Aerosol retrievals from the EKO MS-711 spectral direct irradiance measurements and corrections of the circumsolar radiation
Rosa Delia García-Cabrera, Emilio Cuevas-Agulló, África Barreto, Victoria Eugenia Cachorro, Mario Pó, Ramón Ramos, and Kees Hoogendijk
Atmos. Meas. Tech., 13, 2601–2621, https://doi.org/10.5194/amt-13-2601-2020, 2020
Spectral direct UV–visible normal solar irradiance, measured with an EKO MS-711 grating spectroradiometer at the Izaña Atmospheric Observatory (Spain), has been used to determine aerosol optical depth (AOD) at several wavelengths, and has been compared to synchronous AOD measurements from a reference AERONET (Aerosol RObotic NETwork) Cimel sun photometer.
Simultaneous measurements of the relative-humidity-dependent aerosol light extinction, scattering, absorption, and single-scattering albedo with a humidified cavity-enhanced albedometer
Jiacheng Zhou, Xuezhe Xu, Weixiong Zhao, Bo Fang, Qianqian Liu, Yuanqing Cai, Weijun Zhang, Dean S. Venables, and Weidong Chen
Atmos. Meas. Tech., 13, 2623–2634, https://doi.org/10.5194/amt-13-2623-2020, 2020
We report the first demonstration of a humidified cavity-enhanced albedometer (H-CEA) that combines a broadband cavity-enhanced aerosol albedometer with a humidigraph system for simultaneous and accurate measurements of multiple optical hygroscopic parameters (f(RH)ext,scat,abs,ω) at λ = 532 nm. The instrument is suitable for operating under high RH-conditions and has sampling advantages over independent measurements of different parameters with different instruments.
TanSat ACGS on-orbit spectral calibration by use of individual
solar lines and entire atmospheric spectra
Yanmeng Bi, Qian Wang, Zhongdong Yang, Chengbao Liu, Chao Lin, Longfei Tian, Naiqiang Zhang, Yanping Luo, and Yacheng Wang
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-20,2020
Preprint under review for AMT (discussion: open, 0 comments)
We have used two types of on-orbit methods to evaluate the TANSAT/ACGS wavelength calibration. The first method is to use the solar Fraunhofer absorption lines as the reference.The second method uses the entire atmospheric spectra as the reference.For TanSat ACGS, the wavelength variations derived from the two methods agree closely. The accuracy of wavelength offsets is better than 10 % of the FWHM that meet the requirements of spectral calibration of the ACGS on orbit.
Hydrometeor classification of quasi-vertical profiles of polarimetric
radar measurements using a top-down iterative hierarchical
clustering method
Maryna Lukach, David Dufton, Jonathan Crosier, Joshua M. Hampton, Lindsay Bennett, and Ryan R. Neely III
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-143,2020
Preprint under review for AMT (discussion: open, 0 comments)
This paper presents a novel technique of data-driven hydrometeor classification (HC) from QVPs, where the hydrometeor types are identified from an optimal number of hierarchical clusters, obtained recursively. This data-driven HC approach is capable of providing an optimal number of classes from the dual-polarimetric weather radar observations and the embedded flexibility in the extent of granularity is the main advantage of this technique.
Learning about the vertical structure of radar reflectivity using hydrometeor classes and neural networks in the Swiss Alps
Floor van den Heuvel, Loris Foresti, Marco Gabella, Urs Germann, and Alexis Berne
Atmos. Meas. Tech., 13, 2481–2500, https://doi.org/10.5194/amt-13-2481-2020, 2020
In areas with reduced visibility at the ground level, radar precipitation measurements higher up in the atmosphere need to be extrapolated to the ground and be corrected for the vertical change (i.e. growth and transformation) of precipitation. This study proposes a method based on hydrometeor proportions and machine learning (ML) to apply these corrections at smaller spatiotemporal scales. In comparison with existing techniques, the ML methods can make predictions from higher altitudes.
