Atmos. Meas. techniques

Characterization of stratospheric particle size distribution uncertainties using SAGE II and SAGE III/ISS extinction spectra
Travis N. Knepp, Mahesh Kovilakam, Larry Thomason, and Stephen J. Miller
Atmos. Meas. Tech., 17, 2025–2054, https://doi.org/10.5194/amt-17-2025-2024, 2024
An algorithm is presented to derive a new SAGE III/ISS (Stratospheric Aerosol and Gas Experiment III on the International Space Station) Level-2 product: the size distribution of stratospheric particles. This is a significant improvement over previous techniques in that we now provide uncertainty estimates for all inferred parameters. We also evaluated the stability of this method in retrieving bimodal distribution parameters. We present a special application to the 2022 eruption of Hunga Tonga.

Evaluation of Aeris mid-infrared absorption (MIRA), Picarro CRDS (cavity ring-down spectroscopy) G2307, and dinitrophenylhydrazine (DNPH)-based sampling for long-term formaldehyde monitoring efforts
Asher P. Mouat, Zelda A. Siegel, and Jennifer Kaiser
Atmos. Meas. Tech., 17, 1979–1994, https://doi.org/10.5194/amt-17-1979-2024, 2024
Three fast-measurement formaldehyde monitors were deployed at two field sites in Atlanta, GA, over 1 year. Four different zeroing methods were tested to develop an optimal field setup as well as procedures for instrument calibration. Observations agreed well after calibration but were much higher compared to the TO-11A monitoring method, which is the golden standard. Historical HCHO concentrations were compared with measurements in this work, showing a 22 % reduction in midday HCHO since 1999.

Comparing FY-2F/CTA products to ground-based manual total cloud cover observations in Xinjiang under complex underlying surfaces and different weather conditions
Shuai Li, Hua Zhang, Yonghang Chen, Zhili Wang, Xiangyu Li, Yuan Li, and Yuanyuan Xue
Atmos. Meas. Tech., 17, 2011–2024, https://doi.org/10.5194/amt-17-2011-2024, 2024
In this paper, Xinjiang was the test area, and nine evaluation indexes of FY-2F/CTA, including precision rate, false rate, missing rate, consistency rate, strong rate, weak rate, bias, AE, and RMSE, were calculated and analyzed under complex underlying surface (subsurface types, temperature and altitude conditions) and different weather conditions (dust effects and different cloud cover levels). The precision, consistency, and error indexes of FY-2F/CTA were tested and evaluated.

An improved BRDF hotspot model and its use in VLIDORT for studying the impact of atmospheric scattering on hotspot directional signatures in the atmosphere
Xiaozhen Xiong, Xu Liu, Robert Spurr, Ming Zhao, Qiguang Yang, Wan Wu, and Liqiao Lei
Atmos. Meas. Tech., 17, 1965–1978, https://doi.org/10.5194/amt-17-1965-2024, 2024
The term “hotspot” refers to the sharp increase in reflectance occurring when incident (solar) and reflected (viewing) directions coincide in the backscatter direction. The accurate simulation of hotspot directional signatures is important for many remote sensing applications, but current models typically require large values of computations to represent the hotspot accurately. This paper provides a numerically improved hotspot BRDF model that converges much faster and is used in VLIDORT.

A multi-decadal time series of upper stratospheric temperature profiles from Odin-OSIRIS limb-scattered spectra
Daniel Zawada, Kimberlee Dubé, Taran Warnock, Adam Bourassa, Susann Tegtmeier, and Douglas Degenstein
Atmos. Meas. Tech., 17, 1995–2010, https://doi.org/10.5194/amt-17-1995-2024, 2024
There remain large uncertainties in long-term changes of stratospheric–atmospheric temperatures. We have produced a time series of more than 20 years of satellite-based temperature measurements from the OSIRIS instrument in the upper–middle stratosphere. The dataset is publicly available and intended to be used for a better understanding of changes in stratospheric temperatures.

An advanced spatial co-registration of cloud properties for the atmospheric Sentinel missions: Application to TROPOMI
Athina Argyrouli, Diego Loyola, Fabian Romahn, Ronny Lutz, Víctor Molina García, Pascal Hedelt, Klaus-Peter Heue, and Richard Siddans
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-28,2024
Preprint under review for AMT (discussion: open, 0 comments)
This manuscript describes a new treatment of the spatial mis-registration of cloud properties for Sentinel-5 Precursor, when the footprints of different spectral bands are not perfectly aligned. The methodology exploits synergies between spectrometers and imagers, like TROPOMI and VIIRS. The largest improvements have been identified for heterogeneous scenes at cloud edges. This approach is generic and can also be applied to future Sentinel-4 and Sentinel-5 instruments.

