Engineering topics
Publications and source records attributed to Ludwig, C. B..
The feasibility of observing air pollutants from satellite-borne sensors is investigated. Radiative transfer calculations, using both line-by-line and band-model methods, are made to establish the signal changes that originate from the presence of various amounts of pollutants in the atmosphere. The effect of interfering species is considered.
The conceptual design of an FOV nadir radiometer was examined for its applicability to monitoring the radiation process in the atmosphere as it relates to aerosol behavior. The instrument employs a gas filter correlation technique and is suitable for transportation onboard satellite.
A study is presented on the remote sensing of gaseous and particulate air pollutants which is an extension of a previous report. Pollutants can be observed by either active or passive remote sensing systems. Calculations discussed herein indicate that tropospheric CO, CO2, SO2, NO2, NH3, HCHO, and CH4 can be measured by means of nadir looking passive systems. Additional species such as NO, HNO3, O3, and H2O may be measured in the stratosphere through a horizon experiment. A brief theoretical overview of resonance Raman scattering and resonance fluorescence is given. It is found that radiance measurements are most promising for general global applications, and that stratospheric aerosols may be measured using a sun occultation technique. The instrumentation requirements for both active and passive systems are examined and various instruments now under development are described.
The author has identified the following significant results. Significant results, relating the radiance over water surfaces to the atmospheric aerosol content, have been obtained. The results indicate that the MSS channels 4, 5, and 6 centered at 0.55, 0.65, and 0.75 microns have comparable sensitivity, and that the aerosol content can be determined within + or - 10% with the assumed measurement errors of the MSS. The fourth channel, MSS 7, is not useful for aerosol determination due to the water radiance values from this channel generally being less than the instrument noise. The accuracy of the aerosol content measurement could be increased by using an instrument specifically designed for this purpose. This radiance-aerosol content relationship can possibly provide a basis for monitoring the atmospheric aerosol content on a global basis, allowing a base-line value of aerosols to be established. The contrast-aerosol content investigation shows useful linear relationships in MSS channels 4 and 5, allowing the aerosol content to be determined within + or - 10%. MSS 7 is not useful due to the low accuracy in the water radiance, and MSS 6 is found to be too insensitive. These results rely on several assumptions due to the lack of ground truth data, but do serve to indicate which channels are most useful.
The author has identified the following significant results. Useful empirical relationships between apparent contrast at the Salton Sea/desert test site and the aerosol content of the atmosphere have been found for MSS 4, 5, and 6. This provides another technique to measure the atmospheric aerosol content, in addition to the method of measuring radiance over water surfaces previously reported. Analysis of desert data has shown, as predicted by theory, that the radiance over high albedo surfaces is insensitive to changes in the aersol content of the atmosphere.
There are no author-identified significant results in this report.
There are no author-identified significant results in this report.
The treatment of radiant emission and absorption by combustion gases are discussed. Typical applications include: (1) rocket combustion chambers and exhausts, (2) turbojet engines and exhausts, and (3) industrial furnaces. Some mention is made of radiant heat transfer problems in planetary atmospheres, in stellar atmospheres, and in reentry plasmas. Particular consideration is given to the temperature range from 500K to 3000K and the pressure range from 0.001 atmosphere to 30 atmospheres. Strong emphasis is given to the combustion products of hydrocarbon fuels with oxygen, specifically to carbon dioxide, water vapor, and carbon monoxide. In addition, species such as HF, HC1, CN, OH, and NO are treated.
There are no author-identified significant results in this report.
Results are reported upon which the design of a satellite remote gas filter correlation (RGFC) instrument can be based. Although a final decision about the feasibility of measuring some of the pollutants with the required accuracy is still outstanding and subject to further theoretical and experimental verifications, viable concepts are presented which permit the initiation of the design phase. The pollutants which are of concern in the troposphere and stratosphere were selected. The infrared bands of these pollutants were identified, together with the bands of interfering gases, and the line parameters of the pollutants as well as interfering gases were generated through a computer program. Radiative transfer calculations (line-by-line) were made to establish the radiation levels at the top of the atmosphere and the signal levels at the detector of the RGFC instrument. Based upon these results the channels for the RGFC were selected. Finally, the problem areas, which need further investigations, were delineated and the supporting data requirements were established.
Hot water vapor curve of growth, using statistical band model with exponential line intensity distribution yielding spectral absorption coefficients
Data from absorption coefficients and fine-structure parameters measured for water vapor have been incorporated in an analytic program useful in evaluating heating by radiation from the exhaust plume of a large rocket.
Air pollution detection using satellite observation
Measurement of absorptivity and fine structure parameters of water vapor for use in evaluating radiative base heating of Saturn 5 launch vehicles
Radiation from carbon particle clouds produced by research rocket motors
Band models for high temperature water vapor and carbon dioxide
Prediction of total emissivity of nitrogen- broadened and self-broadened hot water vapor
Total emissivity and upper limit of hot water vapor determined from IR spectral emissivity