Atmos. Meas. techniques

Synergy of active and passive airborne observations for heating rates calculation during the AEROCLO-SA field campaign in Namibia
Mégane Ventura, Fabien Waquet, Isabelle Chiapello, Gérard Brogniez, Frédéric Parol, Frédérique Auriol, Rodrigue Loisil, Cyril Delegove, Luc Blarel, Oleg Dubovik, Marc Mallet, Cyrille Flamant, and Paola Formenti
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-121,2024
Preprint under review for AMT (discussion: open, 0 comments)
Biomass burning aerosols (BBA) from Central Africa, are transported above stratocumulus clouds. The absorption of solar energy by aerosols induce warming, altering the clouds dynamics. We developed an approach that combines polarimeter and lidar to quantify it. This methodology is assessed during the AEROCLO-SA campaign. To validate it, we used flux measurements acquired during aircraft loop descents. Major perspective is the generalization of this method to the global level.

Vertical Retrieval of AOD using SEVIRI data, Case Study: European Continent
Maryam Pashayi, Mehran Satari, and Mehdi Momeni Shahraki
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-105,2024
Preprint under review for AMT (discussion: open, 0 comments)
Our study estimates the SEVIRI AOD profile across Europe with 3 km spatial and 15-minute temporal resolution. Using machine learning models trained on 2017–2019 SEVIRI data and validated with 2020 CALIOP data, we found that RF performs best at higher altitudes, with wind speed and direction playing a crucial role in improving accuracy. Validation with EARLINET data confirms strong agreement with XGB.

Characterization of a new Teflon chamber and on-line analysis of isomeric multifunctional photooxidation products
Finja Löher, Esther Borrás, Amalia Muñoz, and Anke Christine Nölscher
Atmos. Meas. Tech., 17, 4553–4579, https://doi.org/10.5194/amt-17-4553-2024, 2024
We constructed and characterized a new indoor Teflon atmospheric simulation chamber. We evaluated wall losses, photolysis rates, and secondary reactions of multifunctional photooxidation products in the chamber. To measure these products on-line, we combined chromatographic and mass spectrometric analyses to obtain both isomeric information and a high temporal resolution. For method validation, we studied the formation yields of the main ring-retaining products of toluene.

Verification of weather-radar-based hail metrics with crowdsourced observations from Switzerland
Jérôme Kopp, Alessandro Hering, Urs Germann, and Olivia Martius
Atmos. Meas. Tech., 17, 4529–4552, https://doi.org/10.5194/amt-17-4529-2024, 2024
We present a verification of two products based on weather radars to detect the presence of hail and estimate its size.  Radar products are remote detection of hail, so they must be verified against ground-based observations. We use reports from users of the Swiss Weather Services phone app to do the verification. We found that the product estimating the presence of hail provides fair results but that it should be recalibrated and that estimating the hail size with radar is more challenging.

Evaluation of optimized flux chamber design for measurement of ammonia emission after field application of slurry with full-scale farm machinery
Johanna Pedersen, Sasha D. Hafner, Andreas Pacholski, Valthor I. Karlsson, Li Rong, Rodrigo Labouriau, and Jesper N. Kamp
Atmos. Meas. Tech., 17, 4493–4505, https://doi.org/10.5194/amt-17-4493-2024, 2024
Field-applied animal slurry is a significant source of NH3 emission. A new system of dynamic flux chambers for NH3 measurements was developed and validated using three field trials in order to assess the variability after application with a trailing hose at different scales: manual (handheld) application,  a 3 m slurry boom, and a 30 m slurry boom. The system facilitates NH3 emission measurement with replication after both manual and farm-scale slurry application with relatively high precision.

A novel, balloon-borne UV–Vis spectrometer for direct sun measurements of stratospheric bromine
Karolin Voss, Philip Holzbeck, Klaus Pfeilsticker, Ralph Kleinschek, Gerald Wetzel, Blanca Fuentes Andrade, Michael Höpfner, Jörn Ungermann, Björn-Martin Sinnhuber, and André Butz
Atmos. Meas. Tech., 17, 4507–4528, https://doi.org/10.5194/amt-17-4507-2024, 2024
A novel balloon-borne instrument for direct sun and solar occultation measurements of several UV–Vis absorbing gases (e.g. O3, NO2, BrO, IO, and HONO) is described. Its major design features and performance during two stratospheric deployments are discussed. From the measured overhead BrO concentration and a suitable photochemical correction, total stratospheric bromine is inferred to (17.5 ± 2.2) ppt in air masses which entered the stratosphere around early 2017 ± 1 year.

