Pub Date : 2024-09-19DOI: 10.5194/egusphere-2024-2797
Lisa Schneider, Jann Schrod, Daniel Weber, Heinz Bingemer, Konrad Kandler, Joachim Curtius, Martin Ebert
Abstract. To understand and predict the formation of clouds and rain and their influence on our climate, it is crucial to know the characteristics and abundance of ice-nucleating particles (INPs) in the atmosphere. As the ice-nucleating efficiency is a result of individual particle properties, a detailed knowledge on these properties is essential. Here, we present an offline method for the comprehensive analysis of ambient INPs that benefits from the combination of two instruments already used for ice nucleation measurements. First, the aerosol is sampled on silicon wafers. INPs are then activated at different temperature and humidity conditions in the deposition nucleation and condensation freezing mode using a static diffusion chamber. Activated INPs are located in a coordinate system, which allows for recovery of the individual particles causing the nucleation in a scanning electron microscope. Here, the size, chemistry and morphology of the particles are identified. Finally, the INPs are classified into categories based on their measured properties. As a result, a size resolved spectrum of the INP classes can be determined. The performance of this coupling method is investigated in a case study on samples from the high-altitude field side Jungfraujoch (JFJ), Switzerland. 200 individual INPs from 14 samples obtained during a 5-week period were classified. Most deposition nucleation / condensation freezing mode INPs from Jungfraujoch, activated at −30 °C, were of irregular shape and had projected area diameters in the range from 300 nm to 35 µm, with a distinct maximum at 1–2 µm. A major contribution of mineral particles, mainly aluminosilicates / Al-rich particles, but also carbonates and silica, was identified for the entire INP size spectrum at −30°C. Further contributions were from carbon-rich particles, consisting of both smaller soot particles and larger biological particles. Mixed particles, here mostly particles rich in Al and C, were identified in higher abundances primarily between 3 µm and 9 µm. Minor contributions were seen from sulfates and metal oxides, with the latter ones found with increased proportion in the size range below 500 nm. Such results are useful for evaluating INP type-specific parametrizations, e.g., for use in atmospheric modeling, and in closure studies.
{"title":"Analyzing the chemical composition, morphology and size of ice-nucleating particles by coupling a scanning electron microscope to an offline diffusion chamber","authors":"Lisa Schneider, Jann Schrod, Daniel Weber, Heinz Bingemer, Konrad Kandler, Joachim Curtius, Martin Ebert","doi":"10.5194/egusphere-2024-2797","DOIUrl":"https://doi.org/10.5194/egusphere-2024-2797","url":null,"abstract":"<strong>Abstract.</strong> To understand and predict the formation of clouds and rain and their influence on our climate, it is crucial to know the characteristics and abundance of ice-nucleating particles (INPs) in the atmosphere. As the ice-nucleating efficiency is a result of individual particle properties, a detailed knowledge on these properties is essential. Here, we present an offline method for the comprehensive analysis of ambient INPs that benefits from the combination of two instruments already used for ice nucleation measurements. First, the aerosol is sampled on silicon wafers. INPs are then activated at different temperature and humidity conditions in the deposition nucleation and condensation freezing mode using a static diffusion chamber. Activated INPs are located in a coordinate system, which allows for recovery of the individual particles causing the nucleation in a scanning electron microscope. Here, the size, chemistry and morphology of the particles are identified. Finally, the INPs are classified into categories based on their measured properties. As a result, a size resolved spectrum of the INP classes can be determined. The performance of this coupling method is investigated in a case study on samples from the high-altitude field side Jungfraujoch (JFJ), Switzerland. 