The influence of the baseline drift on the resulting extinction values of a cavity attenuated phase shift-based extinction monitor (CAPS PMex)
Sascha Pfeifer, Thomas Müller, Andrew Freedman, and Alfred Wiedensohler
Atmos. Meas. Tech., 13, 2161–2167, https://doi.org/10.5194/amt-13-2161-2020, 2020
The effect of the baseline drift on the resulting extinction values of three CAPS PMex monitors with different wavelengths was analysed for an urban background station. A significant baseline drift was observed, which leads to characteristic measurement artefacts for particle extinction. Two alternative methods for recalculating the baseline are shown. With these methods the extinction artefacts are diminished and the effective scattering of the resulting extinction values is reduced.
How to estimate total differential attenuation due to hydrometeors with ground-based multi-frequency radars?
Frédéric Tridon, Alessandro Battaglia, and Stefan Kneifel
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-159,2020
Preprint under review for AMT (discussion: open, 0 comments)
At millimeter wavelengths, attenuation by hydrometeors, such as liquid droplets or large snowflakes, is generally not negligible. When using multi-frequency ground-based radar measurements, it is common practice to use the Rayleigh targets at cloud top as a reference in order to derive attenuation-corrected reflectivities and meaningful dual-frequency ratios (DFR). By capitalizing on this idea, this study describes a new quality-controlled approach aiming at identifying regions of the cloud where particle growth is negligible. The core of the method is the identification of a Rayleigh plateau, i.e. a large enough region near cloud top where the vertical gradient of DFR remains small.
By analyzing collocated Ka-W band radar and microwave radiometer (MWR) observations taken at two European sites under various meteorological conditions, it is shown how the resulting estimates of differential path-integrated attenuation (DeltaPIA) can be used to characterize hydrometeor properties. When the DeltaPIA is predominantly produced by cloud liquid droplets, this technique alone can provide accurate estimates of the liquid water path. When combined with MWR observations, this methodology paves the way towards profiling the cloud liquid water and/or quality flagging the MWR retrieval for rain/drizzle contamination and/or estimating the snow differential attenuation.
The influence of the baseline drift on the resulting extinction values of a cavity attenuated phase shift-based extinction monitor (CAPS PMex)
Sascha Pfeifer, Thomas Müller, Andrew Freedman, and Alfred Wiedensohler
Atmos. Meas. Tech., 13, 2161–2167, https://doi.org/10.5194/amt-13-2161-2020, 2020
The effect of the baseline drift on the resulting extinction values of three CAPS PMex monitors with different wavelengths was analysed for an urban background station. A significant baseline drift was observed, which leads to characteristic measurement artefacts for particle extinction. Two alternative methods for recalculating the baseline are shown. With these methods the extinction artefacts are diminished and the effective scattering of the resulting extinction values is reduced.
How to estimate total differential attenuation due to hydrometeors with ground-based multi-frequency radars?
Frédéric Tridon, Alessandro Battaglia, and Stefan Kneifel
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-159,2020
Preprint under review for AMT (discussion: open, 0 comments)
At millimeter wavelengths, attenuation by hydrometeors, such as liquid droplets or large snowflakes, is generally not negligible. When using multi-frequency ground-based radar measurements, it is common practice to use the Rayleigh targets at cloud top as a reference in order to derive attenuation-corrected reflectivities and meaningful dual-frequency ratios (DFR). By capitalizing on this idea, this study describes a new quality-controlled approach aiming at identifying regions of the cloud where particle growth is negligible. The core of the method is the identification of a Rayleigh plateau, i.e. a large enough region near cloud top where the vertical gradient of DFR remains small.
By analyzing collocated Ka-W band radar and microwave radiometer (MWR) observations taken at two European sites under various meteorological conditions, it is shown how the resulting estimates of differential path-integrated attenuation (DeltaPIA) can be used to characterize hydrometeor properties. When the DeltaPIA is predominantly produced by cloud liquid droplets, this technique alone can provide accurate estimates of the liquid water path. When combined with MWR observations, this methodology paves the way towards profiling the cloud liquid water and/or quality flagging the MWR retrieval for rain/drizzle contamination and/or estimating the snow differential attenuation.
