Measurements Of Atmospheric Trace Species Research Articles

Robust extraction of baseline signal of atmospheric trace species using local regression

Abstract. The identification of atmospheric trace species measurements that are representative of well-mixed background air masses is required for monitoring atmospheric composition change at background sites. We present a statistical method based on robust local regression that is well suited for the selection of background measurements and the estimation of associated baseline curves. The bootstrap technique is applied to calculate the uncertainty in the resulting baseline curve. The non-parametric nature of the proposed approach makes it a very flexible data filtering method. Application to carbon monoxide (CO) measured from 1996 to 2009 at the high-alpine site Jungfraujoch (Switzerland, 3580 m a.s.l.), and to measurements of 1,1-difluoroethane (HFC-152a) from Jungfraujoch (2000 to 2009) and Mace Head (Ireland, 1995 to 2009) demonstrates the feasibility and usefulness of the proposed approach. The determined average annual change of CO at Jungfraujoch for the 1996 to 2009 period as estimated from filtered annual mean CO concentrations is −2.2 ± 1.1 ppb yr−1. For comparison, the linear trend of unfiltered CO measurements at Jungfraujoch for this time period is −2.9 ± 1.3 ppb yr−1.

In Situ Measurements of Atmospheric Nitrous Acid by Chemical Ionization Mass Spectrometry Using Chloride Ion Transfer Reactions

Recently, chemical ionization mass spectrometry (CIMS) has been widely applied to the in situ measurements of atmospheric trace species. In this article, we propose a new chemical ionization scheme using a chloride ion transfer reaction from SO(2)Cl(-) as the reagent ion and discuss the applicability of this technique to the detection of nitrous acid (HONO) in the atmosphere. From laboratory investigations, the detection sensitivity was found to depend on the flow rate of SO(2) introduced into the ion source region and the pressure inside the chemical ionization region, which suggests that the chemical ionization reaction is reversible. The detection sensitivity was well described in terms of the forward and backward rates. The present limit of detection is estimated to be 60 parts per trillion by volume (pptv) for an integration time of 1 min. Improvement of the CIMS instrument would enable the measurements of the daytime level of HONO, which might be less than 50 pptv. In addition, the possibility of the interference is discussed from thermodynamic considerations based on ab initio calculations, and the effects of the sampling artifacts are experimentally quantified.

Atmospheric concentrations of the Cl atom, CIO radical, and HO radical in the coastal marine boundary layer

Atmospheric concentrations of chlorine atom (Cl ), chlorine monoxide radical (ClO ), and hydroxyl radical (HO ) in the coastal marine boundary layer are estimated in this study. A steady-state approach to their concentrations in equilibrium with other atmospheric chemical species is used. Measurements of atmospheric trace species, HCl, Cl 2, HCHO, H 2O 2, CH 3OOH, CH 4, CO, SO 2, NO, NO 2, and O 3, were performed at four sites in Taiwan during the spring of 1999. The results indicate that the concentrations of the Cl atom and the ClO and HO radicals decrease significantly with cloud cover. The calculated average daytime concentrations of Cl , ClO , and HO are 3×10 5, 1×10 7, and 6×10 5 molecules/cm 3, respectively. Due to the high reactivity of Cl with hydrocarbons and its concentration level competitive to that of HO , Cl should be a significant sink for hydrocarbons in these cases.

Optical Design of a Space Retroreflector Using a Hybrid Search

Retroreflectors on satellites are used as targets for laser ranging and laser long-path absorption measurements of atmospheric trace species. To compensate for the velocity aberration, slight tuning of the design is necessary. The curvatures of mirrors, the angles between mirrors, and the direction of the retroreflector on the satellite must be tuned to optimize the optical efficiency of the retroreflector. An enumerative scheme is not applicable when the number of parameters is large. We proposed earlier a technique using a genetic algorithm for the optical design of a space retroreflector.1) In this paper, we have improved the method introducing a hybrid technique that is a combination of a genetic algorithm and simulated annealing.

Laser transmitter/receiver system for earth-satellite-earth long-path absorption measurements of atmospheric trace species using the retroreflector in space

A laser transmitter/receiver system using a retroreflector in space (RIS) to experiment with earth-satellite-earth laser long-path absorption measurements of atmospheric trace species is described. The system employs two single-longitudinal-mode pulsed CO2 lasers to measure the atmospheric spectrum and a second-harmonic Nd:YAG laser for active satellite tracking using the image of the RIS reflection. Details of the laser system and the initial experiment are reported.

Balloon-borne infrared Fourier transform spectroscopy for measurements of atmospheric trace species

Fourier transform spectroscopy in the infrared is a very powerful technique for remote sensing measurements of atmospheric constituents. The use of the sun as a radiation source for absorption measurements allows the combination of high spectral resolution together with high signal-to-noise ratio, hence leading to high sensitivity. The possibility of using such a technique under stratospheric balloons adds the capability of good vertical resolution for the measurement of trace species concentration profiles in the solar occultation mode. A description of such an instrumentation and samples of representative results are given.

