ALBERT

Description: 〈b〉Comparison of the GRUAN data products for Meisei RS-11G and Vaisala RS92-SGP radiosondes at Tateno (36.06° N, 140.13° E), Japan〈/b〉〈br〉 Eriko Kobayashi, Shunsuke Hoshino, Masami Iwabuchi, Takuji Sugidachi, Kensaku Shimizu, and Masatomo Fujiwara〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-416,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 The authors carried out dual flights of RS-11G and RS92-SGP radiosondes and investigated the differences in the performance of the radiosondes to help characterize GRUAN data products. A novel aspect of GRUAN data products is that vertically resolved uncertainty estimates and metadata are provided for each sounding and comparison of GRUAN data products is important in securing the temporal homogeneity of climate data records.

Description: 〈b〉Low-cost eddy covariance: a case study of evapotranspiration overagroforestry in Germany〈/b〉〈br〉 Christian Markwitz and Lukas Siebicke〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-392,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Turbulent fluxes are usually measured by the eddy covariance method as a combination of a costly gas analyser and a sonic anemometer. In the present manuscript we present an eddy covariance set-up of low cost to measure evapotranspiration over agricultural fields. The method showed to be comparable to a conventional eddy covariance set-up and is a viable alternative when spatial replicates are required.

Description: 〈b〉Two decades observing smoke above clouds in the south-eastern Atlantic Ocean: Deep Blue algorithm updates and validation with ORACLES field campaign data〈/b〉〈br〉 Andrew M. Sayer, N. Christina Hsu, Jaehwa Lee, Woogyung V. Kim, Sharon Burton, Marta A. Fenn, Richard A. Ferrare, Meloë Kacenelenbogen, Samuel LeBlanc, Kristina Pistone, Jens Redemann, Michal Segal-Rozenhaimer, Yohei Shinozuka, and Si-Chee Tsay〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-58,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Aerosols are small particles in the atmosphere such as dust or smoke. They are routinely monitored by satellites due to their importance for climate and air quality. However aerosols above clouds are more difficult to monitor. This study describes an improvement to a technique to monitor light-absorbing aerosols above clouds from four Earth-orbiting satellite instruments. The improved method is evaluated using data from the ORACLES field campaign, which measured these aerosols from aircraft.

Description: 〈b〉Application of Factor and Cluster Analyses to Determine Source–Receptor Relationships of Industrial Volatile Organic Odor Species in a Dual-Optical Sensing System〈/b〉〈br〉 Jen-Chih Yang, Pao-Erh Chang, Chi-Chang Ho, and Chang-Fu Wu〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-344,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 A new approach for the determination of source–receptor relationships of volatile organic odor species in an industrial odor nuisance site is proposed. A dual-optical sensing system and a meteorological station were used collaboratively to generate both receptor and source data. Factor and cluster analyses were employed to improve the quality and completeness of the source profiles. The major odor emission source was identified and future emission reductions can be accomplished accordingly.

Description: 〈b〉Development of a general calibration model and long-term performance evaluation of low-cost sensors for air pollutant gas monitoring〈/b〉〈br〉 Carl Malings, Rebecca Tanzer, Aliaksei Hauryliuk, Sriniwasa P. N. Kumar, Naomi Zimmerman, Levent B. Kara, Albert A. Presto, and R. Subramanian〈br〉 Atmos. Meas. Tech., 12, 903-920, https://doi.org/10.5194/amt-12-903-2019, 2019〈br〉 This paper compares several methods for calibrating data from low-cost air quality monitors to reflect the concentrations of various gaseous pollutants in the atmosphere, identifying the best-performing approaches. With these calibration methods, such monitors can be used to gather information on air quality at a higher spatial resolution than is possible using traditional technologies and can be deployed to areas (e.g. developing countries) where there are no existing monitor networks.

Description: 〈b〉Tropospheric water vapor profiles obtained with FTIR: comparison with balloon-borne frost point hygrometers and influence on trace gas retrievals〈/b〉〈br〉 Ivan Ortega, Rebecca R. Buchholz, Emrys G. Hall, Dale F. Hurst, Allen F. Jordan, and James W. Hannigan〈br〉 Atmos. Meas. Tech., 12, 873-890, https://doi.org/10.5194/amt-12-873-2019, 2019〈br〉 In this work we evaluate the accuracy of water vapor ground-based FTIR retrievals in the lower and upper troposphere using coincident high-quality vertically resolved balloon-borne NOAA FPH measurements. Our results suggest that highly structured water vapor vertical gradients are captured with the FTIR and found a negligible bias in the immediate layer above the instrument altitude accounting for a water vapor time variability of less than 2 %.

Description: 〈b〉Measurements of hydroperoxy radicals (HO〈sub〉2〈/sub〉) at atmospheric concentrations using bromide chemical ionisation mass spectrometry〈/b〉〈br〉 Sascha R. Albrecht, Anna Novelli, Andreas Hofzumahaus, Sungah Kang, Yare Baker, Thomas Mentel, Andreas Wahner, and Hendrik Fuchs〈br〉 Atmos. Meas. Tech., 12, 891-902, https://doi.org/10.5194/amt-12-891-2019, 2019〈br〉 Within this study we demonstrate reliable measurement of hydroperoxy (HO〈sub〉2〈/sub〉) radicals via chemical ionisation mass spectrometry. HO〈sub〉2〈/sub〉 is detected as an ion cluster with bromide ions, which allows a selective detection. This direct and sensitive measurement provides reliable data of HO〈sub〉2〈/sub〉 radical concentrations in the atmosphere as demonstrated in the first application in simulation chamber experiments.

Description: 〈b〉A new MesosphEO data set of temperature profiles from 35 to 85 km using Rayleigh scattering at limb from GOMOS/ENVISAT daytime observations〈/b〉〈br〉 Alain Hauchecorne, Laurent Blanot, Robin Wing, Philippe Keckhut, Sergey Khaykin, Jean-Loup Bertaux, Mustapha Meftah, Chantal Claud, and Viktoria Sofieva〈br〉 Atmos. Meas. Tech., 12, 749-761, https://doi.org/10.5194/amt-12-749-2019, 2019〈br〉 This paper presents a new dataset of temperature profiles in the upper stratosphere and mesosphere acquired with the GOMOS spectrometer on board the European satellite ENVISAT. The principle is to observe the scattering of sunlight by air molecules at the Earth limb. The observed signal is proportional to the atmospheric density from which the temperature is derived. This technique provides a new source of information on temperature where satellite observations are sparse.

Description: 〈b〉Towards imaging of atmospheric trace gases using Fabry–Pérot interferometer correlation spectroscopy in the UV and visible spectral range〈/b〉〈br〉 Jonas Kuhn, Ulrich Platt, Nicole Bobrowski, and Thomas Wagner〈br〉 Atmos. Meas. Tech., 12, 735-747, https://doi.org/10.5194/amt-12-735-2019, 2019〈br〉 We study a novel remote-sensing technique for atmospheric trace gases absorbing in the UV and visible spectral range. Using Fabry–Perot interferometers with a spectral transmission matched to the trace gas's spectral absorption allows for imaging trace gases with high sensitivity and selectivity. The thereby achieved high spatio-temporal resolution enables the study of small-scale and dynamic processes in the atmosphere. We present sample calculations and a proof-of-concept study.

Description: 〈b〉Retrieval of CO〈sub〉2〈/sub〉, CH〈sub〉4〈/sub〉, CO and N〈sub〉2〈/sub〉O using ground- based FTIR data and validation against satellite observations over the Shadnagar, India〈/b〉〈br〉 Mahesh Pathakoti, Sreenivas Gaddamidi, Biswadip Gharai, Sesha Sai Mullapudi Venkata Rama, Rajan Kumar Sundaran, and Wei Wang〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-7,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Present study retrieved improved dry column averaged concentrations of CO2, CH4, CO and N2O using Solar Spectra over the Shadnagar region of India using GFIT model. It is the only site which is equipped with FTIR 125M for measuring the solar spectra to retrieve the precise column GHG while meeting the TCCON standards. Present study also attempted preliminary validation of satellite retrieved column averaged concentrations of CO2 and CO against ground-based FTIR retrieved concentrations.

Description: 〈b〉Cross-verification of simulated GEMS tropospheric ozone retrievals and ozonesonde measurements over Northeast Asia〈/b〉〈br〉 Juseon Bak, Kang-Hyeon Baek, Jae-Hwan Kim, Xiong Liu, Jhoon Kim, and Kelly Chance〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-19,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 GEMS will be launched in late 2019 on board the GeoKOMPSAT (Geostationary Korea Multi-Purpose Satellite) to measure O〈sub〉3〈/sub〉, NO〈sub〉2〈/sub〉, SO〈sub〉2〈/sub〉, H〈sub〉2〈/sub〉CO, CHOCHO, and aerosols in East Asia. To support the development of the GEMS ozone profile algorithm, we perform the cross-verification of simulated GEMS ozone profile retrievals based on the Optimal Estimation and ozonesonde measurements within the GEMS domain.

Description: 〈b〉Seasonal and intra-diurnal variability of small-scale gravity waves in OH airglow at two Alpine stations〈/b〉〈br〉 Patrick Hannawald, Carsten Schmidt, René Sedlak, Sabine Wüst, and Michael Bittner〈br〉 Atmos. Meas. Tech., 12, 457-469, https://doi.org/10.5194/amt-12-457-2019, 2019〈br〉 We use a near-infrared camera for the investigation of gravity waves. The camera observes the airglow layer, which is modulated by the gravity waves. The image processing, including the removal of the stars is explained. We describe the analysis with a 2D fast Fourier transform and automatic derivation of the wave parameters. The results show a clear seasonal and intra-diurnal variability, which is characterised in order to improve our understanding of gravity waves in the middle atmosphere.

Description: 〈b〉Aerosol backscatter profiles from ceilometers: validation of water vapor correction in the framework of CeiLinEx2015〈/b〉〈br〉 Matthias Wiegner, Ina Mattis, Margit Pattantyús-Ábrahám, Juan Antonio Bravo-Aranda, Yann Poltera, Alexander Haefele, Maxime Hervo, Ulrich Görsdorf, Ronny Leinweber, Josef Gasteiger, Martial Haeffelin, Frank Wagner, Jan Cermak, Katerina Komínková, Mike Brettle, Christoph Münkel, and Kornelia Pönitz〈br〉 Atmos. Meas. Tech., 12, 471-490, https://doi.org/10.5194/amt-12-471-2019, 2019〈br〉 Many ceilometers are influenced by water vapor absorption in the spectral range around 910 nm. Thus, a correction is required to retrieve aerosol optical properties. Validation of this correction scheme was performed in the framework of CeiLinEx2015 for several ceilometers with good agreement for Vaisala's CL51 ceilometer. For future applications we recommend monitoring the emitted wavelength and providing 〈q〉dark〈/q〉 measurements on a regular basis to be able to correct for signal artifacts.

