Nd:Glass-Raman laser for water vapor dial

A tunable solid-state Raman shifted laser which was used in a water vapor Differential Absorption Lidar (DIAL) system at 9400 A is described. The DIAL transmitter is based on a tunable glass laser operating at 1.06 microns, a hydrogen Raman cell to shift the radiation to 1.88 microns, and a frequency doubling crystal. The results of measurements which characterize the output of the laser with respect to optimization of optical configuration and of Raman parameters were reported. The DIAL system was also described and preliminary atmospheric returns shown

Measurement of Chemical Vapors Emitted from Industrial Sources in an Urban Environment Using Open-path FTIR

A RAM2000 Open-Path (OP) FTIR analyzer was set up to measure ambient air continuously, with 1-min avg, over a 1-mo period at the interface between an industrial area and a residential area (Forest Park) in northwest Portland. There have been numerous complaints from the citizens who live in the Forest Park area about odors and chemicals coming from the industrial area. Twelve chemicals were detected and measured: ammonia, methanol, acetone, propylene glycol methyl ether acetate, n-butyl acetate, isobutanol, 1,1,1,2-tetrafluoroethane, chlorodifluoromethane, tetrachloroethlyene, isopropyl alcohol, 2-butanol, and chloroform. The spectral data was analyzed for 18 other chemicals that are of concern and have appeared in canister samples: benzene, toluene, three isomers of xylene, naphthalene, phenol, CCl 4, dichloromethane, formaldehyde, acetaldehyde, acrolein, styrene, hydrogen cyanide, 1,3-butadiene, 1,2-dibromoethane, 1,2-dichloroethane, and 1,1-dichloroethane. The OP-FTIR technology would be a very valuable tool for monitoring the progress of the Integrated Urban Strategy in reducing the concentrations of the urban hazardous air pollutants. OP-FTIR measurements can produce very large amounts of information on the chemical environment. This is an abstract of a paper presented at the AWMA 97th Annual Conference and Exhibition (Indianapolis, IN 6/22-25/2004)

Ground-Based Infrared Measurements of Carbonyl Sulfide Total Column Abundances: Long - Term Trends and Variability

Total vertical column abundances of carbonyl sulfide (OCS) have been derived from time series of high‐resolution infrared solar absorption spectra recorded at the National Solar Observatory McMath solar telescope facility on Kitt Peak (altitude 2.09 km, latitude 31.9°N, longitude 111.6°W), southwest of Tucson, Arizona, and at the International Scientific Station of the Jungfraujoch (altitude 3.58 km, latitude 46.5°N, longitude 8.0°E), in the Swiss Alps. The analysis of both data sets is based on nonlinear least squares spectral fittings of narrow intervals centered on lines of the intense v 3 band of OCS, the P(37) transition at 2045.5788 cm−1 and the P(15) transition at 2055.8609 cm−1, with a consistent set of spectroscopic line parameters. The Kitt Peak measurements, recorded on 30 different days between May 1977 and March 1991, show a 10% peak‐to‐peak seasonal cycle with a summer maximum and a winter minimum and a trend in the total column abundance equal to (0.1 ± 0.2)% yr−l, 2σ. Jungfraujoch solar spectra recorded on 67 different days between October 1984 and April 1991 have been analyzed. The fitted trend in the Jungfraujoch total columns, (−0.1 ± 0.5)% yr−1, 2σ, is consistent with the Kitt Peak trend results within the errors. The Jungfraujoch total columns show a more complex seasonal variation than noted in the Kitt Peak data. The mean of the daily averaged total columns, 8.44 × 1015 molecules cm−2 above Kitt Peak and 6.41 × 1015 molecules cm−2 above the Jungfraujoch station, correspond respectively to mean tropospheric mixing ratios of 0.54 ± 0.04 and 0.52 ± 0.04 parts per billion by volume; these values are consistent with previously reported remote and in situ measurements. Taken together, the results from the two sites indicate that there has been no significant change in the OCS total column abundance at northern mid‐latitudes over the last decade

Trace gas trends and their potential role in climate change

Examines the potential climatic effects of the radiatively active trace gases that have been detected in the atmosphere including chlorofluorocarbons, chlorobarbons, hydrocarbons, fluorinated and brominated species, and other compounds of nitrogen and sulphur, in addition to CO2 and O3. A one-dimensional radiative-convective model is used to estimate trace gas effects on atmospheric and surface temperatures for three cases. Trace gases other than CO2 are shown to be potentially as important as CO2 for long-term climate trends.-from Author