An inter-laboratory comparison of aerosol in organic ion measurements by Ion Chromatography: implications for aerosol pH estimate
Jingsha Xu, Shaojie Song, Roy M. Harrison, Congbo Song, Lianfang Wei, Qiang Zhang, Yele Sun, Lu Lei, Chao Zhang, Xiaohong Yao, Dihui Chen, Weijun Li, Miaomiao Wu, Hezhong Tian, Lining Luo, Shengrui Tong, Weiran Li, Junling Wang, Guoliang Shi, Yanqi Huangfu, Yingze Tian, Baozhu Ge, Shaoli Su, Chao Peng, Yang Chen, Fumo Yang, Aleksandra Mihajlidi-Zelić, Dragana Đorđević, Stefan J. Swift, Imogen Andrews, Jacqueline F. Hamilton, Ye Sun, Agung Kramawijaya, Jinxiu Han, Supattarachai Saksakulkrai, Clarissa Baldo, Siqi Hou, Feixue Zheng, Kaspar R. Daellenbach, Chao Yan, Yongchun Liu, Markku Kulmala, Pingqing Fu, and Zongbo Shi
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-156,2020
Preprint under review for AMT (discussion: open, 0 comments)
An inter-laboratory comparison exercise was conducted for the first time to examine the difference of water-soluble inorganic ions (WSII) measured by 10 labs using Ion Chromatography and by 2 online Aerosol Chemical Speciation Monitor method. Major ions including SO42−, NO3−, NH4+ agreed well in 10 IC labs, and correlated well with ACSM. WSII inter-lab variability strongly affected aerosol acidity results based on ion balance, but aerosol pH computed by ISORROPIA-II were very similar.
Three-dimensional radiative transfer effects on airborne, satellite
and ground-based trace gas remote sensing
Marc Schwaerzel, Claudia Emde, Dominik Brunner, Randulph Morales, Thomas Wagner, Alexis Berne, Brigitte Buchmann, and Gerrit Kuhlmann
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-146,2020
Preprint under review for AMT (discussion: open, 0 comments)
Horizontal homogeneity is often assumed for trace gases remote sensing, although it is not valid where trace gas concentrations have high spatial variability, e.g. in cities. We show the importance of 3D effects for MAX-DOAS and airborne imaging spectrometers using 3D-box air mass factors implemented in the MYSTIC radiative transfer solver. In both cases, 3D information is invaluable for interpreting the measurements, as not considering 3D effects can lead to misinterpretation of measurements.
Ground-based FTIR O3 retrievals from the 3040 cm−1 spectral
range at Xianghe, China
Minqiang Zhou, Pucai Wang, Bavo Langerock, Corinne Vigouroux, Christian Hermans, Nicolas Kumps, Ting Wang, Yang Yang, Denghui Ji, Liang Ran, Jinqiang Zhang, Yuejian Xuan, Hongbin Chen, Françoise Posny, Valentin Duflot, Jean-Marc Metzger, and Martine De Mazière
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-127,2020
Preprint under review for AMT (discussion: open, 0 comments)
We study O3 retrievals in the 3040 cm−1 spectral range from FTIR measurements at Xianghe China (39.75N, 116.96E, 50 m a.s.l.) between June 2018 and December 2019. It is found that the FTIR O3 (3040 cm−1) retrievals capture very well the seasonal and synoptic variations of O3. The systematic and random uncertainties of FTIR O3 (3040 cm−1) total column are about 5.5–9.0 % and 1.4%, respectively. The DOF is 2.4±0.3 (1σ), with 2 individual pieces of information in surface-20 km and 20–40 km.
Three-dimensional radiative transfer effects on airborne, satellite
and ground-based trace gas remote sensing
Marc Schwaerzel, Claudia Emde, Dominik Brunner, Randulph Morales, Thomas Wagner, Alexis Berne, Brigitte Buchmann, and Gerrit Kuhlmann
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-146,2020
Preprint under review for AMT (discussion: open, 0 comments)
Horizontal homogeneity is often assumed for trace gases remote sensing, although it is not valid where trace gas concentrations have high spatial variability, e.g. in cities. We show the importance of 3D effects for MAX-DOAS and airborne imaging spectrometers using 3D-box air mass factors implemented in the MYSTIC radiative transfer solver. In both cases, 3D information is invaluable for interpreting the measurements, as not considering 3D effects can lead to misinterpretation of measurements.