Assessment of NO2 observations during DISCOVER-AQ and KORUS-AQ field campaigns
Sungyeon Choi, Lok N. Lamsal, Melanie Follette-Cook, Joanna Joiner, Nickolay A. Krotkov, William H. Swartz, Kenneth E. Pickering, Christopher P. Loughner, Wyat Appel, Gabriele Pfister, Pablo E. Saide, Ronald C. Cohen, Andrew J. Weinheimer, and Jay R. Herman
Atmos. Meas. Tech., 13, 2523–2546, https://doi.org/10.5194/amt-13-2523-2020, 2020
NASA's Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ, conducted in 2011–2014) campaign in the United States and the joint NASA and National Institute of Environmental Research (NIER) Korea–United States Air Quality Study (KORUS-AQ, conducted in 2016) in South Korea were two field study programs that provided comprehensive, integrated datasets of airborne and surface observations of atmospheric constituents, including nitrogen dioxide (NO2), with the goal of improving the interpretation of spaceborne remote sensing data. Various types of NO2 measurements were made, including in situ concentrations and column amounts of NO2 using ground- and aircraft-based instruments, while NO2 column amounts were being derived from the Ozone Monitoring Instrument (OMI) on the Aura satellite. This study takes advantage of these unique datasets by first evaluating in situ data taken from two different instruments on the same aircraft platform, comparing coincidently sampled profile-integrated columns from aircraft spirals with remotely sensed column observations from ground-based Pandora spectrometers, intercomparing column observations from the ground (Pandora), aircraft (in situ vertical spirals), and space (OMI), and evaluating NO2 simulations from coarse Global Modeling Initiative (GMI) and high-resolution regional models. We then use these data to interpret observed discrepancies due to differences in sampling and deficiencies in the data reduction process. Finally, we assess satellite retrieval sensitivity to observed and modeled a priori NO2 profiles. Contemporaneous measurements from two aircraft instruments that likely sample similar air masses generally agree very well but are also found to differ in integrated columns by up to 31.9 %. These show even larger differences with Pandora, reaching up to 53.9 %, potentially due to a combination of strong gradients in NO2 fields that could be missed by aircraft spirals and errors in the Pandora retrievals. OMI NO2 values are about a factor of 2 lower in these highly polluted environments due in part to inaccurate retrieval assumptions (e.g., a priori profiles) but mostly to OMI's large footprint (>312 km2).
A technical description of the Balloon Lidar Experiment BOLIDE
Bernd Kaifler, Dimitry Rempel, Philipp Roßi, Christian Büdenbender, Natalie Kaifler, and Volodymyr Baturkin
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-150,2020
Preprint under review for AMT (discussion: open, 0 comments)
The Balloon Lidar Experiment was the first lidar dedicated to measurements in the mesosphere flown on a balloon. During a 6 day flight it made high resolution observations of polar mesospheric clouds which form at high latitudes during summer in ~83 km altitude and are the highest clouds in Earth's atmosphere. We describe the instrument and assess its performance. We could detect fainter clouds with higher resolution than what is possible with ground-based instruments.
Learning about the vertical structure of radar reflectivity using hydrometeor classes and neural networks in the Swiss Alps
Floor van den Heuvel, Loris Foresti, Marco Gabella, Urs Germann, and Alexis Berne
Atmos. Meas. Tech., 13, 2481–2500, https://doi.org/10.5194/amt-13-2481-2020, 2020
In areas with reduced visibility at the ground level, radar precipitation measurements higher up in the atmosphere need to be extrapolated to the ground and be corrected for the vertical change (i.e. growth and transformation) of precipitation. This study proposes a method based on hydrometeor proportions and machine learning (ML) to apply these corrections at smaller spatiotemporal scales. In comparison with existing techniques, the ML methods can make predictions from higher altitudes.
Assessment of NO2 observations during DISCOVER-AQ and KORUS-AQ field campaigns
Sungyeon Choi, Lok N. Lamsal, Melanie Follette-Cook, Joanna Joiner, Nickolay A. Krotkov, William H. Swartz, Kenneth E. Pickering, Christopher P. Loughner, Wyat Appel, Gabriele Pfister, Pablo E. Saide, Ronald C. Cohen, Andrew J. Weinheimer, and Jay R. Herman
Atmos. Meas. Tech., 13, 2523–2546, https://doi.org/10.5194/amt-13-2523-2020, 2020
NASA's Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ, conducted in 2011–2014) campaign in the United States and the joint NASA and National Institute of Environmental Research (NIER) Korea–United States Air Quality Study (KORUS-AQ, conducted in 2016) in South Korea were two field study programs that provided comprehensive, integrated datasets of airborne and surface observations of atmospheric constituents, including nitrogen dioxide (NO2), with the goal of improving the interpretation of spaceborne remote sensing data. Various types of NO2 measurements were made, including in situ concentrations and column amounts of NO2 using ground- and aircraft-based instruments, while NO2 column amounts were being derived from the Ozone Monitoring Instrument (OMI) on the Aura satellite. This study takes advantage of these unique datasets by first evaluating in situ data taken from two different instruments on the same aircraft platform, comparing coincidently sampled profile-integrated columns from aircraft spirals with remotely sensed column observations from ground-based Pandora spectrometers, intercomparing column observations from the ground (Pandora), aircraft (in situ vertical spirals), and space (OMI), and evaluating NO2 simulations from coarse Global Modeling Initiative (GMI) and high-resolution regional models. We then use these data to interpret observed discrepancies due to differences in sampling and deficiencies in the data reduction process. Finally, we assess satellite retrieval sensitivity to observed and modeled a priori NO2 profiles. Contemporaneous measurements from two aircraft instruments that likely sample similar air masses generally agree very well but are also found to differ in integrated columns by up to 31.9 %. These show even larger differences with Pandora, reaching up to 53.9 %, potentially due to a combination of strong gradients in NO2 fields that could be missed by aircraft spirals and errors in the Pandora retrievals. OMI NO2 values are about a factor of 2 lower in these highly polluted environments due in part to inaccurate retrieval assumptions (e.g., a priori profiles) but mostly to OMI's large footprint (>312 km2).
