scholarly journals An assessment of the climatological representativeness of IAGOS-CARIBIC trace gas measurements using EMAC model simulations

2016 ◽  
Author(s):  
Johannes Eckstein ◽  
Roland Ruhnke ◽  
Andreas Zahn ◽  
Marco Neumaier ◽  
Ole Kirner ◽  
...  
Keyword(s):  
Climate Model ◽  
Trace Gases ◽  
Measurement Data ◽  
Trace Gas ◽  
Statistical Measures ◽  
Kolmogorov Smirnov ◽  
Gas Measurements ◽  
Passenger Aircraft ◽  
Relative Differences ◽  
Smirnov Test

Abstract. Measurement data from the long-term passenger aircraft project IAGOS-CARIBIC is often used to derive trace gas climatologies. We investigate to what extent such derived climatologies can be assumed to be representative for the true state of the atmosphere. Using the chemistry-climate model EMAC we sample the modelled trace gases along CARIBIC flight tracks. Different trace gases are considered and climatologies relative to the mid-latitude tropopause are calculated. Representativeness can now be assessed by comparing the CARIBIC sampled model data to the true climatological model state. Three statistical methods are applied for this purpose: the Kolomogorov-Smirnov test, and scores based on the variability and relative differences. Generally, representativeness is expected to decrease with increasing variability and to increase with the number of available samples. Based on this assumption, we investigate the suitability of the different statistical measures for our problem. The Kolmogorov-Smirnov test seems too strict and does not identify any climatology as representative – not even long lived well observed trace gases. In contrast, the variability based scores pass the general requirements for representativeness formulated above. In addition, even the simplest metric (relative differences) seems applicable for investigating representativeness. Using the relative differences score we investigate the representativeness of a large number of different trace gases. For our final consideration we assume that the EMAC model is a reasonable representation of the real world and that representativeness in the model world can be translated to representativeness for CARIBIC measurements. This assumption is justified by comparing the model variability to the variability of CARIBIC measurements. Finally, we show how the representativeness score can be translated into a number of flights necessary to achieve a certain degree of representativeness.

scholarly journals An assessment of the climatological representativeness of IAGOS-CARIBIC trace gas measurements using EMAC model simulations

2017 ◽  
Vol 17 (4) ◽  
pp. 2775-2794 ◽  
Author(s):  
Johannes Eckstein ◽  
Roland Ruhnke ◽  
Andreas Zahn ◽  
Marco Neumaier ◽  
Ole Kirner ◽  
...  
Keyword(s):  
Climate Model ◽  
Trace Gases ◽  
Measurement Data ◽  
Final Analysis ◽  
Trace Gas ◽  
Measurement Variability ◽  
Statistical Measures ◽  
Kolmogorov Smirnov ◽  
Relative Differences ◽  
Smirnov Test

Abstract. Measurement data from the long-term passenger aircraft project IAGOS-CARIBIC are often used to derive climatologies of trace gases in the upper troposphere and lower stratosphere (UTLS). We investigate to what extent such climatologies are representative of the true state of the atmosphere. Climatologies are considered relative to the tropopause in mid-latitudes (35 to 75° N) for trace gases with different atmospheric lifetimes. Using the chemistry–climate model EMAC, we sample the modeled trace gases along CARIBIC flight tracks. Representativeness is then assessed by comparing the CARIBIC sampled model data to the full climatological model state. Three statistical methods are applied for the investigation of representativeness: the Kolmogorov–Smirnov test and two scores based on the variability and relative differences. Two requirements for any score describing representativeness are essential: representativeness is expected to increase (i) with the number of samples and (ii) with decreasing variability of the species considered. Based on these two requirements, we investigate the suitability of the different statistical measures for investigating representativeness. The Kolmogorov–Smirnov test is very strict and does not identify any trace-gas climatology as representative – not even of long-lived trace gases. In contrast, the two scores based on either variability or relative differences show the expected behavior and thus appear applicable for investigating representativeness. For the final analysis of climatological representativeness, we use the relative difference score and calculate a representativeness uncertainty for each trace gas in percent. In order to justify the transfer of conclusions about representativeness of individual trace gases from the model to measurements, we compare the trace gas variability between model and measurements. We find that the model reaches 50–100 % of the measurement variability. The tendency of the model to underestimate the variability is caused by the relatively coarse spatial and temporal model resolution. In conclusion, we provide representativeness uncertainties for several species for tropopause-referenced climatologies. Long-lived species like CO2 have low uncertainties ( ≤ 0.4 %), while shorter-lived species like O3 have larger uncertainties (10–15 %). Finally, we translate the representativeness score into a number of flights that are necessary to achieve a certain degree of representativeness. For example, increasing the number of flights from 334 to 1000 would reduce the uncertainty in CO to a mere 1 %, while the uncertainty for shorter-lived species like NO would drop from 80 to 10 %.

