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Satellite retrievals of XCO2 at northern high latitudes currently have sparser coverage and lower data quality than most other regions of the world. We use a neural network (NN) to filter Orbiting Carbon Observatory 2 (OCO-2) B10 bias-corrected XCO2 retrievals and compare the quality of the filtered data to the quality of the data filtered with the standard B10 quality control filter. To assess the performance of the NN filter, we use Total Carbon Column Observing Network (TCCON) data at selected northern high latitude sites as a truth proxy. We found that the NN filter decreases the overall bias by 0.25 ppm (∼ 50 %), improves the precision by 0.18 ppm (∼ 12 %), and increases the throughput by 16 % at these sites when compared to the standard B10 quality control filter. Most of the increased throughput was due to an increase in throughput during the spring, fall, and winter seasons. There was a decrease in throughput during the summer, but as a result the bias and precision were improved during the summer months. The main drawback of using the NN filter is that it lets through fewer retrievals at the highest-latitude Arctic TCCON sites compared to the B10 quality control filter, but the lower throughput improves the bias and precision. [ABSTRACT FROM AUTHOR]

A better understanding of greenhouse gas surface sources and sinks is required in order to address the global challenge of climate change. Space-borne remote estimations of greenhouse gas atmospheric concentrations can offer the global coverage that is necessary to improve the constraint on their fluxes, thus enabling a better monitoring of anthropogenic emissions. In this work, we introduce the Adaptable 4A Inversion (5AI) inverse scheme that aims to retrieve geophysical parameters from any remote sensing observation. The algorithm is based on the Optimal Estimation algorithm, relying on the Operational version of the Automatized Atmospheric Absorption Atlas (4A/OP) radiative transfer forward model along with the Gestion et Étude des Informations Spectroscopiques Atmosphériques: Management and Study of Atmospheric Spectroscopic Information (GEISA) spectroscopic database. Here, the 5AI scheme is applied to retrieve the column-averaged dry air mole fraction of carbon dioxide (XCO2) from a sample of measurements performed by the Orbiting Carbon Observatory-2 (OCO-2) mission. Those have been selected as a compromise between coverage and the lowest aerosol content possible, so that the impact of scattering particles can be neglected, for computational time purposes. For air masses below 3.0, 5AI XCO2 retrievals successfully capture the latitudinal variations of CO2 and its seasonal cycle and long-term increasing trend. Comparison with ground-based observations from the Total Carbon Column Observing Network (TCCON) yields a bias of 1.30±1.32 ppm (parts per million), which is comparable to the standard deviation of the Atmospheric CO2 Observations from Space (ACOS) official products over the same set of soundings. These nonscattering 5AI results, however, exhibit an average difference of about 3 ppm compared to ACOS results. We show that neglecting scattering particles for computational time purposes can explain most of this difference that can be fully corrected by adding to OCO-2 measurements an average calculated–observed spectral residual correction, which encompasses all the inverse setup and forward differences between 5AI and ACOS. These comparisons show the reliability of 5AI as an optimal estimation implementation that is easily adaptable to any instrument designed to retrieve column-averaged dry air mole fractions of greenhouse gases. [ABSTRACT FROM AUTHOR]

Perfluoro-n-propane, perfluorocyclobutane, perfluoro-n-butane, and perfluoro-n-pentane are non-ozone-depleting industrial alternatives to chlorofluorocarbons and hydrochlorofluorocarbons. However, these perfluoroalkanes have significant band strength in the atmospheric window from 800 to 1200 cm−1. Coupled with their millennial-scale atmospheric lifetimes, they can lead to significant long-term global warming. Infrared spectra are required to quantify the climate impacts. This work provides a set of high-temperature infrared absorption cross-sections in the range 298–350 K at 0.1 cm−1 resolution from 515 to 1500 cm−1 for each compound. Our cross-sections generally agree with literature measurements except for perfluoro-n-pentane. We use density functional theory to calculate the absorption cross-sections from 0 to 515 cm−1 using the B3LYP functional and several basis sets. The 6-31G(d,p) basis set provides the best results for linear perfluoroalkanes, while the def2-TZVP basis set provides the best results for cyclic perfluoroalkanes. Using experimental cross-sections, we calculate the radiative efficiency and global warming potential for each compound, utilizing the Pinnock curve from Shine and Myhre (2020) and atmospheric lifetimes from Hodnebrog et al. (2020). These quantities are found to be independent of temperature. The average 100-year global warming potential derived from all cross-sections is 9,610±1,260, 10,800±1,420, 10,100±1,330, and 9,380±1,230 for perfluoro-n-propane, perfluorocyclobutane, perfluoro-n-butane, and perfluoro-n-pentane, respectively. Combining the data in this work with our previous measurements reveals that the global warming potential for perfluoroalkanes with an increasing number of C F bonds depends on the ratio of radiative efficiency to molecular weight. [Display omitted] • Measured n-C 3 F 8 , n-C 4 F 10 , and n-C 5 F 12 cross-sections from 515–1500 cm−1 and 298–350 K. • Improved n-C 5 F 12 cross-sections compared to literature using a 99% pure sample. • Determined conformer populations for all compounds using density functional theory. • Investigated band strength and climate metrics trends with an increasing number of C F bonds. • Showed temperature independence of integrated cross-sections and climate metrics. [ABSTRACT FROM AUTHOR]

Wintertime Arctic surface emissivities are retrieved from Advanced Technology Microwave Sounder (ATMS) passive microwave measurements at 88.2, 165.5, and 183.31 GHz. Surface emitting layer temperatures are simultaneously retrieved at 183.31 GHz. Random errors in emissivities are estimated to be 2.0%, 2.0%, and 3.5% at 88.2, 165.5, and 183.31 GHz, respectively, and the random errors in surface emitting layer temperatures are 4.3 K. A series of tests on the retrieved products reveal that land and sea ice are Lambertian reflectors and ocean is a specular reflector. The retrieved emissivities show broad agreement with products from published databases, with differences partly due to the uncertainties in surface emitting layer temperatures. The geographical distribution of 165.5/183.31 GHz surface reflectance ratios over land and sea ice, which is important for the retrieval of microwave satellite water vapor column (WVC), is presented. Neglecting the geographical variations leads to random errors in retrieved wintertime Arctic WVCs of approximately 1.8% and 25% in the mid (1.5 – 9 kgm−2) and extended (8 – 15 kgm−2) slant column retrieval regimes, respectively. Choosing specular instead of Lambertian reflection in the surface emissivity retrievals over land and sea ice causes systematic WVC retrieval errors of up to −4.1%. [ABSTRACT FROM AUTHOR]