Description: 〈b〉Minimizing aerosol effects on the OMI tropospheric NO〈sub〉2〈/sub〉 retrieval – An improved use of the 477 nm O〈sub〉2〈/sub〉 − O〈sub〉2〈/sub〉 band and an estimation of the aerosol correction uncertainty〈/b〉〈br〉 Julien Chimot, J. Pepijn Veefkind, Johan F. de Haan, Piet Stammes, and Pieternel F. Levelt〈br〉 Atmos. Meas. Tech., 12, 491-516, https://doi.org/10.5194/amt-12-491-2019, 2019〈br〉 The reference OMI tropospheric NO〈sub〉2〈/sub〉 product was reprocessed by new aerosol correction parameters retrieved from the 477 nm O〈sub〉2〈/sub〉–O〈sub〉2〈/sub〉 band over eastern China and South America for 2 years. These new parameters are from different and separate algorithms, allowing improved use of the 477 nm O〈sub〉2〈/sub〉–O〈sub〉2〈/sub〉 band. All the tested approaches improve the aerosol correction in the OMI tropospheric NO〈sub〉2〈/sub〉 product. We demonstrate the possibility of applying an explicit aerosol correction based on the 477 nm O〈sub〉2〈/sub〉–O〈sub〉2〈/sub〉 band.

Description: 〈b〉Spatial heterodyne observations of water (SHOW) from a high-altitude airplane: characterization, performance, and first results〈/b〉〈br〉 Jeffery Langille, Daniel Letros, Adam Bourassa, Brian Solheim, Doug Degenstein, Fabien Dupont, Daniel Zawada, and Nick D. Lloyd〈br〉 Atmos. Meas. Tech., 12, 431-455, https://doi.org/10.5194/amt-12-431-2019, 2019〈br〉 The SHOW instrument is a prototype satellite concept that is being developed through collaboration between the University of Saskatchewan, the Canadian Space Agency, and ABB Inc. to provide high vertical resolution (

Description: 〈b〉Polarimetric radar characteristics of lightning initiation and propagating channels〈/b〉〈br〉 Jordi Figueras i Ventura, Nicolau Pineda, Nikola Besic, Jacopo Grazioli, Alessandro Hering, Oscar A. van der Velde, David Romero, Antonio Sunjerga, Amirhossein Mostajabi, Mohammad Azadifar, Marcos Rubinstein, Joan Montanyà, Urs Germann, and Farhad Rachidi-Haeri〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-31,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 This paper presents an analysis of a large dataset of lightning and polarimetric weather radar data collected in the course of a lightning measurement campaign that took place in the summer of 2017 in the area surrounding the Säntis mountain, in the northeastern part of Switzerland. We show that polarimetric weather radar data can be helpful in determining regions where lightning is more likely to occur which is a first step towards a lightning nowcasting system.

Description: 〈b〉The use of QBO, ENSO, and NAO perturbations in the evaluation of GOME-2 MetOp A total ozone measurements〈/b〉〈br〉 Kostas Eleftheratos, Christos S. Zerefos, Dimitris S. Balis, Maria-Elissavet Koukouli, John Kapsomenakis, Diego G. Loyola, Pieter Valks, Melanie Coldewey-Egbers, Christophe Lerot, Stacey M. Frith, Amund S. Haslerud, Ivar S. A. Isaksen, and Seppo Hassinen〈br〉 Atmos. Meas. Tech., 12, 987-1011, https://doi.org/10.5194/amt-12-987-2019, 2019〈br〉 We examine the ability of GOME-2A total ozone data to capture variability related to known natural oscillations, such as the QBO, ENSO and NAO, with respect to other satellite datasets, ground-based data, and chemical transport model simulations. The analysis is based on the GOME-2 satellite total ozone columns for the period 2007–2016 which form part of the operational EUMETSAT AC SAF GOME-2 MetOp A GDP4.8 latest data product.

Description: 〈b〉Trend quality ozone from NPP OMPS: the version 2 processing〈/b〉〈br〉 Richard McPeters, Stacey Frith, Natalya Kramarova, Jerry Ziemke, and Gordon Labow〈br〉 Atmos. Meas. Tech., 12, 977-985, https://doi.org/10.5194/amt-12-977-2019, 2019〈br〉 A version 2 processing of data from the OMPS nadir ozone mapper and nadir ozone profiler on Suomi NPP has now been completed. Total column ozone data from the OMPS nadir mapper now agree with data from the SBUV/2 instrument on NOAA 19, with a zonal average bias of −0.2 % over the 60° S to 60° N latitude zone. For the profile retrieval, zonal average ozone in the upper stratosphere (between 2.5 and 4 hPa) agrees with that from NOAA 19 within ±3 % and an average bias of −1.1 %.

Description: 〈b〉A novel post-processing algorithm for Halo Doppler lidars〈/b〉〈br〉 Ville Vakkari, Antti J. Manninen, Ewan J. O'Connor, Jan H. Schween, Pieter G. van Zyl, and Eleni Marinou〈br〉 Atmos. Meas. Tech., 12, 839-852, https://doi.org/10.5194/amt-12-839-2019, 2019〈br〉 Commercially available Doppler lidars have been proven to be efficient tools for studying winds and turbulence in the planetary boundary layer. However, in many cases low signal is still a limiting factor for utilising measurements by these devices. Here, we present a novel post-processing algorithm for Halo Stream Line Doppler lidars, which enables an improvement in sensitivity of a factor of 5 or more.

Description: 〈b〉Novel Aerosol Flow Reactor to Study Secondary Organic Aerosol〈/b〉〈br〉 Kelly L. Pereira, Grazia Rovelli, Young C. Song, Alfred W. Mayhew, Jonathan P. Reid, and Jacqueline F. Hamilton〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-22,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 We present the design and operation of a newly built continuous flow reactor (CFR) which can be used as a tool to gain considerable insights into the composition and physical state of secondary organic aerosol (SOA). The CFR was used to generate large quantities of SOA mass, allowing the use of highly accurate techniques which are not usually accessible. We demonstrate how this unique approach can be used to investigate the relationship/s between SOA formation and physiochemical properties.

Description: 〈b〉3-D tomographic limb sounder retrieval techniques: irregular grids and Laplacian regularisation〈/b〉〈br〉 Lukas Krasauskas, Jörn Ungermann, Stefan Ensmann, Isabell Krisch, Erik Kretschmer, Peter Preusse, and Martin Riese〈br〉 Atmos. Meas. Tech., 12, 853-872, https://doi.org/10.5194/amt-12-853-2019, 2019〈br〉 Many limb sounder measurements from the same atmospheric region taken at different angles can be combined into a 3-D tomographic image of the atmosphere. Mathematically, this is a complex, computationally expensive, underdetermined problem that needs additional constraints (regularisation). We introduce an improved regularisation method based on physical properties of the atmosphere with a new irregular grid implementation. Simulated data tests show improved results and lower computational cost.

Description: 〈b〉A new method to determine the aerosol optical properties from multiple wavelength O〈sub〉4〈/sub〉 absorptions by MAX-DOAS observation〈/b〉〈br〉 Chengzhi Xing, Cheng Liu, Shanshan Wang, Qihou Hu, Haoran Liu, Wei Tan, Wenqiang Zhang, Bo Li, and Jianguo Liu〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-15,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Ground based MAX-DOAS has been utilized for the remote sensing of aerosol and trace gases more than ten years. Here we developed a new method to determine the aerosol optical properties, including scattering and absorption, etc., from multiple wavelength O〈sub〉4〈/sub〉 absorptions by ground-based MAX-DOAS observation, which were validated well by other independent instruments at low elevations. It is worthy of being expected to obtain the vertical profiles of aerosol properties using multiple elevations.

Description: 〈b〉X-band dual-polarization radar-based hydrometeor classification for Brazilian tropical precipitation systems〈/b〉〈br〉 Jean-François Ribaud, Luiz Augusto Toledo Machado, and Thiago Biscaro〈br〉 Atmos. Meas. Tech., 12, 811-837, https://doi.org/10.5194/amt-12-811-2019, 2019〈br〉 The dominant hydrometeor types associated with Brazilian tropical precipitation systems are identified for the Amazon region during both the wet and dry seasons. Overall the stratiform regions are composed of five hydrometeor classes: drizzle, rain, wet snow, aggregates, and ice crystals, whereas convective echoes are generally associated with light rain, moderate rain, heavy rain, graupel, aggregates and ice crystals.

Description: 〈b〉Flow-induced errors in airborne in-situ measurements of aerosols and clouds〈/b〉〈br〉 Antonio Spanu, Maximilian Dollner, Josef Gasteiger, T. Paul Bui, and Bernadett Weinzierl〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-27,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Aerosols and clouds affect atmospheric radiative processes and climate in many complex ways and still pose the largest uncertainty in current estimates of the Earth’s changing energy budget. 〈br〉〈br〉 Airborne in-situ sensors such as the Cloud, Aerosol, and Precipitation Spectrometer (CAPS) or other optical spectrometers and optical array probes provide detailed information about the horizontal and vertical distribution of aerosol and cloud properties. However, flow distortions occurring at the location where these instruments are mounted on the outside of an aircraft may directly produce artifacts in detected particle number concentration and also cause droplet deformation and/or break-up during the measurement process. 〈br〉〈br〉 Several studies have investigated flow-induced errors assuming that air is incompressible. However, for fast-flying aircraft, the impact of air compressibility is no longer negligible. In this study, we combine airborne data with numerical simulations to investigate the flow around wing-mounted instruments and the induced errors for different realistic flight conditions. A correction scheme for deriving particle number concentrations from in-situ aerosol and cloud probes is proposed, and a new formula is provided for deriving the droplet volume from images taken by optical array probes, reducing errors by up to one order of magnitude. Shape distortions of liquid droplets can either be caused by errors in the speed with which the images are recorded or by aerodynamic forces acting at the droplet surface caused by changes in the airflow around the instrument. These forces can lead to the dynamic breakup of droplets causing artifacts in particle number concentration and size. Furthermore, an estimation of the critical breakup diameter, as a function of flight conditions is provided. 〈br〉〈br〉 Experimental data show that flow speed at the instrument location is smaller than the ambient flow speed. Our simulations confirm the observed difference and reveal a size-dependent impact on particle speed and concentration. This leads, on average, to a 25 % overestimation of the number concentration of particles larger than ~10 μm} diameter and causes distorted images of droplets and ice crystals if the flow values recorded at the instrument are used. With the proposed correction scheme both errors are significantly reduced by a factor 10. 〈br〉〈br〉 Although the presented correction scheme is derived for the DLR Falcon research aircraft (SALTRACE campaign) and validated for the DLR Falcon (A-LIFE campaign) and the NASA DC-8 (ATom campaign), the general conclusions hold for any fast-flying research airplane.