Cross-isentropic mixing: A DEEPWAVE case study

2020 ◽  
Author(s):  
Hans-Christoph Lachnitt ◽  
Peter Hoor ◽  
Daniel Kunkel ◽  
Stafan Hofmann ◽  
Martina Bramberger ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Trace Gases ◽  
Measurement Data ◽  
Wave Activity ◽  
Southern Alps ◽  
Trace Gas ◽  
Leeward Side ◽  
Mixing Processes ◽  
Stability Parameters

<p>The tropopause acts as a transport barrier between the upper troposphere and the lower stratosphere. Non-conservative (i.e. PV changing) processes are required to overcome this barrier. Orographically generated gravity waves (i.e. mountain waves) can potentially lead to cross-isentropic fluxes of trace gases via the generation of turbulence. Thus they may alter the isentropic gradient of these trace species across the tropopause.<br>The specific goal of this study is to identify cross-isentropic mixing processes at the tropopause based on the distribution of trace gases (i.e. tracer-tracer correlations). Based on airborne in-situ trace gas measurements of CO and N<sub>2</sub>O during the DEEPWAVE (Deep Propagating Gravity Wave Experiment) campaign in July 2014 we identified mixing regions above the Southern Alps during periods of gravity wave activity. These in-situ data show that the composition of the air above the Southern Alps change from the upstream to the leeward side of the mountains indicating cross isentropic mixing of trace gases in the region of gravity wave activity.<br>We complement our analysis of the measurement data with high resolution operational analysis data from the ECMWF (European Centre for Medium-Range Weather Forecasts). Furthermore, using potential vorticity and stability parameters.<br>Using 3D wind fields, data form Graphical Turbulence Guidance (GTG) system and in-situ measurements of the vertical wind we identify occurrence of turbulence in the region of mixing events. Using wavelet analysis, we could identify the spatial and temporal scales of local trace gas fluxes. We also give estimates of cross-isentropic flux, i.e. we want to quantify the mixing in terms of exchange.</p>

scholarly journals Statistical analysis of water vapour and ozone in the UT/LS observed during SPURT and MOZAIC

2008 ◽  
Vol 8 (22) ◽  
pp. 6603-6615 ◽  
Author(s):  
A. Kunz ◽  
C. Schiller ◽  
F. Rohrer ◽  
H. G. J. Smit ◽  
P. Nedelec ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Water Vapour ◽  
Trace Gases ◽  
Distribution Functions ◽  
Variance Analysis ◽  
Trace Gas ◽  
Data Sets ◽  
Data Set ◽  
Atmospheric Processes ◽  
Passenger Aircraft

