Pub Date : 2024-08-16DOI: 10.5194/egusphere-2024-2115
Paul S. Jeffery, James R. Drummond, C. Thomas McElroy, Kaley A. Walker, Jiansheng Zou
Abstract. Launched aboard the Canadian satellite SCISAT in August 2003, the Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation (MAESTRO) instrument has been measuring solar absorption spectra in the ultraviolet (UV) and visible part of the spectrum for more than 20 years. The UV channel measurements from MAESTRO are used to retrieve profiles of ozone from the short-wavelength end of the Chappuis band (UV-ozone) and NO2, while measurements made in the visible part of the spectrum are used to retrieve a separate ozone (Vis.-ozone) product. The latest ozone and NO2 profile products, version 4.5, have been released, which nominally cover the period from February 2004 to December 2023. Due to the buildup of an unknown contaminant, the UV-ozone and NO2 products are only viable up to June 2009 for NO2 and December 2009 for UV-ozone. This study presents comparisons of the version 4.5 MAESTRO ozone and NO2 measurements with coincident, both spatially and temporally, measurements from an ensemble of 11 other satellite limb-viewing instruments. In the stratosphere, the Vis.-ozone product was found to possess a small high bias, with stratosphere averaged relative differences between 2.3 % and 8.2 %, but overall good agreement with the comparison datasets is found. A similar bias, albeit with slightly poorer agreement, is found with the UV-ozone product in the stratosphere, with the average stratospheric agreement between MAESTRO and the other datasets ranging from 2.9 % to 11.9 %. For NO2, general agreement with the comparison datasets is only found in the range from 20 to 40 km. Within this range, MAESTRO is found to have a low bias for NO2, and most of the datasets agree to within 27.5 %, although the average agreement ranges from 8.5 % to 43.4 %.
{"title":"Validation of the version 4.5 MAESTRO ozone and NO2 measurements","authors":"Paul S. Jeffery, James R. Drummond, C. Thomas McElroy, Kaley A. Walker, Jiansheng Zou","doi":"10.5194/egusphere-2024-2115","DOIUrl":"https://doi.org/10.5194/egusphere-2024-2115","url":null,"abstract":"<strong>Abstract.</strong> Launched aboard the Canadian satellite SCISAT in August 2003, the Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation (MAESTRO) instrument has been measuring solar absorption spectra in the ultraviolet (UV) and visible part of the spectrum for more than 20 years. The UV channel measurements from MAESTRO are used to retrieve profiles of ozone from the short-wavelength end of the Chappuis band (UV-ozone) and NO<sub>2</sub>, while measurements made in the visible part of the spectrum are used to retrieve a separate ozone (Vis.-ozone) product. The latest ozone and NO<sub>2</sub> profile products, version 4.5, have been released, which nominally cover the period from February 2004 to December 2023. Due to the buildup of an unknown contaminant, the UV-ozone and NO<sub>2</sub> products are only viable up to June 2009 for NO<sub>2</sub> and December 2009 for UV-ozone. This study presents comparisons of the version 4.5 MAESTRO ozone and NO<sub>2</sub> measurements with coincident, both spatially and temporally, measurements from an ensemble of 11 other satellite limb-viewing instruments. In the stratosphere, the Vis.-ozone product was found to possess a small high bias, with stratosphere averaged relative differences between 2.3 % and 8.2 %, but overall good agreement with the comparison datasets is found. A similar bias, albeit with slightly poorer agreement, is found with the UV-ozone product in the stratosphere, with the average stratospheric agreement between MAESTRO and the other datasets ranging from 2.9 % to 11.9 %. For NO<sub>2</sub>, general agreement with the comparison datasets is only found in the range from 20 to 40 km. Within this range, MAESTRO is found to have a low bias for NO<sub>2</sub>, and most of the datasets agree to within 27.5 %, although the average agreement ranges from 8.5 % to 43.4 %.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"217 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-15DOI: 10.5194/amt-17-4737-2024
Matteo Ottaviani, Gabriel Harris Myers, Nan Chen
Abstract. This study presents a detailed theoretical assessment of the information content of passive polarimetric observations over snow scenes, using a global sensitivity analysis (GSA) method. Conventional sensitivity studies focus on varying a single parameter while keeping all other parameters fixed. In contrast, the GSA correctly addresses the covariance of state parameters across their entire parameter space, hence favoring a more correct interpretation of inversion algorithms and the optimal design of their state vectors. The forward simulations exploit a vector radiative transfer model to obtain the Stokes vector emerging at the top of the atmosphere for different solar zenith angles, when the bottom boundary consists of a vertically resolved snowpack of non-spherical grains. The presence of light-absorbing particulates (LAPs), either embedded in the snow or aloft in the atmosphere above in the form of aerosols, is also considered. The results are presented for a set of wavelengths spanning the visible (VIS), near-infrared (NIR), and shortwave infrared (SWIR) region of the spectrum. The GSA correctly captures the expected, high sensitivity of the reflectance to LAPs in the VIS–NIR and to grain size at different depths in the snowpack in the NIR–SWIR. With adequate viewing geometries, mono-angle measurements of total reflectance in the VIS–SWIR (akin to those of the Moderate Resolution Imaging Spectroradiometer, MODIS) resolve grain size in the top layer of the snowpack sufficiently well. The addition of multi-angle polarimetric observations in the VIS–NIR provides information on grain shape and microscale roughness. The simultaneous sensitivity in the VIS–NIR to both aerosols and snow-embedded impurities can be disentangled by extending the spectral range to the SWIR, which contains information on aerosol optical depth while remaining essentially unaffected when the same particulates are mixed with the snow. Multi-angle polarimetric observations can therefore (i) effectively partition LAPs between the atmosphere and the surface, which represents a notorious challenge for snow remote sensing based on measurements of total reflectance only and (ii) lead to better estimates of grain shape and roughness and, in turn, the asymmetry parameter, which is critical for the determination of albedo. The retrieval uncertainties are minimized when the degree of linear polarization is used in place of the polarized reflectance. The Sobol indices, which are the main metric for the GSA, were used to select the state parameters in retrievals performed on data simulated for multiple instrument configurations. Improvements in retrieval quality with the addition of measurements of polarization, multi-angle views, and different spectral channels reflect the information content, identified by the Sobol indices, relative to each configuration. The results encourage the development of new remote sensing algorithms that fully leverage multi-angle and polarimetric
