scholarly journals Field Testing of Cavity Ring-Down Spectroscopy Analyzers Measuring Carbon Dioxide and Water Vapor

2012 ◽  
Vol 29 (3) ◽  
pp. 397-406 ◽  
Author(s):  
Scott J. Richardson ◽  
Natasha L. Miles ◽  
Kenneth J. Davis ◽  
Eric R. Crosson ◽  
Chris W. Rella ◽  
...  
Keyword(s):  
Water Vapor ◽  
Field Measurements ◽  
Field Testing ◽  
The United States ◽  
Upper Midwest ◽  
Cavity Ring Down Spectroscopy ◽  
The North ◽  
Improved Stability ◽  
Field Deployment ◽  
Cavity Ring Down

Abstract Prevalent methods for making high-accuracy tower-based measurements of the CO2 mixing ratio, notably nondispersive infrared spectroscopy (NDIR), require frequent system calibration and sample drying. Wavelength-scanned cavity ring-down spectroscopy (WS-CRDS) is an emerging laser-based technique with the advantages of improved stability and concurrent water vapor measurements. Results are presented from 30 months of field measurements from WS-CRDS systems at five sites in the upper Midwest of the United States. These systems were deployed in support of the North American Carbon Program’s Mid-Continent Intensive (MCI) from May 2007 to November 2009. Excluding one site, 2σ of quasi-daily magnitudes of the drifts, before applying field calibrations, are less than 0.38 ppm over the entire 30-month field deployment. After applying field calibrations using known tanks sampled every 20 h, residuals from known values are, depending on site, from 0.02 ±0.14 to 0.17 ±0.07 ppm. Eight months of WS-CRDS measurements collocated with a National Oceanographic and Atmospheric Administrations (NOAA)/Earth System Research Laboratory (ESRL) NDIR system at West Branch, Iowa, show median daytime-only differences of −0.13 ±0.63 ppm on a daily time scale.

Water-vapor measurement via cavity ring down spectroscopy in the visible

1998 ◽  
Author(s):  
Fuge Sun ◽  
Dongxu Dai ◽  
Lu Kang ◽  
Guohea Sha ◽  
JinChun Xie ◽  
...  
Keyword(s):  
Water Vapor ◽  
Cavity Ring Down Spectroscopy ◽  
Cavity Ring Down

Joint Canada-U.S. Survey in the Mount Kennedy Region

ARCTIC ◽  
1965 ◽  
Vol 18 (2) ◽  
pp. 70
Author(s):  
Canada. Surveys and Mapping Branch
Keyword(s):  
Large Scale ◽  
Field Measurements ◽  
The United States ◽  
Geodetic Survey ◽  
Yukon Territory ◽  
Mountain Range ◽  
National Geographic Society ◽  
National Geographic ◽  
The North ◽  
Alaskan Coast

In 1935 a National Geographic Society glaciological expedition working in the St. Elias mountain range near the Alaska-Yukon Territory boundary described an unnamed mountain in the area as "magnificent, a granite peak sheathed in snow and ice on the south and west sides, and on the north and east sides has fantastic rock cliffs." Thirty years later this same peak was officially named Mount Kennedy in honour of the late President John F. Kennedy. A surge of activity in the area followed immediately. Senator Robert Kennedy climbed the mountain, an expedition sponsored by the National Geographic Society is engaged in producing a large scale map of the mountain and its environs, and a joint U.S.-Canadian party has just completed a survey through the area which will determine the precise geographic position of the mountain's summit and its elevation. The survey party was composed of six men from the United States Coast and Geodetic Survey and two men from the Surveys and Mapping Branch of the Canadian Department of Mines and Technical Surveys. The main purpose of the work was to connect existing surveys along the Alaska Highway with similar surveys along the Alaskan coast. The work will strengthen the control surveys throughout the area and provide new control points for mapping. The decision to include Mount Kennedy in the survey, while adding a touch of glamour to the operation, greatly increased the difficulties. The survey itself consists of five main stations, connected by traverse, with auxiliary points established at alternate stations to provide additional checks on field measurements. The lengths of the four traverse courses varied from eight to thirty-nine miles; the distances were measured by electronic distance measuring equipment, and the angles were measured with precise theodolites using signal lights and heliotropes for targets. ...

Comparative Field Measurements of Tire Pavement Noise of Selected Texas Pavements

1998 ◽  
Vol 1626 (1) ◽  
pp. 78-84 ◽  
Author(s):  
Michael T. Mcnerney ◽  
B.J. Landsberger ◽  
Tracy Turen ◽  
Albert Pandelides
Keyword(s):  
South Africa ◽  
Research Effort ◽  
Traffic Noise ◽  
Test Procedure ◽  
Field Measurements ◽  
Field Testing ◽  
The United States ◽  
Noise Barriers ◽  
Set Up ◽  
Pavement Noise

