Emission spectrum of hot HDO below 4000 cm-1

Fourier transform emission spectra were recorded using a mixture of H2O and D2O at a temperature of 1500 °C. The spectra were recorded in three overlapping sections and cover the wavenumber range 1800–3932 cm−1. This spectrum is analyzed together with a previously reported one spanning the 380–2190 cm−1 range [Parekunnel et al., J. Mol. Spectrosc. 2001 (28) 101]. This analysis leads to 4409 newly assigned HDO emission lines. This work particularly extends data on the (200) and (120) states of HDO for which newly determined energy levels are presented

Laboratory spectroscopy of hot water near 2-microns and sunspot spectroscopy in the H-band region

The infrared spectrum of sunspots is analyzed in the H-band region (55406997 cm-1) with the aid of a new, hot (T = 1800 K) laboratory emission spectrum of water covering 48787552 cm-1. There are 682 lines in the sunspot spectrum and 5589 lines in the laboratory spectrum assigned quantum numbers corresponding to transitions due to H216O using a combination of previously known experimental energy levels for water and variational line lists. A further 201 unassigned lines common to both spectra can also be associated with water

Greenhouse Gas Measurements Over a 144 km Open Path in the Canary Islands

A new technique for the satellite remote sensing of greenhouse gases in the atmosphere via the absorption of short-wave infrared laser signals transmitted between counter-rotating satellites in low Earth orbit has recently been proposed; this would enable the acquisition of a long-term, stable, global set of altitude-resolved concentration measurements. We present the first ground-based experimental demonstration of this new infrared-laser occultation method, in which the atmospheric absorption of CO2 near 2.1µm was measured over a ∼144km path length between two peaks in the Canary Islands (at an altitude of ∼2.4 km), using relatively low power diode lasers (∼4 to 10mW). The retrieved CO2 volume mixing ratio of 400 ppm (±15 ppm) is consistent within experimental uncertainty with simultaneously recorded in situ validation measurements. We conclude that the new method has a sound basis for monitoring CO2 in the free atmosphere; other greenhouse gases such as methane, nitrous oxide and water vapour can be monitored in the same way

Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS) experiment: design, execution and science overview

We describe the design and execution of the BORTAS (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites) experiment, which has the overarching objective of understanding the chemical aging of air masses that contain the emission products from seasonal boreal wildfires and how these air masses subsequently impact downwind atmospheric composition. The central focus of the experiment was a two-week deployment of the UK BAe-146-301 Atmospheric Research Aircraft (ARA) over eastern Canada, based out of Halifax, Nova Scotia. Atmospheric ground-based and sonde measurements over Canada and the Azores associated with the planned July 2010 deployment of the ARA, which was postponed by 12 months due to UK-based flights related to the dispersal of material emitted by the Eyjafjallajökull volcano, went ahead and constituted phase A of the experiment. Phase B of BORTAS in July 2011 involved the same atmospheric measurements, but included the ARA, special satellite observations and a more comprehensive ground-based measurement suite. The high-frequency aircraft data provided a comprehensive chemical snapshot of pyrogenic plumes from wildfires, corresponding to photochemical (and physical) ages ranging from 45 sr 10 days, largely by virtue of widespread fires over Northwestern Ontario. Airborne measurements reported a large number of emitted gases including semi-volatile species, some of which have not been been previously reported in pyrogenic plumes, with the corresponding emission ratios agreeing with previous work for common gases. Analysis of the NOy data shows evidence of net ozone production in pyrogenic plumes, controlled by aerosol abundance, which increases as a function of photochemical age. The coordinated ground-based and sonde data provided detailed but spatially limited information that put the aircraft data into context of the longer burning season in the boundary layer. Ground-based measurements of particulate matter smaller than 2.5 μm (PM2.5) over Halifax show that forest fires can on an episodic basis represent a substantial contribution to total surface PM2.5

Investigation of CO, C2H6 and aerosols in a boreal fire plume over eastern Canada during BORTAS 2011 using ground- and satellite-based observations, and model simulations

We present the results of total column measurements of CO, C2H6 and fine mode aerosol optical depth (AOD) during the "Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites" (BORTAS-B) campaign over Eastern Canada. Ground-based observations, using Fourier transform spectrometers (FTSs) and sun photometers, were carried out in July and August 2011. These measurements were taken in Halifax, Nova Scotia, which is an ideal location to monitor the outflow of boreal fires from North America, and also in Toronto, Ontario. Measurements of fine mode AOD enhancements were highly correlated with enhancements in coincident trace gas (CO and C2H6) observations between 19 and 21 July 2011, which is typical for a smoke plume event. In this paper, we focus on the identification of the origin and the transport of this smoke plume. We use back-trajectories calculated by the Canadian Meteorological Centre as well as FLEXPART forward-trajectories to demonstrate that the enhanced CO, C2H6 and fine mode AOD seen near Halifax and Toronto originated from forest fires in Northwestern Ontario that occurred between 17 and 19 July 2011. In addition, total column measurements of CO from the satellite-borne Infrared Atmospheric Sounding Interferometer (IASI) have been used to trace the smoke plume and to confirm the origin of the CO enhancement. Furthermore, the emission ratio (ERC2H6/CO) and the emission factor (EFC2H6) of C2H6 (with respect to the CO emission) were estimated from these ground-based observations. These C2H6 emission results from boreal fires in Northwestern Ontario agree well with C2H6 emission measurements from other boreal regions, and are relatively high compared to fires from other geographical regions. The ground-based CO and C2H6 observations were compared with outputs from the 3-D global chemical transport model GEOS-Chem, using the Fire Locating And Monitoring of Burning Emissions (FLAMBE) inventory. Agreement within the stated measurement uncertainty was found for the magnitude of the enhancement of the total columns of CO (~3%) and C2H6 (~8%) between the measured and modelled results. However, there is a small shift in time (of approximately 6 h) of arrival of the plume over Halifax between the results