{"title":"Global sensitivity analysis of simulated remote sensing polarimetric observations over snow","authors":"Matteo Ottaviani, Gabriel Harris Myers, Nan Chen","doi":"10.5194/amt-17-4737-2024","DOIUrl":"https://doi.org/10.5194/amt-17-4737-2024","url":null,"abstract":"Abstract. This study presents a detailed theoretical assessment of the information content of passive polarimetric observations over snow scenes, using a global sensitivity analysis (GSA) method. Conventional sensitivity studies focus on varying a single parameter while keeping all other parameters fixed. In contrast, the GSA correctly addresses the covariance of state parameters across their entire parameter space, hence favoring a more correct interpretation of inversion algorithms and the optimal design of their state vectors. The forward simulations exploit a vector radiative transfer model to obtain the Stokes vector emerging at the top of the atmosphere for different solar zenith angles, when the bottom boundary consists of a vertically resolved snowpack of non-spherical grains. The presence of light-absorbing particulates (LAPs), either embedded in the snow or aloft in the atmosphere above in the form of aerosols, is also considered. The results are presented for a set of wavelengths spanning the visible (VIS), near-infrared (NIR), and shortwave infrared (SWIR) region of the spectrum. The GSA correctly captures the expected, high sensitivity of the reflectance to LAPs in the VIS–NIR and to grain size at different depths in the snowpack in the NIR–SWIR. With adequate viewing geometries, mono-angle measurements of total reflectance in the VIS–SWIR (akin to those of the Moderate Resolution Imaging Spectroradiometer, MODIS) resolve grain size in the top layer of the snowpack sufficiently well. The addition of multi-angle polarimetric observations in the VIS–NIR provides information on grain shape and microscale roughness. The simultaneous sensitivity in the VIS–NIR to both aerosols and snow-embedded impurities can be disentangled by extending the spectral range to the SWIR, which contains information on aerosol optical depth while remaining essentially unaffected when the same particulates are mixed with the snow. Multi-angle polarimetric observations can therefore (i) effectively partition LAPs between the atmosphere and the surface, which represents a notorious challenge for snow remote sensing based on measurements of total reflectance only and (ii) lead to better estimates of grain shape and roughness and, in turn, the asymmetry parameter, which is critical for the determination of albedo. The retrieval uncertainties are minimized when the degree of linear polarization is used in place of the polarized reflectance. The Sobol indices, which are the main metric for the GSA, were used to select the state parameters in retrievals performed on data simulated for multiple instrument configurations. Improvements in retrieval quality with the addition of measurements of polarization, multi-angle views, and different spectral channels reflect the information content, identified by the Sobol indices, relative to each configuration. The results encourage the development of new remote sensing algorithms that fully leverage multi-angle and polarimetric","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"89 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Han Mei, Peng Wei, Meisam Ahmadi Ghadikolaei, Nirmal Kumar Gali, Ya Wang, Zhi Ning
Abstract. The rapid expansion of low-cost sensor networks for air quality monitoring necessitates rigorous calibration to ensure data accuracy. Despite numerous published field calibration studies, a universal and comprehensive assessment of factors affecting sensor calibration remains elusive, leading to potential discrepancies in data quality across different networks. To address these challenges, this study deployed eight sensor-based monitors equipped with electrochemical sensors for NO2, NO, CO, and O3 measurement in strategically chosen locations within Hong Kong, Macau, and Shanghai, covering a wide range of climatic conditions: Hong Kong's subtropical climate, Macau's similar yet distinct urban environment, and Shanghai's more variable climate. This strategic deployment ensured that the sensors' performance and calibration processes were tested across diverse atmospheric conditions. Each monitor employed a patented dynamic baseline tracking method for the gas sensors, which isolates the concentration signals from temperature and humidity effects, enhancing the sensors' accuracy and reliability. The tests, which involved evaluating the validation performance by analyzing randomly selected calibration sample subsets ranging from 1 to 15 days, indicated that the length of the calibration period, pollutant concentration range, and time averaging period are pivotal for sensor calibration quality. We determined that a 5–7 days calibration period minimizes calibration coefficient errors, and a wider concentration range improves the validation R2 values for all sensors, suggesting the necessity of setting specific concentration range thresholds. Moreover, a time averaging period of at least 5 minutes for data with 1-minute resolution was recommended to enable optimal calibration in field operation. This study emphasizes the need for a comprehensive calibration assessment and the importance of considering environmental variability in sensor calibration condition. These findings offer methodological guidance for the calibration of other sensor types, providing a reference for future research in the field of sensor calibration.
