Atmos. Meas. techniques

Using a portable FTIR spectrometer to evaluate the consistency of Total Carbon Column Observing Network (TCCON) measurements on a global scale: the Collaborative Carbon Column Observing Network (COCCON) travel standard
Benedikt Herkommer, Carlos Alberti, Paolo Castracane, Jia Chen, Angelika Dehn, Florian Dietrich, Nicholas M. Deutscher, Matthias Max Frey, Jochen Groß, Lawson Gillespie, Frank Hase, Isamu Morino, Nasrin Mostafavi Pak, Brittany Walker, and Debra Wunch
Atmos. Meas. Tech., 17, 3467–3494, https://doi.org/10.5194/amt-17-3467-2024, 2024
The Total Carbon Column Observing Network is a network of ground-based Fourier transform infrared (FTIR) spectrometers used mainly for satellite validation. To ensure the highest-quality validation data, the network needs to be highly consistent. This is a major challenge, which so far is solved by site comparisons with airborne in situ measurements. In this work, we describe the use of a portable FTIR spectrometer as a travel standard for evaluating the consistency of TCCON sites.

An evaluation of microphysics in a numerical model using Doppler velocity measured by ground-based radar for application to the EarthCARE satellite
Woosub Roh, Masaki Satoh, Yuichiro Hagihara, Hiroaki Horie, Yuichi Ohno, and Takuji Kubota
Atmos. Meas. Tech., 17, 3455–3466, https://doi.org/10.5194/amt-17-3455-2024, 2024
The advantage of the use of Doppler velocity in the categorization of the hydrometeors is that Doppler velocities suffer less impact from the attenuation of rain and wet attenuation on an antenna. The ground Cloud Profiling Radar observation of the radar reflectivity for the precipitation case is limited because of wet attenuation on an antenna. We found the main contribution to Doppler velocities is the terminal velocity of hydrometeors by analysis of simulation results.

Comparison of the H2O, HDO and δD stratospheric climatologies between the MIPAS-ESA V8, MIPAS-IMK V5 and ACE-FTS V4.1/4.2 satellite datasets
Karen De Los Ríos, Paulina Ordoñez, Gabriele P. Stiller, Piera Raspollini, Marco Gai, Kaley A. Walker, Cristina Peña-Ortiz, and Luis Acosta
Atmos. Meas. Tech., 17, 3401–3418, https://doi.org/10.5194/amt-17-3401-2024, 2024
This study examines newer versions of H2O and HDO retrievals from Envisat/MIPAS and SCISAT/ACE-FTS. Results reveal a better agreement in stratospheric H2O profiles than in HDO profiles. The H2O tape recorder signal is consistent across databases, but δD tape recorder composites show differences that impact the interpretation of water vapour transport. These findings enhance the need for intercomparisons to refine our insights.

Characterisation of particle single-scattering albedo with a modified airborne dual-wavelength CAPS monitor
Chenjie Yu, Edouard Pangui, Kevin Tu, Mathieu Cazaunau, Maxime Feingesicht, Landsheere Xavier, Thierry Bourrianne, Vincent Michoud, Christopher Cantrell, Timothy B. Onasch, Andrew Freedman, and Paola Formenti
Atmos. Meas. Tech., 17, 3419–3437, https://doi.org/10.5194/amt-17-3419-2024, 2024
To meet the requirements for measuring aerosol optical properties on airborne platforms and conducting dual-wavelength measurements, we introduced A2S2, an airborne dual-wavelength cavity-attenuated phase-shift single monitor. This study reports the results in the laboratory and an aircraft campaign over Paris and its surrounding regions. The results demonstrate A2S2's reliability in measuring aerosol optical properties at both wavelengths and its suitability for future aircraft campaigns.

Can remote sensing combustion phase improve estimates of landscape fire smoke emission rate and composition?
Farrer Owsley-Brown, Martin J. Wooster, Mark J. Grosvenor, and Yanan Liu
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-73,2024
Preprint under review for AMT (discussion: open, 0 comments)
Landscape fires produce vast amounts of smoke, affecting the atmosphere locally and globally. Whether a fire is flaming or smoldering strongly impacts the rate at which smoke is produced as well as its composition. This study tested two methods to determine these combustion phases in laboratory fires and compared them to the smoke emitted. One of these methods improved estimates of smoke emission significantly. This suggests potential for improvement in global emission estimates.

Innovative aerosol hygroscopic growth study from Mie–Raman–fluorescence lidar and microwave radiometer synergy
Robin Miri, Olivier Pujol, Qiaoyun Hu, Philippe Goloub, Igor Veselovskii, Thierry Podvin, and Fabrice Ducos
Atmos. Meas. Tech., 17, 3367–3375, https://doi.org/10.5194/amt-17-3367-2024, 2024
This paper focuses on the use of fluorescence to study aerosols with lidar. An innovative method for aerosol hygroscopic growth study using fluorescence is presented. The paper presents case studies to showcase the effectiveness and potential of the proposed approach. These advancements will contribute to better understanding the interactions between aerosols and water vapor, with future work expected to be dedicated to aerosol–cloud interaction.