Description: 〈b〉Identification of gas-phase pyrolysis products in a prescribed fire: first detections using infrared spectroscopy for naphthalene, methyl nitrite, allene, acrolein and acetaldehyde〈/b〉〈br〉 Nicole K. Scharko, Ashley M. Oeck, Russell G. Tonkyn, Stephen P. Baker, Emily N. Lincoln, Joey Chong, Bonni M. Corcoran, Gloria M. Burke, David R. Weise, Tanya L. Myers, Catherine A. Banach, David W. T. Griffith, and Timothy J. Johnson〈br〉 Atmos. Meas. Tech., 12, 763-776, https://doi.org/10.5194/amt-12-763-2019, 2019〈br〉 We report five species (naphthalene, methyl nitrite, allene, acrolein and acetaldehyde) that were detected in biomass burning fires that had been seen before in burn studies, but are reported for the first time when using infrared spectroscopy for detection.

Description: 〈b〉Discriminating between clouds and aerosols in the CALIOP version 4.1 data products〈/b〉〈br〉 Zhaoyan Liu, Jayanta Kar, Shan Zeng, Jason Tackett, Mark Vaughan, Melody Avery, Jacques Pelon, Brian Getzewich, Kam-Pui Lee, Brian Magill, Ali Omar, Patricia Lucker, Charles Trepte, and David Winker〈br〉 Atmos. Meas. Tech., 12, 703-734, https://doi.org/10.5194/amt-12-703-2019, 2019〈br〉 We describe the enhancements made to the cloud–aerosol discrimination (CAD) algorithms used to produce the CALIPSO version 4 (V4) data products. Revisions to the CAD probability distribution functions have greatly improved the recognition of aerosol layers lofted into the upper troposphere, and CAD is now applied to all layers detected in the stratosphere and all layers detected at single-shot resolution. Detailed comparisons show significant improvements relative to previous versions.

Description: 〈b〉Humidity effects on the detection of soluble and insoluble nanoparticles in butanol operated condensation particle counters〈/b〉〈br〉 Christian Tauber, Sophia Brilke, Peter Josef Wlasits, Paulus Salomon Bauer, Gerald Köberl, Gerhard Steiner, and Paul Martin Winkler〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-23,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 In this manuscript we show that sodium chloride particles with a mobility diameter below 10 nm indicate different activation regimes. The results of our studies reveal that with increasing humidity the activation of NaCl particles with a standard butanol-based CPC can be enhanced. For Ag this humidity dependence could not be observed – an indicator for the importance of molecular interactions between seed and vapor molecules.

Description: 〈b〉Photoacoustic measurement may significantly overestimate NH〈sub〉3〈/sub〉 emissions from cattle houses due to VOC interferences〈/b〉〈br〉 Dezhao Liu, Li Rong, Jesper Kamp, Xianwang Kong, Anders Peter Adamsen, Albarune Chowdhury, and Anders Feilberg〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-412,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 〈p〉Infrared photoacoustic spectroscopy (PAS) is a widely used method for measurement of NH〈sub〉3〈/sub〉 and greenhouse gas emissions especially in agriculture, but non-targeted gases such as volatile organic compounds (VOCs) from cattle barns may interfere with target gases causing inaccurate results. This study made an estimation of NH〈sub〉3〈/sub〉 interference in PAS caused by selected non-targeted VOCs which were simultaneously measured by a PAS and a PTR-MS (proton transfer reaction mass spectrometry). Laboratory calibration were performed for NH〈sub〉3〈/sub〉 measurement and VOCs were selected based on a headspace test of the feeding material maize silage. Various levels of interference of tested VOCs were observed on NH〈sub〉3〈/sub〉 and greenhouse emissions measured by the PAS. Particularly, ethanol, methanol, 1-butanol, 1-propanol and acetic acid were found to have highest interference on NH〈sub〉3〈/sub〉. A linear response was typically obtained, with non-linear relation was however observed for VOCs on N〈sub〉2〈/sub〉O emissions. The corrected online NH〈sub〉3〈/sub〉 concentrations measured by the PAS from a field study were confirmed to be reasonably correlated to the NH〈sub〉3〈/sub〉 concentration measured simultaneously by the PTR-MS. It was concluded that the correction factors could be used for possible data corrections when the concentrations of VOCs could be obtained by using e.g. PTR-MS.〈/p〉

Description: 〈b〉Characterization of the particle emission from a ship operating at sea using an unmanned aerial vehicle〈/b〉〈br〉 Tommaso F. Villa, Reece A. Brown, E. Rohan Jayaratne, L. Felipe Gonzalez, Lidia Morawska, and Zoran D. Ristovski〈br〉 Atmos. Meas. Tech., 12, 691-702, https://doi.org/10.5194/amt-12-691-2019, 2019〈br〉 This research demonstrates the use of an unmanned aerial vehicle (UAV) to characterize the gaseous and diesel particle emissions of a ship at sea. The field study was part of the research voyage “The Great Barrier Reef as a significant source of climatically relevant aerosol particles” on board the RV 〈i〉Investigator〈/i〉 around the Australian Great Barrier Reef. Measurements of the RV 〈i〉Investigator〈/i〉 exhaust plume were carried out while the ship was operating at sea, at a steady engine load.

Description: 〈b〉Can liquid cloud microphysical processes be used for vertically-pointing cloud radar calibration?〈/b〉〈br〉 Maximilian Maahn, Fabian Hoffmann, Matthew D. Shupe, Gijs de Boer, Sergey Y. Matrosov, and Edward P. Luke〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-20,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Cloud radars are unique instruments for observing cloud processes, but uncertainties in radar calibration have frequently limited data quality. Here, we present, apply and evaluate three novel methods for calibrating vertically pointing cloud radars. These calibration methods are based on microphysical processes of liquid clouds such as the transition of cloud droplets to drizzle drops.

Description: 〈b〉Technical note: Absorption aerosol optical depth components from AERONET observations of mixed dust plumes〈/b〉〈br〉 Sung-Kyun Shin, Matthias Tesche, Detlef Müller, and Youngmin Noh〈br〉 Atmos. Meas. Tech., 12, 607-618, https://doi.org/10.5194/amt-12-607-2019, 2019〈br〉 We present a methodology to infer the contribution of mineral dust and non-dust aerosol to the absorbing aerosol optical depth (AAOD) of mixed aerosol layers. The method presents an adaptation of a lidar-based aerosol-type separation technique to passive measurements with AERONET sun photometers by using lidar-specific parameters obtained from the AERONET inversion. The findings on BC-related AAOD are compared to CAMS aerosol reanalysis data with promising results for sites in east Asia.

Description: 〈b〉Updated MISR over-water research aerosol retrieval algorithm – Part 2: A multi-angle aerosol retrieval algorithm for shallow, turbid, oligotrophic, and eutrophic waters〈/b〉〈br〉 James A. Limbacher and Ralph A. Kahn〈br〉 Atmos. Meas. Tech., 12, 675-689, https://doi.org/10.5194/amt-12-675-2019, 2019〈br〉 Coastal waters serve as transport pathways to the ocean for all runoff from terrestrial sources; they are also some of the most biologically productive waters on the planet. Here, we retrieve atmospheric aerosol loading (and properties) from the space-based instrument MISR over all types of water (dark, coastal, etc). Results from the MISR research aerosol retrieval algorithm agree well with validation, indicating that MISR may add value to commonly used ocean color imagers such as MODIS.

Description: 〈b〉A Fourier transform spectroradiometer for ground-based remote sensing of the atmospheric downwelling long-wave radiance〈/b〉〈br〉 Giovanni Bianchini, Francesco Castagnoli, Gianluca Di Natale, and Luca Palchetti〈br〉 Atmos. Meas. Tech., 12, 619-635, https://doi.org/10.5194/amt-12-619-2019, 2019〈br〉 The characterization of infrared radiation emitted by the atmosphere is a crucial task in the study of the Earth's climate. The Radiation Explorer in the Far Infrared (REFIR) spectroradiometer allows us to perform this task adding the capability of resolving, through spectroscopy, the atmospheric components responsible for the measured radiative effects. The analysis of the measurements also allows us to retrieve the atmospheric structure, making REFIR a complete tool for atmospheric studies.

Description: 〈b〉A decade of CH〈sub〉4〈/sub〉, CO and N〈sub〉2〈/sub〉O in situ measurements at Lauder, New Zealand: assessing the long-term performance of a Fourier transform infrared trace gas and isotope analyser〈/b〉〈br〉 Dan Smale, Vanessa Sherlock, David W. T. Griffith, Rowena Moss, Gordon Brailsford, Sylvia Nichol, and Michael Kotkamp〈br〉 Atmos. Meas. Tech., 12, 637-673, https://doi.org/10.5194/amt-12-637-2019, 2019〈br〉 We present a 10-year (Jan 2007–Dec 2016) time series of continuous in situ measurements of methane, carbon monoxide and nitrous oxide made by an in situ Fourier transform infrared trace gas and isotope analyser operated at Lauder, New Zealand. We perform a practical evaluation of multi-year performance of the analyser and report on operational methodology, measurement precision, reproducibility, accuracy and instrument reliability.

Description: 〈b〉Simultaneous observations by sky radiometer and MAX-DOAS for characterization of biomass burning plumes in central Thailand in January–April 2016〈/b〉〈br〉 Hitoshi Irie, Hossain Mohammed Syedul Hoque, Alessandro Damiani, Hiroshi Okamoto, Al Mashroor Fatmi, Pradeep Khatri, Tamio Takamura, and Thanawat Jarupongsakul〈br〉 Atmos. Meas. Tech., 12, 599-606, https://doi.org/10.5194/amt-12-599-2019, 2019〈br〉 The first intensive multicomponent observation by sky radiometer and MAX-DOAS was performed in Thailand during the 2016 dry season. We found that the concentration of formaldehyde (HCHO) was a useful tracer for biomass burning plumes. With the HCHO enhancement, the ratio of gaseous glyoxal to HCHO concentrations decreased and the aerosol absorption optical depths (AAODs) increased. The wavelength dependence of AAODs was quantified, providing evidence for the presence of brown carbon aerosols.

Description: 〈b〉Cloud identification and classification from high spectral resolution data in the far and mid infrared〈/b〉〈br〉 Tiziano Maestri, William Cossich, and Iacopo Sbrolli〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-28,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 A new algorithm (CIC) for cloud identification and classification from passive remote sensing data is introduced. CIC is tested on a large synthetic dataset simulating measurements from the ESA Earth Explorer Fast Track 9 competing mission FORUM (Far Infrared Outgoing Radiation Understanding and Monitoring). The high information content within the far infrared part of the spectrum is exploited to improve clouds (especially cirri) detection scores obtained from mid infrared data only.