{"title":"Impact and Optimization of Calibration Conditions for Air Quality Sensors in the Long-term Field Monitoring","authors":"Han Mei, Peng Wei, Meisam Ahmadi Ghadikolaei, Nirmal Kumar Gali, Ya Wang, Zhi Ning","doi":"10.5194/amt-2024-130","DOIUrl":"https://doi.org/10.5194/amt-2024-130","url":null,"abstract":"<strong>Abstract.</strong> The rapid expansion of low-cost sensor networks for air quality monitoring necessitates rigorous calibration to ensure data accuracy. Despite numerous published field calibration studies, a universal and comprehensive assessment of factors affecting sensor calibration remains elusive, leading to potential discrepancies in data quality across different networks. To address these challenges, this study deployed eight sensor-based monitors equipped with electrochemical sensors for NO<sub>2</sub>, NO, CO, and O<sub>3</sub> measurement in strategically chosen locations within Hong Kong, Macau, and Shanghai, covering a wide range of climatic conditions: Hong Kong's subtropical climate, Macau's similar yet distinct urban environment, and Shanghai's more variable climate. This strategic deployment ensured that the sensors' performance and calibration processes were tested across diverse atmospheric conditions. Each monitor employed a patented dynamic baseline tracking method for the gas sensors, which isolates the concentration signals from temperature and humidity effects, enhancing the sensors' accuracy and reliability. The tests, which involved evaluating the validation performance by analyzing randomly selected calibration sample subsets ranging from 1 to 15 days, indicated that the length of the calibration period, pollutant concentration range, and time averaging period are pivotal for sensor calibration quality. We determined that a 5–7 days calibration period minimizes calibration coefficient errors, and a wider concentration range improves the validation <em>R<sup>2</sup></em> values for all sensors, suggesting the necessity of setting specific concentration range thresholds. Moreover, a time averaging period of at least 5 minutes for data with 1-minute resolution was recommended to enable optimal calibration in field operation. This study emphasizes the need for a comprehensive calibration assessment and the importance of considering environmental variability in sensor calibration condition. These findings offer methodological guidance for the calibration of other sensor types, providing a reference for future research in the field of sensor calibration.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"17 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Water vapour isotopes are important tools to better understand processes governing the atmospheric hydrological cycle. Their measurement in polar regions is crucial to improve the interpretation of water isotopic records in ice cores. In situ water vapour isotopic monitoring is however an important challenge, especially in dry places of the East Antarctic plateau where water mixing ratio can be as low as 10 ppmv. We present in this article new commercial laser spectrometers based on the optical feedback – cavity enhanced absorption spectroscopy (OF-CEAS) technique, adapted for water vapour isotopic measurement in dry regions. We characterize a first instrument adapted for Antarctic coastal monitoring with an optical cavity finesse of 64,000 (ringdown time of 54 µs), installed at Dumont d’Urville station during the summer campaign 2022–2023, and a second instrument with a high finesse of 116,000 (98 µs ringdown), to be deployed inland East Antarctica. The high finesse instrument demonstrates a stability up to two days of acquisition, with a limit of detection down to 10 ppmv humidity for 𝛿D and 100 ppmv for 𝛿18O.