The TROPOspheric Monitoring Instrument (TROPOMI) aboard the Sentinel-5 Precursor satellite (launched on 13 October 2017) is a nadir-viewing spectrometer measuring reflected sunlight in the ultraviolet, visible, near-infrared, and shortwave infrared spectral ranges. The measured spectra are used to retrieve total columns of trace gases, including nitrogen dioxide (NO2). For ground validation of these satellite measurements, Pandora spectrometers, which retrieve high-quality NO2 total columns via direct-sun measurements, are widely used. In this study, Pandora NO2 measurements made at three sites located in or north of the Greater Toronto Area (GTA) are used to evaluate the TROPOMI NO2 data products, including a standard Royal Netherlands Meteorological Institute (KNMI) tropospheric and stratospheric NO2 data product and a TROPOMI research data product developed by Environment and Climate Change Canada (ECCC) using a high-resolution regional air quality forecast model (in the air mass factor calculation). It is found that these current TROPOMI tropospheric NO2 data products (standard and ECCC) met the TROPOMI design bias requirement (< 10 %). Using the statistical uncertainty estimation method, the estimated TROPOMI upper-limit precision falls below the design requirement at a rural site but above in the other two urban and suburban sites. The Pandora instruments are found to have sufficient precision (< 0.02 DU) to perform TROPOMI validation work. In addition to the traditional satellite validation method (i.e., pairing ground-based measurements with satellite measurements closest in time and space), we analyzed TROPOMI pixels located upwind and downwind from the Pandora site. This makes it possible to improve the statistics and better interpret the high-spatial-resolution measurements made by TROPOMI. By using this wind-based validation technique, the number of coincident measurements can be increased by about a factor of 5. With this larger number of coincident measurements, this work shows that both TROPOMI and Pandora instruments can reveal detailed spatial patterns (i.e., horizontal distributions) of local and transported NO2 emissions, which can be used to evaluate regional air quality changes. The TROPOMI ECCC NO2 research data product shows improved agreement with Pandora measurements compared to the TROPOMI standard tropospheric NO2 data product (e.g., lower multiplicative bias at the suburban and urban sites by about 10 %), demonstrating benefits from the high-resolution regional air quality forecast model. [ABSTRACT FROM AUTHOR]

Zenith-Sky scattered light Differential Optical Absorption Spectroscopy (ZS-DOAS) has been used widely to retrieve total column ozone (TCO). ZS-DOAS measurements have the advantage of being less sensitive to clouds than direct-sun measurements. However, the presence of clouds still affects the quality of ZS-DOAS TCO. Clouds are thought to be the largest contributor to random uncertainty in ZS-DOAS TCO, but their impact on data quality still needs to be quantified. This study has two goals: (1) to investigate whether clouds have a significant impact on ZS-DOAS TCO, and (2) to develop a cloud-screening algorithm to improve ZS-DOAS measurements in the Arctic under cloudy conditions. To quantify the impact of weather, 8 years of measured and modelled TCO have been used, along with information about weather conditions at Eureka, Canada (80.05 ∘ N, 86.41 ∘ W). Relative to direct-sun TCO measurements by Brewer spectrophotometers and modelled TCO, a positive bias is found in ZS-DOAS TCO measured in cloudy weather, and a negative bias is found for clear conditions, with differences of up to 5 % between clear and cloudy conditions. A cloud-screening algorithm is developed for high latitudes using the colour index calculated from ZS-DOAS spectra. The quality of ZS-DOAS TCO datasets is assessed using a statistical uncertainty estimation model, which suggests a 3 %–4 % random uncertainty. The new cloud-screening algorithm reduces the random uncertainty by 0.6 %. If all measurements collected during cloudy conditions, as identified using the weather station observations, are removed, the random uncertainty is reduced by 1.3 %. This work demonstrates that clouds are a significant contributor to uncertainty in ZS-DOAS TCO and proposes a method that can be used to screen clouds in high-latitude spectra. [ABSTRACT FROM AUTHOR]

Highlights • Cross-sections of 1,1,1,2,3,3-hexafluoropropane (HFC-236ea) and 1,1,2,2,3-pentafluoropropane (HFC-245ca) were measured from 550 to 3400 cm − 1 for a temperature range of 300–362 K. • Good agreement between new results, prior data, and density functional theory (DFT). • Radiative efficiency and global warming potential are calculated using a combination of DFT and experimental spectra to obtain a wider spectral range than previous calculations. Abstract Absorption cross-sections of 1,1,1,2,3,3-hexafluoropropane (HFC-236ea) and 1,1,2,2, 3-pentafluoropropane (HFC-245ca) were derived from Fourier transform infrared spectra recorded from 550 to 3400 cm − 1 with a resolution of 0.1 cm − 1 over a temperature range of 300–365 K. Good agreement was found between the experimentally derived results, theoretical spectra from density functional theory (DFT) calculations, and previously published experimental measurements. The only temperature dependence observed was in the amplitude of some of the absorption peaks due to the changing ratio of the stable conformations of both molecules studied. This temperature dependence does not result in a significant trend in integrated band strength as a function of temperature. The average value for the integrated band strength of HFC-236ea was found to be (1.982 ± 0.012)x10 − 16 cm molecule − 1 over the spectral range of 550 to 3026 cm − 1. The average value for the integrated band strength of HFC-245ca was found to be (1.348 ± 0.35)x10 − 16 cm molecule − 1 over the spectral range of 570 to 3035 cm − 1. Radiative efficiency (RE) and the global warming potential (GWP) for both molecules were also derived, accounting for corrections due to atmospheric lifetimes and stratospheric temperature adjustment. A RE of 0.256 ± 0.034 Wm − 2 ppbv − 1 was obtained for HFC-236ea, which leads to a GWP 100 of 1141 ± 402 for 550–3000 cm − 1. For HFC-245ca, a RE of 0.197 ± 0.023 Wm − 2 ppbv − 1 was derived, which leads to a GWP 100 of 588 ± 205 for 550–3000 cm − 1. The DFT calculation was linearly adjusted to match the experimental spectrum. Using this adjusted DFT spectrum to expand the range below 550 to 0 cm − 1 increases the RE to 0.265 ± 0.035 Wm − 2 ppbv − 1 and the GWP 100 to 1181 ± 417 for HFC-236ea; while for HFC-245ca, the RE increases to 0.202 ± 0.027 Wm − 2 ppbv − 1 and the GWP 100 to 602 ± 210. [ABSTRACT FROM AUTHOR]