Abstract. A statistical analysis for the comparability of water (H2O) and ozone (O3) data sets sampled during the SPURT aircraft campaigns and the MOZAIC passenger aircraft flights is presented. The Kolmogoroff-Smirnoff test reveals that the distribution functions from SPURT and MOZAIC trace gases differ from each other with a confidence of 95%. A variance analysis shows a different variability character in both trace gas data sets. While the SPURT H2O data only contain atmospheric processes variable on a diurnal or synoptical timescale, MOZAIC H2O data also reveal processes, which vary on inter-seasonal and seasonal timescales. The SPURT H2O data set does not represent the full MOZAIC H2O variance in the UT/LS for climatological investigations, whereas the variance of O3 is much better represented. SPURT H2O data are better suited in the stratosphere, where the MOZAIC RH sensor looses its sensitivity.

scholarly journals The airborne mass spectrometer AIMS – Part 2: Measurements of trace gases with stratospheric or tropospheric origin in the UTLS

2015 ◽  
Vol 8 (12) ◽  
pp. 13567-13607 ◽  
Author(s):  
T. Jurkat ◽  
S. Kaufmann ◽  
C. Voigt ◽  
D. Schäuble ◽  
P. Jeßberger ◽  
...  
Keyword(s):  
Nitrogen Oxide ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Trace Gases ◽  
Measurement Techniques ◽  
Ion Source ◽  
Trace Gas ◽  
Ionization Mass ◽  
Custom Made ◽  
Gas Measurements

Abstract. Understanding the role of climate-sensitive trace gas variabilities in the upper troposphere and lower stratosphere region (UTLS) and their impact on its radiative budget requires accurate measurements. The composition of the UTLS is governed by transport and chemistry of stratospheric and tropospheric constituents, such as chlorine, nitrogen oxide and sulphur components. The Airborne chemical Ionization Mass Spectrometer AIMS has been developed to accurately measure a set of these constituents on aircraft by means of chemical ionization. Here we present a setup using chemical ionization with SF5− reagent ions for the simultaneous measurement of trace gas concentrations in the pptv to ppmv (10−12 to 10−6 mol mol−1) range of HCl, HNO3 and SO2 with in-flight and online calibration called AIMS-TG. Part 1 of this paper (Kaufmann et al., 2015) reports on the UTLS water vapour measurements with the AIMS-H2O configuration. The instrument can be flexibly switched between two configurations depending on the scientific objective of the mission. For AIMS-TG, a custom-made gas discharge ion source has been developed generating a characteristic ionization scheme. HNO3 and HCl are routinely calibrated in-flight using permeation devices, SO2 is permanently calibrated during flight adding an isotopically labelled 34SO2 standard. In addition, we report on trace gas measurements of HONO which is sensitive to the reaction with SF5−. The detection limit for the various trace gases is in the low ten pptv range at a 1 s time resolution with an overall uncertainty of the measurement in the order of 20 %. AIMS has been integrated and successfully operated on the DLR research aircraft Falcon and HALO. Exemplarily, measurements conducted during the TACTS/ESMVal mission with HALO in 2012 are presented, focusing on a classification of tropospheric and stratospheric influences in the UTLS region. Comparison of AIMS measurements with other measurement techniques allow to draw a comprehensive picture of the sulphur, chlorine and reactive nitrogen oxide budget in the UTLS. The combination of the trace gases measured with AIMS exhibit the potential to gain a better understanding of the trace gas origin and variability at and near the tropopause.

scholarly journals Technical Note: Anthropogenic and natural offline emissions and the online EMissions and dry DEPosition submodel EMDEP of the Modular Earth Submodel system (MESSy)

2006 ◽  
Vol 6 (3) ◽  
pp. 5457-5483 ◽  
Author(s):  
L. N. Ganzeveld ◽  
J. A. van Aardenne ◽  
T. M. Butler ◽  
M. G. Lawrence ◽  
S. M. Metzger ◽  
...  
Keyword(s):  
Dry Deposition ◽  
Climate Model ◽  
Trace Gases ◽  
High Sensitivity ◽  
Technical Note ◽  
Trace Gas ◽  
Model Parameters ◽  
Spatial And Temporal Variability ◽  
Surface Exchange ◽  
Emission Height