{"title":"OF-CEAS laser spectroscopy to measure water isotopes in dry environments: example of application in Antarctica","authors":"Thomas Lauwers, Elise Fourré, Olivier Jossoud, Daniele Romanini, Frédéric Prié, Giordano Nitti, Mathieu Casado, Kévin Jaulin, Markus Miltner, Morgane Farradèche, Valérie Masson-Delmotte, Amaëlle Landais","doi":"10.5194/egusphere-2024-2149","DOIUrl":"https://doi.org/10.5194/egusphere-2024-2149","url":null,"abstract":"<strong>Abstract.</strong> Water vapour isotopes are important tools to better understand processes governing the atmospheric hydrological cycle. Their measurement in polar regions is crucial to improve the interpretation of water isotopic records in ice cores. <em>In situ</em> water vapour isotopic monitoring is however an important challenge, especially in dry places of the East Antarctic plateau where water mixing ratio can be as low as 10 ppmv. We present in this article new commercial laser spectrometers based on the optical feedback – cavity enhanced absorption spectroscopy (OF-CEAS) technique, adapted for water vapour isotopic measurement in dry regions. We characterize a first instrument adapted for Antarctic coastal monitoring with an optical cavity finesse of 64,000 (ringdown time of 54 µs), installed at Dumont d’Urville station during the summer campaign 2022–2023, and a second instrument with a high finesse of 116,000 (98 µs ringdown), to be deployed inland East Antarctica. The high finesse instrument demonstrates a stability up to two days of acquisition, with a limit of detection down to 10 ppmv humidity for 𝛿D and 100 ppmv for 𝛿<sup>18</sup>O.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"27 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-15DOI: 10.5194/amt-17-4725-2024
John Ericksen, Tobias P. Fischer, G. Matthew Fricke, Scott Nowicki, Nemesio M. Pérez, Pedro Hernández Pérez, Eleazar Padrón González, Melanie E. Moses
Abstract. We report in-plume carbon dioxide (CO2) concentrations and carbon isotope ratios during the 2021 eruption of Tajogaite volcano, island of La Palma, Spain. CO2 measurements inform our understanding of volcanic contributions to the global climate carbon cycle and the role of CO2 in eruptions. Traditional ground-based methods of CO2 collection are difficult and dangerous, and as a result only about 5 % of volcanoes have been directly surveyed. We demonstrate that unpiloted aerial system (UAS) surveys allow for fast and relatively safe measurements. Using CO2 concentration profiles we estimate the total flux during several measurements in November 2021 to be 1.76±0.20×103 to 2.23±0.26×104 t d−1. Carbon isotope ratios of plume CO2 indicate a deep magmatic source, consistent with the intensity of the eruption. Our work demonstrates the feasibility of UASs for CO2 surveys during active volcanic eruptions, particularly for deriving rapid emission estimates.
{"title":"Drone CO2 measurements during the Tajogaite volcanic eruption","authors":"John Ericksen, Tobias P. Fischer, G. Matthew Fricke, Scott Nowicki, Nemesio M. Pérez, Pedro Hernández Pérez, Eleazar Padrón González, Melanie E. Moses","doi":"10.5194/amt-17-4725-2024","DOIUrl":"https://doi.org/10.5194/amt-17-4725-2024","url":null,"abstract":"Abstract. We report in-plume carbon dioxide (CO2) concentrations and carbon isotope ratios during the 2021 eruption of Tajogaite volcano, island of La Palma, Spain. CO2 measurements inform our understanding of volcanic contributions to the global climate carbon cycle and the role of CO2 in eruptions. Traditional ground-based methods of CO2 collection are difficult and dangerous, and as a result only about 5 % of volcanoes have been directly surveyed. We demonstrate that unpiloted aerial system (UAS) surveys allow for fast and relatively safe measurements. Using CO2 concentration profiles we estimate the total flux during several measurements in November 2021 to be 1.76±0.20×103 to 2.23±0.26×104 t d−1. Carbon isotope ratios of plume CO2 indicate a deep magmatic source, consistent with the intensity of the eruption. Our work demonstrates the feasibility of UASs for CO2 surveys during active volcanic eruptions, particularly for deriving rapid emission estimates.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"171 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-13DOI: 10.5194/amt-17-4709-2024
Stéphanie Alage, Vincent Michoud, Sergio Harb, Bénédicte Picquet-Varrault, Manuela Cirtog, Avinash Kumar, Matti Rissanen, Christopher Cantrell
Abstract. Volatile organic compounds (VOCs) play a key role in tropospheric chemistry, giving rise to secondary products such as highly oxygenated organic molecules (HOMs) and secondary organic aerosols (SOAs). HOMs, a group of low-volatility gas-phase products, are formed through the autoxidation process of peroxy radicals (RO2) originating from the oxidation of VOCs. The measurement of HOMs is made by a NO3- ToFCIMS instrument, which also detects other species like small highly oxygenated VOCs (e.g., dicarboxylic acids) and sulfuric acid (H2SO4). The instrument response to HOMs is typically estimated using H2SO4, as HOMs are neither commercially available nor easily synthesized in the laboratory. The resulting calibration factor is then applied to quantify all species detected using this technique. In this study, we explore the sensitivity of the instrument to commercially available small organic compounds, primarily dicarboxylic acids, given the limitations associated with producing known amounts of HOMs for calibration. We compare these single-compound calibration factors to the one obtained for H2SO4 under identical operational conditions. The study found that the sensitivity of the NO3- ToFCIMS varies depending on the specific type of organic compound, illustrating how a single calibration factor derived from sulfuric acid is clearly inadequate for quantifying all detected species using this technique. The results highlighted substantial variability in the calibration factors for the tested organic compounds, with 4-nitrocatechol exhibiting the highest sensitivity and pyruvic acid the lowest. The obtained sulfuric acid calibration factor agreed well with the previous values from the literature. In summary, this research emphasized the need to develop reliable and precise calibration methods for progressively oxygenated reaction products measured with a NO3- chemical-ionization mass spectrometer (CIMS), for example, HOMs.
