scholarly journals Technical note: Water vapour concentration and flux measurements with PTR-MS

2006 ◽  
Vol 6 (12) ◽  
pp. 4643-4651 ◽  
Author(s):  
C. Ammann ◽  
A. Brunner ◽  
C. Spirig ◽  
A. Neftel
Keyword(s):  
Water Vapour ◽  
Eddy Covariance ◽  
High Frequency ◽  
Reference System ◽  
Transfer Functions ◽  
Water Vapour Flux ◽  
Water Vapour Concentration ◽  
Vapour Concentration ◽  
Frequency Correction ◽  
Vapour Flux

Abstract. The most direct approach for measuring the exchange of biogenic volatile organic compounds between terrestrial ecosystems and the atmosphere is the eddy covariance technique. It has been applied several times in the last few years using fast response proton-transfer-reaction mass spectrometry (PTR-MS). We present an independent validation of this technique by applying it to measure the water vapour flux in comparison to a common reference system comprising an infra-red gas analyser (IRGA). Water vapour was detected in the PTR-MS at mass 37 (atomic mass units) corresponding to the cluster ion H3O+·H2O. During a five-week field campaign at a grassland site, we obtained a non-linear but stable calibration function between the mass 37 signal and the reference water vapour concentration. With a correction of the high-frequency damping loss based on empirical ogive analysis, the eddy covariance water vapour flux obtained with the PTR-MS showed a very good agreement with the flux of the reference system. The application of the empirical ogive method for high-frequency correction led to significantly better results than using a correction based on theoretical spectral transfer functions. This finding is attributed to adsorption effects on the tube walls that are presently not included in the theoretical correction approach. The proposed high-frequency correction method can also be used for other trace gases with different adsorption characteristics.

scholarly journals Technical note: Water vapour concentration and flux measurements with PTR-MS

2006 ◽  
Vol 6 (3) ◽  
pp. 5329-5355 ◽  
Author(s):  
C. Ammann ◽  
A. Brunner ◽  
C. Spirig ◽  
A. Neftel
Keyword(s):  
Water Vapour ◽  
Eddy Covariance ◽  
High Frequency ◽  
Reference System ◽  
Transfer Functions ◽  
Terrestrial Ecosystems ◽  
Water Vapour Flux ◽  
Water Vapour Concentration ◽  
Vapour Concentration ◽  
Vapour Flux

Abstract. The most direct approach for measuring the exchange of biogenic volatile organic compounds between terrestrial ecosystems and the atmosphere is the eddy covariance technique. It has been applied several times in the last few years using fast response proton-transfer-reaction mass spectrometry (PTR-MS). We present an independent validation of this technique by applying it to measure the water vapour flux in comparison to a common reference system comprising an infra-red gas analyser (IRGA). Water vapour was detected in the PTR-MS at mass 37 (atomic mass units) corresponding to the cluster ion H3O+·H2O. During a five-week field campaign at a grassland site, we obtained a non-linear but stable calibration function between the mass 37 signal and the reference water vapour concentration. With a correction of the high-frequency damping loss based on empirical ogive analysis, the eddy covariance water vapour flux obtained with the PTR-MS showed a very good agreement with the flux of the reference system. The application of the empirical ogive method for high-frequency correction led to significantly better results than using a correction based on theoretical spectral transfer functions. This finding is attributed to adsorption effects on the tube walls that are presently not included in the theoretical correction approach.

scholarly journals Effect of moisture condensation on vapour transmission through porous membranes

2021 ◽  
pp. 152808372110142
Author(s):  
Ariana Khakpour ◽  
Michael Gibbons ◽  
Sanjeev Chandra
Keyword(s):  
Water Vapour ◽  
Moisture Diffusion ◽  
Porous Membrane ◽  
Water Evaporation ◽  
Porous Membranes ◽  
Water Vapour Concentration ◽  
Vapour Concentration ◽  
Vapour Diffusion ◽  
Pore Blockage ◽  
The Impact

Porous membranes find natural application in various fields and industries. Water condensation on membranes can block pores, reduce vapour transmissibility, and diminish the porous membranes' performance. This research investigates the rate of water vapour transmission through microporous nylon and nanofibrous Gore-Tex membranes. Testing consisted of placing the membrane at the intersection of two chambers with varied initial humidity conditions. One compartment is initially set to a high ([Formula: see text]water vapour concentration and the other low ([Formula: see text], with changes in humidity recorded as a function of time. The impact of pore blockage was explored by pre-wetting the membranes with water or interposing glycerine onto the membrane pores before testing. Pore blockage was measured using image analysis for the nylon membrane. The mass flow rate of water vapour ( ṁv) diffusing through a porous membrane is proportional to both its area (A) and the difference in vapour concentration across its two faces ([Formula: see text], such that [Formula: see text] where K is defined as the moisture diffusion coefficient. Correlations are presented for the variation of K as a function of [Formula: see text]. Liquid contamination on the porous membrane has been shown to reduce the moisture diffusion rate through the membrane due to pore blockage and the subsequent reduced open area available for vapour diffusion. Water evaporation from the membrane's surface was observed to add to the mass of vapour diffusing through the membrane. A model was developed to predict the effect of membrane wetting on vapour diffusion and showed good agreement with experimental data.