Ground-based FTIR O3 retrievals from the 3040 cm−1 spectral
range at Xianghe, China
Minqiang Zhou, Pucai Wang, Bavo Langerock, Corinne Vigouroux, Christian Hermans, Nicolas Kumps, Ting Wang, Yang Yang, Denghui Ji, Liang Ran, Jinqiang Zhang, Yuejian Xuan, Hongbin Chen, Françoise Posny, Valentin Duflot, Jean-Marc Metzger, and Martine De Mazière
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-127,2020
Preprint under review for AMT (discussion: open, 0 comments)
We study O3 retrievals in the 3040 cm−1 spectral range from FTIR measurements at Xianghe China (39.75N, 116.96E, 50 m a.s.l.) between June 2018 and December 2019. It is found that the FTIR O3 (3040 cm−1) retrievals capture very well the seasonal and synoptic variations of O3. The systematic and random uncertainties of FTIR O3 (3040 cm−1) total column are about 5.5–9.0 % and 1.4%, respectively. The DOF is 2.4±0.3 (1σ), with 2 individual pieces of information in surface-20 km and 20–40 km.
An inter-laboratory comparison of aerosol in organic ion measurements by Ion Chromatography: implications for aerosol pH estimate
Jingsha Xu, Shaojie Song, Roy M. Harrison, Congbo Song, Lianfang Wei, Qiang Zhang, Yele Sun, Lu Lei, Chao Zhang, Xiaohong Yao, Dihui Chen, Weijun Li, Miaomiao Wu, Hezhong Tian, Lining Luo, Shengrui Tong, Weiran Li, Junling Wang, Guoliang Shi, Yanqi Huangfu, Yingze Tian, Baozhu Ge, Shaoli Su, Chao Peng, Yang Chen, Fumo Yang, Aleksandra Mihajlidi-Zelić, Dragana Đorđević, Stefan J. Swift, Imogen Andrews, Jacqueline F. Hamilton, Ye Sun, Agung Kramawijaya, Jinxiu Han, Supattarachai Saksakulkrai, Clarissa Baldo, Siqi Hou, Feixue Zheng, Kaspar R. Daellenbach, Chao Yan, Yongchun Liu, Markku Kulmala, Pingqing Fu, and Zongbo Shi
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-156,2020
Preprint under review for AMT (discussion: open, 0 comments)
An inter-laboratory comparison exercise was conducted for the first time to examine the difference of water-soluble inorganic ions (WSII) measured by 10 labs using Ion Chromatography and by 2 online Aerosol Chemical Speciation Monitor method. Major ions including SO42−, NO3−, NH4+ agreed well in 10 IC labs, and correlated well with ACSM. WSII inter-lab variability strongly affected aerosol acidity results based on ion balance, but aerosol pH computed by ISORROPIA-II were very similar.
Detecting turbulent structures on single Doppler lidar large datasets: an automated classification method for horizontal scans
Ioannis Cheliotis, Elsa Dieudonné, Hervé Delbarre, Anton Sokolov, Egor Dmitriev, Patrick Augustin, and Marc Fourmentin
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-82,2020
Preprint under review for AMT (discussion: open, 0 comments)
The current study presents an automated method to classify turbulent structures near the surface, based on the observations recorded by a single scanning Doppler lidar. This methodology combines texture analysis with a supervised machine learning algorithm in order to study large datasets. The algorithm classified correctly about 91 % cases of a training ensemble (150 scans). Furthermore the results of a two-months classified dataset (4577 scans) by the algorithm are presented.
Assessment of the quality of TROPOMI high-spatial-resolution NO2 data products in the Greater Toronto Area
Xiaoyi Zhao, Debora Griffin, Vitali Fioletov, Chris McLinden, Alexander Cede, Martin Tiefengraber, Moritz Müller, Kristof Bognar, Kimberly Strong, Folkert Boersma, Henk Eskes, Jonathan Davies, Akira Ogyu, and Sum Chi Lee
Atmos. Meas. Tech., 13, 2131–2159, https://doi.org/10.5194/amt-13-2131-2020, 2020
Pandora NO2 measurements made at three sites located in the Toronto area are used to evaluate the TROPOspheric Monitoring Instrument (TROPOMI) NO2 data products, including standard NO2 and research data developed using a high-resolution regional air quality forecast model. TROPOMI pixels located upwind and downwind from the Pandora sites were analyzed by a new wind-based validation method, which revealed the spatial patterns of local and transported emissions and regional air quality changes.