{"title":"A nitrate ion chemical-ionization atmospheric-pressure-interface time-of-flight mass spectrometer (NO3− ToFCIMS) sensitivity study","authors":"Stéphanie Alage, Vincent Michoud, Sergio Harb, Bénédicte Picquet-Varrault, Manuela Cirtog, Avinash Kumar, Matti Rissanen, Christopher Cantrell","doi":"10.5194/amt-17-4709-2024","DOIUrl":"https://doi.org/10.5194/amt-17-4709-2024","url":null,"abstract":"Abstract. Volatile organic compounds (VOCs) play a key role in tropospheric chemistry, giving rise to secondary products such as highly oxygenated organic molecules (HOMs) and secondary organic aerosols (SOAs). HOMs, a group of low-volatility gas-phase products, are formed through the autoxidation process of peroxy radicals (RO2) originating from the oxidation of VOCs. The measurement of HOMs is made by a NO3- ToFCIMS instrument, which also detects other species like small highly oxygenated VOCs (e.g., dicarboxylic acids) and sulfuric acid (H2SO4). The instrument response to HOMs is typically estimated using H2SO4, as HOMs are neither commercially available nor easily synthesized in the laboratory. The resulting calibration factor is then applied to quantify all species detected using this technique. In this study, we explore the sensitivity of the instrument to commercially available small organic compounds, primarily dicarboxylic acids, given the limitations associated with producing known amounts of HOMs for calibration. We compare these single-compound calibration factors to the one obtained for H2SO4 under identical operational conditions. The study found that the sensitivity of the NO3- ToFCIMS varies depending on the specific type of organic compound, illustrating how a single calibration factor derived from sulfuric acid is clearly inadequate for quantifying all detected species using this technique. The results highlighted substantial variability in the calibration factors for the tested organic compounds, with 4-nitrocatechol exhibiting the highest sensitivity and pyruvic acid the lowest. The obtained sulfuric acid calibration factor agreed well with the previous values from the literature. In summary, this research emphasized the need to develop reliable and precise calibration methods for progressively oxygenated reaction products measured with a NO3- chemical-ionization mass spectrometer (CIMS), for example, HOMs.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"69 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-13DOI: 10.5194/amt-17-4675-2024
Yudong Gao, Lidou Huyan, Zheng Wu, Bojun Liu
Abstract. Given that the Gaussianity of the observation error distribution is the fundamental principle of some data assimilation and machine learning algorithms, the error structure of radar reflectivity has become increasingly important with the development of high-resolution forecasts and nowcasts of convective systems. This study examines the error distribution of radar reflectivity and discusses what causes the non-Gaussian error distribution using 6-month observations minus backgrounds (OmBs) of composites of vertical maximum reflectivity (CVMRs) in mountainous and hilly areas. By following the symmetric error model in all-sky satellite radiance assimilation, we reveal the error structure of CVMRs as a function of symmetric rain rates, which is the average of the observed and simulated rain rates. Unlike satellite radiance, the error structure of CVMRs shows a sharper slope for light precipitation than for moderate precipitation. Thus, a three-piecewise fitting function is more suitable for CVMRs. The probability density functions of OmBs normalized by symmetric rain rates become more Gaussian than the probability density functions normalized by all samples. Moreover, the possibility of using a third-party predictor to construct the symmetric error model is also discussed in this study. The result shows that the Gaussian distribution of OmBs can be further improved via more accurate precipitation observations. According to the Jensen–Shannon divergence, a more linear predictor, the logarithmic transformation of the rain rate, can provide the most Gaussian error distribution in comparison with other predictors.