Description: 〈b〉Linearization of the effect of slit function changes for improving OMI ozone profile retrievals〈/b〉〈br〉 Juseon Bak, Xiong Liu, Kang Sun, Kelly Chance, and Jae-Hwan Kim〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-47,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 This work improves OMI ozone profile retrievals by accounting for spectral fit residuals caused by the slit function errors as a pseudo absorbers in optimal estimation based spectral fitting process.

Description: 〈b〉Evaluating and Improving the Reliability of Gas-Phase Sensor System Calibrations Across New Locations for Ambient Measurements and Personal Exposure Monitoring〈/b〉〈br〉 Sharad Vikram, Ashley Collier-Oxandale, Michael Ostertag, Massimiliano Menarini, Camron Chermak, Sanjoy Dasgupta, Tajana Rosing, Michael Hannigan, and William G. Griswold〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-30,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Low-cost air quality sensors are enabling people to collect data to better understand their local environment and potential exposures. However, there is some concern regarding how reliable the calibrations of these sensors are in new and different environments. To explore this issue, our team co-located sensors at three different sites with high-quality monitoring instruments to compare to. We explored the transferability of calibration models as well as approaches to improve reliability.

Description: 〈b〉All-sky assimilation of infrared radiances sensitive to mid- and upper-tropospheric moisture and cloud〈/b〉〈br〉 Alan J. Geer, Stefano Migliorini, and Marco Matricardi〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-9,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Satellite radiance observations are used to initialise weather forecasts, but only recently have the data been used in conditions of cloud and precipitation. By starting to fill this gap in coverage of the earth's atmosphere using data taken in the microwave part of the spectrum, the quality of operational forecasts has been improved. The current work shows that cloudy infrared data, with its stronger and more nonlinear sensitivity, can also benefit operational-quality forecasts.

Description: 〈b〉Aerosol optical depth retrievals in central Amazonia from a multi-filter rotating shadow-band radiometer calibrated on-site〈/b〉〈br〉 Nilton E. Rosário, Thamara Sauini, Theotonio Pauliquevis, Henrique M. J. Barbosa, Marcia A. Yamasoe, and Boris Barja〈br〉 Atmos. Meas. Tech., 12, 921-934, https://doi.org/10.5194/amt-12-921-2019, 2019〈br〉 Does pristine Amazonian forest atmosphere provide successful calibration of a Sun photometer based on the Langley plot method? This question emerged from the challenge of maintaining regular calibration of a Sun photometer dedicated to long-term monitoring of aerosol optical properties in Amazonia, far from clean mountaintops. Our results show that on-site calibrated Sun photometers, under pristine Amazonian conditions, are able to provide consistent retrieval of aerosol optical depth.

Description: 〈b〉Evaluation of differential absorption radars in the 183 GHz band for profiling water vapour in ice clouds〈/b〉〈br〉 Alessandro Battaglia and Pavlos Kollias〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-14,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 This work investigates the potential of an innovative differential absorption radar in retrieving relative humidity inside ice clouds. The radar exploits the strong spectral dependence of the water vapour absorption for frequency close to the 183 GHz water vapour band. Results show that observations from a system with 4–6 frequencies can provide novel information for understanding the formation and growth of ice crystals.

Description: 〈b〉Separation and detection of aqueous atmospheric aerosol mimics using supercritical fluid chromatography–mass spectrometry〈/b〉〈br〉 Daisy N. Grace, Melissa B. Sebold, and Melissa M. Galloway〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-42,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 The identification and quantification of compounds within an atmospheric particle can be difficult to achieve. We present a new supercritical fluid chromatography method to separate these compounds prior to mass spectrometry analysis. The aqueous methylglyoxal-ammonium sulfate system was used as a proxy for atmospheric aerosol; polar columns combined with a carbon dioxide and methanol mobile phase provided the most efficient separation. This method can be extended to other atmospheric systems.

Description: 〈b〉Structural changes of CAST soot during a thermal-optical measurement protocol〈/b〉〈br〉 Theresa Haller, Christian Rentenberger, Jannik C. Meyer, Laura Felgitsch, Hinrich Grothe, and Regina Hitzenberger〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-10,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 In thermal-optical measurement techniques – widely used techniques to separate organic and elemental carbon – a filter sample is heated stepwise first in He, then in He+O〈sub〉2〈/sub〉. Pyrolysis of organic material occurring during heating in He influences the results but is not fully understood. In this study, structural changes of carbonaceous material during a thermal-optical heating procedure are analyzed with Raman spectroscopy, TEM, UV-VIS and the integrating sphere method.

Description: 〈b〉Measurements of Delays of Gas-Phase Compounds in a Wide Variety of Tubing Materials due to Gas-Wall Interactions〈/b〉〈br〉 Benjamin Deming, Demetrios Pagonis, Xiaoxi Liu, Douglas Day, Ranajit Talukdar, Jordan Krechmer, Joost A. de Gouw, Jose L. Jimenez, and Paul J. Ziemann〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-25,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Losses or measurement delays of gas-phase compounds sampled through tubing are important to atmospheric science. Here we characterize 14 tubing materials by measuring the effects on step changes in organic compound concentration. We find that polymeric tubings exhibit absorptive partitioning behaviour while glass and metal tubings show adsorptive partitioning. Adsorptive materials impart complex humidity, concentration, and VOC-VOC interaction dependencies that absorptive tubings do not.

Description: 〈b〉Joint retrieval of surface reflectance and aerosol properties with continuous variation of the state variables in the solution space – Part 2: application to geostationary and polar-orbiting satellite observations〈/b〉〈br〉 Marta Luffarelli and Yves Govaerts〈br〉 Atmos. Meas. Tech., 12, 791-809, https://doi.org/10.5194/amt-12-791-2019, 2019〈br〉 This paper presents the application of the CISAR (Combined Inversion of Surface and AeRosol) algorithm on both geostationary (SEVIRI) and polar-orbiting (Proba-V) satellite data. This paper analyses the information content associated with the observations acquired by these two instruments and its implication on the joint retrieval of surface and atmospheric properties. CISAR-retrieved aerosol properties and surface albedo are compared with the AERONET and MODIS data respectively.

Description: 〈b〉Retrieval of aerosol properties from ceilometer and photometer measurements: long-term evaluation with in-situ data and statistical analysis at Montsec (southern Pyrenees)〈/b〉〈br〉 Gloria Titos, Marina Ealo, Roberto Román, Alberto Cazorla, Yolanda Sola, Oleg Dubovik, Andrés Alastuey, and Marco Pandolfi〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-431,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 We present new results of vertically-resolved extensive aerosol optical properties (backscattering, scattering and extinction) and volume concentrations retrieved with the GRASP algorithm from ceilometer and photometer measurements. Long-term evaluation with in-situ data gathered at the Montsec mountaintop observatory (northeastern Spain) shows good agreement, being a step-forward towards a better representation of aerosol vertical distribution with wide spatial coverage.

Description: 〈b〉Method to retrieve cloud condensation nuclei number concentrations using lidar measurements〈/b〉〈br〉 Wangshu Tan, Gang Zhao, Yingli Yu, Chengcai Li, Jian Li, Ling Kang, Tong Zhu, and Chunsheng Zhao〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-21,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 〈p〉Determination of cloud condensation nuclei (CCN) number concentrations at cloud base is important to constrain aerosol-cloud interactions. A new method to retrieve CCN number concentrations using backscatter and extinction profiles from multiwavelength Raman lidars is proposed. The method implements hygroscopic enhancements of backscatter/extinction with relative humidity to derive dry backscatter/extinction and humidogram parameters. Humidogram parameters, Ångström exponents, and lidar extinction-to-backscatter ratios are then linked to the ratio of CCN number concentration to dry backscatter/extinction coefficient (AR〈sub〉ξ〈/sub〉). This linkage is established based on the datasets simulated by Mie theory and κ-Köhler theory with in situ measured particle size distributions and chemical compositions. CCN number concentration can thus be calculated with AR〈sub〉ξ〈/sub〉 and dry backscatter/extinction. An independent theoretical simulated datasets is used to validate this new method and results show that the retrieved CCN number concentrations at supersaturations of 0.07 %, 0.10 %, and 0.20 % are in good agreement with theoretical calculated values. Sensitivity tests indicate that retrieval error in CCN arise mostly from uncertainties in extinction coefficients and RH profiles. The proposed method improves CCN retrieval from lidar measurements and has great potential in deriving scarce long-term CCN data at cloud base which benefits aerosol-cloud interaction studies.〈/p〉

Description: 〈b〉ELIFAN, an algorithm for the estimation of cloud cover from sky imagers〈/b〉〈br〉 Marie Lothon, Paul Barnéoud, Omar Gabella, Fabienne Lohou, Solène Derrien, Sylvain Rondi, Marjolaine Chiriaco, Sophie Bastin, Jean-Charles Dupont, Martial Haeffelin, Jordi Badosa, Nicolas Pascal, and Nadège Montoux〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-452,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 In the context of an atmospheric network of instrumented sites equipped with sky camera for cloud monitoring, we present an algorithm named ELIFAN which aims at estimating the cloud cover amount from full sky visible daytime images. ELIFAN is based on red over blue ratio thresholding applied on the image pixels, and on the use of a blue sky library. We present its principle, its performance, and highlight the interest of combining several complementary instruments.

Description: 〈b〉Retrieval of convective available potential energy from INSAT-3D measurements: comparison with radiosonde data and their spatial–temporal variations〈/b〉〈br〉 Uriya Veerendra Murali Krishna, Subrata Kumar Das, Kizhathur Narasimhan Uma, and Govindan Pandithurai〈br〉 Atmos. Meas. Tech., 12, 777-790, https://doi.org/10.5194/amt-12-777-2019, 2019〈br〉 Convective available potential energy (CAPE) is an indicator of the occurrence of extreme weather. For the first time over India, this study estimated CAPE from high spatial–temporal resolution measurements of the geostationary satellite, INSAT-3D. INSAT-3D estimates that CAPE reasonably represents the radiosonde CAPE. This study allows the atmospheric science community to select the best available dataset for their use in nowcasting and making severe weather warnings based on numerical models.

Description: 〈b〉Description of a formaldehyde retrieval algorithm for the Geostationary Environment Monitoring Spectrometer (GEMS)〈/b〉〈br〉 Hyeong-Ahn Kwon, Rokjin J. Park, Gonzalo González Abad, Kelly Chance, Thomas P. Kurosu, Jhoon Kim, Isabelle De Smedt, Michel Van Roozendael, Enno Peters, and John Burrows〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-2,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 The Geostationary Environment Monitoring Spectrometer (GEMS) will be launched by South Korea in 2019, and it will measure radiances ranging from 300 to 500 nm every hour with a fine spatial resolution of 7 × 8 km〈sup〉2〈/sup〉 over Seoul in South Korea to monitor column concentrations of air pollutants including O〈sub〉3〈/sub〉, NO〈sub〉2〈/sub〉, SO〈sub〉2〈/sub〉, and HCHO, and aerosol optical properties. This paper describes a GEMS formaldehyde retrieval algorithm including a number of sensitivity tests for algorithm evaluation.