A methodology for retrieving high-latitude winter water vapour columns from passive microwave satellite measurements from Perro et al. (2016) is extended to use measured surface reflectance ratios under more realistic surface reflection assumptions. Pan-Arctic wintertime water vapour is retrieved from Advanced Technology Microwave Sounder (ATMS) measurements made from January 2012 through March 2015 (December to March). The water vapour retrievals are validated using two ground based instruments: the G-band Vapor Radiometer (GVR) at Barrow, Alaska, and the Extended-Range Atmospheric Emitted Radiance Interferometer (E-AERI) at Eureka, Nunavut. E-AERI was chosen as an additional point of validation compared to Perro et al. (2016) due to the different technology and frequencies employed to determine water vapour column compared to the ATMS and GVR. For water vapour columns less than 6 kg m-2, the biases are +2.6 % and +0.01 % relative to the GVR and E-AERI, respectively. A comparison with radiosonde humidity measurements shows they are dry relative to the ATMS measurements in North America and Western Europe, and moist in Asia and Eastern Europe, with an apparent dependence on radiosonde manufacturer. Reanalyses (ERA-5, ERA-Interim, ASR V2, JRA-55 and NCEP) are systematically drier than the ATMS measurements for water vapour columns less than 6 kg m-2, with relative biases ranging from -10 % to -23 %. These differences could have implications for the understanding of the Arctic water budget and climate. [ABSTRACT FROM AUTHOR]

Perfluoro-n-hexane and perfluoro-2-methylpentane are fully fluorinated alkanes used as non-ozone-depleting alternatives to chlorofluorocarbons and hydrochlorofluorocarbons. These compounds are long-lived and potent greenhouse gases due to their strong C F bonds and infrared absorption in the atmospheric window. Infrared absorption cross-sections are required to quantify the climate impact of these compounds via the radiative efficiency and global warming potential. To our knowledge, there are only two experimental measurements for perfluoro-n-hexane, and there are no experimental measurements for perfluoro-2-methylpentane in the infrared. In this work, we provide a set of absorption cross-sections in the range 515–1500 cm−1, at 0.1 cm−1 resolution from 298 to 350 K for each compound. We calculate the absorption cross-section between 0 and 515 cm−1 using density functional theory with various basis sets. The 6-31,G(d,p) basis set with the B3LYP functional is found to provide the best results. Using both measurements and calculations combined, we calculate the radiative efficiency and global warming potential for each compound. No significant temperature dependence was observed in these quantities. The average radiative efficiency derived from all cross-sections is 0.48 ± 0.06 W m−2 ppbv−1 for perfluoro-n-hexane and 0.46 ± 0.06 W m−2 ppbv−1 for perfluoro-2-methylpentane. The average 100-year global warming potential derived from all cross-sections is 9590 ± 1260 for perfluoro-n-hexane and 9220 ± 1210 for perfluoro-2-methylpentane. [Display omitted] • Obtained first measurements of the cross-sections of i C 6 F 14 from 515 to 1500 cm−1. • Measured cross-sections of n C 6 F 14 and confirmed the peak at 1255 cm−1. • Performed DFT calculations for all major C 6 F 14 conformers and determined their populations. • Derived global warming potentials of 9590 ± 1260 and 9220 ± 1210 for n C 6 F 14 and i C 6 F 14. • Showed temperature independence of integrated cross-sections and climate metrics. [ABSTRACT FROM AUTHOR]

Zenith-Sky scattered light Differential Optical Absorption Spectroscopy (ZS-DOAS) has been used widely to retrieve total column ozone (TCO). ZS-DOAS measurements have the advantage of being less sensitive to clouds than direct-sun measurements. However, the presence of clouds still affects the quality of ZS-DOAS TCO. Clouds are thought to be the largest contributor to random uncertainty in ZS-DOAS TCO, but their impact on data quality still needs to be quantified. This study has two goals: (1) to study whether clouds have a significant impact on ZS-DOAS TCO, and (2) to develop a cloud-screening algorithm to improve ZS-DOAS measurements in the Arctic under cloudy conditions. To quantify the impact of weather, eight years of measured and modelled TCO have been used, along with information about weather conditions at Eureka, Canada (80.05° N, 86.41° W). Relative to direct-sun TCO measurements by Brewer spectrophotometers and modelled TCO, a positive bias is found in ZS-DOAS TCO measured in cloudy weather, and a negative bias is found for clear conditions, with differences of up to 5 % between clear and cloudy conditions. A cloud-screening algorithm is developed for high-latitudes using the colour index calculated from ZS-DOAS spectra. The quality of ZS-DOAS TCO datasets is assessed using a statistical uncertainty estimation model, which suggests a 3-4 % random uncertainty. The new cloud-screening algorithm reduces the random uncertainty by 0.6 %. If all measurements collected during cloudy conditions, as identified using the weather station observations, are removed, the random uncertainty is reduced by 1.3 %. This work demonstrates that clouds are a significant contributor to uncertainty in ZS-DOAS TCO and proposes a method that can be used to screen clouds in high-latitude spectra. [ABSTRACT FROM AUTHOR]