{"title":"Improving the Gaussianity of radar reflectivity departures between observations and simulations using symmetric rain rates","authors":"Yudong Gao, Lidou Huyan, Zheng Wu, Bojun Liu","doi":"10.5194/amt-17-4675-2024","DOIUrl":"https://doi.org/10.5194/amt-17-4675-2024","url":null,"abstract":"Abstract. Given that the Gaussianity of the observation error distribution is the fundamental principle of some data assimilation and machine learning algorithms, the error structure of radar reflectivity has become increasingly important with the development of high-resolution forecasts and nowcasts of convective systems. This study examines the error distribution of radar reflectivity and discusses what causes the non-Gaussian error distribution using 6-month observations minus backgrounds (OmBs) of composites of vertical maximum reflectivity (CVMRs) in mountainous and hilly areas. By following the symmetric error model in all-sky satellite radiance assimilation, we reveal the error structure of CVMRs as a function of symmetric rain rates, which is the average of the observed and simulated rain rates. Unlike satellite radiance, the error structure of CVMRs shows a sharper slope for light precipitation than for moderate precipitation. Thus, a three-piecewise fitting function is more suitable for CVMRs. The probability density functions of OmBs normalized by symmetric rain rates become more Gaussian than the probability density functions normalized by all samples. Moreover, the possibility of using a third-party predictor to construct the symmetric error model is also discussed in this study. The result shows that the Gaussian distribution of OmBs can be further improved via more accurate precipitation observations. According to the Jensen–Shannon divergence, a more linear predictor, the logarithmic transformation of the rain rate, can provide the most Gaussian error distribution in comparison with other predictors.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"69 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-12DOI: 10.5194/amt-17-4649-2024
Marcel Bühler, Christoph Häni, Albrecht Neftel, Patrice Bühler, Christof Ammann, Thomas Kupper
Abstract. Emissions from agricultural sources substantially contribute to global warming. The inverse dispersion method (IDM) has been successfully used for emission measurements from various agricultural sources. The IDM has also been validated in multiple studies with artificial gas releases mostly in open fields. Release experiments from buildings have rarely been conducted and were partly affected by additional nearby sources of the target gas. Specific release studies for naturally ventilated animal housings are lacking. In this study, a known and predefined amount of methane (CH4) was released from an artificial source inside a barn that mimicked a naturally ventilated dairy housing, and IDM recovery rates, using a backward Lagrangian stochastic (bLS) model, were determined. For concentration measurements, open-path devices (OPs) with a path length of 110 m were placed in a downwind direction of the barn at fetches of 2.0h, 5.3h, 8.6h, and 12h (h equals the height of the highest obstacle), and a 3D ultrasonic anemometer (UA) was placed in the middle of the first three OP paths. Upwind of the barn, an additional OP and a UA were installed. The median IDM recovery rates determined with the UA placed upwind of the barn and the downwind OP ranged between 0.55–0.75. It is concluded that, for the present study case, the effect of the building and a tree in the main wind axis led to a systematic underestimation of the IDM-derived emission rate probably due to deviations in the wind field and turbulent dispersion from the underlying assumptions of the used dispersion model.
摘要农业污染源的排放严重加剧了全球变暖。反向弥散法（IDM）已成功用于各种农业源的排放测量。IDM 还在多项研究中得到了验证，这些研究主要是在空旷的田野中进行人工气体释放。来自建筑物的释放实验很少进行，并且部分受到附近额外目标气体源的影响。对于自然通风的动物房舍，还缺乏具体的释放研究。在这项研究中，从模拟自然通风奶牛舍的谷仓内的人工源释放了已知和预定量的甲烷（CH4），并使用后向拉格朗日随机（bLS）模型确定了 IDM 回收率。为了测量浓度，在牛舍下风方向的 2.0 小时、5.3 小时、8.6 小时和 12 小时（h 等于最高障碍物的高度）处放置了路径长度为 110 米的开放路径装置（OP），并在前三个 OP 路径的中间放置了三维超声波风速计（UA）。在谷仓的上风处，安装了一个额外的 OP 和一个 UA。谷仓上风向的 UA 和下风向的 OP 所确定的 IDM 回收率中值在 0.55-0.75 之间。结论是，在本研究案例中，主风向轴上的建筑物和一棵树的影响导致系统性地低估了 IDM 排放率，这可能是由于风场和湍流扩散与所使用的扩散模型的基本假设存在偏差。