Description: 〈b〉Correcting atmospheric CO〈sub〉2〈/sub〉 and CH〈sub〉4〈/sub〉 mole fractions obtained with Picarro analyzers for sensitivity of cavity pressure to water vapor〈/b〉〈br〉 Friedemann Reum, Christoph Gerbig, Jost V. Lavric, Chris W. Rella, and Mathias Göckede〈br〉 Atmos. Meas. Tech., 12, 1013-1027, https://doi.org/10.5194/amt-12-1013-2019, 2019〈br〉 Atmospheric CO〈sub〉2〈/sub〉 and CH〈sub〉4〈/sub〉 mole fractions are often measured using greenhouse gas analyzers manufactured by Picarro, Inc. We report biases in these measurements that are related to pressure changes in the optical cavity of the analyzers and occur mainly at low water vapor mole fractions. We provide a method to correct the biases, which contributes to keeping the overall accuracy of CO〈sub〉2〈/sub〉 and CH〈sub〉4〈/sub〉 measurements with Picarro analyzers within the WMO interlaboratory compatibility goals.

Description: 〈b〉Possible errors in flux measurements due to limited digitalization〈/b〉〈br〉 Thomas Foken, Wolfgang Babel, and Christoph Thomas〈br〉 Atmos. Meas. Tech., 12, 971-976, https://doi.org/10.5194/amt-12-971-2019, 2019〈br〉 Recently reported trends of carbon dioxide uptake pose the question of whether trends may be the result of the limited digitalization of gas analysers and sonic anemometers used in the 1990s. Modifying a 12 bit digitalization and the instrument error reported for the R2 and R3 sonic anemometers found elsewhere, the influence of these deficits in comparison to the now commonly used 16 bit digitalization were quantified. Both issues have an effect only on trace gas fluxes of small magnitude.

Description: 〈b〉Improving the mean and uncertainty of ultraviolet multi-filter rotating shadowband radiometer in situ calibration factors: utilizing Gaussian process regression with a new method to estimate dynamic input uncertainty〈/b〉〈br〉 Maosi Chen, Zhibin Sun, John M. Davis, Yan-An Liu, Chelsea A. Corr, and Wei Gao〈br〉 Atmos. Meas. Tech., 12, 935-953, https://doi.org/10.5194/amt-12-935-2019, 2019〈br〉 Combining a new dynamic uncertainty estimation method with Gaussian process regression (GP), we provide a generic and robust solution to estimate the underlying mean and uncertainty functions of time series with variable mean, noise, sampling density, and length of gaps. The GP solution was applied and validated on three UV-MFRSR Vo time series at three ground sites with improved accuracy of the smoothed time series in terms of aerosol optical depth compared with two other smoothing methods.

Description: 〈b〉Enhancing the spatiotemporal features of polar mesosphere summer echoes using coherent MIMO and radar imaging at MAARSY〈/b〉〈br〉 Juan Miguel Urco, Jorge Luis Chau, Tobias Weber, and Ralph Latteck〈br〉 Atmos. Meas. Tech., 12, 955-969, https://doi.org/10.5194/amt-12-955-2019, 2019〈br〉 For decades, radar observations have been used to study complicated atmospheric dynamics. Previous observations of the mesosphere, between 80 and 90 km altitude, over polar regions have been limited to a spatial resolution of a few kilometers. In this work, we present a technique which allows 3-D radar observations of the mesospheric dynamics, with an unprecedented spatial resolution of ~ 900 m. We combine the concept of MIMO and high-resolution algorithms to improve the spatial resolution.

Description: 〈b〉Relationship Analysis of PM〈sub〉2.5〈/sub〉 and BLH using Aerosol and Turbulence Detection Lidar〈/b〉〈br〉 Chong Wang, Mingjiao Jia, Haiyun Xia, Yunbin Wu, Tianwen Wei, Xiang Shang, Chengyun Yang, Xianghui Xue, and Xiankang Dou〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-406,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 To investigate the relationship between BLH and air pollution under different conditions, a compact micro-pulse lidar integrated both direct detection lidar and coherent Doppler wind lidar is built. Evolution of atmospheric boundary layer height (BLH), aerosol layer and fine structure in cloudbase are well retrieved. Negative correlation exists between BLH and PM2〈sub〉2.5〈/sub〉. Different trends show that the relationship between PM〈sub〉2.5〈/sub〉 and BLH should be considered in different boundary layer categories.

Description: 〈b〉Assimilation of GNSS tomography products into WRF using radio occultation data assimilation operator〈/b〉〈br〉 Natalia Hanna, Estera Trzcina, Gregor Möller, Witold Rohm, and Robert Weber〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-419,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 In the study, the potential of GNSS tomography as an important supplementary data source for Numerical Weather Prediction models was examined. We used the two GNSS tomography models (TUW, WUELS) in different configurations. The GNSS tomography outputs were assimilated into the WRF model using a radio occultation observations operator (non-standard approach). Promising results show the improvement in the weather forecasting of relative humidity and temperature during heavy precipitation events.

Description: 〈b〉Pan-Arctic measurements of wintertime water vapour column using a satellite-borne microwave radiometer〈/b〉〈br〉 Christopher Perro, Thomas J. Duck, Glen Lesins, Kimberly Strong, Penny M. Rowe, James R. Drummond, and Robert J. Sica〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-381,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 A satellite retrieval for water vapour column was adapted for use over different surfaces in the wintertime Arctic. The retrieval was validated at multiple locations where there was excellent agreement. Reanalyses were found to be 10–15 % drier compared to our water vapour retrieval. Reanalyses represent the present day understanding of the atmosphere so this discrepancy between reanalyses and our retrieval could have implications for the current understanding of the climate.

Description: 〈b〉Atmospheric bending effects in GNSS tomography〈/b〉〈br〉 Gregor Möller and Daniel Landskron〈br〉 Atmos. Meas. Tech., 12, 23-34, https://doi.org/10.5194/amt-12-23-2019, 2019〈br〉 The paper describes a ray-tracing approach for the proper reconstruction of GNSS signal paths through the lower atmosphere, identifies possible error sources during ray tracing and provides a strategy for reducing their effect on the GNSS tomography solution, thereby contributing to a more reliable reconstruction of the 3-D water vapor distribution in the lower atmosphere from GNSS measurements.

Description: 〈b〉CALIPSO lidar calibration at 1064 nm: version 4 algorithm〈/b〉〈br〉 Mark Vaughan, Anne Garnier, Damien Josset, Melody Avery, Kam-Pui Lee, Zhaoyan Liu, William Hunt, Jacques Pelon, Yongxiang Hu, Sharon Burton, Johnathan Hair, Jason L. Tackett, Brian Getzewich, Jayanta Kar, and Sharon Rodier〈br〉 Atmos. Meas. Tech., 12, 51-82, https://doi.org/10.5194/amt-12-51-2019, 2019〈br〉 The version 4 (V4) release of the CALIPSO data products includes substantial improvements to the calibration of the CALIOP 1064 nm channel. In this paper we review the fundamentals of 1064 nm lidar calibration, explain the motivations for the changes made to the algorithm, and describe the mechanics of the V4 calibration technique. Internal consistency checks and comparisons to collocated high spectral resolution lidar measurements show the V4 1064 nm calibration coefficients to within ~ 3 %.

Description: 〈b〉Using a speed-dependent Voigt line shape to retrieve O〈sub〉2〈/sub〉 from Total Carbon Column Observing Network solar spectra to improve measurements of XCO〈sub〉2〈/sub〉〈/b〉〈br〉 Joseph Mendonca, Kimberly Strong, Debra Wunch, Geoffrey C. Toon, David A. Long, Joseph T. Hodges, Vincent T. Sironneau, and Jonathan E. Franklin〈br〉 Atmos. Meas. Tech., 12, 35-50, https://doi.org/10.5194/amt-12-35-2019, 2019〈br〉 In order to study the carbon cycle, accurate remote sensing measurements of XCO〈sub〉2〈/sub〉 are required. This means that accurate absorption coefficients of CO〈sub〉2〈/sub〉 and O〈sub〉2〈/sub〉 in the retrieval algorithm are required. We use high-resolution laboratory spectra of O〈sub〉2〈/sub〉 to derive accurate absorption coefficients. By applying the O〈sub〉2〈/sub〉 absorption coefficients to the retrieval of XCO〈sub〉2〈/sub〉 from ground-based solar absorption spectra we show that the error on retrieved XCO〈sub〉2〈/sub〉 is decreased.

Description: 〈b〉Cavity-enhanced photoacoustic sensor based on a whispering-gallery-mode diode laser〈/b〉〈br〉 Yufeng Pan, Lei Dong, Hongpeng Wu, Weiguang Ma, Lei Zhang, Wangbao Yin, Liantuan Xiao, Suotang Jia, and Frank K. Tittel〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-457,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Photoacoustic spectroscopy has one important advantage: its sensitivity is proportional to the excitation light power and thus the performance of PAS-based sensors can benefit from a high excitation light power. We developed a cavity-enhanced photoacoustic sensor in which a photoacoustic cell was placed into a high finesse optical cavity. A signal gain factor of 166 was observed. For C〈sub〉2〈/sub〉H〈sub〉2〈/sub〉 detection, a 1σ detection limit of 0.45 ppmV was obtained at atmospheric pressure with a 1-s averaging time.

Description: 〈b〉Development of a balloon-borne instrument for CO〈sub〉2〈/sub〉 vertical profile observations in the troposphere〈/b〉〈br〉 Mai Ouchi, Yutaka Matsumi, Tomoki Nakayama, Kensaku Shimizu, Takehiko Sawada, Toshinobu Machida, Hidekazu Matsueda, Yousuke Sawa, Isamu Morino, Osamu Uchino, Tomoaki Tanaka, and Ryoichi Imasu〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-376,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 A novel, practical observation system for measuring tropospheric carbon dioxide (CO〈sub〉2〈/sub〉) concentrations carried by a small helium-filled balloon (CO〈sub〉2〈/sub〉 sonde), has been developed for the first time. The low-cost CO〈sub〉2〈/sub〉 sondes can potentially be used for frequently measurements of vertical profiles of CO〈sub〉2〈/sub〉 in any parts of the world providing as useful information to understand the global and regional carbon budgets by replenishing the present sparse observation coverage.