HFC-43-10mee (C 5 H 2 F 10 ) is a substitute for CFC-113, HCFC-141b and methyl chloroform, as well as an alternative to perfluorocarbons with high radiative efficiencies. Recent observations have shown that the global mean tropospheric abundance of HFC-43-10mee has increased steadily from the 1990s to reach 0.211 ppt in 2012. To date, the emission of this compound is not regulated. The radiative efficiency (RE) of HFC-43-10mee has recently been re-evaluated at 0.42 W m −2 ppb −1 , giving a 100-year time horizon global warming potential (GWP 100 ) of 1650. However, the initial RE, from which the new values were derived, originated from an unpublished source. We calculated a new RE of 0.36 W m −2 ppb −1 and a GWP 100 of 1410 from laboratory absorption cross-section spectra of a pure vapour of HFC-43-10mee. Acquisitions were performed in the 550–3500 cm −1 spectral range using Fourier transform spectroscopy. The results were compared with the broadened spectra from the Pacific Northwest National Laboratory (PNNL) database and with theoretical calculations using density functional theory. [ABSTRACT FROM AUTHOR]

Perfluorodecalin (PFD) is a molecule used in various medical applications for its capacity to dissolve gases. This potent greenhouse gas was detected for the first time in the atmosphere in 2005. We present infrared absorption cross-section spectra of a pure vapour of cis - and trans -perfluorodecalin at a resolution of 0.1 cm −1 . Measurements were performed in the 560–3000 cm −1 spectral range using Fourier transform spectroscopy. The spectra have been compared with previous experimental data and theoretical calculations by density functional theory. The new experimental absorption cross-sections have been used to calculate a lifetime-corrected radiative efficiency at 300 K of 0.62 W m −2 ppb −1 and 0.57 W.m −2 .ppb −1 for the cis and trans isomers respectively. This leads to a 100-year time horizon global warming potential of 8030 for cis -PFD and 7440 for trans -PFD. [ABSTRACT FROM AUTHOR]

A response from the authors of the article "Does Lack of 'Genetic-Relative Family Health History' Represent a Potentially Avoidable Health Disparity for Adoptees?" in the December 2016 issue is presented.

The Measurements of Pollution in the Troposphere (MOPITT) satellite instrument provides the longest continuous dataset of carbon monoxide (CO) from space. We perform the first validation of MOPITT version 6 retrievals using total column CO measurements from groundbased remote-sensing Fourier transform infrared spectrometers (FTSs). Validation uses data recorded at 14 stations, that span a wide range of latitudes (80° N to 78° S), in the Network for the Detection of Atmospheric Composition Change (NDACC). MOPITT measurements are spatially co-located with each station, and different vertical sensitivities between instruments are accounted for by using MOPITT averaging kernels (AKs). All three MOPITT retrieval types are analyzed: thermal infrared (TIR-only), joint thermal and near infrared (TIR-NIR), and near infrared (NIR-only). Generally, MOPITT measurements overestimate CO relative to FTS measurements, but the bias is typically less than 10%. Mean bias is 2.4% for TIR-only, 5.1% for TIR-NIR, and 6.5% for NIR-only. The TIR-NIR and NIR-only products consistently produce a larger bias and lower correlation than the TIR-only. Validation performance of MOPITT for TIR-only and TIR-NIR retrievals over land or water scenes is equivalent. The four MOPITT detector element pixels are validated separately to account for their different uncertainty characteristics. Pixel 1 produces the highest standard deviation and lowest correlation for all three MOPITT products. However, for TIR-only and TIR-NIR, the error-weighted average that includes all four pixels often provides the best correlation, indicating compensating pixel biases and well-captured error characteristics. We find that MOPITT bias does not depend on latitude but rather is influenced by the proximity to rapidly changing atmospheric CO. MOPITT bias drift has been bound geographically to within ±0.5%yr-1 or lower at almost all locations. [ABSTRACT FROM AUTHOR]

The differential optical absorption spectroscopy (DOAS) method is a well-known remote sensing technique that is nowadays widely used for measurements of atmospheric trace gases, creating the need for harmonization and characterization efforts. In this study, an intercomparison exercise of DOAS retrieval codes from 17 international groups is presented, focusing on NO2 slant columns. The study is based on data collected by one instrument during the Multi-Axis DOAS Comparison campaign for Aerosols and Trace gases (MAD-CAT) in Mainz, Germany, in summer 2013. As data from the same instrument are used by all groups, the results are free of biases due to instrumental differences, which is in contrast to previous intercomparison exercises. While in general an excellent correlation of NO2 slant columns between groups of >99.98% (noon reference fits) and >99.2% (sequential reference fits) for all elevation angles is found, differences between individual retrievals are as large as 8% for NO2 slant columns and 100% for rms residuals in small elevation angles above the horizon. Comprehensive sensitivity studies revealed that absolute slant column differences result predominantly from the choice of the reference spectrum while relative differences originate from the numerical approach for solving the DOAS equation as well as the treatment of the slit function. Furthermore, differences in the implementation of the intensity offset correction were found to produce disagreements for measurements close to sunrise (8-10% for NO2, 80% for rms residual). The largest effect of ≈ 8% difference in NO2 was found to arise from the reference treatment; in particular for fits using a sequential reference. In terms of rms fit residual, the reference treatment has only a minor impact. In contrast, the wavelength calibration as well as the intensity offset correction were found to have the largest impact (up to 80 %) on rms residual while having only a minor impact on retrieved NO2 slant columns. [ABSTRACT FROM AUTHOR]