200 individual INPs from 14 samples obtained during a 5-week period were classified. Most deposition nucleation / condensation freezing mode INPs from Jungfraujoch, activated at −30 °C, were of irregular shape and had projected area diameters in the range from 300 nm to 35 µm, with a distinct maximum at 1–2 µm. A major contribution of mineral particles, mainly aluminosilicates / Al-rich particles, but also carbonates and silica, was identified for the entire INP size spectrum at −30°C. Further contributions were from carbon-rich particles, consisting of both smaller soot particles and larger biological particles. Mixed particles, here mostly particles rich in Al and C, were identified in higher abundances primarily between 3 µm and 9 µm. Minor contributions were seen from sulfates and metal oxides, with the latter ones found with increased proportion in the size range below 500 nm. Such results are useful for evaluating INP type-specific parametrizations, e.g., for use in atmospheric modeling, and in closure studies.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"65 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250834","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. This work aims at investigating the effect of NO2 absorption on aerosol-optical-depth (AOD) measurements and Ångström exponent (AE) retrievals of sun photometers by the synergistic use of accurate NO2 characterization for optical-depth estimation from co-located ground-based measurements. The analysis was performed for ∼ 7 years (2017–2023) at several sites worldwide for the AOD measurements and AE retrievals by Aerosol Robotic Network (AERONET) sun photometers which use OMI (Ozone Monitoring Instrument) climatology for NO2 representation. The differences in AOD and AE retrievals by NO2 absorption are accounted for using high-frequency columnar NO2 measurements by a co-located Pandora spectroradiometer belonging to the Pandonia Global Network (PGN). NO2 absorption affects the AOD measurements in UV-Vis (visible) range, and we found that the AOD bias is the most affected at 380 nm by NO2 differences, followed by 440, 340, and 500 nm, respectively. AERONET AOD was found to be overestimated in half of the cases, while also underestimated in other cases as an impact of the NO2 difference from “real” (PGN NO2) values. Overestimations or underestimations are relatively low. About one-third of these stations showed a mean difference in NO2 and AOD (at 380 and 440 nm) above 0.5 × 10−4 mol m−2 and 0.002, respectively, which can be considered a systematic contribution to the uncertainties in the AOD measurements that are reported to be of the order of 0.01. However, under extreme NO2 loading scenarios (i.e. 10 % highest differences) at highly urbanized/industrialized locations, even higher AOD differences were observed that were at the limit of or higher than the reported 0.01 uncertainty in the AOD measurement. PGN NO2-based sensitivity analysis of AOD difference suggested that for PGN NO2 varying between 2 × 10−4 and 8 × 10−4 mol m−2, the median AOD differences were found to rise above 0.01 (even above 0.02) with the increase in NO2 threshold (i.e. the lower limit from 2 × 10−4 to 8 × 10−4 mol m−2). The AOD-derivative product, AE, was also affected by the NO2 correction (discrepancies between the AERONET OMI climatological representation of NO2 values and the real PGN NO2 measurements) on the spectral AOD. Normalized frequency distribution of AE (at 440–870 and 340–440 nm wavelength pair) was found to be narrower for a broader AOD distribution for some stations, and vice versa for other stations, and a higher relative error at the shorter wavelength (among the wavelength pairs used for AE estimation) led to a shift in the peak of the AE difference distribution towards a higher positive value, while a higher relative error at a lower wavelength shifted the AE difference distribution to a negative value for the AOD overestimation case, and vice versa for the AOD underestimation case. For rural locations, the mean NO2 differences were found to be mostly below 0.50 × 10−4 mol m−2, with the corresponding AOD differences being below 0.002, and in ext
