Engineering topics

Matthews, W. A.

Publications and source records attributed to Matthews, W. A..

22 records · Page 2

NASA NTRS1987

Comparison of in situ stratospheric ozone measurements obtained during the MAP/GLOBUS 1983 campaign

Data from five types of in situ ozone sensors flown aboard ballons during the MAP/GLOBUS 1983 campaign were found to agree to within 5 percent uncertainty throughout the middle atmosphere. A description of the individual techniques and the error budget is given in addition to explanations for the discrepancies found at higher and lower altitudes. In comparison to UV photometry values, results from two electrochemical techniques were found to be greater in the lower atmosphere and to be lower in the upper atmosphere. In general, olefin chemiluminescence results were within 8 percent of the UV photometry results. Ozone column contents measured by the indigo colorization technique for two altitude regions of about 6 km height were greater than measurements from other techniques by 52 and 17 percent, respectively.

Aimedieu, P.↗

NASA NTRS1987

General comparison of ozone vertical profiles obtained by various techniques during the 1983 MAP/GLOBUS campaign

As part of the 1983 MAP/GLOBUS campaign, atmospheric ozone profile measurements were made using a large variety of different techniques both from balloon platforms and the ground. It is shown that, for most techniques, the measured height distributions agree to within + or - 5 percent with the exception of the remote visible absorption method. This + or - 5 percent uncertainty is of the order of the individual intersystem accuracy. It is suggested that since the differences with the visible absorption method are in magnitude rather than in form, the absorption cross-section data could be the possible cause for the discrepancy.

Matthews, W. A.↗

NASA NTRS1985

Nitric oxide profile from 7 to 32 km

An analysis is given of some results of the LIMS experiment, launched on the Nimbus 7 satellite on October 24, 1978 for the purpose of sounding the middle atmosphere composition and structure. One of the LIMS channels was centered spectrally in the 6 micron region to measure vertical profiles and the global distribution of NO2 mixing ratio. The data reveal that NO2 is highly variable with altitude, latitude, longitude and time. Steep latitudinal gradients are observed in high latitude winter ('the NO2 cliff') when a wave number one pattern exists in the geopotential height field. The daytime gradient under these conditions is less than that for the night. The summer hemisphere column amount is considerably greater (by a factor of about 2) than in the winter hemisphere. The largest mixing ratios occur at 4 mb at night (about 20 ppbv) and 9 mb in the day (about 7 ppbv) and the latitude region of the peak mixing ratio is skewed toward the Southern Hemisphere. The mixing ratio variability is greater at night (by a factor of about 2 to 3) than in the day and there are significant long-term changes revealed by mixing ratio time series analyses on a pressure vs time grid.

Matthews, W. A.↗

NASA NTRS1977

Problems in the use of interference filters for spectrophotometric determination of total ozone

An analysis of the use of ultraviolet narrow-band interference filters for total ozone determination is given with reference to the New Zealand filter spectrophotometer under the headings of filter monochromaticity, temperature dependence, orientation dependence, aging, and specification tolerances and nonuniformity. Quantitative details of each problem are given, together with the means used to overcome them in the New Zealand instrument. The tuning of the instrument's filter center wavelengths to a common set of values by tilting the filters is also described, along with a simple calibration method used to adjust and set these center wavelengths.

Basher, R. E.↗