{"title":"Applicability of the inverse dispersion method to measure emissions from animal housings","authors":"Marcel Bühler, Christoph Häni, Albrecht Neftel, Patrice Bühler, Christof Ammann, Thomas Kupper","doi":"10.5194/amt-17-4649-2024","DOIUrl":"https://doi.org/10.5194/amt-17-4649-2024","url":null,"abstract":"Abstract. Emissions from agricultural sources substantially contribute to global warming. The inverse dispersion method (IDM) has been successfully used for emission measurements from various agricultural sources. The IDM has also been validated in multiple studies with artificial gas releases mostly in open fields. Release experiments from buildings have rarely been conducted and were partly affected by additional nearby sources of the target gas. Specific release studies for naturally ventilated animal housings are lacking. In this study, a known and predefined amount of methane (CH4) was released from an artificial source inside a barn that mimicked a naturally ventilated dairy housing, and IDM recovery rates, using a backward Lagrangian stochastic (bLS) model, were determined. For concentration measurements, open-path devices (OPs) with a path length of 110 m were placed in a downwind direction of the barn at fetches of 2.0h, 5.3h, 8.6h, and 12h (h equals the height of the highest obstacle), and a 3D ultrasonic anemometer (UA) was placed in the middle of the first three OP paths. Upwind of the barn, an additional OP and a UA were installed. The median IDM recovery rates determined with the UA placed upwind of the barn and the downwind OP ranged between 0.55–0.75. It is concluded that, for the present study case, the effect of the building and a tree in the main wind axis led to a systematic underestimation of the IDM-derived emission rate probably due to deviations in the wind field and turbulent dispersion from the underlying assumptions of the used dispersion model.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"197 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141939548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-12DOI: 10.5194/amt-17-4659-2024
Robert Reichert, Natalie Kaifler, Bernd Kaifler
Abstract. Continuous wavelet transform (CWT) is a commonly used mathematical tool when it comes to the time–frequency (or distance–wavenumber) analysis of non-stationary signals that is used in a variety of research areas. In this work, we use the CWT to investigate signatures of atmospheric internal gravity waves (GWs) as observed in vertical temperature profiles obtained, for instance, by lidar. The focus is laid on the determination of vertical wavelengths of dominant GWs. According to linear GW theory, these wavelengths are a function of horizontal wind speed, and hence, vertical wind shear causes shifts in the evolution of the vertical wavelength. The resulting signal fulfills the criteria of a chirp. Using complex Morlet wavelets, we apply CWT to test mountain wave signals modeling wind shear of up to 5m s-1km-1 and investigate the capabilities and limitations. We find that the sensitivity of the CWT decreases for large chirp rates, i.e., strong wind shear. For a fourth-order Morlet wavelet, edge effects become dominant at a vertical wind shear of 3.4m s-1km-1. For higher-order wavelets, edge effects dominate at even smaller values. In addition, we investigate the effect of GW amplitudes growing exponentially with altitude on the determination of vertical wavelengths. It becomes evident that in the case of conservative amplitude growth, spectral leakage leads to artificially enhanced spectral power at lower altitudes. Therefore, we recommend normalizing the GW signal before the wavelet analysis and before the determination of vertical wavelengths. Finally, the cascading of receiver channels, which is typical of middle-atmosphere lidar measurements, results in an exponential sawtooth-like pattern of measurement uncertainties as a function of altitude. With the help of Monte Carlo simulations, we compute a wavelet noise spectrum and determine significance levels, which enable the reliable determination of vertical wavelengths. Finally, the insights obtained from the analysis of artificial chirps are used to analyze and interpret real GW measurements from the Compact Rayleigh Autonomous Lidar in April 2018 in Río Grande, Argentina. Comparison of commonly used analyses and our suggested wavelet analysis demonstrate improvements in the accuracy of determined wavelengths. For future analyses, we suggest the usage of a fourth-order Morlet wavelet, normalization of GW amplitudes before wavelet analysis, and computation of the significance level based on measurement uncertainties.