{"title":"Assessment of the impact of NO2 contribution on aerosol-optical-depth measurements at several sites worldwide","authors":"Akriti Masoom, Stelios Kazadzis, Masimo Valeri, Ioannis-Panagiotis Raptis, Gabrielle Brizzi, Kyriakoula Papachristopoulou, Francesca Barnaba, Stefano Casadio, Axel Kreuter, Fabrizio Niro","doi":"10.5194/amt-17-5525-2024","DOIUrl":"https://doi.org/10.5194/amt-17-5525-2024","url":null,"abstract":"Abstract. This work aims at investigating the effect of NO2 absorption on aerosol-optical-depth (AOD) measurements and Ångström exponent (AE) retrievals of sun photometers by the synergistic use of accurate NO2 characterization for optical-depth estimation from co-located ground-based measurements. The analysis was performed for ∼ 7 years (2017–2023) at several sites worldwide for the AOD measurements and AE retrievals by Aerosol Robotic Network (AERONET) sun photometers which use OMI (Ozone Monitoring Instrument) climatology for NO2 representation. The differences in AOD and AE retrievals by NO2 absorption are accounted for using high-frequency columnar NO2 measurements by a co-located Pandora spectroradiometer belonging to the Pandonia Global Network (PGN). NO2 absorption affects the AOD measurements in UV-Vis (visible) range, and we found that the AOD bias is the most affected at 380 nm by NO2 differences, followed by 440, 340, and 500 nm, respectively. AERONET AOD was found to be overestimated in half of the cases, while also underestimated in other cases as an impact of the NO2 difference from “real” (PGN NO2) values. Overestimations or underestimations are relatively low. About one-third of these stations showed a mean difference in NO2 and AOD (at 380 and 440 nm) above 0.5 × 10−4 mol m−2 and 0.002, respectively, which can be considered a systematic contribution to the uncertainties in the AOD measurements that are reported to be of the order of 0.01. However, under extreme NO2 loading scenarios (i.e. 10 % highest differences) at highly urbanized/industrialized locations, even higher AOD differences were observed that were at the limit of or higher than the reported 0.01 uncertainty in the AOD measurement. PGN NO2-based sensitivity analysis of AOD difference suggested that for PGN NO2 varying between 2 × 10−4 and 8 × 10−4 mol m−2, the median AOD differences were found to rise above 0.01 (even above 0.02) with the increase in NO2 threshold (i.e. the lower limit from 2 × 10−4 to 8 × 10−4 mol m−2). The AOD-derivative product, AE, was also affected by the NO2 correction (discrepancies between the AERONET OMI climatological representation of NO2 values and the real PGN NO2 measurements) on the spectral AOD. Normalized frequency distribution of AE (at 440–870 and 340–440 nm wavelength pair) was found to be narrower for a broader AOD distribution for some stations, and vice versa for other stations, and a higher relative error at the shorter wavelength (among the wavelength pairs used for AE estimation) led to a shift in the peak of the AE difference distribution towards a higher positive value, while a higher relative error at a lower wavelength shifted the AE difference distribution to a negative value for the AOD overestimation case, and vice versa for the AOD underestimation case. For rural locations, the mean NO2 differences were found to be mostly below 0.50 × 10−4 mol m−2, with the corresponding AOD differences being below 0.002, and in ext","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"156 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250835","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}
Darren Cheng, Stavros Amanatidis, Gregory S. Lewis, Coty N. Jen
Abstract. New particle formation (NPF) is the atmospheric process whereby gas molecules react and nucleate to form detectable particles. NPF has a strong impact on Earth’s radiative balance as it produces roughly half of global cloud condensation nuclei. However, time resolution and sensitivity of current instrumentation are inadequate in measuring the size distribution of sub‑3 nm particles, the particles critical for understanding NPF. Here we present the Condensation Particle Counters For Atmospheric Rapid Measurements (CPC FARM), a method to measure the concentrations of freshly nucleated particles. The CPC FARM consists of five CPCs operating in parallel, each configured to operate at different detectable particle sizes between 1–3 nm. This study explores two methods to calculate the size distribution from the differential measurements across the CPC channels. The performance of both inversion methods were tested against the size distribution measured by a pair of stepping particle mobility sizers (SMPS) during an ambient air sampling study in Pittsburgh, PA. Observational results indicate that the CPC FARM is more accurate with higher time resolution and sensitivity in the sub-3 nm range compared to the SMPS.