Abstract. We present the online calculated Earth's surface trace gas and aerosol emissions and dry deposition in the Modular Earth Submodel System (MESSy) submodel EMDEP as well as the currently applied anthropogenic and natural emissions inventories. These inventories, being read-in by the MESSy submodel OFFLEM, include the industrial, fossil fuel, agricultural and biomass burning emissions considering emission height profiles as a function of the source category based on the EDGAR v3.2 fast track 2000 inventory. Terrestrial and marine emissions of a selection of trace gases and aerosols are calculated online in EMDEP using climate model parameters such as wind speed, temperature and land cover and land use parameters. The online dry deposition calculation includes gases and aerosols, where the default selection for the trace gases for the dry deposition scheme can be easily extended using a commonly applied method based on trace gas solubility and reactivity. In general, the simulated global annual emissions agree with previously reported inventories, although differences exist, partly dependent on the applied model resolution. A high sensitivity of the simulated dry deposition to the applied emission height profiles stresses the importance of a realistic and consistent representation of the spatial and temporal variability in surface exchange processes in Earth system models.

scholarly journals Assessing the ability to derive rates of polar middle-atmospheric descent using trace gas measurements from remote sensors

2017 ◽  
Author(s):  
Niall J. Ryan ◽  
Douglas E. Kinnison ◽  
Rolando R. Garcia ◽  
Uwe Raffalski ◽  
Mathias Palm ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Climate Model ◽  
Microwave Radiometer ◽  
Trace Gas ◽  
Night Time ◽  
Concentration Data ◽  
Time Layer ◽  
Vertical Advection ◽  
The Mean ◽  
Gas Measurements

Abstract. We investigate the reliability of using trace gas measurements from remote sensing instruments to infer polar atmospheric descent rates during winter. Using output from the Specified Dynamics Whole Atmosphere Community Climate Model (SD-WACCM) between 2008 and 2014, tendencies of carbon monoxide (CO) concentrations are used to assess a common assumption of dominant vertical advection of tracers during polar winter. The results show that dynamical processes other than vertical advection are not negligible, meaning that the transport rates derived from trace gas measurements do not represent the mean descent of the atmosphere. The relative importance of vertical advection is lessened during periods directly before and after a sudden stratospheric warming. It was also found that CO chemistry cannot be ignored in the mesosphere due to the night-time layer of OH at approximately 80 km altitude. CO concentration data from the Kiruna Microwave Radiometer and the Microwave Limb Sounder are used in combination with the modelled CO tendencies to estimate errors involved in calculating the mean descent of the atmosphere from remote sensing measurements. The results indicate errors on the same scale as the calculated descent rates, and often a misinterpretation of the direction of air motion. We suggest an alternative definition of the rate calculated using remote sensing measurements: not as the mean descent of the atmosphere, but as an effective rate of vertical transport for the trace gas under observation.

scholarly journals Versatile soil gas concentration and isotope monitoring: optimization and integration of novel soil gas probes with online trace gas detection

2022 ◽  
Vol 19 (1) ◽  
pp. 165-185
Author(s):  
Juliana Gil-Loaiza ◽  
Joseph R. Roscioli ◽  
Joanne H. Shorter ◽  
Till H. M. Volkmann ◽  
Wei-Ren Ng ◽  
...  
Keyword(s):  
Real Time ◽  
Trace Gases ◽  
Soil Gas ◽  
Redox Conditions ◽  
Trace Gas ◽  
Soil System ◽  
Isotopic Signatures ◽  
Gas Measurements ◽  
The Impact