On Path Length, Beam Divergence, and Retroreflector Array Size in Open-Path FTIR Spectroscopy
Cameron E. N. Power and Aldona Wiacek
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-97,2024
Preprint under review for AMT (discussion: open, 0 comments)
The choice of path length and retroreflector array size in open-path FTIR spectroscopy must be made with care.  Longer paths increase target gas absorption (lowering detection limits) and larger retroreflector arrays improve the SNR of spectra by increasing the return signal (improving retrieved concentration precision), but there are limitations to both.  An optimum array size and path combination exists in each specific observational environment and application, as explored in this work.

A measurement system for CO2 and CH4 emissions quantification of industrial sites using a new in situ concentration sensor operated on board uncrewed aircraft vehicles
Jean-Louis Bonne, Ludovic Donnat, Grégory Albora, Jérémie Burgalat, Nicolas Chauvin, Delphine Combaz, Julien Cousin, Thomas Decarpenterie, Olivier Duclaux, Nicolas Dumelié, Nicolas Galas, Catherine Juery, Florian Parent, Florent Pineau, Abel Maunoury, Olivier Ventre, Marie-France Bénassy, and Lilian Joly
Atmos. Meas. Tech., 17, 4471–4491, https://doi.org/10.5194/amt-17-4471-2024, 2024
We present a top-down approach to quantify CO2 and CH4 emissions at the scale of an industrial site, based on a mass balance model relying on atmospheric concentrations measurements from a new sensor embarked on board uncrewed aircraft vehicles (UAVs). We present a laboratory characterization of our sensor and a field validation of our quantification method, together with field application to the monitoring of two real-world offshore oil and gas platforms.

A Bias Correction Scheme for FY-3E/ HIRAS-II Observation Data Assimilation
Hongtao Chen and Li Guan
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-65,2024
Preprint under review for AMT (discussion: open, 0 comments)
In order to correctly assimilate satellite radiance observations in data assimilation systems, the systematic observation biases must be corrected to conform to a Gaussian normal distribution with a mean of 0.In this paper, a two-step bias correction scheme is established based on radiation observations of HIRAS-II (Hyperspectral Infrared Atmospheric Sounder-II) carried on FY-3E.

Multi-angle aerosol optical depth retrieval method based on improved surface reflectance
Lijuan Chen, Ren Wang, Ying Fei, Peng Fang, Yong Zha, and Haishan Chen
Atmos. Meas. Tech., 17, 4411–4424, https://doi.org/10.5194/amt-17-4411-2024, 2024
This study explores the problems of surface reflectance estimation from previous MISR satellite remote sensing images and develops an error correction model to obtain a higher-precision aerosol optical depth (AOD) product. High-accuracy AOD is important not only for the daily monitoring of air pollution but also for the study of energy exchange between land and atmosphere. This will help further improve the retrieval accuracy of multi-angle AOD on large spatial scales and for long time series.

Comparison of diurnal aerosol products retrieved from combinations of micro-pulse lidar and sun photometer observations over the KAUST observation site
Anton Lopatin, Oleg Dubovik, Georgiy Stenchikov, Ellsworth J. Welton, Illia Shevchenko, David Fuertes, Marcos Herreras-Giralda, Tatsiana Lapyonok, and Alexander Smirnov
Atmos. Meas. Tech., 17, 4445–4470, https://doi.org/10.5194/amt-17-4445-2024, 2024
We compare aerosol properties over the King Abdullah University of Science and Technology campus using Generalized Retrieval of Aerosol and Surface Properties (GRASP) and the Micro-Pulse Lidar Network (MPLNET). We focus on the impact of different aerosol retrieval assumptions on daytime and nighttime retrievals and analyze seasonal variability in aerosol properties, aiding in understanding aerosol behavior and improving retrieval. Our work has implications for climate and public health.