Absorption cross-sections of 2,2,3,3,3-pentafluoropropanol (PFPO) were derived from Fourier transform infrared spectra recorded from 565 to 3400 cm −1 with a resolution of 0.1 cm −1 over a temperature range of 298–362 K. These results were compared to previously published theoretical density functional theory (DFT) calculations and experimental measurements made at room temperature. We find good agreement between our experimentally derived results, DFT calculations, and previously published data. The only temperature dependence observed was in the centroid shift of the 850–1500 cm −1 band and in the amplitude of some of the absorption peaks. However, this temperature dependence does not result in a significant trend in integrated band strength as a function of temperature. We calculate an average integrated band strength of (1.991±0.001)×10 −16 cm molecule −1 for PFPO over the spectral range studied. Radiative efficiencies (REs) and the global warming potential (GWP) for PFPO were also derived. We find an average RE of 0.2603 ± 0.0007 W m − 2 ppbv − 1 and a GWP 100 of 19.8. The calculated radiative efficiencies show that no dependence on temperature and our findings are consistent with previous studies, increasing our confidence in the value of the GWP of PFPO. [ABSTRACT FROM AUTHOR]

This study evaluates the performance of the recently developed Pandora spectrometer by comparing it with the Brewer reference triad. This triad was established by Environment and Climate Change Canada (ECCC) in the 1980s and is used to calibrate Brewer instruments around the world, ensuring high-quality total column ozone (TCO) measurements. To reduce stray light, the double Brewer instrument was introduced in 1992, and a new reference triad of double Brewers is also operational at Toronto. Since 2013, ECCC has deployed two Pandora spectrometers co-located with the old and new Brewer triads, making it possible to study the performance of three generations of ozone-monitoring instruments. The statistical analysis of TCO records from these instruments indicates that the random uncertainty for the Brewer is below 0.6 %, while that for the Pandora is below 0.4%. However, there is a 1 % seasonal difference and a 3 % bias between the standard Pandora and Brewer TCO data, which is related to the temperature dependence and difference in ozone cross sections. A statistical model was developed to remove this seasonal difference and bias. It was based on daily temperature profiles from the European Centre for Medium-Range Weather Forecasts ERA-Interim data over Toronto and TCO from the Brewer reference triads. When the statistical model was used to correct Pandora data, the seasonal difference was reduced to 0.25 % and the bias was reduced to 0.04 %. Pandora instruments were also found to have low air mass dependence up to 81.6° solar zenith angle, comparable to double Brewer instruments. [ABSTRACT FROM AUTHOR]

Perfluoroalkanes are fully fluorinated greenhouse gases. These compounds are chemically inert due to their C–F bonds and therefore have atmospheric lifetimes of thousands of years. Although regulated under the Kyoto Protocol, atmospheric concentrations of perfluoroalkanes have continued to increase since 1997. To quantify the climate impact of perfluoro-n-heptane and perfluoro-n-octane, spectral data are required to calculate climate metrics such as the radiative efficiency and global warming potential. Experimental measurements are scarce for these compounds and are only available at 296 and 297 K. In this work, a set of absorption cross-sections is provided in the range 515–1500 cm−1 at 0.1 cm−1 resolution for nine temperatures between 300 and 350 K. There is general agreement between literature values and the absorption cross-sections and climate metrics measured in this work. These quantities do not show significant temperature dependence. The temperature averaged radiative efficiency is 0.50 ± 0.06 and 0.54 ± 0.07 Wm−2ppbv−1 for n–C 7 F 16 and n–C 8 F 18 , respectively. The temperature averaged 100-year global warming potential is 8738 ± 1149 for n–C 7 F 16 and 8392 ± 1103 for n–C 8 F 18. [Display omitted] • Infrared cross-sections for n–C 7 F 16 and n–C 8 F 18 measured from 300 to 350 K. • Cross-sections confirm literature values for the spectral peak at 1250 cm−1. • Radiative efficiency is 0.50 ± 0.06 and 0.54 ± 0.07 Wm−2ppbv−1 for n–C 7 F 16 and n–C 8 F 18. • 100-year global warming potential is 8738 ± 1149 for n–C 7 F 16 and 8392 ± 1103 for n–C 8 F 18. • Integrated cross-sections and climate metrics are temperature-independent over 300–350 K. [ABSTRACT FROM AUTHOR]

The Differential Optical Absorption Spectroscopy (DOAS) method is a well-known remote sensing technique that is nowadays widely used for measurements of atmospheric trace gases, creating the need for harmonization and characterization efforts. In this study, an intercomparison exercise of DOAS retrieval codes from 17 international groups is presented focusing on NO2 slant columns. The study is based on data collected by one instrument during the Multi-Axis DOAS Comparison campaign for Aerosols and Trace gases (MAD-CAT) in Mainz, Germany, in summer 2013. As data from the same instrument is used by all groups, the results are free of biases due to instrumental differences, which is in contrast to previous intercomparison exercises. While in general an excellent correlation of NO2 slant columns between groups of > 99.98% (noon reference fits), and > 99.2% (sequential reference fits) for all elevation angles is found, differences between individual retrievals are as large as 8% for NO2 slant columns and 100% for RMS residuals. Two kinds of disagreements were identified: (1) Absolute slant column differences were found to result predominantly from the choice of the reference spectrum. (2) Relative differences were found to originate from the numerical approach for solving the DOAS equation as well as the treatment of the slit function. Differences in the implementations of the intensity offset correction lead to disagreements for retrievals close to sunrise (8-10% for NO2, 80% for RMS residual). Apart from this, the largest effect of ≈ 8% difference in NO2 was found to arise from the reference treatment, in particular for fits using a sequential reference. In terms of RMS fit residual, the reference treatment has only a minor impact. In contrast, the wavelength calibration as well as the intensity offset correction were found to have the largest impact (up to 80%) on RMS residual while having only a minor impact on retrieved NO2 slant columns. [ABSTRACT FROM AUTHOR]