Laboratory evaluation of water vapour concentration dependence of commercial water vapour isotope cavity ring-down spectrometers for continuous onsite atmospheric measurements in the Amazon rainforest

2021 ◽  
Author(s):  
Shujiro Komiya ◽  
Fumiyoshi Kondo ◽  
Heiko Moossen ◽  
Thomas Seifert ◽  
Uwe Schultz ◽  
...  
Keyword(s):  
Water Vapour ◽  
Concentration Dependence ◽  
Field Measurements ◽  
Amazon Rainforest ◽  
Laboratory Evaluation ◽  
Atmospheric Measurements ◽  
Water Vapour Concentration ◽  
Vapour Concentration ◽  
Hydrological Cycles ◽  
Cavity Ring Down

<p>Commercially available laser-based spectrometers permit continuous field measurements of water vapour (H<sub>2</sub>O) stable isotope compositions, yet continuous observations in the Amazon, a region that significantly influences atmospheric hydrological cycles on regional to global scales, are largely missing. In order to achieve accurate on-site observations in such conditions, these instruments will require regular on-site calibration, including for H<sub>2</sub>O concentration dependence ([H<sub>2</sub>O]-dependence) of isotopic accuracy.</p><p>With the aim of conducting accurate continuous δ<sup>18</sup>O and δ<sup>2</sup>H on-site observation in the Amazon rainforest, we conducted a laboratory experiment to investigate the performance and determine the optimal [H<sub>2</sub>O]-dependence calibration strategy for two commercial cavity-ring down (CRDS) analysers (L1102i and L2130i models, Picarro, Inc., USA), coupled to our custom-built automated calibration unit. We particularly focused on the rarely investigated performance of the instruments at atmospheric H<sub>2</sub>O contents above 35,000 ppm, a value regularly reached at our site.</p><p>The later analyser model (L2130i) had better precision and accuracy of δ<sup>18</sup>O and δ<sup>2</sup>H measurements with a less pronounced [H<sub>2</sub>O]-dependence compared to the older L1102i. The [H<sub>2</sub>O]-dependence calibration uncertainties did not significantly change with calibration intervals from 28 h up to 196 h, suggesting that one [H<sub>2</sub>O]-dependence calibration per week for the L2130i and L1102i analysers is enough. This study shows that with both CRDS analysers, correctly calibrated, we should be able to discriminate natural diel, seasonal and interannual signals of stable water vapour isotopes in a tropical rainforest environment.</p><p> </p>

scholarly journals Influence of water vapour on the height distribution of positive ions, effective recombination coefficient and ionisation balance in the quiet lower ionosphere

2014 ◽  
Vol 32 (3) ◽  
pp. 207-222 ◽  
Author(s):  
V. Barabash ◽  
A. Osepian ◽  
P. Dalin
Keyword(s):  
Water Vapour ◽  
Electron Density ◽  
Electron Number Density ◽  
Lower Ionosphere ◽  
Recombination Coefficient ◽  
Height Distribution ◽  
Number Density ◽  
Electron Number ◽  
Water Vapour Concentration ◽  
Vapour Concentration

Abstract. Mesospheric water vapour concentration effects on the ion composition and electron density in the lower ionosphere under quiet geophysical conditions were examined. Water vapour is an important compound in the mesosphere and the lower thermosphere that affects ion composition due to hydrogen radical production and consequently modifies the electron number density. Recent lower-ionosphere investigations have primarily concentrated on the geomagnetic disturbance periods. Meanwhile, studies on the electron density under quiet conditions are quite rare. The goal of this study is to contribute to a better understanding of the ionospheric parameter responses to water vapour variability in the quiet lower ionosphere. By applying a numerical D region ion chemistry model, we evaluated efficiencies for the channels forming hydrated cluster ions from the NO+ and O2+ primary ions (i.e. NO+.H2O and O2+.H2O, respectively), and the channel forming H+(H2O)n proton hydrates from water clusters at different altitudes using profiles with low and high water vapour concentrations. Profiles for positive ions, effective recombination coefficients and electrons were modelled for three particular cases using electron density measurements obtained during rocket campaigns. It was found that the water vapour concentration variations in the mesosphere affect the position of both the Cl2+ proton hydrate layer upper border, comprising the NO+(H2O)n and O2+(H2O)n hydrated cluster ions, and the Cl1+ hydrate cluster layer lower border, comprising the H+(H2O)n pure proton hydrates, as well as the numerical cluster densities. The water variations caused large changes in the effective recombination coefficient and electron density between altitudes of 75 and 87 km. However, the effective recombination coefficient, αeff, and electron number density did not respond even to large water vapour concentration variations occurring at other altitudes in the mesosphere. We determined the water vapour concentration upper limit at altitudes between 75 and 87 km, beyond which the water vapour concentration ceases to influence the numerical densities of Cl2+ and Cl1+, the effective recombination coefficient and the electron number density in the summer ionosphere. This water vapour concentration limit corresponds to values found in the H2O-1 profile that was observed in the summer mesosphere by the Upper Atmosphere Research Satellite (UARS). The electron density modelled using the H2O-1 profile agreed well with the electron density measured in the summer ionosphere when the measured profiles did not have sharp gradients. For sharp gradients in electron and positive ion number densities, a water profile that can reproduce the characteristic behaviour of the ionospheric parameters should have an inhomogeneous height distribution of water vapour.