The effects of traffic noise are a serious concern in the United States and in the rest of the world. One significant component of traffic noise is tire-pavement interaction. If tire-pavement noise can be reduced at the source instead of through the use of traffic noise barriers set up to protect individual receivers, then potential savings can accrue. This research effort conducted field testing on 15 different pavement types found in Texas, and on six pavement types found in South Africa. A test procedure was developed with roadside microphones and microphones mounted on a test trailer to record and analyze the differences in tire-pavement noise. The test procedure was designed to develop comparisons of pavements while other variables were kept constant. The results, measured on the standard A-weighted scale, indicated for the 15 test pavements in Texas a difference of roadside noise levels of up to 7 dBA. Additionally, a roadside noise level of one pavement measured in South Africa was more than 2 dBA quieter than any Texas pavement.

scholarly journals Sample drying to improve HCHO measurements by PTR-MS instruments: laboratory and field measurements

2009 ◽  
Vol 9 (5) ◽  
pp. 19845-19877 ◽  
Author(s):  
B. T. Jobson ◽  
J. K. McCoskey
Keyword(s):  
Water Vapor ◽  
Field Measurements ◽  
Field Testing ◽  
Water Soluble ◽  
Dew Point ◽  
Cold Trap ◽  
Ice Surface ◽  
Quasi Liquid Layer ◽  
Significant Uptake ◽  
Humidity Dependence

Abstract. A significant improvement in the PTR-MS instrument sensitivity to formaldehyde was obtained by drying the air sample to a dew point of −30°C using a cold trap to condense and freeze water vapor. At warmer trap temperatures there was significant uptake of formaldehyde and other water soluble organics, suggesting the presence of a quasi-liquid layer on the ice surface. By removing water vapor to a low constant dew point, the PTR-MS can be operated at low E/N ratios, significantly increasing normalized sensitivities for all organics and removing their humidity dependence due to reactions with H+(H2O)2. At an E/N ratio of 80 Td the formaldehyde normalized sensitivity was 25 Hz/ppbv per MHz H3O+ with an estimated detection limit of 78 pptv. Field testing demonstrated good agreement between HCHO measurements made at ambient humidity and corrected for water vapor effects compared to dehumidified sampling at −30°C. Field testing also revealed that at an E/N ratio of 100 Td or lower there was a significant ion signal at m/z=49, likely CH3OOH. Sampling drying and operation at low E/N ratios enables sensitive measurements of HCHO and potentially CH3OOH, both important tropospheric photoproducts.

scholarly journals High-accuracy continuous airborne measurements of greenhouse gases (CO<sub>2</sub> and CH<sub>4</sub>) using the cavity ring-down spectroscopy (CRDS) technique

2010 ◽  
Vol 3 (2) ◽  
pp. 375-386 ◽  
Author(s):  
H. Chen ◽  
J. Winderlich ◽  
C. Gerbig ◽  
A. Hoefer ◽  
C. W. Rella ◽  
...  
Keyword(s):  
Water Vapor ◽  
Greenhouse Gases ◽  
Ambient Air ◽  
High Accuracy ◽  
Mean Difference ◽  
Pressure Broadening ◽  
Cavity Ring Down Spectroscopy ◽  
Airborne Measurements ◽  
The Mean ◽  
Cavity Ring Down

Abstract. High-accuracy continuous measurements of greenhouse gases (CO2 and CH4) during the BARCA (Balanço Atmosférico Regional de Carbono na Amazônia) phase B campaign in Brazil in May 2009 were accomplished using a newly available analyzer based on the cavity ring-down spectroscopy (CRDS) technique. This analyzer was flown without a drying system or any in-flight calibration gases. Water vapor corrections associated with dilution and pressure-broadening effects for CO2 and CH4 were derived from laboratory experiments employing measurements of water vapor by the CRDS analyzer. Before the campaign, the stability of the analyzer was assessed by laboratory tests under simulated flight conditions. During the campaign, a comparison of CO2 measurements between the CRDS analyzer and a nondispersive infrared (NDIR) analyzer on board the same aircraft showed a mean difference of 0.22±0.09 ppm for all flights over the Amazon rain forest. At the end of the campaign, CO2 concentrations of the synthetic calibration gases used by the NDIR analyzer were determined by the CRDS analyzer. After correcting for the isotope and the pressure-broadening effects that resulted from changes of the composition of synthetic vs. ambient air, and applying those concentrations as calibrated values of the calibration gases to reprocess the CO2 measurements made by the NDIR, the mean difference between the CRDS and the NDIR during BARCA was reduced to 0.05±0.09 ppm, with the mean standard deviation of 0.23±0.05 ppm. The results clearly show that the CRDS is sufficiently stable to be used in flight without drying the air or calibrating in flight and the water corrections are fully adequate for high-accuracy continuous airborne measurements of CO2 and CH4.

Cavity ring-down spectroscopy of 17O-enriched water vapor between 12,055 and 12,260 cm−1

2019 ◽  
Vol 239 ◽  
pp. 106651 ◽  
Author(s):  
A.-W. Liu ◽  
G.-L. Liu ◽  
X.-Q. Zhao ◽  
J. Wang ◽  
Y. Tan ◽  
...  
Keyword(s):  
Water Vapor ◽  
Cavity Ring Down Spectroscopy ◽  
Cavity Ring Down
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