{"title":"Fast and sensitive measurements of sub-3 nm particles using Condensation Particle Counters For Atmospheric Rapid Measurements (CPC FARM)","authors":"Darren Cheng, Stavros Amanatidis, Gregory S. Lewis, Coty N. Jen","doi":"10.5194/amt-2024-157","DOIUrl":"https://doi.org/10.5194/amt-2024-157","url":null,"abstract":"<strong>Abstract.</strong> New particle formation (NPF) is the atmospheric process whereby gas molecules react and nucleate to form detectable particles. NPF has a strong impact on Earth’s radiative balance as it produces roughly half of global cloud condensation nuclei. However, time resolution and sensitivity of current instrumentation are inadequate in measuring the size distribution of sub‑3 nm particles, the particles critical for understanding NPF. Here we present the Condensation Particle Counters For Atmospheric Rapid Measurements (CPC FARM), a method to measure the concentrations of freshly nucleated particles. The CPC FARM consists of five CPCs operating in parallel, each configured to operate at different detectable particle sizes between 1–3 nm. This study explores two methods to calculate the size distribution from the differential measurements across the CPC channels. The performance of both inversion methods were tested against the size distribution measured by a pair of stepping particle mobility sizers (SMPS) during an ambient air sampling study in Pittsburgh, PA. Observational results indicate that the CPC FARM is more accurate with higher time resolution and sensitivity in the sub-3 nm range compared to the SMPS.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"14 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250838","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}
Benjamin W. Clouser, Laszlo C. Sarkozy, Clare E. Singer, Carly C. KleinStern, Adrien Desmoulin, Dylan Gaeta, Sergey Khaykin, Stephen Gabbard, Stephen Shertz, Elisabeth J. Moyer
Abstract. We describe a new version of the Chicago Water Isotope Spectrometer (ChiWIS), designed for airborne measurements of vapor-phase water isotopologues in the dry upper troposphere and lower stratosphere (UTLS) aboard research aircraft. This version of the instrument is a tunable diode laser (TDL), off-axis integrated cavity output spectrometer (OA-ICOS). The instrument was designed to measure the HDO/H2O ratio in the 2017 Asian Summer Monsoon flight aboard the M-55 Geophysica during the StratoClim campaign, and so far has also flown aboard the WB-57F in the 2021 and 2022 ACCLIP campaigns. The spectrometer scans absorption lines of both H2O and HDO near 2.647 μm wavelength in a single current sweep, and has an effective path length of 7.5 km under optimal conditions. The instrument utilizes a novel non-axially-symmetric optical component which increases the signal-to-noise ratio by a factor of 3. Ultra-polished, 4-inch diameter cavity mirrors suppress scattering losses, maximize mirror reflectivity, and yield optical fringing significantly below typical electrical noise levels. In laboratory conditions, the instrument has demonstrated a 5-second measurement precision of 3.6 ppbv and 82 pptv in H2O and HDO, respectively.
{"title":"The Airborne Chicago Water Isotope Spectrometer: An Integrated Cavity Output Spectrometer for Measurements of the HDO/H2O Isotopic Ratio in the Asian Summer Monsoon","authors":"Benjamin W. Clouser, Laszlo C. Sarkozy, Clare E. Singer, Carly C. KleinStern, Adrien Desmoulin, Dylan Gaeta, Sergey Khaykin, Stephen Gabbard, Stephen Shertz, Elisabeth J. Moyer","doi":"10.5194/amt-2024-98","DOIUrl":"https://doi.org/10.5194/amt-2024-98","url":null,"abstract":"<strong>Abstract.