Assessment of the quality of TROPOMI high-spatial-resolution NO2 data products in the Greater Toronto Area
Xiaoyi Zhao, Debora Griffin, Vitali Fioletov, Chris McLinden, Alexander Cede, Martin Tiefengraber, Moritz Müller, Kristof Bognar, Kimberly Strong, Folkert Boersma, Henk Eskes, Jonathan Davies, Akira Ogyu, and Sum Chi Lee
Atmos. Meas. Tech., 13, 2131–2159, https://doi.org/10.5194/amt-13-2131-2020, 2020
Pandora NO2 measurements made at three sites located in the Toronto area are used to evaluate the TROPOspheric Monitoring Instrument (TROPOMI) NO2 data products, including standard NO2 and research data developed using a high-resolution regional air quality forecast model. TROPOMI pixels located upwind and downwind from the Pandora sites were analyzed by a new wind-based validation method, which revealed the spatial patterns of local and transported emissions and regional air quality changes.
Detecting turbulent structures on single Doppler lidar large datasets: an automated classification method for horizontal scans
Ioannis Cheliotis, Elsa Dieudonné, Hervé Delbarre, Anton Sokolov, Egor Dmitriev, Patrick Augustin, and Marc Fourmentin
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-82,2020
Preprint under review for AMT (discussion: open, 0 comments)
The current study presents an automated method to classify turbulent structures near the surface, based on the observations recorded by a single scanning Doppler lidar. This methodology combines texture analysis with a supervised machine learning algorithm in order to study large datasets. The algorithm classified correctly about 91 % cases of a training ensemble (150 scans). Furthermore the results of a two-months classified dataset (4577 scans) by the algorithm are presented.
Validation of acetonitrile (CH3CN) measurements in the stratosphere and lower mesosphere from the SMILES instrument on the International Space Station
Tamaki Fujinawa, Tomohiro O. Sato, Takayoshi Yamada, Seidai Nara, Yuki Uchiyama, Kodai Takahashi, Naohiro Yoshida, and Yasuko Kasai
Atmos. Meas. Tech., 13, 2119–2129, https://doi.org/10.5194/amt-13-2119-2020, 2020
We performed an error analysis of SMILES observations for acetonitrile and a validation using the MLS observations by extracting the coincident points between SMILES and MLS data. The major error sources for the SMILES observations were quantitatively estimated. At upper pressure levels the difference between the two datasets increased because of an uncertainty in MLS observations. The results showed that SMILES has an advantage in measuring acetonitrile in the upper stratosphere and mesosphere.
Retrieval of daytime mesospheric ozone using OSIRIS observation of O2(a1∆g) emission
Anqi Li, Chris Roth, Kristell Pérot, Ole Martin Christensen, Adam M. Bourassa, Doug Degenstein, and Donal Murtagh
Atmos. Meas. Tech. Discuss., https//doi.org/10.5194/amt-2020-56,2020
Preprint under review for AMT (discussion: open, 0 comments)
Improving knowledge of the ozone global distributions in the mesosphere-lower thermosphere (MLT) is a crucial step in understanding the behaviour of the middle atmosphere. However, the ozone concentration under sunlit conditions in the MLT is often so low that its measurement requires instruments with very high sensitivity. Fortunately, the bright oxygen airglow can serve as a proxy to retrieve the daytime ozone density indirectly, due to the strong connection to ozone photolysis in the Hartley band. The OSIRIS IR imager (hereafter IRI), one of the instruments on the Odin satellite, routinely measures the oxygen infrared atmospheric band (IRA band) at 1.27 μm. In this paper, we will describe the detailed steps of retrieving the calibrated IRA band limb radiance, the volume emission rate of O2(a1∆g) and, finally, the ozone number density. This retrieval technique is applied to a one-year-sample IRI dataset. The resulting product is a completely new ozone dataset with very high along-track resolution. The performance of the retrieval technique is demonstrated by a comparison of the coincident ozone measurements from the same spacecraft, as well as zonal mean and monthly average comparisons between OS, SMR, MIPAS and ACE-FTS. The consistency of this IRI ozone dataset implies that such a retrieval technique can be further applied to all the measurements made throughout the 19 years-long mission, leading to a long-term, high resolution dataset in the middle atmosphere.