Heterodyne Spectroscopy Using Broadband Short-Pulse Laser for Long-Path Absorption Measurement of Atmospheric Trace Species

A concept of heterodyne spectroscopy for absorption measurements which employs a broadband short-pulse laser is presented. The absorption line structure of the sample in the spectral width of a short-pulse laser is measured with broadband heterodyne detection. The absorption spectrum can be measured, in principle, with a single laser shot, and the method is potentially useful for laser long-path absorption measurements of atmospheric trace species. Application to an airborne laser long-path absorption system for measuring CH4 is discussed.

An Inexpensive Simple Driver for an Array of Instrumentation Systems

A simple low cost contact closure circuit has been developed to control an array of instruments for atmospheric trace species measurements. The modular design allows reconfiguration of existing instrumentation, addition of new instruments and trouble-shooting, with minimum interruption to the ongoing measurements

Comment on “Indications of photochemical histories of Pacific air masses from measurements of atmospheric trace species at Point Arena, California” by D. D. Parrish et al.

Comment on “Indications of photochemical histories of Pacific air masses from measurements of atmospheric trace species at Point Arena, California” by D. D. Parrish et al.

Reply [to “Comment on ‘Indications of photochemical histories of Pacific air masses from measurements of atmospheric trace species at Point Arena, California’ by D. D. Parrish et al.”

Reply [to “Comment on ‘Indications of photochemical histories of Pacific air masses from measurements of atmospheric trace species at Point Arena, California’ by D. D. Parrish et al.”

Indications of photochemical histories of Pacific air masses from measurements of atmospheric trace species at Point Arena, California

Measurements of light hydrocarbons, ozone, peroxyacetyl nitrate (PAN), HNO3, NO3−, NOx, NOy, and meteorological parameters were made during a 10‐day period in April and May 1985 at Point Arena, a coastal inflow site on the Pacific Ocean in northern California. The meteorological measurements indicate that during this study the sampled air was usually from the marine boundary layer with little land influence on the meteorological parameters. In this marine air the mixing ratios of the alkanes, ozone, PAN, and HNO3 showed strong correlations coincident with variations in the origins of calculated air parcel trajectories and with variations in the ratios of the light alkanes. This variation in the ratios is attributed to different degrees of photochemical aging of the alkanes that are generally consistent with the calculated trajectories. This behavior indicates that the alkane levels are determined by transport to the marine area from continental sources, most likely Asian, followed by photochemical removal over the Pacific Ocean. Since the concentrations of PAN and ozone correlate well with the alkane ratios, it is concluded that the observed PAN and ozone were dominated by continental sources and removal processes in the marine areas. This and other marine studies have observed a strong correlation of PAN and ozone, and it is suggested that production over the continents, transport to the marine areas, and parallel removal processes account for much of the observed correlation. From the correlation of these two species with the measured alkane ratios, approximate net lifetimes of PAN and ozone in the marine troposphere of ≤2.5 and ≥19 days, respectively, are derived. The primary conclusion is that the alkanes, ozone, and PAN in these air parcels from the Pacific marine troposphere are dominated by transport from continental sources and removal by photochemical processes. Direct emissions of the alkanes and in situ photochemical production of PAN and ozone from precursors emitted into the marine region from the surface or the stratosphere must play less important roles. Similar indications of continental influence in marine areas have been seen in other studies of ozone, the sulfur cycle, oxidized nitrogen, and hydrocarbons. It is suggested that the ratios of the light alkanes provide photochemical “clocks” that are useful for gauging the importance of continental influence in a particular marine measurement.

INSTRUMENTATION FOR CHEMICAL SPECIES MEASUREMENTS IN THE TROPOSPHERE AND STRATOSPHERE

Instrument advances made during 1987-1990 for atmospheric trace species measurements are reviewed. Problems discussed include types of measurement strategies, oxidant species, reductant species, and flux measurement. Particular attention is given to odd oxygen species, hydrogen oxides, hydrocarbon oxy and peroxy radicals, halogen oxides, sulfur oxides, carbon monoxides, hydrocarbons, oxygenated hydrocarbons, halogenated hydrocarbons, reduced sulfur compounds, ammonia, cyanide compounds, water vapor, nitrous oxide, hydrogen halides, fully halogenated carbon compounds, fully halogenated carbonyl compounds, and sulfur hexafluoride. 195 refs.

Hadamard transform active long-path absorption spectrometer system for measurements of atmospheric trace species

A new Hadamard transform long-path absorption spectrometer system using an array of light sources modulated directly by the Hadamard matrix code and an array of detectors is proposed and evaluated.