A versatile water vapor generation module for vapor isotope calibration and liquid isotope measurements
Hans Christian Steen-Larsen and Daniele Zannoni
Atmos. Meas. Tech., 17, 4391–4409, https://doi.org/10.5194/amt-17-4391-2024, 2024
The water vapor generation module is completely scalable, allowing autonomous calibrations to use N standards and providing integration times only restricted by sample availability. We document improved reproducibility in 17O-excess liquid measurements. This module makes spectroscopy measurements comparable to mass spectrometry. We document that the vapor generation module can be used to analyze instrument performance and for vapor isotope calibration during field campaign measurements.

Aerosol optical property measurement using the orbiting high-spectral-resolution lidar on board the DQ-1 satellite: retrieval and validation
Chenxing Zha, Lingbing Bu, Zhi Li, Qin Wang, Ahmad Mubarak, Pasindu Liyanage, Jiqiao Liu, and Weibiao Chen
Atmos. Meas. Tech., 17, 4425–4443, https://doi.org/10.5194/amt-17-4425-2024, 2024
China has launched the atmospheric environment monitoring satellite DQ-1, which consists of an advanced lidar system. Our research presents a retrieval algorithm of the DQ-1 lidar system, and the retrieval results are consistent with other datasets. We also use the DQ-1 dataset to investigate dust and volcanic aerosols. This research shows that the DQ-1 lidar system can accurately measure the Earth's atmosphere and has potential for scientific applications.

An interlaboratory comparison to quantify oxidative potential measurement in aerosol particles: challenges and recommendations for harmonisation
Pamela A. Dominutti, Jean-Luc Jaffrezo, Anouk Marsal, Takoua Mhadhbi, Rhabira Elazzouzi, Camille Rak, Fabrizia Cavalli, Jean-Philippe Putaud, Aikaterini Bougiatioti, Nikolaos Mihalopoulos, Despina Paraskevopoulou, Ian S. Mudway, Athanasios Nenes, Kaspar R. Daellenbach, Catherine Banach, Steven J. Campbell, Hana Cigánková, Daniele Contini, Greg Evans, Maria Georgopoulou, Manuella Ghanem, Drew A. Glencross, Maria Rachele Guascito, Hartmut Herrmann, Saima Iram, Maja Jovanović, Milena Jovašević-Stojanović, Markus Kalberer, Ingeborg M. Kooter, Suzanne E. Paulson, Anil Patel, Esperanza Perdrix, Maria Chiara Pietrogrande, Pavel Mikuška, Jean-Jacques Sauvain, Aikaterina Seitanidi, Pourya Shahpoury, Eduardo J. S. Souza, Sarah Steimer, Svetlana Stevanovic, Guillaume Suarez, P. S. Ganesh Subramanian, Battist Utinger, Marloes F. van Os, Vishal Verma, Xing Wang, Rodney J. Weber, Yuhan Yang, Xavier Querol, Gerard Hoek, Roy M. Harrison, and Gaëlle Uzu
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-107,2024
Preprint under review for AMT (discussion: open, 0 comments)
In this work, 20 labs worldwide collaborated to evaluate the measurement of air pollution's oxidative potential (OP), a key indicator of its harmful effects. The study aimed to identify disparities in the widely used OP DTT assay and assess the consistency of OP among labs using the same protocol. The results showed that half of the labs achieved acceptable results. However, variability was also found, highlighting the need for standardization in OP procedures.

First atmospheric aerosol-monitoring results from the Geostationary Environment Monitoring Spectrometer (GEMS) over Asia
Yeseul Cho, Jhoon Kim, Sujung Go, Mijin Kim, Seoyoung Lee, Minseok Kim, Heesung Chong, Won-Jin Lee, Dong-Won Lee, Omar Torres, and Sang Seo Park
Atmos. Meas. Tech., 17, 4369–4390, https://doi.org/10.5194/amt-17-4369-2024, 2024
Aerosol optical properties have been provided by the Geostationary Environment Monitoring Spectrometer (GEMS), the world’s first geostationary-Earth-orbit (GEO) satellite instrument designed for atmospheric environmental monitoring. This study describes improvements made to the GEMS aerosol retrieval algorithm (AERAOD) and presents its validation results. These enhancements aim to provide more accurate and reliable aerosol-monitoring results for Asia. 