Cross-sections of perfluorotributylamine (PFTBA) were derived from Fourier transform spectroscopy at 570–3400 cm −1 with a resolution of 0.1 cm −1 over a temperature range of 298–344 K. These results were compared to theoretical density functional theory (DFT) calculations and to previous measurements of PFTBA made at room temperature. DFT calculations were performed using the B3LYP method and the 6-311G(d,p) basis set. We find good agreement between our experimentally derived results, DFT calculations, and previously published data. No significant temperature dependence in the PFTBA cross-sections was observed for the temperature range studied. We calculate an average integrated band strength of 7.81 × 10 −16 cm/molecule for PFTBA over the spectral range studied. Radiative efficiencies (RE) and global warming potentials (GWP) for PFTBA were also derived. The calculated radiative efficiencies show no dependence on temperature and agree with prior publications. We find an average RE of 0.77 Wm −2 ppbv −1 and a range of GWP from 6874 to 7571 depending on the lifetime used. Our findings are consistent with previous studies and increase our confidence in the value of the GWP of PFTBA. [ABSTRACT FROM AUTHOR]

We present cross-validation of remote sensing measurements of methane profiles in the Canadian high Arctic. Accurate and precise measurements of methane are essential to understand quantitatively its role in the climate system and in global change. Here, we show a crossvalidation between three data sets: two from spaceborne instruments and one from a ground-based instrument. All are Fourier transform spectrometers (FTSs). We consider the Canadian SCISAT Atmospheric Chemistry Experiment (ACE)-FTS, a solar occultation infrared spectrometer operating since 2004, and the thermal infrared band of the Japanese Greenhouse Gases Observing Satellite (GOSAT) Thermal And Near infrared Sensor for carbon Observation (TANSO)-FTS, a nadir/off-nadir scanning FTS instrument operating at solar and terrestrial infrared wavelengths, since 2009. The ground-based instrument is a Bruker 125HR Fourier transform infrared (FTIR) spectrometer, measuring mid-infrared solar absorption spectra at the Polar Environment Atmospheric Research Laboratory (PEARL) Ridge Laboratory at Eureka, Nunavut (80° N, 86° W) since 2006. For each pair of instruments, measurements are collocated within 500 km and 24 h. An additional collocation criterion based on potential vorticity values was found not to significantly affect differences between measurements. Profiles are regridded to a common vertical grid for each comparison set. To account for differing vertical resolutions, ACE-FTS measurements are smoothed to the resolution of either PEARL-FTS or TANSO-FTS, and PEARL-FTS measurements are smoothed to the TANSO-FTS resolution. Differences for each pair are examined in terms of profile and partial columns. During the period considered, the number of collocations for each pair is large enough to obtain a good sample size (from several hundred to tens of thousands depending on pair and configuration). Considering full profiles, the degrees of freedom for signal (DOFS) are between 0.2 and 0.7 for TANSO-FTS and between 1.5 and 3 for PEARL-FTS, while ACE-FTS has considerably more information (roughly 1 DOFS per altitude level). We take partial columns between roughly 5 and 30 km for the ACE-FTS-PEARL-FTS comparison, and between 5 and 10 km for the other pairs. The DOFS for the partial columns are between 1.2 and 2 for PEARL-FTS collocated with ACE-FTS, between 0.1 and 0.5 for PEARL-FTS collocated with TANSO-FTS or for TANSO-FTS collocated with either other instrument, while ACE-FTS has much higher information content. For all pairs, the partial column differences are within ±3×1022 moleculescm-2. Expressed as median±median absolute deviation (expressed in partial column units or as a percentage), these differences are 0.11±9.60×1020 moleculescm-2(0.012±1.018 %) for TANSO-FTS-PEARL-FTS, -2:6±2:6×1021 moleculescm-2(-1:6±1:6 %) for ACEFTS- PEARL-FTS, and 7:4±6:0×1020 moleculescm-2(0:78±0:64 %) for TANSO-FTS-ACE-FTS. The differences for ACE-FTS-PEARL-FTS and TANSO-FTS-PEARL-FTS partial columns decrease significantly as a function of PEARL partial columns, whereas the range of partial column values for TANSO-FTS-ACE-FTS collocations is too small to draw any conclusion on its dependence on ACE-FTS partial columns. [ABSTRACT FROM AUTHOR]

Motivated by the initial selection of a highresolution solar occultation Fourier transform spectrometer (FTS) to fly to Mars on the ExoMars Trace Gas Orbiter, we have been developing algorithms for retrieving volume mixing ratio vertical profiles of trace gases, the primary component of which is a new algorithm and software for retrieving vertical profiles of temperature and pressure from the spectra. In contrast to Earth-observing instruments, which can rely on accurate meteorological models, a priori information, and spacecraft position, Mars retrievals require a method with minimal reliance on such data. The temperature and pressure retrieval algorithms developed for this work were evaluated using Earth-observing spectra from the Atmospheric Chemistry Experiment (ACE) FTS, a solar occultation instrument in orbit since 2003, and the basis for the instrument selected for a Mars mission. ACE-FTS makes multiple measurements during an occultation, separated in altitude by 1.5-5 km, and we analyse 10 CO2 vibration-rotation bands at each altitude, each with a different usable altitude range. We describe the algorithms and present results of their application and their comparison to the ACE-FTS data products. The Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) provides vertical profiles of temperature up to 40 km with high vertical resolution. Using six satellites and GPS radio occultation, COSMIC's data product has excellent temporal and spatial coverage, allowing us to find coincident measurements with ACE with very tight criteria: less than 1.5 h and 150 km. We present an intercomparison of temperature profiles retrieved from ACE-FTS using our algorithm, that of the ACE Science Team (v3.5), and from COSMIC. When our retrievals are compared to ACE-FTS v3.5, we find mean differences between -5 and +2K and that our retrieved profiles have no seasonal or zonal biases but do have a warm bias in the stratosphere and a cold bias in the mesosphere. When compared to COSMIC, we do not observe a warm/cool bias and mean differences are between -4 and +1 K. COSMIC comparisons are restricted to below 40 km, where our retrievals have the best agreement with ACE-FTS v3.5. When comparing ACE-FTS v3.5 to COSMIC we observe a cold bias in COSMIC of 0.5 K, and mean differences are between -0.9 and +0.6 K. [ABSTRACT FROM AUTHOR]