Retrieval and Validation of Carbon Dioxide, Methane, and Water Vapor for the Canary Islands IR-Laser Occultation Experiment

The first ground-based experiment to prove the concept of a novel space-based observation technique for microwave and infrared-laser occultation between low-Earthorbit satellites was performed in the Canary Islands between La Palma and Tenerife. For two nights from 21 to 22 July 2011 the experiment delivered the infrared-laser differential transmission principle for the measurement of greenhouse gases (GHGs) in the free atmosphere. Such global and long-term stable measurements of GHGs, accompanied also by measurements of thermodynamic parameters and line-of-sight wind in a self-calibrating way, have become very important for climate change monitoring. The experiment delivered promising initial data for demonstrating the new observation concept by retrieving volume mixing ratios of GHGs along a ~ 144 km signal path at altitudes of ~ 2.4 km. Here, we present a detailed analysis of the measurements, following a recent publication that introduced the experiment\u27s technical setup and first results for an example retrieval of CO2. We present the observational and validation data sets, the latter simultaneously measured at the transmitter and receiver sites; the measurement data handling; and the differential transmission retrieval procedure. We also determine the individual and combined uncertainties influencing the results and present the retrieval results for 12CO2, 13CO2, C18OO, H2O and CH4. The new method is found to have a reliable basis for monitoring of greenhouse gases such as CO2, CH4, and H2O in the free atmosphere

FOURIER TRANSFORM EMISSION SPECTROSCOPY OF THE B′2Σ+−X2Σ+B^{\prime} {^{2}}\Sigma^{+} - X {^{2}}\Sigma^{+} TRANSITIONS OF MgH AND MgD

Author Institution: Department of Chemistry, University of WaterlooEmission spectra of MgH and MgD have been investigated in the $8000 - 22000 cm^{-1}$ region using a high resolution Fourier transform spectrometer. These molecules were generated in a furnace-discharge source, at about 900 K and 333 mA discharge current with magnesium and a mixture of Ar and $H_{2}$ or $D_{2}$ gases. The recorded spectra contain not only the well-known $A {^{2}}\pi - X {^{2}}\Sigma^{+}$ transitions, but also the $B^{\prime} {^{2}}\Sigma^{+} - X {^{2}}\Sigma^{+}$ transitions of MgH and MgD. We obtained data for $v^{\prime \prime} = 2$ to 9 for the ground state of MgH and $v^{\prime \prime} = 3$ to 13 for MgD. Analyses of the data is in progress, and will lead to improved potential energy curves for the $X {^{2}}\Sigma^{+}$ states of MgH and MgD. These results will be presented at the time of symposium

ROTATIONAL PREDISSOCIATION IN THE GROUND X2Σ+X^{2}\Sigma^{+} STATE OF ZnH

Author Institution: University of Waterloo; Department of Chemistry, University of WaterlooIt is known that ZnH has a relatively shallow potential curve in its ground state ($D_{e} \sim 7$, $660 cm^{-1}$), however, accurate spectral information on the higher vibrational levels in the $X^{2}\Sigma^{+}$ state is not available. In this study, we recorded Fourier transform spectra in 400-500 nm region using a DC discharge inside a tube furnace. A deep blue emission was observed over the granulated zinc heated to 770 K in a slow flow of Ar ($\sim 5$ Torr) with a trace of $H_{2}$. So far we identified $A_{2}\Pi - X^{2}\Sigma^{+}$ transitions up to $v^{\prime} = 2$ and $v^{\prime\prime} = 4$, as well as the $B^{2}\Sigma^{+} - X^{2}\Sigma^{+} 0-4$ band. In this $B - X$ band, lines are found to be diffuse around $N^{\prime\prime} = 21$ and completely dissapear for higher-$N^{\prime\prime}$. Based on the potential curve in the ground state, we found that this happens because of rotational predissociation. We also discuss a deperturbation of the $A^{2}\Pi$ and $B^{2}\Sigma^{+}$ states

THE E2Π−X2Σ+E {^{2}}\Pi - X^{2} \Sigma^{+} STATE OF CaH / D

Author Institution: Department of Chemistry, University of WaterlooOur group has recently investigated the $E^{2}\Pi-X^{2} \Sigma^{+}$ band system of CaH/D, while searching for the elusive double minima electronic states of the $D^{2} \Sigma^{+}-X^{2} \Sigma^{+}$ system. Emission spectra of CaH and CaD, in the visible region, have been obtained by means of a new discharge-furnace source. Calcium metal was placed into an evacuated, alumina tube and heated to a temperature of $600 ^{\circ}$C in a tube furnace. A mixture of argon and hydrogen gas was allowed to flow through the tube and was then excited by a DC electrical discharge. The spectra were recorded using a photomultiplier tube with our Bruker IFS 120 HR spectrometer. We will report improved values for the vibrational and rotational constants of CaH/D

Vibration-rotation emission spectrum of free BeH2

The gaseous BeH2 molecule has been synthesized by means of an electrical discharge inside a high-temperature furnace and identified with infrared emission spectroscopy. The antisymmetric stretching mode 3 has been detected near 2179 reciprocal centimeters. The BeH2 molecule has a linear, symmetric structure with an r0 BeH bond length of 1.333761(2) angstroms