Description: 〈b〉Improved aerosol correction for OMI tropospheric NO〈sub〉2〈/sub〉 retrieval over East Asia: constraint from CALIOP aerosol vertical profile〈/b〉〈br〉 Mengyao Liu, Jintai Lin, K. Folkert Boersma, Gaia Pinardi, Yang Wang, Julien Chimot, Thomas Wagner, Pinhua Xie, Henk Eskes, Michel Van Roozendael, François Hendrick, Pucai Wang, Ting Wang, Yingying Yan, Lulu Chen, and Ruijing Ni〈br〉 Atmos. Meas. Tech., 12, 1-21, https://doi.org/10.5194/amt-12-1-2019, 2019〈br〉 China has become the world’s largest emitter of NO〈sub〉〈i〉x〈/i〉〈/sub〉, which mainly comes from vehicle exhaust, power plants, etc. However, there are no official ground-based measurements before 2013, so satellites have been widely used to monitor and analyze NO〈sub〉〈i〉x〈/i〉〈/sub〉 pollution here. Aerosol is the key factor influencing the accuracy of the satellite NO〈sub〉〈i〉x〈/i〉〈/sub〉 product. Our study provides a more accurate way to account for aerosol's influence compared to current widely used products.

Description: 〈b〉Automated Wind Turbine Wake Characterization in Complex Terrain〈/b〉〈br〉 Rebecca J. Barthelmie and Sara C. Pryor〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-461,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Wakes are low wind speed volumes of air downwind of wind turbines. Wake properties/behaviour determine optimal turbine spacing in wind farms. The objective is to develop an automated system to measure and detect wind turbine wakes. The paper presents measurements and analyses of six months of measurements with a scanning Doppler lidar at a complex terrain site in Portugal. Wakes are successfully detected and characterized and their behavior linked to wind speed and other atmospheric conditions.

Description: 〈b〉Comparison between the assimilation of IASI Level 2 retrievals and Level 1 radiances for ozone reanalyses〈/b〉〈br〉 Emanuele Emili, Brice Barret, Eric Le Flochmoën, and Daniel Cariolle〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-426,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 We examine the differences between assimilating ozone profiles retrieved from IASI and the corresponding infrared spectra in a chemical transport model. The motivation was to quantify the impact of the retrieval's prior on ozone reanalyses. We found that significant differences arise between the two approaches, depending on the latitude. In general, superior results are obtained assimilating directly IASI radiances. This suggests interesting implications for highly coupled Earth system models.

Description: 〈b〉Evaluation of wake influence on high-resolution balloon-sonde measurements〈/b〉〈br〉 Jens Söder, Michael Gerding, Andreas Schneider, Andreas Dörnbrack, Henrike Wilms, Johannes Wagner, and Franz-Josef Lübken〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-449,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Atmospheric measurements on rising balloons can be compromised by the balloon's wake. The aim of this study is to provide a tool for assessing the likelihood of encountering the balloon's wake at the position of the gondola. This includes an uncertainty analysis of the calculation and a retrieval of vertical winds. We find an average wake encounter probability of 28 % for a standard radiosonde. Additionally, we evaluate the influence of wake from smaller objects on turbulence measurements.

Description: 〈b〉Using Doppler lidar systems to detect atmospheric turbulence in Iceland〈/b〉〈br〉 Shu Yang, Guðrún Nína Petersen, Sibylle von Löwis, Jana Preißler, and David Christian Finger〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-3,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Lidar is an instrument similar to radar but can ‘see’ smaller particles in the air. The small particles in the air will move, driven by wind. Thus lidar can detect this movement, and measure the wind. We use lidars in Iceland to detect wind and developed an algorithm to identify and quantify the turbulence from lidar data, so we can see where and when the turbulence is happening and how strong the turbulence is, in near-real time. This could be valuable to air traffic controllers.

Description: 〈b〉A shape model of internally mixed soot particles derived from artificial surface tension〈/b〉〈br〉 Hiroshi Ishimoto, Rei Kudo, and Kouji Adachi〈br〉 Atmos. Meas. Tech., 12, 107-118, https://doi.org/10.5194/amt-12-107-2019, 2019〈br〉 We developed a shape model of coated soot particles and created a dataset of their optical properties. To simulate the detailed shape properties of mixtures of soot aggregates and adhered water-soluble substances, we propose a simple model of surface tension derived from the artificial surface potential. The results of some single-scattering properties including lidar backscattering were discussed.

Description: 〈b〉Analysis Algorithm for Sky Type and Ice Halo Recognition in All-Sky Images〈/b〉〈br〉 Sylke Boyd, Stephen Sorenson, Shelby Richard, Michelle King, and Morton Greenslit〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-401,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 How cirroform clouds affect the radiation balance of the atmosphere depends on their properties, including ice particle types such as crystals, pellets, fragments etc. Ice halos form if ice particles in these clouds are in smooth hexagonal crystalline form. This paper introduces a method to search long-term records of sky images for ice halos, which will allow to explore geographical and seasonal variations in cirrus cloud particle types.

Description: 〈b〉A new laser–based and ultra–portable gas sensor for indoor and outdoor formaldehyde (HCHO) monitoring〈/b〉〈br〉 Joshua D. Shutter, Norton T. Allen, Thomas F. Hanisco, Glenn M. Wolfe, Jason M. St. Clair, and Frank N. Keutsch〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-443,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 A new mid-infrared and ultra-portable formaldehyde (HCHO) sensor from Aeris Technologies is characterized and evaluated against well-established laser-induced fluorescence (LIF) instrumentation. The Aeris sensor displays linear behavior (R-squared 〉 0.94) and shows good agreement with LIF instruments. While the compact sensor is not currently a replacement for the most sensitive research-grade instrumentation available, its sub-ppbv precision is sufficient for indoor and outdoor HCHO monitoring.

Description: 〈b〉Strategies of Method Selection for Fine Scale PM〈sub〉2.5〈/sub〉 Mapping in Intra-Urban Area Under Crowdsourcing Monitoring〈/b〉〈br〉 Shan Xu, Bin Zou, Yan Lin, Xiuge Zhao, Shenxin Li, and Chengxia Hu〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-402,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 This study presents a crowdsourcing sampling campaign and strategies of method selection for hundred meter-scale PM〈sub〉2.5〈/sub〉 mapping. What interesting is, PM〈sub〉2.5〈/sub〉 concentrations in micro-environments varied significantly in intra urban area. And these local PM〈sub〉2.5〈/sub〉 variations can be effectively revealed by crowdsourcing sampling rather than national air quality monitoring sites. The selection of models for fine scale PM〈sub〉2.5〈/sub〉 mapping should be adjusted with the changing sampling and pollution circumstances.

Description: 〈b〉Assessing the impact of different liquid water permittivity models on the fit between model and observations〈/b〉〈br〉 Katrin Lonitz and Alan J. Geer〈br〉 Atmos. Meas. Tech., 12, 405-429, https://doi.org/10.5194/amt-12-405-2019, 2019〈br〉 Permittivity models for microwave frequencies of liquid water below 0°C are poorly constrained due to limited laboratory experiments and observations, especially for high microwave frequencies. This uncertainty translates directly into errors in retrieved liquid water paths of up to 80 %. This study investigates the effect of different liquid water permittivity models including models based on the most recent observations.

Description: 〈b〉A study of synthetic 〈sup〉13〈/sup〉CH〈sub〉4〈/sub〉 retrievals from TROPOMI and Sentinel 5/UVNS Part 1: non scattering atmosphere〈/b〉〈br〉 Edward Malina, Haili Hu, Jochen Landgraf, and Ben Veihelmann〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-450,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 1 comment)〈br〉 We present a feasibility study on retrieving 〈sup〉12〈/sup〉CH〈sub〉4〈/sub〉 and 〈sup〉13〈/sup〉CH〈sub〉4〈/sub〉, using the recently launched TROPOMI on the Copernicus Sentinel 5P satellite, and the future UVNS instrument on Sentinel 5. The ratio of 〈sup〉12〈/sup〉CH〈sub〉4〈/sub〉 and 〈sup〉13〈/sup〉CH〈sub〉4〈/sub〉 can be used to calculate the δ〈sup〉13〈/sup〉C value. Which has been shown to be able to distinguish between biological and non-biological sources of methane. We show that Sentinel 5/UVNS may be used to distinguish between methane source types, while Sentinel 5P/TROPOMI is subject to large biases.

Description: 〈b〉4DVAR assimilation of GNSS zenith path delays and precipitable water into a numerical weather prediction model WRF〈/b〉〈br〉 Witold Rohm, Jakub Guzikowski, Karina Wilgan, and Maciej Kryza〈br〉 Atmos. Meas. Tech., 12, 345-361, https://doi.org/10.5194/amt-12-345-2019, 2019〈br〉 Assimilation of satellite navigation data into a popular weather model is yet another example of how to turn non-meteorological data into valuable information about the current state of the troposphere. Results show that observations from ground-based GPS receivers can improve humidity and rain forecasts in most severe weather events. It is another reason to extend the adoption of GPS data into weather forecasting across Europe.

Description: 〈b〉Neural Network Radiative Transfer for Imaging Spectroscopy〈/b〉〈br〉 Brian D. Bue, David R. Thompson, Shubhankar Deshpande, Michael Eastwood, Robert O. Green, Terry Mullen, Vijay Natraj, and Mario Parente〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-436,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Imaging spectrometers provide valuable remote measurements of Earth's surface and atmosphere. These measurements rely on computationally-expensive Radiative Transfer Models (RTMs). Spectrometers produce too much data to process with RTMs directly, requiring approximations that trade accuracy for speed. We demonstrate that neural networks can quickly emulate RTM calculations more accurately than current approaches, enabling the application of more sophisticated RTMs than current methods permit.

Description: 〈b〉Analysis of Flow in Complex Terrain Using Multi-Doppler Lidar Retrievals〈/b〉〈br〉 Tyler Bell, Petra Klein, Norman Wildmann, and Robert Menke〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-417,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 This study investigates the utility of using multi-Doppler retrievals during the Perdigão 2017 campaign. By combining scans from the multitude of Doppler lidars, it was possible to derive virtual towers that greatly extend the range of traditional in-situ meteorological towers. Uncertainties from the measurements are analyzed and discussed. Despite multiple sources of error, it was found that the virtual towers are useful for analyzing the complex flows observed during the campaign.

Description: 〈b〉High-precision atmospheric oxygen measurement comparisons between a newly built CRDS analyzer and existing measurement techniques〈/b〉〈br〉 Tesfaye A. Berhanu, John Hoffnagle, Chris Rella, David Kimhak, Peter Nyfeler, and Markus Leuenberger〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-396,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Accurate measurement of variations in atmospheric oxygen, which is a challenging task, can provide a useful information about atmospheric, biospheric and oceanic processes. In this manuscript, we introduce and compare laboratory and field test results between a newly built CRDS analyzer (picarro G-2207) and existing technologies.