Dual adaptive differential threshold method for automated detection of faint and strong echo features in radar observations of winter storms
Laura M. Tomkins, Sandra E. Yuter, and Matthew A. Miller
Atmos. Meas. Tech., 17, 3377–3399, https://doi.org/10.5194/amt-17-3377-2024, 2024
We have created a new method to better identify enhanced features in radar data from winter storms. Unlike the clear-cut features seen in warm-season storms, features in winter storms are often fuzzier with softer edges. Our technique is unique because it uses two adaptive thresholds that change based on the background radar values. It can identify both strong and subtle features in the radar data and takes into account uncertainties in the detection process.

Accounting for the effect of aerosols in GHGSat methane retrieval
Qiurun Yu, Dylan Jervis, and Yi Huang
Atmos. Meas. Tech., 17, 3347–3366, https://doi.org/10.5194/amt-17-3347-2024, 2024
This study estimated the effects of aerosols on GHGSat satellite methane retrieval and investigated the performance of simultaneously retrieving aerosol and methane information using a multi-angle viewing method. Results suggested that the performance of GHGSat methane retrieval improved when aerosols were considered, and the multi-angle viewing method is insensitive to the satellite angle setting. This performance assessment is useful for improving future GHGSat-like instruments.

Evaluation of calibration performance of a low-cost particulate matter sensor using collocated and distant NO2
Kabseok Ko, Seokheon Cho, and Ramesh R. Rao
Atmos. Meas. Tech., 17, 3303–3322, https://doi.org/10.5194/amt-17-3303-2024, 2024
In our study, we examined how NO2, temperature, and relative humidity influence the calibration of PurpleAir PA-II sensors. We found that incorporating NO2 data from collocated reliable instruments enhances PM2.5 calibration performance. Due to the impracticality of collocating reliable NO2 instruments with sensors, we suggest using distant NO2 data for calibration. We demonstrated that performance improves when distant NO2 correlates highly with collocated NO2 measurements.

Identification of ice-over-water multilayer clouds using multispectral satellite data in an artificial neural network
Sunny Sun-Mack, Patrick Minnis, Yan Chen, Gang Hong, and William L. Smith Jr.
Atmos. Meas. Tech., 17, 3323–3346, https://doi.org/10.5194/amt-17-3323-2024, 2024
Multilayer clouds (MCs) affect the radiation budget differently than single-layer clouds (SCs) and need to be identified in satellite images. A neural network was trained to identify MCs by matching imagery with lidar/radar data. This method correctly identifies ~87 % SCs and MCs with a net accuracy gain of 7.5 % over snow-free surfaces. It is more accurate than most available methods and constitutes a first step in providing a reasonable 3-D characterization of the cloudy atmosphere.

Calibration of Optical Particle Spectrometers Using Mounted Fibres
Jessica Girdwood, Harry Ballington, Chris Stopford, Rob Lewis, and Evelyn Hesse
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-55,2024
Preprint under review for AMT (discussion: open, 0 comments)
Optical particle spectrometers (OPSs) are a class of instruments, commonly used for measurement of particle size distributions, which require calibration. Conventionally, this is performed using a known aerosol source, which has reliability issues. In this paper, we present a technique for OPS calibration which involves placing objects in the instrument, which generate a known response. The fibre calibration was more reliable when the technique was compared with a conventional calibration.

A Portable Nitrogen Dioxide Instrument Using Cavity-Enhanced Absorption Spectroscopy
Steven A. Bailey, Reem A. Hannun, Andrew K. Swanson, and Thomas F. Hanisco
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-61,2024
Preprint under review for AMT (discussion: open, 1 comment)
We have developed a portable, optically based instrument that measures NO2. It consumes less than 6 watts of power so can easily run off a small battery. This instrument has made both balloon and UAV flights. NO2 measurement results compare favorably with other known NO2 instruments. We find this instrument to be stable with repeatable results compared with calibration sources. Materials cost to build a single instrument is around $4 k. This number could be lowered with economies of scale.

Geostationary aerosol retrievals of extreme biomass burning plumes during the 2019–2020 Australian bushfires
Daniel J. V. Robbins, Caroline A. Poulsen, Steven T. Siems, Simon R. Proud, Andrew T. Prata, Roy G. Grainger, and Adam C. Povey
Atmos. Meas. Tech., 17, 3279–3302, https://doi.org/10.5194/amt-17-3279-2024, 2024
Extreme wildfire events are becoming more common with climate change. The smoke plumes associated with these wildfires are not captured by current operational satellite products due to their high optical thickness. We have developed a novel aerosol retrieval for the Advanced Himawari Imager to study these plumes. We find very high values of optical thickness not observed in other operational satellite products, suggesting these plumes have been missed in previous studies.