Abstract: The PEARL-GBS (Polar Environment Atmospheric Research Laboratory-Ground-Based Spectrometer) was permanently installed at Eureka, Nunavut (, ) in August 2006 as part of the establishment of PEARL by CANDAC (Canadian Network for the Detection of Atmospheric Change). The instrument is a ground-based, UV–visible, triple-grating spectrometer and is very similar to the UT-GBS (University of Toronto-GBS), which has an 11-year heritage of measurements, including 10 High Arctic field campaigns. From spectra of zenith-scattered sunlight, vertical column densities (VCDs) of ozone and , and differential slant column densities (DSCDs) of BrO and OCIO can be retrieved. The DSCDs and VCDs of ozone and have been compared to the UT-GBS and a SAOZ (Système d’Analyse par Observations Zénitales) following the protocols established by the UV–visible Working Group of the Network for the Detection of Atmospheric Composition Change (NDACC). The PEARL-GBS and UT-GBS comparisons meet all standards, while the comparisons with SAOZ partially meet the standards. The VCDs from the three instruments agree, on average, to within 4% for ozone and 8% for . The BrO DSCDs from the PEARL-GBS and UT-GBS agree to within 14%. These are within the combined error bars of the instruments. In 2009, the PEARL-GBS and UT-GBS became affiliated with the NDACC measurement programme. [Copyright &y& Elsevier]

[Display omitted] • Investigation of HFE-347pcf2 (1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether). • Acquisition of experimental absorption cross sections in the 550–3500 cm−1 range. • Extension of the spectrum in the low wavenumbers by theoretical simulations. • A radiative efficiency of 0.46 W m−2 ppb−1 and a 100-year global warming potential of 980 have been calculated. Composite absorption cross-sections of the hydrofluoroether HFE-347pcf2 (CAS number 406-78-0) have been determined from experimental and theoretical data. The experimental cross-sections have been used as a gauge to evaluate the accuracy of computational data obtained from different density functional theory methods. The B3LYP functional with a small 6-31G(d) basis set was found to provide the best results. A simulated spectrum was added to our experimental data to calculate the radiative efficiency and global warming potential of the molecule over the entire atmospheric spectral window. We found a radiative efficiency of 0.46 Wm−2ppb−1 and a 100-year global warming potential of 980. [ABSTRACT FROM AUTHOR]

• Experimental absorption cross‐sections of HFE‐356mec3 have been acquired. • Results have been compared with density functional theory and ab initio methods. • The lifetime‐corrected radiative efficiency was found to be 0.31 W.m−2 ppb−1. • This leads to a 100‐year time horizon global warming potential of 260. Experimental absorption cross-section spectra of HFE-356mec3 (CH 3 OCF 2 CHFCF 3) have been acquired at three temperatures and at a resolution of 0.1 cm−1 over the spectral range 550–3500 cm−1. The results have been completed with theoretical calculations using density functional theory and ab initio methods at different levels of theory. A lifetime-corrected radiative efficiency of 0.31 Wm−2ppb−1 was obtained, leading to a 100-year time horizon global warming potential of 260 using an atmospheric lifetime of 2.5 years. [ABSTRACT FROM AUTHOR]

The increasing quality and diminishing cost of next-generation sequencing has transformed our ability to interrogate large quantities of genetic information. This has led to a dramatic increase in the number of elective genomic tests performed. In this article, elective test denotes a test that a patient chooses to undertake without a clinical indication. The variety of elective genomic testing options is considerable. Because these offerings provide differing levels of sensitivity and specificity, it can be difficult to choose among them. A simple rubric to compare offerings is not readily available. We propose a framework designated completeness that evaluates both analytical and interpretative components of genomic tests. We then illustrate how this framework can be used to evaluate the expanding landscape of elective genomic testing., (Copyright © 2019 American Society for Investigative Pathology and the Association for Molecular Pathology. Published by Elsevier Inc. All rights reserved.)

High-resolution, laboratory, absorption spectra of the a 1 Δ g ← X 3 ∑ g - oxygen (O 2 ) band measured using cavity ring-down spectroscopy were fitted using the Voigt and speed-dependent Voigt line shapes. We found that the speed-dependent Voigt line shape was better able to model the measured absorption coefficients than the Voigt line shape. We used these line shape models to calculate absorption coefficients to retrieve atmospheric total columns abundances of O 2 from ground-based spectra from four Fourier transform spectrometers that are apart of the Total Carbon Column Observing Network (TCCON) Lower O 2 total columns were retrieved with the speed-dependent Voigt line shape, and the difference between the total columns retrieved using the Voigt and speed-dependent Voigt line shapes increased as a function of solar zenith angle. Previous work has shown that carbon dioxide (CO 2 ) total columns are better retrieved using a speed-dependent Voigt line shape with line mixing. The column-averaged dry-air mole fraction of CO 2 (XCO 2 ) was calculated using the ratio between the columns of CO 2 and O 2 retrieved (from the same spectra) with both line shapes from measurements made over a one-year period at the four sites. The inclusion of speed dependence in the O 2 retrievals significantly reduces the airmass dependence of XCO 2 and the bias between the TCCON measurements and calibrated integrated aircraft profile measurements was reduced from 1% to 0.4%. These results suggest that speed dependence should be included in the forward model when fitting near-infrared CO 2 and O 2 spectra to improve the accuracy of XCO 2 measurements.