Remote sensing of lower-middle thermosphere temperatures using the N2 Lyman-Birge-Hopfield (LBH) bands
Richard Eastes, J. Scott Evans, Quan Gan, Bill McClintock, and Jerry Lumpe
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-52,2024
Preprint under review for AMT (discussion: open, 0 comments)
The temperature is essential to understanding the thermosphere. Most temperature measurements have indirect or had large uncertainties, especially in the lower-middle thermosphere where data are rarely available. Since October 2018 NASA’s GOLD mission has produced disk images of neutral temperatures near 160 km at locations over the Americas and Atlantic Ocean. This paper discusses both temperature retrieval techniques and issues in interpreting GOLD’s images of temperatures.

The added value and potential of long-term radio occultation data for climatological wind field monitoring
Irena Nimac, Julia Danzer, and Gottfried Kirchengast
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-59,2024
Preprint under review for AMT (discussion: open, 0 comments)
Due to shortcomings of available observations, having accurate global 3D wind fields remains a challenge. Promising option is the use of radio occultation (RO) satellite data, which enable to derive winds based on the wind approximations. We test how well RO winds describe the ERA5 reanalysis winds. We separate the total wind difference into the approximation bias and the systematic difference between the two datasets. The results show the utility of RO winds for climate monitoring and analyses.

Advantages of assimilating multispectral satellite retrievals of atmospheric composition: a demonstration using MOPITT carbon monoxide products
Wenfu Tang, Benjamin Gaubert, Louisa Emmons, Daniel Ziskin, Debbie Mao, David Edwards, Avelino Arellano, Kevin Raeder, Jeffrey Anderson, and Helen Worden
Atmos. Meas. Tech., 17, 1941–1963, https://doi.org/10.5194/amt-17-1941-2024, 2024
We assimilate different MOPITT CO products to understand the impact of (1) assimilating multispectral and joint retrievals versus single spectral products, (2) assimilating satellite profile products versus column products, and (3) assimilating multispectral and joint retrievals versus assimilating individual products separately.

Using OMPS-LP color ratio to extract stratospheric aerosol particle median radius and concentration with application to two volcanic eruptions
Yi Wang, Mark Schoeberl, and Ghassan Taha
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2023-267,2024
Preprint under review for AMT (discussion: open, 0 comments)
The OMPS-LP satellite instrument assesses aerosol scattering in the atmospheric limb. Using a dual-wavelength extinction coefficient algorithm, we extract stratospheric aerosol vertical profiles from OMPS-LP data. Our study addresses uncertainties and validates these profiles against in-situ balloon data and SAGE-III/ISS retrievals. Investigating the Raikoke and Hunga Tonga-Hunga Ha'apai eruptions, we analyze the evolution of aerosol size and concentration, confirming our method's reliability.

An improved OMI ozone profile research product version 2.0 with collection 4 L1b data and algorithm updates
Juseon Bak, Xiong Liu, Kai Yang, Gonzalo Gonzalez Abad, Ewan O'Sullivan, Kelly Chance, and Cheol-Hee Kim
Atmos. Meas. Tech., 17, 1891–1911, https://doi.org/10.5194/amt-17-1891-2024, 2024
The new version (V2) of the OMI ozone profile product is introduced to improve retrieval quality and long-term consistency of tropospheric ozone by incorporating the recent collection 4 OMI L1b spectral products and refining radiometric correction, forward model calculation, and a priori ozone data.

Spatial analysis of PM2.5 using a Concentration Similarity Index applied to air quality sensor networks
Rósín Byrne, John C. Wenger, and Stig Hellebust
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-38,2024
Preprint under review for AMT (discussion: open, 0 comments)
This study presents the Concentration Similarity Index (CSI) for a quantitative and robust comparison of PM2.5 measurements within air quality sensor networks. Developed and tested on two Irish sensor networks, the CSI revealed real spatial variations in PM2.5 and enables assessment of the representativeness of regulatory monitoring locations. It underscores the impact of solid fuel combustion on PM2.5 and highlights the importance of wintertime data for accurate exposure assessments.

Multi-decadal atmospheric carbon dioxide measurements in Central Europe, Hungary
László Haszpra
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-29,2024
Preprint under review for AMT (discussion: open, 0 comments)
The paper evaluates a 30-year-long atmospheric CO2 data series from a mid-continental Central European site, Hegyhátsál (HUN). It presents the site-specific features observed in the long-term evolution of the atmospheric CO2 concentration. Since the measurement data are widely used in atmospheric inverse models and budget calculations all around the world, the paper provides potentially valuable information for model tuning and interpretation of the model results.

Multiphysical description of atmospheric pressure interface chemical ionisation in MION2 and Eisele type inlets
Henning Finkenzeller, Jyri Mikkilä, Cecilia Righi, Paxton Juuti, Mikko Sipilä, Matti Rissanen, Douglas Worsnop, Aleksei Shcherbinin, Nina Sarnela, and Juha Kangasluoma
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-48,2024
Preprint under review for AMT (discussion: open, 0 comments)
Chemical ionization mass spectrometry is used in atmospheric sciences to measure trace gas concentrations. Neutral gases require charging in inlets before the mass-to-charge ratio of the resulting ions can be analyzed. This study uses multi-physics modelling to investigate how the MION2 and Eisele type inlets work, shows the effect of tuning parameters, and their current limitations. The findings are helpful for the inlet users and are expected to aid in developing improved inlets.