scholarly journals Robust, spatially scanning, open-path TDLAS hygrometer using retro-reflective foils for fast tomographic 2-D water vapour concentration field measurements

2014 ◽  
Vol 7 (12) ◽  
pp. 12827-12849 ◽  
Author(s):  
A. Seidel ◽  
S. Wagner ◽  
A. Dreizler ◽  
V. Ebert
Keyword(s):  
Water Vapour ◽  
Single Channel ◽  
Greenhouse Gas Emission ◽  
Concentration Field ◽  
Field Measurements ◽  
Tunable Diode Laser ◽  
Environmental Research ◽  
Soil Physics ◽  
Water Vapour Concentration ◽  
Vapour Concentration

Abstract. We have developed a fast, spatially direct scanning tunable diode laser absorption spectrometer (dTDLAS) that combines four polygon-mirror based scanning units with low-cost retro-reflective foils. With this instrument, tomographic measurements of absolute 2-D water vapour concentration profiles are possible without any calibration using a reference gas. A spatial area of 0.8 m × 0.8 m was covered, which allows for application in soil physics, where greenhouse gas emission from certain soil structures shall be monitored. The whole concentration field was measured with up to 2.5 Hz. In this paper, we present the setup and spectroscopic performance of the instrument regarding the influence of the polygon rotation speed and mode on the absorption signal. Homogeneous H2O distributions were measured and compared to a single channel, bi-static reference TDLAS spectrometer for validation of the instrument. Good accuracy and precision with errors of less than 6% of the absolute concentration and length and bandwidth normalized detection limits of up to 1.1 ppmv · m · √Hz−1 were achieved. The spectrometer is a robust and easy to set up instrument for tomographic reconstructions of 2-D-concentration fields that can be considered a good basis for future field measurements in environmental research.

Spatiotemporal variability of Hokkaido's seasonal precipitation in recent decades and connection to water vapour flux

2016 ◽  
Vol 37 (9) ◽  
pp. 3660-3673 ◽  
Author(s):  
Weili Duan ◽  
Bin He ◽  
Netrananda Sahu ◽  
Pingping Luo ◽  
Daniel Nover ◽  
...  
Keyword(s):  
Water Vapour ◽  
Spatiotemporal Variability ◽  
Seasonal Precipitation ◽  
Water Vapour Flux ◽  
Vapour Flux

Characterization of the time evolution of the PBL structure and dry-layers based on the us of Raman Lidar measurements collected during HYMEX-SOP1

2021 ◽  
Author(s):  
Donato Summa ◽  
Paolo Di Girolamo ◽  
Noemi Franco ◽  
Benedetto De Rosa ◽  
Fabio Madonna ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Boundary Layer ◽  
Water Vapour ◽  
Planetary Boundary Layer ◽  
Grid Point ◽  
Laser Source ◽  
Raman Lidar ◽  
Water Vapour Concentration ◽  
Vapour Concentration

