Engineering topics

Wallio, H. Andrew

Publications and source records attributed to Wallio, H. Andrew.

4 records

NASA NTRS1992

Comparison of eye-safe solid state laser DIAL with passive gas filter correlation measurements from aircraft and spacecraft

Differential Absorption Lidar (DIAL) using solid state Ti:sapphire lasers finds current application in the NASA/LASE Project for H2O vapor measurements in the approximately = 0.820 micron region for the lower and mid-troposphere and in potential future applications in planned measurements of the approximately = 0.940 micron region where both strong and weak absorption lines enables measurements throughout the troposphere and lower stratosphere. The challenge exists to perform measurements in the eye-safe greater than 1.5 micron region. A comparison between DIAL and passive Gas Filter Correlation Radiometer (GFCR) measurements is made. The essence of the differences in signal to noise ratio for DIAL and passive GFCR measurements is examined. The state of the art of lasers and optical parametric oscillators (OPO's) is discussed.

Hess, Robert V.↗

NASA NTRS1990

The distribution of middle tropospheric carbon monoxide during early October 1984

The measurement of Air Pollution from Satellite experiment measured the distribution of middle-tropospheric CO from the Space Shuttle during October 1984. The data represent average mixing ratios between 57 deg N and 57 deg S. Approximately 75,000 individual CO measurements were obtained during the 9-day mission. The data are presented in maps that show the CO mixing ratios averaged over 5 x 5-deg areas for 6 days of the mission. Comparisons with concurrent direct measurements taken aboard aircraft show that the inferred concentrations are systematically low by 20-40 percent, depending upon which direct measurement calibration standard is used. The data show that there are very large CO sources resulting from biomass burning over South America and southern Africa. Measured mixing ratios were high over northeast Asia and were highly variable over Europe.

Reichle, Henry G., Jr.↗

NASA NTRS1989

Feasibility of determining the vertical profile of carbon monoxide from a space platform

The results of a feasibility study conducted to determine the possibility of passively measuring the vertical profile of carbon monoxide in the troposphere on a global basis are presented. The instrument considered is a nadir-viewing gas correlation filter radiometer (GCFR). The basic instrument concept and radiative transfer equations are presented. The calculated signal functions, signal levels, sensitivity, and system noise levels of a spaceborne GCFR instrument are presented and discussed. It is concluded that a three- or four-level measurement of the atmospheric carbon monoxide mixing ratio in the troposphere is possible with this type of instrument.

Reichle, Henry, Jr.↗

NASA NTRS1989

The distribution of middle tropospheric carbon monoxide during early October 1984

The distribution of middle tropospheric carbon monoxide measure by the Measurement of Air Pollution from Satellites (MAPS) instrument carried aboard the space shuttle is reported. The data represent average mixing ratios in the middle troposphere and are presented in the form of maps that show the carbon monoxide mixing ratios averaged for 6 days of the mission. Comparisons with concurrent, direct measurements taken aboard aircraft show that the inferred concentrations are systematically low by from 20 to 40 percent depending upon which direct measurement calibration standard is used. The data show that there are very large CO sources resulting from biomass burning over South America and southern Africa. Measured mixing ratios were high over northeast Asia and were highly variable over Europe.

Reichle, Henry G., Jr.↗