Abstract. Gas concentrations and isotopic signatures can unveil microbial metabolisms and their responses to environmental changes in soil. Currently, few methods measure in situ soil trace gases such as the products of nitrogen and carbon cycling or volatile organic compounds (VOCs) that constrain microbial biochemical processes like nitrification, methanogenesis, respiration, and microbial communication. Versatile trace gas sampling systems that integrate soil probes with sensitive trace gas analyzers could fill this gap with in situ soil gas measurements that resolve spatial (centimeters) and temporal (minutes) patterns. We developed a system that integrates new porous and hydrophobic sintered polytetrafluoroethylene (sPTFE) diffusive soil gas probes that non-disruptively collect soil gas samples with a transfer system to direct gas from multiple probes to one or more central gas analyzer(s) such as laser and mass spectrometers. Here, we demonstrate the feasibility and versatility of this automated multiprobe system for soil gas measurements of isotopic ratios of nitrous oxide (δ18O, δ15N, and the 15N site preference of N2O), methane, carbon dioxide (δ13C), and VOCs. First, we used an inert silica matrix to challenge probe measurements under controlled gas conditions. By changing and controlling system flow parameters, including the probe flow rate, we optimized recovery of representative soil gas samples while reducing sampling artifacts on subsurface concentrations. Second, we used this system to provide a real-time window into the impact of environmental manipulation of irrigation and soil redox conditions on in situ N2O and VOC concentrations. Moreover, to reveal the dynamics in the stable isotope ratios of N2O (i.e., 14N14N16O, 14N15N16O, 15N14N16O, and 14N14N18O), we developed a new high-precision laser spectrometer with a reduced sample volume demand. Our integrated system – a tunable infrared laser direct absorption spectrometry (TILDAS) in parallel with Vocus proton transfer reaction mass spectrometry (PTR-MS), in line with sPTFE soil gas probes – successfully quantified isotopic signatures for N2O, CO2, and VOCs in real time as responses to changes in the dry–wetting cycle and redox conditions. Broadening the collection of trace gases that can be monitored in the subsurface is critical for monitoring biogeochemical cycles, ecosystem health, and management practices at scales relevant to the soil system.

scholarly journals A Coupled Experimental and Statistical Approach for an Assessment of the Airborne Infection Risk in Event Locations

2022 ◽  
Author(s):  
Lukas Siebler ◽  
Torben Rathje ◽  
Maurizio Calandri ◽  
Konstantinos Stergiaropoulos ◽  
Bernhard Richter ◽  
...  
Keyword(s):  
Measurement Data ◽  
Epidemiological Data ◽  
Trace Gas ◽  
Vaccination Rates ◽  
Airborne Infection ◽  
Reproduction Numbers ◽  
Gas Measurements ◽  
Infection Processes ◽  
Flexible Application ◽  
First Time

Operators of event locations are particularly affected by a pandemic. Resulting restrictions may cause uneconomical business. With previous models, only an incomplete quantitative risk assessments is possible, whereby no suitable restrictions can be derived. Hence, a mathematical and statistical model has been developed in order to link measurement data of substance dispersion in rooms with epidemiological data like incidences, reproduction numbers, vaccination rates and test qualities. This allows a first time overall assessment of airborne infection risks in large event locations. In these venues displacement ventilation concepts are often implemented. In this case simplified theoretical assumptions fail for the prediction of relevant airflows for infection processes. Thus, with locally resolving trace gas measurements and specific data of infection processes, individual risks can be computed more detailed. Via inclusion of many measurement positions, an assessment of entire event locations is possible. Embedding the overall model in a flexible application, daily updated epidemiological data allow latest calculations of expected new infections and individual risks of single visitors for a certain event. With this model, an instrument has been created that can help policymakers and operators to take appropriate measures and to check restrictions for their effect.

scholarly journals Comparison of Accuracy of Current Ten Intraoral Scanners

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Pokpong Amornvit ◽  
Dinesh Rokaya ◽  
Sasiwimol Sanohkan
Keyword(s):  
High Resolution ◽  
Measurement Data ◽  
Reference Points ◽  
San Jose ◽  
Control Precision ◽  
Dental Model ◽  
Kolmogorov Smirnov ◽  
Scan Pattern ◽  
Stereolithography Files ◽  
Smirnov Test