<p>The exchange processes between the Earth and the atmosphere play a crucial role in the development of the Planetary Boundary Layer (PBL). Different remote sensing techniques can provide PBL measurement with different spatial and temporal resolutions. Vertical profiles of atmospheric thermodynamic variables, i.e.  temperature and humidity, or wind speed, clouds and aerosols can be used as proxy to retrieve PBL height from active and passive remote sensing instruments. The University of BASILicata ground-based Raman Lidar system (BASIL) was deployed in the North-Western Mediterranean basin in the Cévennes-Vivarais site (Candillargues, Southern France, Lat: 43°37' N, Long: 4° 4' E, Elev: 1 m) and operated between 5 September and 5 November 2012, collecting more than 600 hours of measurements, distributed over 51 days and 19 intensive observation periods (IOPs). BASIL is capable to provide high-resolution and accurate measurements of atmospheric temperature and water vapour, both in daytime and night-time, based on the application of the rotational and vibrational Raman lidar techniques in the UV. This measurement capability makes BASIL a key instrument for the characterization of the water vapour concentration. BASIL makes use of a Nd:YAG laser source capable of emitting pulses at 355, 532 and 1064 nm, with a single pulse energy at 355nm of 500 mJ [1] .In the presented research effort, water vapour concentration was  computed and used to determine the PBL height. [2]. A dynamic index  included in the European Centre for Medium-range Weather Forecasts (ECMWF) ERA5 atmospheric reanalysis (CAPE, Friction velocity, etc.) is also considered and compared with BASIL resutls. ERA5 provides hourly data on regular latitude-longitude grids at 0.25° x 0.25° resolution at 37 pressure levels [3]. ERA5 is publicly available through the Copernicus Climate Data Store (CDS, https://cds.climate.copernicus.eu).  In order to properly carry out the comparison, the nearest ERA5 grid point to the lidar site has been considered assuming the representativeness uncertainty due to the use of the nearest grid-point comparable with other methods (e.g. kriging, bilinear interpolation, etc.). More results from this  measurement  effort will  be reported and discussed at the Conference.</p><p><strong>Reference</strong></p><p>[1] Di Girolamo, Paolo, De Rosa, Benedetto, Flamant, Cyrille, Summa, Donato, Bousquet, Olivier, Chazette, Patrick, Totems, Julien, Cacciani, Marco. Water vapor mixing ratio and temperature inter-comparison results in the framework of the Hydrological Cycle in the Mediterranean Experiment—Special Observation Period 1. BULLETIN OF ATMOSPHERIC SCIENCE AND TECHNOLOGY, ISSN: 2662-1495, doi: 10.1007/s42865-020-00008-3</p><p>[2] D. Summa, P. Di Girolamo, D. Stelitano, and M. Cacciani. Characterization of the planetary boundary layer height and structure by Raman lidar: comparison of different approaches  Atmos. Meas. Tech., 6, 3515–3525, 2013 www.atmos-meas-tech.net/6/3515/2013/doi:10.5194/amt-6-3515-2013</p><p>[3] Hersbach et al. The ERA5 global reanalysis Hans  https://doi.org/10.1002/qj.3803[3]</p>

scholarly journals Linking the uncertainty in simulated arctic ozone losses to modelling of tropical stratospheric water vapour

2018 ◽  
Author(s):  
Laura Thölix ◽  
Alexey Karpechko ◽  
Leif Backman ◽  
Rigel Kivi
Keyword(s):  
Water Vapour ◽  
Climate Models ◽  
Polar Vortex ◽  
The Arctic ◽  
Ozone Loss ◽  
Tropical Tropopause ◽  
Water Vapour Concentration ◽  
Vapour Concentration ◽  
The Impact ◽  
Stratospheric Water Vapour

Abstract. Stratospheric water vapor plays a key role in radiative and chemical processes, it e.g. influences the chemical ozone loss via controlling the polar stratospheric cloud formation in the polar stratosphere. The amount of water entering the stratosphere through the tropical tropopause differs substantially between chemistry-climate models. This is because the present-day models have difficulties in capturing the whole complexity of processes that control the water transport across the tropopause. As a result there are large differences in the stratospheric water vapour between the models. In this study we investigate the sensitivity of simulated Arctic ozone loss to the amount of water, which enters the stratosphere through the tropical tropopause. We used a chemical transport model, FinROSE-CTM, forced by ERA-Interim meteorology. The water vapour concentration in the tropical tropopause was varied between 0.5 and 1.6 times the concentration in ERA-Interim, which is similar to the range seen in chemistry climate models. The water vapour changes in the tropical tropopause led to about 1.5 and 2 ppm more water vapour in the Arctic polar vortex compared to the ERA-Interim, respectively. We found that the impact of water vapour changes on ozone loss in the Arctic polar vortex depend on the meteorological conditions. Polar stratospheric clouds form in the cold conditions within the Arctic vortex, and chlorine activation on their surface lead to ozone loss. If the cold conditions persist long enough (e.g. in 2010/11), the chlorine activation is nearly complete. In this case addition of water vapour to the stratosphere increased the formation of ICE clouds, but did not increase the chlorine activation and ozone destruction significantly. In the warm winter 2012/13 the impact of water vapour concentration on ozone loss was small, because the ozone loss was mainly NOx induced. In intermediately cold conditions, e.g. 2013/14, the effect of added water vapour was more prominent than in the other studied winters. The results show that the simulated water vapour concentration in the tropical tropopause has a significant impact on the Arctic ozone loss and deserves attention in order to improve future projections of ozone layer recovery.

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