Fruits and vegetables are rich in vitamin C with antioxidant properties which are known to influence bone quality. This study evaluated whether vitamin C (1000 mg/L) added to drinking water reverses the bone loss in ovariectomized rats. Ninety-day-old female Sprague-Dawley rats were randomly assigned to either sham ( n = 14) or ovariecotmized groups ( n = 28). Sixty days after ovariectomy, the treatments were sham, ovariectomy (OVX), OVX + vitamin C (22 mg oral intake daily) for 60 days. Urine was collected for deoxypyridinoline (DPD) evaluation, rats were sacrificed, and antioxidant capacity, osteopontin, alkaline phosphatase (ALP), and bone specific tartrate resistant acid phosphatase (TRAP) were evaluated in the plasma. Right femur and 5 th lumbar were evaluated for bone density, strength, ash, Ca, and Mg concentrations. Antioxidant capacity, ALP activity, osteopontin decreased (p-value < 0.05), while TRAP and urinary DPD increased (p-value < 0.05) with ovariectomy. In contrast, vitamin C increased (p-value < 0.05) antioxidant capacity, ALP activity, osteopontin concentration and reduced (p-value < 0.05) TRAP and urinary DPD excretion, respectively. Ovariectomy reduced (p-value < 0.05) bone quality, bone ash, Ca and Mg concentrations. Vitamin C increased (p-value < 0.05) femoral density without affecting (p-value > 0.1) femoral strength, ash, or Ca, and Mg concentrations, while it increased (p-value < 0.05) the 5 th lumbar density, ash, and Ca and Mg concentrations. In conclusion, vitamin C increased bone quality and antioxidant capacity in ovariectomized rats.

Introduction: Decreasing costs and increased availability of genetic testing and genome sequencing mean many physicians will consider using these services over the next few years. Despite this promising future, some argue the present roadmap for translating genetics and genomics into routine clinical practice is unclear., Objective: We conducted a pilot study to explore Wisconsin physicians' views, practices and educational desires regarding genetic and genomic testing., Methods: Our study consists of an Internet survey (n=155) conducted in August and September 2015 and follow-up phone interviews with a portion of survey participants. Physicians of all specialties were invited to participate. Variables measured include physicians' general knowledge and experience regarding genetic and genomic testing, attitudes and perceptions toward these tests, testing intentions, and educational desires. Sociodemographic variables included gender, age, and medical specialty., Results: In our exploratory survey of Wisconsin physicians, adult primary care providers (PCPs) lagged behind other providers in terms of familiarity and experience with genetic and genomic testing. PCPs in our sample were less likely than other physicians to feel their training in genetics and genomics is adequate. Physicians younger than 50 were more likely than older colleagues to feel their training is adequate., Conclusions: Our exploratory study suggests a gap in physician education and understanding regarding genomic testing, which is fast becoming part of personalized medical care. Future studies with larger samples should examine ways for physicians to close this gap, with special focus on the needs of PCPs.

Many adoptees face a number of challenges relating to separation from biological parents during the adoption process, including issues concerning identity, intimacy, attachment, and trust, as well as (for older adopted children) language and other cultural challenges. One common health challenge faced by adoptees involves lack of access to genetic-relative family health history (GRFHx). Lack of GRFHx represents a disadvantage due to a reduced capacity to identify diseases and recommend appropriate screening for conditions for which the adopted person may be at increased risk. In this article, we draw out common features of traditionally understood "health disparities" in order to identify analogous features in the context of adoptees' lack of GRFHx.

Next generation sequencing (NGS) technology is rapidly being implemented into clinical practice. Qualitative research was performed to gain an improved understanding of the landscape surrounding the use of NGS in cancer genetics. A focus group was conducted at the Wisconsin Cancer Risk Programs Network biannual meeting. Free flowing discussion with occasional open-ended questions provided insights into the use of NGS. 19 genetic counselors and medical professionals participated. Three major themes were identified with respect to NGS and its use in cancer genetics: knowledge gaps, the evolving clinician role, and uncertain utility. Several corresponding subthemes were identified. With respect to knowledge gaps, participants expressed concern regarding unexpected results and variants of unknown significance, lack of data about NGS findings, absence of standardization regarding use of NGS and guidelines for interpretation, and discomfort with new technology. Regarding the evolving clinician role, necessary changes to the roles of genetic counselors and physicians were noted, as was the resultant impact on care received by patients and their families. Finally, the clinical and economic utility of NGS was questioned. While a shift from traditional Sanger sequencing to NGS is occurring in molecular genetic testing for disease susceptibility, there are several obstacles that need to be overcome before widespread adoption of this technology can occur. Furthermore, key aspects of NGS and it utility remain unexplored. Continued investigation into these subjects is necessary before this technology will consistently be of benefit to patients and their families.

Background: Use of genome sequencing in the clinic continues to increase. In addition to its potential to provide findings of clinical benefit, it also has the potential to identify findings unrelated to the indication for testing (incidental findings). Incidental findings are the subject of considerable debate, particularly following the publication of recommendations by the American College of Medical Genetics and Genomics. This debate involves how and which results should be returned as well as stakeholders' desires for such results. Part of the difficulty in determining best practice in relation to returning incidental findings is the dearth of empirical data available regarding laypersons' attitudes and desire for the sometimes controversial information., Methods: In an effort to contribute data on views regarding the return of incidental findings following genome sequencing in a clinical setting, a survey specifically designed around the various types of incidental findings that occur, ranging from clinically actionable to nonactionable, was administered to a nonmedical population of medical coders working at a medical school (N = 97). Almost all (98%) of the respondents were women, 80% had 6 or more years of experience as a medical coder, and about three-fourths (74%) of participants reported that they had children., Results: The group surveyed was considerably more interested in receiving all types of results for both themselves and their children than previously surveyed genetics professionals., Conclusion: Results from this study offer a snapshot of opinions beyond those of the professional genetic community and demonstrate a striking difference between genetic professionals and a more lay population in terms of their attitudes and desires regarding the return of incidental findings. Additional research is needed to explain the nuances in the perspectives motivating these variations.

This paper argues that it will be important for new genomic technologies to recognize the limits of traditional approaches to informed consent, so that other-regarding implications of genomic information can be properly contextualized and individual rights respected. Respect for individual autonomy will increasingly require dynamic consideration of the interrelated dimensions of individual and broader community interests, so that the interests of one do not undermine fundamental interests of the other. In this, protection of individual rights will be a complex interplay between individual and community concerns.

The price of whole-genome and -exome sequencing has fallen to the point where these methods can be applied to clinical medicine. Here, we outline the lessons we have learned in converting a sequencing laboratory designed for research into a fully functional clinical program.