The Chalmers Cloud Ice Climatology: retrieval implementation and validation
Adrià Amell, Simon Pfreundschuh, and Patrick Eriksson
Atmos. Meas. Tech., 17, 4337–4368, https://doi.org/10.5194/amt-17-4337-2024, 2024
The representation of clouds in numerical weather and climate models remains a major challenge that is difficult to address because of the limitations of currently available data records of cloud properties. In this work, we address this issue by using machine learning to extract novel information on ice clouds from a long record of satellite observations. Through extensive validation, we show that this novel approach provides surprisingly accurate estimates of clouds and their properties.

Quantifying the uncertainties in thermal–optical analysis of carbonaceous aircraft engine emissions: an interlaboratory study
Timothy A. Sipkens, Joel C. Corbin, Brett Smith, Stéphanie Gagné, Prem Lobo, Benjamin T. Brem, Mark P. Johnson, and Gregory J. Smallwood
Atmos. Meas. Tech., 17, 4291–4302, https://doi.org/10.5194/amt-17-4291-2024, 2024
Carbonaceous particles, such as soot, contribute to climate forcing, air pollution, and human health impacts. Thermal–optical analysis is a calibration standard used to measure these particles, but significant differences have been observed in the measurements across identical instruments. We report on the reproducibility of these measurements for aircraft emissions, which range from 8.0 % of the nominal value for organic carbon to 17 % for elemental carbon. 

Aerosol optical depth data fusion with Geostationary Korea Multi-Purpose Satellite (GEO-KOMPSAT-2) instruments GEMS, AMI, and GOCI-II: statistical and deep neural network methods
Minseok Kim, Jhoon Kim, Hyunkwang Lim, Seoyoung Lee, Yeseul Cho, Yun-Gon Lee, Sujung Go, and Kyunghwa Lee
Atmos. Meas. Tech., 17, 4317–4335, https://doi.org/10.5194/amt-17-4317-2024, 2024
Information about aerosol loading in the atmosphere can be collected from various satellite instruments. Aerosol products from various satellite instruments have their own error characteristics. This study statistically merged aerosol optical depth datasets from multiple instruments aboard geostationary satellites considering uncertainties. Also, a deep neural network technique is adopted for aerosol data merging.

Determination of high-precision tropospheric delays using crowdsourced smartphone GNSS data
Yuanxin Pan, Grzegorz Kłopotek, Laura Crocetti, Rudi Weinacker, Tobias Sturn, Linda See, Galina Dick, Gregor Möller, Markus Rothacher, Ian McCallum, Vicente Navarro, and Benedikt Soja
Atmos. Meas. Tech., 17, 4303–4316, https://doi.org/10.5194/amt-17-4303-2024, 2024
Crowdsourced smartphone GNSS data were processed with a dedicated data processing pipeline and could produce millimeter-level accurate estimates of zenith total delay (ZTD) – a critical atmospheric variable. This breakthrough not only demonstrates the feasibility of using ubiquitous devices for high-precision atmospheric monitoring but also underscores the potential for a global, cost-effective tropospheric monitoring network.

An oxidation flow reactor for simulating and accelerating secondary aerosol formation in aerosol liquid water and cloud droplets
Ningjin Xu, Chen Le, David R. Cocker, Kunpeng Chen, Ying-Hsuan Lin, and Don R. Collins
Atmos. Meas. Tech., 17, 4227–4243, https://doi.org/10.5194/amt-17-4227-2024, 2024
A flow-through reactor was developed that exposes known mixtures of gases or ambient air to very high concentrations of the oxidants that are responsible for much of the chemistry that takes place in the atmosphere. Like other reactors of its type, it is primarily used to study the formation of particulate matter from the oxidation of common gases. Unlike other reactors of its type, it can simulate the chemical reactions that occur in liquid water that is present in particles or cloud droplets.