Validation of acetonitrile (CH3CN) measurements in the stratosphere and lower mesosphere from the SMILES instrument on the International Space Station
Tamaki Fujinawa, Tomohiro O. Sato, Takayoshi Yamada, Seidai Nara, Yuki Uchiyama, Kodai Takahashi, Naohiro Yoshida, and Yasuko Kasai
Atmos. Meas. Tech., 13, 2119–2129, https://doi.org/10.5194/amt-13-2119-2020, 2020
We performed an error analysis of SMILES observations for acetonitrile and a validation using the MLS observations by extracting the coincident points between SMILES and MLS data. The major error sources for the SMILES observations were quantitatively estimated. At upper pressure levels the difference between the two datasets increased because of an uncertainty in MLS observations. The results showed that SMILES has an advantage in measuring acetonitrile in the upper stratosphere and mesosphere.
Retrieval of daytime mesospheric ozone using OSIRIS observation of O2(a1∆g) emission
Anqi Li, Chris Roth, Kristell Pérot, Ole Martin Christensen, Adam M. Bourassa, Doug Degenstein, and Donal Murtagh
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-56,2020
Preprint under review for AMT (discussion: open, 0 comments)
Improving knowledge of the ozone global distributions in the mesosphere-lower thermosphere (MLT) is a crucial step in understanding the behaviour of the middle atmosphere. However, the ozone concentration under sunlit conditions in the MLT is often so low that its measurement requires instruments with very high sensitivity. Fortunately, the bright oxygen airglow can serve as a proxy to retrieve the daytime ozone density indirectly, due to the strong connection to ozone photolysis in the Hartley band. The OSIRIS IR imager (hereafter IRI), one of the instruments on the Odin satellite, routinely measures the oxygen infrared atmospheric band (IRA band) at 1.27 μm. In this paper, we will describe the detailed steps of retrieving the calibrated IRA band limb radiance, the volume emission rate of O2(a1∆g) and, finally, the ozone number density. This retrieval technique is applied to a one-year-sample IRI dataset. The resulting product is a completely new ozone dataset with very high along-track resolution. The performance of the retrieval technique is demonstrated by a comparison of the coincident ozone measurements from the same spacecraft, as well as zonal mean and monthly average comparisons between OS, SMR, MIPAS and ACE-FTS. The consistency of this IRI ozone dataset implies that such a retrieval technique can be further applied to all the measurements made throughout the 19 years-long mission, leading to a long-term, high resolution dataset in the middle atmosphere.
Effects of clouds on the UV Absorbing Aerosol Index from TROPOMI
Maurits L. Kooreman, Piet Stammes, Victor Trees, Maarten Sneep, L. Gijsbert Tilstra, Martin de Graaf, Deborah C. Stein Zweers, Ping Wang, Olaf N. E. Tuinder, and J. Pepijn Veefkind
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-112,2020
Preprint under review for AMT (discussion: open, 0 comments)
We investigated the influence of clouds on the AAI, which is an indicator of the presence of small particles suspended in the atmosphere. Clouds produce artefacts in the AAI calculation on the individual measurement (7 km) scale, which was not seen with previous instruments, as well as large (1000+ km) scales. To reduce these artefacts, we used three different AAI calculation techniques with varying complexity. We find that the AAI artefacts are reduced when using more complex techniques.
Retrieval of Lower-Order Moments of the Drop Size Distribution using CSU-CHILL X-band Polarimetric Radar: A Case Study
Viswanathan Bringi, Kumar Vijay Mishra, Merhala Thurai, Patrick C. Kennedy, and Timothy H. Raupach
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2020-160,2020
Preprint under review for AMT (discussion: open, 0 comments)
The raindrop size distribution and its moments are fundamental in many areas such as radar measurement of rainfall using polarimetry and numerical modelling of the microphysical processes of rain formation and evolution. We develop a technique which uses advanced radar measurements and complete drop size distributions using two collocated instruments to retrieve the lower order moments such as total drop concentration and rain water content. We demonstrate proof-of-concept using a case study.