Description: 〈b〉Development of an online-coupled MARGA upgrade for the 2 h interval quantification of low-molecular-weight organic acids in the gas and particle phases〈/b〉〈br〉 Bastian Stieger, Gerald Spindler, Dominik van Pinxteren, Achim Grüner, Markus Wallasch, and Hartmut Herrmann〈br〉 Atmos. Meas. Tech., 12, 281-298, https://doi.org/10.5194/amt-12-281-2019, 2019〈br〉 A MARGA was combined with an additional IC system specialized for the 2 h interval online quantification of 12 low-molecular-weight organic acids in the gas and particle phases. Low limits of detection and good precision were achieved. The suitability for field measurements was shown. This setup reduces laboratory work and filter sampling artifacts. Diurnal profiles, sources and phase distributions of these compounds will improve the knowledge of the tropospheric multiphase chemistry.

Description: 〈b〉A method to assess the accuracy of sonic anemometer measurements〈/b〉〈br〉 Alfredo Peña, Ebba Dellwik, and Jakob Mann〈br〉 Atmos. Meas. Tech., 12, 237-252, https://doi.org/10.5194/amt-12-237-2019, 2019〈br〉 We propose a method to assess the accuracy of turbulence measurements by sonic anemometers. The idea is to compute the ratio of the vertical to along-wind velocity spectrum within the inertial subrange. We found that the Metek USA-1 and the Campbell CSAT3 sonic anemometers do not show the expected theoretical ratio. A wind-tunnel-based correction recovers the expected ratio for the USA-1. A correction for the CSAT3 does not, illustrating that this sonic anemometer suffers from flow distortion.

Description: 〈b〉Implementation of polarization diversity pulse-pair technique using airborne W-band radar〈/b〉〈br〉 Mengistu Wolde, Alessandro Battaglia, Cuong Nguyen, Andrew L. Pazmany, and Anthony Illingworth〈br〉 Atmos. Meas. Tech., 12, 253-269, https://doi.org/10.5194/amt-12-253-2019, 2019〈br〉 This paper presents an implementation of polarization diversity pulse-pair processing (PDPP) on the National Research Council of Canada airborne W-band radar (NAW) system. A description of the NAW PDPP pulsing schemes and an analysis of comprehensive airborne data collected in diverse weather conditions in Canada is presented. The analysis shows a successful airborne measurement of Doppler velocity exceeding 100 m s〈sup〉−1〈/sup〉 using PDPP approach, the first such measurement from a moving platform.

Description: 〈b〉Evaluating biases in filter-based aerosol absorption measurements using photoacoustic spectroscopy〈/b〉〈br〉 Nicholas W. Davies, Cathryn Fox, Kate Szpek, Michael I. Cotterell, Jonathan W. Taylor, James D. Allan, Paul I. Williams, Jamie Trembath, Jim M. Haywood, and Justin M. Langridge〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-411,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 This research project assesses biases in traditional, filter-based, aerosol absorption measurements by comparison to state of the art, non-filter-based, or in-situ, measurements. We assess biases in traditional absorption measurements for three main aerosol types, including dust, fresh and aged biomass burning aerosols. The main results of this study are that the traditional and state of the art absorption measurements are well correlated and that biases in the former are up to 45 %.

Description: 〈b〉Tropopause altitude determination from temperature profiles of reduced altitude resolution〈/b〉〈br〉 Nils König, Peter Braesicke, and Thomas von Clarmann〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-448,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Inference of the tropopause from temperature profiles of finite vertical resolution entails an uncertainty of the tropopause altitude. We assess this effect by degrading the resolution of the sonde data. For tropical radiosonde profiles the tropopause altitude inferred from coarse grid profiles was found to be lower than that inferred from the original profiles. E.g., the mean displacement of the lapse rate tropopause inferred from a 3 km resolution profile is −240 m.

Description: 〈b〉Use of polarimetric radar measurements to constrain simulated convective cell evolution: A pilot study with Lagrangian tracking〈/b〉〈br〉 Ann M. Fridlind, Marcus van Lier-Walqui, Scott Collis, Scott E. Giangrande, Robert C. Jackson, Xiaowen Li, Toshihisa Matsui, Richard Orville, Mark H. Picel, Daniel Rosenfeld, Alexander Ryzhkov, Richard Weitz, and Pengfei Zhang〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-454,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Weather radars are offering improved capabilities to investigate storm physics, which remain poorly understood. We investigate enhanced use of such data near Houston, Texas, where pollution sources often provide a convenient contrast between polluted and clean air. We conclude that Houston is a favorable location to conduct a future field campaign during June through September months because isolated storms are common and tend to last an hour, allowing frequent observations of a full life cycle.

Description: 〈b〉Aerosol monitoring in Siberia using an 808 nm automatic compact lidar〈/b〉〈br〉 Gerard Ancellet, Iogannes E. Penner, Jacques Pelon, Vincent Mariage, Antonin Zabukovec, Jean Christophe Raut, Grigorii Kokhanenko, and Yuri S. Balin〈br〉 Atmos. Meas. Tech., 12, 147-168, https://doi.org/10.5194/amt-12-147-2019, 2019〈br〉 Aerosol type seasonal variability and sources in Siberia are obtained from an automatic 808 nm micropulse lidar. A total of 540 aerosol backscatter vertical profiles have been retrieved using careful lidar calibration. Aerosol optical depth is retrieved using sun-photometer complementary observations and an aerosol source apportionment based on aerosol transport model simulations. Comparisons with satellite observations are discussed for three case studies.

Description: 〈b〉Multiple technical observations of the atmospheric boundary layer structure of a red warning haze episode in Beijing〈/b〉〈br〉 Yu Shi, Fei Hu, Guangqiang Fan, and Zhe Zhang〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-391,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 In this paper, the boundary layer structure and turbulence characteristics under severe pollution conditions were studied. The data were taken from multiple observation techniques such as Lidar, wind profiler radar, radiosonde and high meteorological tower. Vertical distribution of wind and temperature, evolution of the boundary layer height, turbulent flux, turbulent kinetic energy and friction velocity were analyzed.

Description: 〈b〉Estimation of Liquid Water Path in Stratiform Precipitation Systems using Radar Measurements during MC3E〈/b〉〈br〉 Jingjing Tian, Xiquan Dong, Baike Xi, Christopher R. Williams, and Peng Wu〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-388,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Liquid water path (LWP) is a combination of rain liquid water path (RLWP) and cloud liquid water path (CLWP) in stratiform precipitation systems. The LWP partitioning is important but poorly understood. Here we estimate the RLWP and CLWP below the melting base simultaneously and separately using ceilometer and radars measurements. Results show that the occurrence of cloud particles below the melting base is low, however, when cloud particles exist, the CLWP value is much larger than the RLWP.

Description: 〈b〉An adaptation of the CO〈sub〉2〈/sub〉 slicing technique for the Infrared Atmospheric Sounding Interferometer to obtain the height of tropospheric volcanic ash clouds〈/b〉〈br〉 Isabelle A. Taylor, Elisa Carboni, Lucy J. Ventress, Tamsin A. Mather, and Roy G. Grainger〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-447,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 1 comment)〈br〉 Volcanic ash is a hazard associated with volcanoes. Knowing an ash cloud’s location is essential for minimising the hazard. This includes knowing the height. This study adapted a well-known technique for obtaining the height of meteorological clouds, known as CO〈sub〉2〈/sub〉 slicing, for volcanic ash. Modelled data was used to refine the method and then demonstrate that the technique could work for volcanic ash. It was then successfully applied to data from the Eyjafjallajökull and Grímsvötn eruptions.

Description: 〈b〉Atmospheric particulate matter characterization by Fourier transform infrared spectroscopy: a review of statistical calibration strategies for carbonaceous aerosol quantification in US measurement networks〈/b〉〈br〉 Satoshi Takahama, Ann M. Dillner, Andrew T. Weakley, Matteo Reggente, Charlotte Bürki, Mária Lbadaoui-Darvas, Bruno Debus, Adele Kuzmiakova, and Anthony S. Wexler〈br〉 Atmos. Meas. Tech., 12, 525-567, https://doi.org/10.5194/amt-12-525-2019, 2019〈br〉 Mid-infrared spectra of particulate matter (PM) samples are complex but chemically informative and present an opportunity for cost-effective measurement of PM provided that quantitative calibration models can be built. We review an emerging strategy for building statistical calibration models using collocated measurements, interpreting the physical bases for such models and evaluating the suitability of existing calibration models to new samples.

Description: 〈b〉Gravimetrically prepared carbon dioxide standards in support of atmospheric research〈/b〉〈br〉 Bradley D. Hall, Andrew M. Crotwell, Benjamin R. Miller, Michael Schibig, and James W. Elkins〈br〉 Atmos. Meas. Tech., 12, 517-524, https://doi.org/10.5194/amt-12-517-2019, 2019〈br〉 We have used a one-step method for gravimetric preparation of CO〈sub〉2〈/sub〉-in-air standards in aluminum cylinders. We consider both adsorption to stainless steel surfaces used in the transfer of highly pure CO〈sub〉2〈/sub〉 and adsorption of CO〈sub〉2〈/sub〉 to cylinder walls. This work compliments ongoing efforts to support atmospheric monitoring of CO〈sub〉2〈/sub〉.

Description: 〈b〉Upgrade and automation of the JPL Table Mountain Facility tropospheric ozone lidar (TMTOL) for near-ground ozone profiling and satellite validation〈/b〉〈br〉 Fernando Chouza, Thierry Leblanc, Mark Brewer, and Patrick Wang〈br〉 Atmos. Meas. Tech., 12, 569-583, https://doi.org/10.5194/amt-12-569-2019, 2019〈br〉 〈p〉As part of international efforts to monitor air quality, several satellite missions such as the Tropospheric Monitoring Instrument (TROPOMI) were deployed and others, like Tropospheric Emissions: Monitoring Pollution (TEMPO), are planned for the near future. In support of the validation of these missions, major upgrades to the tropospheric ozone lidar located at the Jet Propulsion Laboratory Table Mountain Facility (TMF) were recently performed. These modifications include the full automation of the system, which now allows unattended measurements during frequent satellite overpasses, and a new receiver that extends the measurement capabilities of the system down to 100 m above surface.〈/p〉 〈p〉The automation led to the systematic operation of the lidar during daily TROPOMI overpasses, providing more than 139 reference profiles since January 2018. Ozone profiles retrieved using the new lidar receiver were compared to ozonesonde profiles obtained from a co-located tethered balloon. An agreement of about 5 % with the ozonesonde down to an altitude range of 100 m a.g.l. was observed. Furthermore, the stability of the receiver configuration was investigated. Comparisons between the lowest point retrieved by the lidar and a co-located surface ozone photometer showed no sign of drift over a 2-month test period and an agreement better than 10 %. Finally, measurements from a 24 h intensive measurement period during a stratospheric intrusion event showed good agreement with two free-flying ozonesondes. These comparisons revealed localized differences between sonde and lidar, possibly owing to the differing vertical resolutions (between 52 and 380 m for lidar and about 100 m for the sonde).〈/p〉