Performance evaluation of MeteoTracker mobile sensor for outdoor applications
Francesco Barbano, Erika Brattich, Carlo Cintolesi, Abdul Ghafoor Nizamani, Silvana Di Sabatino, Massimo Milelli, Esther E. M. Peerlings, Sjoerd Polder, Gert-Jan Steeneveld, and Antonio Parodi
Atmos. Meas. Tech., 17, 3255–3278, https://doi.org/10.5194/amt-17-3255-2024, 2024
The characterization of the urban microclimate starts with atmospheric monitoring using a dense array of sensors to capture the spatial variations induced by the different morphology, land cover, and presence of vegetation. To provide a new sensor for this scope, this paper evaluates the outdoor performance of a commercial mobile sensor. The results mark the sensor's ability to capture the same atmospheric variability as the reference, making it a valid solution for atmospheric monitoring.

Noise filtering options for conically scanning Doppler lidar measurements with low pulse accumulation
Eileen Päschke and Carola Detring
Atmos. Meas. Tech., 17, 3187–3217, https://doi.org/10.5194/amt-17-3187-2024, 2024
Little noise in radial velocity Doppler lidar measurements can contribute to large errors in retrieved turbulence variables. In order to distinguish between plausible and erroneous measurements we developed new filter techniques that work independently of the choice of a specific threshold for the signal-to-noise ratio. The performance of these techniques is discussed both by means of assessing the filter results and by comparing retrieved turbulence variables versus independent measurements.

Estimating errors in vehicle secondary aerosol production factors due to oxidation flow reactor response time
Pauli Simonen, Miikka Dal Maso, Pinja Prauda, Anniina Hoilijoki, Anette Karppinen, Pekka Matilainen, Panu Karjalainen, and Jorma Keskinen
Atmos. Meas. Tech., 17, 3219–3236, https://doi.org/10.5194/amt-17-3219-2024, 2024
Secondary aerosol is formed in the atmosphere from gaseous emissions. Oxidation flow reactors used in secondary aerosol research do not immediately respond to changes in the inlet concentration of gases because of their broad transfer functions. This may result in incorrect secondary aerosol production factors determined for vehicles. We studied the extent of possible errors and found that oxidation flow reactors with faster responses result in smaller errors.

A lightweight holographic imager for cloud microphysical studies from an untethered balloon
Thomas Edward Chambers, Iain Murray Reid, and Murray Hamilton
Atmos. Meas. Tech., 17, 3237–3253, https://doi.org/10.5194/amt-17-3237-2024, 2024
Clouds have been identified as the largest source of uncertainty in climate modelling. We report an untethered balloon launch of a holographic imager through clouds. This is the first time a holographic imager has been deployed in this way, enabled by the light weight and low cost of the imager. This work creates the potential to significantly increase the availability of cloud microphysical measurements required for the calibration and validation of climate models and remote sensing methods.

Use of an uncrewed aerial system to investigate aerosol direct and indirect radiative forcing effects in the marine atmosphere
Patricia K. Quinn, Timothy S. Bates, Derek J. Coffman, James E. Johnson, and Lucia M. Upchurch
Atmos. Meas. Tech., 17, 3157–3170, https://doi.org/10.5194/amt-17-3157-2024, 2024
An uncrewed aerial observing system has been developed for the measurement of vertical profiles of aerosol and cloud properties that affect Earth's radiation balance. The system was successfully deployed from a ship and from a coastal site and flown autonomously up to 3050 m and for 4.5 h. These results indicate the potential of the observing system to make routine, operational flights from ships and land to characterize aerosol interactions with radiation and clouds.

Observing atmospheric rivers using GNSS radio occultation data
Bahareh Rahimi and Ulrich Foelsche
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-81,2024
Preprint under review for AMT (discussion: open, 0 comments)
This study explores the use of GNSS-RO data to improve understanding of the vertical structure of humidity in Atmospheric Rivers (ARs). Specific humidity profiles and IWV values from GNSS-RO are evaluated to assess if this method offers additional insights into ARs' vertical characteristics. The results suggest that combining GNSS-RO data, with its high vertical resolution, with SSMI/S data, known for high horizontal resolution, provides a more complete view of the 3D structure of ARs.

Assessment of Operational Non-Time Critical Sentinel-6A Michael Freilich Radio Occultation Data: Insights into Tropospheric GNSS Signal Cutoff Strategies and Processor Improvements
Saverio Paolella, Axel Von Engeln, Sebastiano Padovan, Riccardo Notarpietro, Christian Marquardt, Francisco Sancho, Veronica Rivas Boscan, Nicolas Morew, and Francisco Martin Alemany
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-82,2024
Preprint under review for AMT (discussion: open, 0 comments)
This study evaluates the ability of the EUMETSAT Sentinel-6A RO-NTC processor to provide high quality bending angle profiles. The analysis spans from the signals SNR and phase noise to the determination of the optimal signals cut-off points in the tropospheric region. Some processor enhancements and the impact on the data quality is also discussed. Data were compared against ECMWF confirming the ability of the EUMETSAT RO processors in maintaining consistent and high-quality data.