical light-airplane air scoop with an exposed filter and a modified system that provided a normal ram inlet with the filter located in a position to Induce inertia separation of the free water from the charge air. The principle of operation of float-type carburetors is proved to make them inherently more susceptible to icing at the throttle plate than pressure-type carburetors.. The results indicated that proper jacketing and heating of all parts exposed to the fuel spray can satisfactorily reduce or eliminate icing in the float-type carburetor and the manifold. Pressure-type carburetors can be protected from serious Icing by proper location of the fuel-discharge nozzle combined with suitable application of heat to critical parts.
Coles, W. D.↗
The digital step edge
The facet model was used to accomplish step edge detection. The essence of the facet model is that any analysis made on the basis of the pixel values in some neighborhood has its final authoritative interpretation relative to the underlying grey tone intensity surface of which the neighborhood pixel values are observed noisy samples. Pixels which are part of regions have simple grey tone intensity surfaces over their areas. Pixels which have an edge in them have complex grey tone intensity surfaces over their areas. Specially, an edge moves through a pixel only if there is some point in the pixel's area having a zero crossing of the second directional derivative taken in the direction of a non-zero gradient at the pixel's center. To determine whether or not a pixel should be marked as a step edge pixel, its underlying grey tone intensity surface was estimated on the basis of the pixels in its neighborhood.
Haralick, R. M.↗
A method of predicting the performance deterioration of a compressor cascade due to sand erosion
Performance deterioration due to sand erosion is a well known phenomena for aircraft engines operating in particulate flow environments. A method for predicting this performance deterioration is developed and applied to a two dimensional compressor cascade. The locations of the particles impacts are computed by analyzing the trajectories of the individual particles. From this analysis, the material removed, the changes in the airfoil shape, and the roughness development over the surface are estimated as a function of time. The resulting airfoil profiles are analyzed for predicting performance by using an inviscid-viscous interaction technique. The analytical solution is compared with experimental results.
Balan, C.↗
Calculations of atmospheric transmittance in the 11 micrometer window for estimating skin temperature from VISSR infrared brightness temperatures
An algorithm for calculating the atmospheric transmittance in the 10 to 20 micro m spectral band from a known temperature and dewpoint profile, and then using this transmittance to estimate the surface (skin) temperature from a VISSR observation in the 11 micro m window is presented. Parameterizations are drawn from the literature for computing the molecular absorption due to the water vapor continuum, water vapor lines, and carbon dioxide lines. The FORTRAN code is documented for this application, and the sensitivity of the derived skin temperature to variations in the model's parameters is calculated. The VISSR calibration uncertainties are identified as the largest potential source of error.
Chesters, D.↗
Radar altimetry over sea ice
To study the sea-ice interactive region in the Bering and Greenland Seas a series of experimental compaigns, the Marginal Ice Zone Experiment (MIZEX) has been planned. A major objective of MIZEX is the development of a capability to relate the morphology and distribution of the sea ice to atmospheric and oceanographic parameters in an overall model. During the first part of the MIZEX, a 13.7 GHz microwave radar altimeter/scatterometer having a pulse length of 16 nanoseconds was flown over the Bering Sea Marginal ice zone. On the same aircraft were the NASA GSFC 19 GHz Electronically Scanning Microwave Radiometer (ESMR), scanning radiometers and an infrared, nadir pointing, temperature sounder. The altimeter/scatterometer was operated in nadir pointing and conically scanning modes to collect measurements of reflectivity and pulse shapes. These will be related to sea-ice classifications, ocean wave spectra and coincident microwave and infrared radiometric measurements and laser profilometer surface roughness estimates.
Powell, J.↗