A technical description of the Balloon Lidar Experiment BOLIDE
Bernd Kaifler, Dimitry Rempel, Philipp Roßi, Christian Büdenbender, Natalie Kaifler, and Volodymyr Baturkin
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-150,2020
Preprint under review for AMT (discussion: open, 0 comments)
The Balloon Lidar Experiment was the first lidar dedicated to measurements in the mesosphere flown on a balloon. During a 6 day flight it made high resolution observations of polar mesospheric clouds which form at high latitudes during summer in ~83 km altitude and are the highest clouds in Earth's atmosphere. We describe the instrument and assess its performance. We could detect fainter clouds with higher resolution than what is possible with ground-based instruments.
Measurement of ammonia, amines and iodine compounds using protonated water cluster chemical ionization mass spectrometry
Joschka Pfeifer, Mario Simon, Martin Heinritzi, Felix Piel, Lena Weitz, Dongyu Wang, Manuel Granzin, Tatjana Müller, Steffen Bräkling, Jasper Kirkby, Joachim Curtius, and Andreas Kürten
Atmos. Meas. Tech., 13, 2501–2522, https://doi.org/10.5194/amt-13-2501-2020, 2020
Ammonia is an important atmospheric trace gas that affects secondary aerosol formation and, together with sulfuric acid, the formation of new particles. A measurement technique is presented that uses high-resolution mass spectrometry and protonated water clusters for the ultrasensitive detection of ammonia at single-digit parts per trillion by volume levels. The instrument is further capable of measuring amines and a suite of iodine compounds at sub-parts per trillion by volume levels.
Measurement of ammonia, amines and iodine compounds using protonated water cluster chemical ionization mass spectrometry
Joschka Pfeifer, Mario Simon, Martin Heinritzi, Felix Piel, Lena Weitz, Dongyu Wang, Manuel Granzin, Tatjana Müller, Steffen Bräkling, Jasper Kirkby, Joachim Curtius, and Andreas Kürten
Atmos. Meas. Tech., 13, 2501–2522, https://doi.org/10.5194/amt-13-2501-2020, 2020
Ammonia is an important atmospheric trace gas that affects secondary aerosol formation and, together with sulfuric acid, the formation of new particles. A measurement technique is presented that uses high-resolution mass spectrometry and protonated water clusters for the ultrasensitive detection of ammonia at single-digit parts per trillion by volume levels. The instrument is further capable of measuring amines and a suite of iodine compounds at sub-parts per trillion by volume levels.
A low-activity ion source for measurement of atmospheric gases by chemical ionization mass spectrometry
Young Ro Lee, Yi Ji, David J. Tanner, and L. Gregory Huey
Atmos. Meas. Tech., 13, 2473–2480, https://doi.org/10.5194/amt-13-2473-2020, 2020
In this work we show how to construct a radioactive ion source for a chemical ionization mass spectrometer (CIMS) from commercially available components. The source is low activity and can be shipped with a minimum of complications. This facilitates the deployment of CIMS to measure atmospheric pollutants at remote ground sites.