There have been various developments in intraoral 3D scanning technology. This study is aimed at investigating the accuracy of 10 scanners developed from 2015 to 2020. A maxillary dental model with reference points was printed from Form 2 (FormLabs, Somerville, MA, USA). The model was scanned 5 times with each intraoral scanner (IOS); Trios 3 (normal and high-resolution mode); Trios 4 (normal and high-resolution mode) (3Shape Trios A/S, Copenhagen, Denmark); iTero Element, iTero 2, and iTero 5D Element (Align Technologies, San Jose, California, USA); Dental Wings (Dental Wings, Montreal QC, Canada); Panda 2 (Pengtum Technologies, Shanghai, China); Medit i500 (Medit Corp. Seoul, South Korea); Planmeca Emerald™ (Planmeca, Helsinki, Finland); and Aoralscan (Shining 3D Tech. Co., Ltd., Hangzhou, China). After the scan, the 3D scanned stereolithography files were created. The various distances were measured five times in X , Y , Z , and X Y axes of various scans and with a vernier caliper (control) and from the Rhinoceros software. The data were analyzed using SPSS 18. Test for the normality of the various measurement data were done using Kolmogorov-Smirnov test. The trueness and precision of the measurements were compared among the various scans using the Kruskal-Wallis test. The significance was considered at P < 0.05 . The trueness of the intraoral scans was analyzed by comparing the measurements from the control. Precision was tested through the measurements of repeated scans. It showed that more the distance is less the accuracy for all scanners. In all studied scanners, the trueness varied but precision was favorably similar. Diagonal scanning showed less accuracy for all the scanners. Hence, when scanning the full arch, the dentist needs to take more caution and good scan pattern. Trios series showed the best scan results compared to other scanners.

scholarly journals Trace gas emissions from combustion of peat, crop residue, biofuels, grasses, and other fuels: configuration and FTIR component of the fourth Fire Lab at Missoula Experiment (FLAME-4)

2014 ◽  
Vol 14 (7) ◽  
pp. 10061-10134 ◽  
Author(s):  
C. E. Stockwell ◽  
R. J. Yokelson ◽  
S. M. Kreidenweis ◽  
A. L. Robinson ◽  
P. J. DeMott ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Crop Residue ◽  
High Resolution Mass Spectrometry ◽  
Trace Gases ◽  
Large Body ◽  
Field Measurements ◽  
Trace Gas ◽  
Asian Rice ◽  
Gas Measurements

Abstract. During the fourth Fire Lab at Missoula Experiment (FLAME-4, October–November~2012) a~large variety of regionally and globally significant biomass fuels was burned at the US Forest Service Fire Sciences Laboratory in Missoula, Montana. The particle emissions were characterized by an extensive suite of instrumentation that measured aerosol chemistry, size distribution, optical properties, and cloud-nucleating properties. The trace gas measurements included high resolution mass spectrometry, one- and two-dimensional gas chromatography, and open-path Fourier transform infrared (OP-FTIR) spectroscopy. This paper summarizes the overall experimental design for FLAME-4 including the fuel properties, the nature of the burn simulations, the instrumentation employed, and then focuses on the OP-FTIR results. The OP-FTIR was used to measure the initial emissions of 20 trace gases: CO2, CO, CH4, C2H2, C2H4, C3H6, HCHO, HCOOH, CH3OH, CH3COOH, glycolaldehyde, furan, H2O, NO, NO2, HONO, NH3, HCN, HCl, and SO2. These species include most of the major trace gases emitted by biomass burning and for several of these compounds it is the first time their emissions are reported for important fuel types. The main fuel types included: African grasses, Asian rice straw, cooking fires (open (3-stone), rocket, and gasifier stoves), Indonesian and extratropical peat, temperate and boreal coniferous canopy fuels, US crop residue, shredded tires, and trash. Comparisons of the OP-FTIR emission factors (EF) and emission ratios (ER) to field measurements of biomass burning verify that the large body of FLAME-4 results can be used to enhance the understanding of global biomass burning and its representation in atmospheric chemistry models.

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