Description: 〈b〉Benefit of ozone observations from Sentinel-5P and future Sentinel-4 missions on tropospheric composition〈/b〉〈br〉 Samuel Quesada-Ruiz, Jean-Luc Attié, William A. Lahoz, Rachid Abida, Philippe Ricaud, Laaziz El Amraoui, Régina Zbinden, Andrea Piacentini, Mathieu Joly, Henk Eskes, Arjo Segers, Lyana Curier, Johan de Haan, Jukka Kujanpää, Albert Oude-Nijhuis, Johanna Tamminen, Renske Timmermans, and Pepijn Veefkind〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-456,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 We present an observing simulated system experiment (OSSE) dedicated to evaluate the potential added value from the Sentinel-4 and the Sentinel-5P observations on tropospheric ozone composition. For this purpose, the ozone data of Sentinel-4 (Ultraviolet Visible Near-infrared) and Sentinel-5P (TROPOspheric Monitoring Instrument) onboard a geostationary (GEO) and a low Earth orbit (LEO) platform, respectively, has been simulated for the summer 2003. To ensure the robustness of the results, the OSSE has been configured with conservative assumptions. We simulate the reality by combining two chemistry transport models (CTMs): the Long Term Ozone Simulation-European Operational Smog (LOTOS-EUROS) and the Transport Model version 5 (TM5). The assimilation system is based on a different CTM, the MOdèle de Chimie Atmosphérique à Grande Echelle (MOCAGE), combined with the 3D variational technique. The background error covariance matrix does not evolve in time and its variance is proportional to the field values. The simulated data are formed of six eigenvectors to minimize the size of the dataset by removing the noise-dominated part of the observations. The results show that the satellite data clearly bring direct added value around 200 hPa for the whole assimilation period and for the whole European domain, while a likely indirect added value is identified but not for the whole period and domain at 500 hPa, and to a lower extent at 700 hPa. In addition, the ozone added value from Sentinel-5P (LEO) appears close to that from Sentinel-4 (GEO) in the free troposphere (200–500 hPa) in our OSSE.

Description: 〈b〉Investigations into the Development of a Satellite-Based Aerosol Climate Data Record using ATSR-2, AATSR and AVHRR data〈/b〉〈br〉 Yahui Che, Jie Guang, Gerrit de Leeuw, Yong Xue, Ling Sun, and Huizheng Che〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-26,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 The use of AOD data retrieved from ATSR-2, AATSR and AVHRR to produce a very long time series is investigated. The study is made over a small area in northern China with a large variation of AOD values. Sun Photometer data from AERONET and CARSNET and radiance-derived AOD are used as reference. The results show that all data sets compare well. However, AVHRR underestimates high AOD (mainly occurring in summer) but performs better than (A)ATSR in winter.

Description: 〈b〉Methods for identifying aged ship plumes and estimating contribution to aerosol exposure downwind of shipping lanes〈/b〉〈br〉 Stina Ausmeel, Axel Eriksson, Erik Ahlberg, and Adam Kristensson〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-445,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 We present a method for identifying individual exhaust plumes of air pollution emitted from shipping, by linking these to specific ships using identification information which all ships transmit. We also quantify the contribution of these plumes to local particle levels, which has relevance for e.g. health effects. Ships emit a lot of nanometre sized particles which proved to be a good indicator of plumes at a distance of about 10 kilometres downwind of a shipping lane in the Baltic Sea.

Description: 〈b〉Observation of nocturnal NO〈sub〉3〈/sub〉 during vehicular activities in the medium sized city of Calicut in coastal India〈/b〉〈br〉 Kuttoth Suhail, Ramachandran Arun, Shreya Joshi, John Shebin, Saseendran Aiswarya, Pakkattil Anoop, Viswanath Deepa, and Ravi Varma〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-6,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 Open Path Incoherent Broad Band Cavity Enhanced Absorption Spectroscopy (OP–IBBCEAS) technique was found useful in sensitive ambient monitoring of nocturnal nitrate radical (NO〈sub〉3〈/sub〉) in a medium sized urban location of Calicut city, India, for the first time; highest observed value was ~0.5 ppbv. The measurement location witnessed idling diesel vehicles activities during high observed NO〈sub〉3〈/sub〉 levels. Concurrent PM measurements showed increased detection uncertainty during high aerosol loading events.

Description: 〈b〉High-resolution temperature profiles retrieved from bichromatic stellar scintillation measurements by GOMOS/Envisat〈/b〉〈br〉 Viktoria F. Sofieva, Francis Dalaudier, Alain Hauchecorne, and Valery Kan〈br〉 Atmos. Meas. Tech., 12, 585-598, https://doi.org/10.5194/amt-12-585-2019, 2019〈br〉 This paper describes the temperature profiles in the stratosphere obtained from unique stellar scintillation measurements by the GOMOS instrument operated on board Envisat in 2002–2012. The high-resolution temperature profiles (HRTPs) are retrieved with a very good vertical resolution of ~ 200 m and a high accuracy of ~ 1–3 K for altitudes 15–32 km as well as a global coverage. HRTPs can be assimilated into atmospheric models and used in analyses of internal gravity wave activity.

Description: 〈b〉The ICAD (Iterative Cavity Enhanced DOAS) Method〈/b〉〈br〉 Martin Horbanski, Denis Pöhler, Johannes Lampel, and Ulrich Platt〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2019-1,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 ICAD allows a precise in-situ measurement of gases like NO〈sub〉2〈/sub〉 in a relative simple and compact setup. The main advantage in comparison to most other optical methods is that it does not require a stable total light intensity. This allows a simpler and mobile instrument setup and additionally it features no observed cross interferences. We validated the high quality for an ICAD NO〈sub〉2〈/sub〉 in different inter-comparisons with a detection limit of 0.02 ppbv.

Description: 〈b〉Automatic pollen recognition with the Rapid-E particle counter: the first-level procedure, experience and next steps〈/b〉〈br〉 Ingrida Šaulienė, Laura Šukienė, Gintautas Daunys, Gediminas Valiulis, Lukas Vaitkevičius, Predrag Matavulj, Sanja Brdar, Marko Panic, Branko Sikoparija, Bernard Clot, Benoît Crouzy, and Mikhail Sofiev〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-432,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 The goal is to evaluate the capabilities of the new Rapid-E monitor and to construct the first-level pollen recognition algorithm. The output data were treated with ANN aiming at classification of the injected pollen. Algorithms based on scattering and fluorescence data alone fall short of acceptable quality. The combinations of these exceeded 80 % accuracy for 5 out of 11 pollen species. Constructing multi-steps algorithms with sequential discrimination of pollen can be a possible way forwards.

Description: 〈b〉Validity and limitations of simple reaction kinetics to calculate concentrations of organic compounds from ion counts in PTR-MS〈/b〉〈br〉 Rupert Holzinger, W. Joe F. Acton, William J. Bloss, Martin Breitenlechner, Leigh R. Crilley, Sébastien Dusanter, Marc Gonin, Valerie Gros, Frank N. Keutsch, Astrid Kiendler-Scharr, Louisa J. Kramer, Jordan E. Krechmer, Baptiste Languille, Nadine Locoge, Felipe Lopez-Hilfiker, Dušan Materić, Sergi Moreno, Eiko Nemitz, Lauriane L. J. Quéléver, Roland Sarda Esteve, Stéphane Sauvage, Simon Schallhart, Roberto Sommariva, Ralf Tillmann, Sergej Wedel, David R. Worton, Kangming Xu, and Alexander Zaytsev〈br〉 Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2018-446,2019〈br〉 〈b〉Manuscript under review for AMT〈/b〉 (discussion: open, 0 comments)〈br〉 In September 2017, we conducted the Proton-transfer-reaction mass-spectrometry (PTR-MS) Intercomparison campaign at CABauw (PICAB), a rural site in central Netherlands. Nine research groups deployed a total of eleven instruments covering a wide range of instrument types and performance. We applied a new calibration method based on fast injection of a gas standard through a sample loop. This approach allows calibrations on time scales of seconds and within a few minutes an automated sequence can be run allowing to retrieve diagnostic parameters that indicate the performance status. We developed a method to retrieve the mass dependent transmission from the fast calibrations, which is an essential characteristic of PTR-MS instruments, limiting the potential to calculate concentrations based on counting statistics and simple reaction kinetics in the reactor/drift tube. Our measurements show that PTR-MS instruments follow the simple reaction kinetics if operated in the standard range for pressures and temperature of the reaction chamber (i.e. 1–4 mbar, 30–120 ℃, respectively), and a reduced field strength 〈i〉E/N〈/i〉 in the range of 100–160 Td. If artefacts can be ruled out, it becomes possible to quantify the signals of uncalibrated organics with accuracies better than ±30 %. The simple reaction kinetics approach produces less accurate results at 〈i〉E/N〈/i〉 levels below 100 Td, because significant fractions of primary ions form water hydronium clusters. De-protonation through reactive collisions of protonated organics with water molecules need to be considered when the collision energy is a substantial fraction of the exoergicity of the proton transfer reaction, and/or if protonated organics undergo many collisions with water molecules.

Description: 〈b〉Demonstration of an off-axis parabolic receiver for near-range retrieval of lidar ozone profiles〈/b〉〈br〉 Betsy M. Farris, Guillaume P. Gronoff, William Carrion, Travis Knepp, Margaret Pippin, and Timothy A. Berkoff〈br〉 Atmos. Meas. Tech., 12, 363-370, https://doi.org/10.5194/amt-12-363-2019, 2019〈br〉 During the 2017 Ozone Water Land Environmental Transition Study (OWLETS), the Langley mobile ozone lidar system utilized a new small diameter receiver to improve the retrieval of near-surface signals from 0.1 to 1 km in altitude. This allowed for improved near-surface ozone concentration measurements, those most important to human health, while also measuring profiles up to stratospheric altitudes. OWLETS provided multiple instrument comparisons for validation of the system improvement.

Description: 〈b〉The Advanced Infra-Red WAter Vapour Estimator (AIRWAVE) version 2: algorithm evolution, dataset description and performance improvements〈/b〉〈br〉 Elisa Castelli, Enzo Papandrea, Alessio Di Roma, Bianca Maria Dinelli, Stefano Casadio, and Bojan Bojkov〈br〉 Atmos. Meas. Tech., 12, 371-388, https://doi.org/10.5194/amt-12-371-2019, 2019〈br〉 The total column water vapour (TCWV) is a key atmospheric variable. The AIRWAVE (Advanced Infra-Red WAter Vapour Estimator) v1 algorithm was developed to retrieve TCWV from satellite measurements. Comparisons with independent TCWV show good agreement with an overall bias of 0.72 kg m〈sup〉−2〈/sup〉 due to the polar and coastal regions. Here, we describe the AIRWAVEv2 dataset, which shows significant improvements with a global bias of 0.02 kg m〈sup〉−2〈/sup〉. This dataset was used to produce a climatology from 1991 to 2012.