Evaluation of FY-4A/AGRI visible reflectance using the equivalents derived from the forecasts of CMA-MESO using RTTOV
Yongbo Zhou, Yubao Liu, Wei Han, Yuefei Zeng, Haofei Sun, and Peilong Yu
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-12,2024
Preprint under review for AMT (discussion: open, 0 comments)
This study reported a method to evaluate the performance of the FY-4A visible instrument and to correct the systematic biases in the visible radiances. The method involves the equivalents derived from the forecasts of the CMA-MESO model using a fast forward operator. After applying the method, the biases in the observations were corrected and the Gaussianess of the observation errors was better respected. The findings facilitate the data assimilation of these data using conventional methods.

Parameterizing spectral surface reflectance relationships for the Dark Target aerosol algorithm applied to a geostationary imager
Mijin Kim, Robert C. Levy, Lorraine A. Remer, Shana Mattoo, and Pawan Gupta
Atmos. Meas. Tech., 17, 1913–1939, https://doi.org/10.5194/amt-17-1913-2024, 2024
The study focused on evaluating and modifying the surface reflectance parameterization (SRP) of the Dark Target (DT) algorithm for geostationary observation. When using the DT SRP with the ABIs sensor on GOES-R, artificial diurnal signatures were present in AOD retrieval. To overcome this issue, a new SRP was developed, incorporating solar zenith angle and land cover type. The revised SRP resulted in improved AOD retrieval, demonstrating reduced bias around local noon.

Effects of clouds and aerosols on downwelling surface solar irradiance nowcasting and short-term forecasting
Kyriakoula Papachristopoulou, Ilias Fountoulakis, Alkiviadis F. Bais, Basil E. Psiloglou, Nikolaos Papadimitriou, Ioannis-Panagiotis Raptis, Andreas Kazantzidis, Charalampos Kontoes, Maria Hatzaki, and Stelios Kazadzis
Atmos. Meas. Tech., 17, 1851–1877, https://doi.org/10.5194/amt-17-1851-2024, 2024
The upgraded systems SENSE2 and NextSENSE2 focus on improving the quality of solar nowcasting and forecasting. SENSE2 provides real-time estimates of solar irradiance across a wide region every 15 min. NextSENSE2 offers short-term forecasts of irradiance up to 3 h ahead. Evaluation with actual data showed that the instantaneous comparison yields the most discrepancies due to the uncertainties of cloud-related information and satellite versus ground-based spatial representativeness limitations.

Aerosol and cloud data processing and optical property retrieval algorithms for the spaceborne ACDL/DQ-1
Guangyao Dai, Songhua Wu, Wenrui Long, Jiqiao Liu, Yuan Xie, Kangwen Sun, Fanqian Meng, Xiaoquan Song, Zhongwei Huang, and Weibiao Chen
Atmos. Meas. Tech., 17, 1879–1890, https://doi.org/10.5194/amt-17-1879-2024, 2024
An overview is given of the main algorithms applied to derive the aerosol and cloud optical property product of the Aerosol and Carbon Detection Lidar (ACDL), which is capable of globally profiling aerosol and cloud optical properties with high accuracy. The paper demonstrates the observational capabilities of ACDL for aerosol and cloud vertical structure and global distribution through two optical property product measurement cases and global aerosol optical depth profile observations.

Directly measuring the power-law exponent and kinetic energy of atmospheric turbulence using coherent Doppler wind lidar
Jinhong Xian, Chao Lu, Xiaoling Lin, Honglong Yang, Ning Zhang, and Li Zhang
Atmos. Meas. Tech., 17, 1837–1850, https://doi.org/10.5194/amt-17-1837-2024, 2024
Improving the monitoring capability of atmospheric turbulence can help unravel the mystery of turbulence. Based on some assumptions, scientists have proposed various detection methods. However, these assumptions limit their applicability. We abandoned these assumptions and proposed a more accurate method, revealing some new results. Our method can provide more accurate three-dimensional features of turbulence, which will have a huge driving effect on the development of turbulence.

Thermal tides in the middle atmosphere at mid-latitudes measured with a ground-based microwave Radiometer
Witali Krochin, Axel Murk, and Gunter Stober
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-42,2024
Preprint under review for AMT (discussion: open, 0 comments)
Atmospheric tides are global-scale oscillations with periods of a fraction of a day. Their observation in the middle atmosphere is challenging and rare, as it requires continuous measurements with a high temporal resolution. In this manuscript, temperature time series of a ground-based microwave radiometer were analyzed with a spectral filter to derive thermal tide amplitudes and phases in an altitude range of 20–50 km at the geographical location of Payerne (Switzerland).