{"title":"Limitations in wavelet analysis of non-stationary atmospheric gravity wave signatures in temperature profiles","authors":"Robert Reichert, Natalie Kaifler, Bernd Kaifler","doi":"10.5194/amt-17-4659-2024","DOIUrl":"https://doi.org/10.5194/amt-17-4659-2024","url":null,"abstract":"Abstract. Continuous wavelet transform (CWT) is a commonly used mathematical tool when it comes to the time–frequency (or distance–wavenumber) analysis of non-stationary signals that is used in a variety of research areas. In this work, we use the CWT to investigate signatures of atmospheric internal gravity waves (GWs) as observed in vertical temperature profiles obtained, for instance, by lidar. The focus is laid on the determination of vertical wavelengths of dominant GWs. According to linear GW theory, these wavelengths are a function of horizontal wind speed, and hence, vertical wind shear causes shifts in the evolution of the vertical wavelength. The resulting signal fulfills the criteria of a chirp. Using complex Morlet wavelets, we apply CWT to test mountain wave signals modeling wind shear of up to 5m s-1km-1 and investigate the capabilities and limitations. We find that the sensitivity of the CWT decreases for large chirp rates, i.e., strong wind shear. For a fourth-order Morlet wavelet, edge effects become dominant at a vertical wind shear of 3.4m s-1km-1. For higher-order wavelets, edge effects dominate at even smaller values. In addition, we investigate the effect of GW amplitudes growing exponentially with altitude on the determination of vertical wavelengths. It becomes evident that in the case of conservative amplitude growth, spectral leakage leads to artificially enhanced spectral power at lower altitudes. Therefore, we recommend normalizing the GW signal before the wavelet analysis and before the determination of vertical wavelengths. Finally, the cascading of receiver channels, which is typical of middle-atmosphere lidar measurements, results in an exponential sawtooth-like pattern of measurement uncertainties as a function of altitude. With the help of Monte Carlo simulations, we compute a wavelet noise spectrum and determine significance levels, which enable the reliable determination of vertical wavelengths. Finally, the insights obtained from the analysis of artificial chirps are used to analyze and interpret real GW measurements from the Compact Rayleigh Autonomous Lidar in April 2018 in Río Grande, Argentina. Comparison of commonly used analyses and our suggested wavelet analysis demonstrate improvements in the accuracy of determined wavelengths. For future analyses, we suggest the usage of a fourth-order Morlet wavelet, normalization of GW amplitudes before wavelet analysis, and computation of the significance level based on measurement uncertainties.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"22 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141939569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-12DOI: 10.5194/egusphere-2024-1278
Jonas Ernő Katona, Manuel de la Torre Juárez, Terence L. Kubar, F. Joseph Turk, Kuo-Nung Wang, Ramon Padullés
Abstract. The polarimetric phase difference between the horizontal and vertical components of GNSS radio signals is correlated with the presence of ice and precipitation in the propagation path of those signals. This study evaluates the ability of k-means clustering to find relationships among polarimetric phase difference, refractivity, liquid water path (LWP), ice water path (IWP), and water vapor pressure using over two years of data matched between the Global Precipitation Measurement (GPM) mission and Radio Occultations through Heavy Precipitation demonstration mission onboard the Spanish Paz spacecraft (ROHP-PAZ). A cluster hierarchy is introduced across these variables. A potential refractivity model for polytropic atmospheres is introduced to ascertain how different types of vertical thermodynamic profiles that can occur during different precipitation scenarios are related to changes in the polytropic index and thereby vertical heat transfer rates. The clustering analyses uncover a relationship between the amplitude and shape of deviations from the potential refractivity model and water vapor pressure and confirm the expected positive correlation between polarimetric phase difference and both LWP and IWP. For certain values, the coefficients of the potential refractivity model indicate when a profile has little to no moisture, and the study reveals a similar relationship between the clustering for these coefficients and different water vapor pressure profiles. The study also confirms the relationship between the integrated polarimetric phase difference and water vapor pressure columns, known as the "precipitation pickup," globally (ρs=0.971 after averaging) and over different latitudinal ranges (>50°, ≥20°, and <20°, with different ρs for each).
{"title":"Cluster Analysis of Vertical Polarimetric Radio Occultation Profiles and Corresponding Liquid and Ice Water Paths From GPM Microwave Data","authors":"Jonas Ernő Katona, Manuel de la Torre Juárez, Terence L. Kubar, F. Joseph Turk, Kuo-Nung Wang, Ramon Padullés","doi":"10.5194/egusphere-2024-1278","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1278","url":null,"abstract":"<strong>Abstract.</strong> The polarimetric phase difference between the horizontal and vertical components of GNSS radio signals is correlated with the presence of ice and precipitation in the propagation path of those signals. This study evaluates the ability of k-means clustering to find relationships among polarimetric phase difference, refractivity, liquid water path (LWP), ice water path (IWP), and water vapor pressure using over two years of data matched between the Global Precipitation Measurement (GPM) mission and Radio Occultations through Heavy Precipitation demonstration mission onboard the Spanish Paz spacecraft (ROHP-PAZ). A cluster hierarchy is introduced across these variables. A potential refractivity model for polytropic atmospheres is introduced to ascertain how different types of vertical thermodynamic profiles that can occur during different precipitation scenarios are related to changes in the polytropic index and thereby vertical heat transfer rates. The clustering analyses uncover a relationship between the amplitude and shape of deviations from the potential refractivity model and water vapor pressure and confirm the expected positive correlation between polarimetric phase difference and both LWP and IWP. For certain values, the coefficients of the potential refractivity model indicate when a profile has little to no moisture, and the study reveals a similar relationship between the clustering for these coefficients and different water vapor pressure profiles. The study also confirms the relationship between the integrated polarimetric phase difference and water vapor pressure columns, known as the \"precipitation pickup,\" globally (ρ<sub>s</sub>=0.971 after averaging) and over different latitudinal ranges (>50°, ≥20°, and <20°, with different ρ<sub>s</sub> for each).","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"58 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141939550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：