Characterization of anthropogenic organic aerosols by TOF-ACSM with the new capture vaporizer
Yan Zheng, Xi Cheng, Keren Liao, Yaowei Li, Yong Jie Li, Ru-Jin Huang, Weiwei Hu, Ying Liu, Tong Zhu, Shiyi Chen, Limin Zeng, Douglas R. Worsnop, and Qi Chen
Atmos. Meas. Tech., 13, 2457–2472, https://doi.org/10.5194/amt-13-2457-2020, 2020
This paper provides important information to help researchers to understand the mass quantification and source apportionment by Aerodyne aerosol mass spectrometers.
MICRU background map and effective cloud fraction algorithms designed for UV/vis satellite instruments with large viewing angles
Holger Sihler, Steffen Beirle, Steffen Dörner, Marloes Gutenstein-Penning de Vries, Christoph Hörmann, Christian Borger, Simon Warnach, and Thomas Wagner
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-182,2020
Preprint under review for AMT (discussion: open, 0 comments)
MICRU is an algorithm for the retrieval of effective cloud fractions (CF) from satellite measurements. CF describe the amount of clouds, which have a significant impact on the vertical sensitivity profile of trace-gases like NO2 and HCHO. MICRU retrieves small CF with an accuracy of 0.04 over the entire satellite swath. It features an empirical surface reflectivity model accounting for physical anisotropy (BRDF, sun glitter) and instrumental effects. MICRU is also applicable to imager data.
A new OCO-2 cloud flagging and rapid retrieval of marine boundary layer cloud properties
Mark Richardson, Matthew D. Lebsock, James McDuffie, and Graeme L. Stephens
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-140,2020
Preprint under review for AMT (discussion: open, 0 comments)
We previously combined data from a lidar on the CALIPSO satellite and measurements of reflected sunlight from the OCO-2 satellite to get new information about low clouds over oceans. The satellites are no longer formation flying, so this work is a step towards getting unique new information about these clouds using OCO-2 data only. We show we can rapidly and accurately identify liquid oceanic clouds and obtain their height better than a widely-used passive sensor.
A low-activity ion source for measurement of atmospheric gases by chemical ionization mass spectrometry
Young Ro Lee, Yi Ji, David J. Tanner, and L. Gregory Huey
Atmos. Meas. Tech., 13, 2473–2480, https://doi.org/10.5194/amt-13-2473-2020, 2020
In this work we show how to construct a radioactive ion source for a chemical ionization mass spectrometer (CIMS) from commercially available components. The source is low activity and can be shipped with a minimum of complications. This facilitates the deployment of CIMS to measure atmospheric pollutants at remote ground sites.
Characterization of anthropogenic organic aerosols by TOF-ACSM with the new capture vaporizer
Yan Zheng, Xi Cheng, Keren Liao, Yaowei Li, Yong Jie Li, Ru-Jin Huang, Weiwei Hu, Ying Liu, Tong Zhu, Shiyi Chen, Limin Zeng, Douglas R. Worsnop, and Qi Chen
Atmos. Meas. Tech., 13, 2457–2472, https://doi.org/10.5194/amt-13-2457-2020, 2020
This paper provides important information to help researchers to understand the mass quantification and source apportionment by Aerodyne aerosol mass spectrometers.
MICRU background map and effective cloud fraction algorithms designed for UV/vis satellite instruments with large viewing angles
Holger Sihler, Steffen Beirle, Steffen Dörner, Marloes Gutenstein-Penning de Vries, Christoph Hörmann, Christian Borger, Simon Warnach, and Thomas Wagner
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-182,2020
Preprint under review for AMT (discussion: open, 0 comments)
MICRU is an algorithm for the retrieval of effective cloud fractions (CF) from satellite measurements. CF describe the amount of clouds, which have a significant impact on the vertical sensitivity profile of trace-gases like NO2 and HCHO. MICRU retrieves small CF with an accuracy of 0.04 over the entire satellite swath. It features an empirical surface reflectivity model accounting for physical anisotropy (BRDF, sun glitter) and instrumental effects. MICRU is also applicable to imager data.
A new OCO-2 cloud flagging and rapid retrieval of marine boundary layer cloud properties
Mark Richardson, Matthew D. Lebsock, James McDuffie, and Graeme L. Stephens
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-140,2020
Preprint under review for AMT (discussion: open, 0 comments)
We previously combined data from a lidar on the CALIPSO satellite and measurements of reflected sunlight from the OCO-2 satellite to get new information about low clouds over oceans. The satellites are no longer formation flying, so this work is a step towards getting unique new information about these clouds using OCO-2 data only. We show we can rapidly and accurately identify liquid oceanic clouds and obtain their height better than a widely-used passive sensor.