</strong> We describe a new version of the Chicago Water Isotope Spectrometer (ChiWIS), designed for airborne measurements of vapor-phase water isotopologues in the dry upper troposphere and lower stratosphere (UTLS) aboard research aircraft. This version of the instrument is a tunable diode laser (TDL), off-axis integrated cavity output spectrometer (OA-ICOS). The instrument was designed to measure the HDO/H<sub>2</sub>O ratio in the 2017 Asian Summer Monsoon flight aboard the M-55 Geophysica during the StratoClim campaign, and so far has also flown aboard the WB-57F in the 2021 and 2022 ACCLIP campaigns. The spectrometer scans absorption lines of both H<sub>2</sub>O and HDO near 2.647 μm wavelength in a single current sweep, and has an effective path length of 7.5 km under optimal conditions. The instrument utilizes a novel non-axially-symmetric optical component which increases the signal-to-noise ratio by a factor of 3. Ultra-polished, 4-inch diameter cavity mirrors suppress scattering losses, maximize mirror reflectivity, and yield optical fringing significantly below typical electrical noise levels. In laboratory conditions, the instrument has demonstrated a 5-second measurement precision of 3.6 ppbv and 82 pptv in H<sub>2</sub>O and HDO, respectively.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"15 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250842","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 : 2024-09-18DOI: 10.5194/egusphere-2024-2615
Min Deng, Scott E. Giangrande, Michael P. Jensen, Karen Johnson, Christopher R. Williams, Jennifer M. Comstock, Ya-Chien Feng, Alyssa Matthews, Iosif A. Lindenmaier, Timothy G. Wendler, Marquette Rocque, Aifang Zhou, Zeen Zhu, Edward Luke, Die Wang
Abstract. A relative calibration technique is developed for the U.S. Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) user facility Ka-Band ARM Zenith Radars (KAZRs). The technique utilizes the signal attenuation due to water collected on the radome for estimates of the reflectivity factor (Ze) offset. The wet-radome attenuation (WRA) is assumed to follow a logarithmic relationship with rainfall rate in light and moderate rain conditions, measured by a collocated surface disdrometer. A practical advantage of this WRA approach to shorter-wavelength radar monitoring is that while it requires a reference disdrometer, it is shown viable for a wider range of collocated disdrometer measurements than traditional disdrometer direct comparisons in light rain. Adding such techniques may provide an additional, cost-effective monitoring tool for remote/longer-term deployments. This technique has been applied during the ARM TRacking Aerosol Convection interactions ExpeRiment (TRACER) from October 2021 through September 2022. The estimated offsets in Ze are evaluated against traditional radar calibration and monitoring methods based on datasets available during this campaign. This WRA technique reports offsets that compare favorably with the mean offsets found between the cloud radars and a nearby disdrometer near the time of rain onset, while also demonstrates similar offset and campaign-long trends with respect to collocated and independently-calibrated reference radars. Overall, the KAZR Ze offsets estimated during TRACER remains stable and at a level 2 dBZ lower than the Ze estimated by disdrometer from the campaign start until the end of June 2022. Thereafter, the radar offsets increase to near 7 dBZ at the end of the campaign.
摘要。为美国能源部（DOE）的大气辐射测量（ARM）用户设施 Ka 波段 ARM 天顶雷达（KAZR）开发了一种相对校准技术。该技术利用雷达罩上收集的水造成的信号衰减来估算反射系数 (Ze) 偏差。在小雨和中雨条件下，湿雷达罩衰减（WRA）被假定为与降雨率呈对数关系，由同位表面测距仪测量。这种 WRA 方法用于较短波长雷达监测的一个实际优势是，虽然它需要一个参考测距仪，但与传统测距仪在小雨中直接比较相比，它在更大范围的同位测距仪测量中显示出了可行性。增加这种技术可为远程/长期部署提供额外的、具有成本效益的监测工具。该技术已在 2021 年 10 月至 2022 年 9 月的 ARM 气溶胶对流跟踪相互作用试验（TRACER）中应用。根据这次试验期间可用的数据集，对照传统的雷达校准和监测方法，对 Ze 中的估计偏移量进行了评估。这种 WRA 技术报告的偏移量与云雷达和附近的测距仪在降雨开始时间附近发现的平均偏移量相当，同时还显示出与同地和独立校准的参考雷达类似的偏移量和活动期间的趋势。总体而言，在 TRACER 期间估算的 KAZR 云层偏移量保持稳定，从活动开始到 2022 年 6 月底，比用测距仪估算的云层偏移量低 2 dBZ。其后，雷达偏移量在活动结束时增加到接近 7 dBZ。
{"title":"Wet-Radome Attenuation in ARM Cloud Radars and Its Utilization in Radar Calibration Using Disdrometer Measurements","authors":"Min Deng, Scott E. Giangrande, Michael P. Jensen, Karen Johnson, Christopher R. Williams, Jennifer M. Comstock, Ya-Chien Feng, Alyssa Matthews, Iosif A. Lindenmaier, Timothy G. Wendler, Marquette Rocque, Aifang Zhou, Zeen Zhu, Edward Luke, Die Wang","doi":"10.5194/egusphere-2024-2615","DOIUrl":"https://doi.org/10.5194/egusphere-2024-2615","url":null,"abstract":"<strong>Abstract.</strong> A relative calibration technique is developed for the U.S. Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) user facility Ka-Band ARM Zenith Radars (KAZRs). The technique utilizes the signal attenuation due to water collected on the radome for estimates of the reflectivity factor (Ze) offset. The wet-radome attenuation (WRA) is assumed to follow a logarithmic relationship with rainfall rate in light and moderate rain conditions, measured by a collocated surface disdrometer. A practical advantage of this WRA approach to shorter-wavelength radar monitoring is that while it requires a reference disdrometer, it is shown viable for a wider range of collocated disdrometer measurements than traditional disdrometer direct comparisons in light rain. Adding such techniques may provide an additional, cost-effective monitoring tool for remote/longer-term deployments. This technique has been applied during the ARM TRacking Aerosol Convection interactions ExpeRiment (TRACER) from October 2021 through September 2022. The estimated offsets in Ze are evaluated against traditional radar calibration and monitoring methods based on datasets available during this campaign. This WRA technique reports offsets that compare favorably with the mean offsets found between the cloud radars and a nearby disdrometer near the time of rain onset, while also demonstrates similar offset and campaign-long trends with respect to collocated and independently-calibrated reference radars. Overall, the KAZR Ze offsets estimated during TRACER remains stable and at a level 2 dBZ lower than the Ze estimated by disdrometer from the campaign start until the end of June 2022. Thereafter, the radar offsets increase to near 7 dBZ at the end of the campaign.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"156 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250475","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}
Miguel Aldana, Seppo Pulkkinen, Annakaisa von Lerber, Matthew R. Kumjian, Dmitri Moisseev
Abstract. Accurate and precise KDP estimates are essential for radar-based applications, especially in quantitative precipitation estimation and radar data quality control routines. The accuracy of these estimates largely depends on the post-processing of the radar's measured ΦDP, which aims to reduce noise and backscattering effects while preserving fine-scale precipitation features. In this study, we evaluate the performance of several publicly available KDP estimation methods implemented in open-source libraries such as PyArt and Wradlib, and the method used in the Vaisala weather radars. To benchmark these methods, we employ a polarimetric self-consistency approach that relates KDP to reflectivity and differential reflectivity in rain, providing a reference self-consistency KDP (KDPSC) for comparison. This approach allows for the construction of the reference KDP observations that can be used to assess the accuracy and robustness of the studied KDP estimation methods. We assess each method by quantifying uncertainties using C-band weather radar observations where the reflectivity values ranged between 20 and 50 dBZ. Using the proposed evaluation framework we could define optimized parameter settings for the methods that have user-configurable parameters. Most of such methods showed significant reduction in the estimation errors after the optimization with respect to the default settings. We have found significant differences in the performances of the studied methods, where the best performing methods showed smaller normalized biases in the high reflectivity values (i.e., ≥ 40 dBZ) and overall smaller normalized root mean squared errors across the range of reflectivity values.
{"title":"Benchmarking KDP in Rainfall: A Quantitative Assessment of Estimation Algorithms Using C-Band Weather Radar Observations","authors":"Miguel Aldana, Seppo Pulkkinen, Annakaisa von Lerber, Matthew R. Kumjian, Dmitri Moisseev","doi":"10.5194/amt-2024-155","DOIUrl":"https://doi.org/10.5194/amt-2024-155","url":null,"abstract":"<strong>Abstract.</strong> Accurate and precise <em>K<sub>DP</sub></em> estimates are essential for radar-based applications, especially in quantitative precipitation estimation and radar data quality control routines. The accuracy of these estimates largely depends on the post-processing of the radar's measured Φ<sub><em>DP</em></sub>, which aims to reduce noise and backscattering effects while preserving fine-scale precipitation features. In this study, we evaluate the performance of several publicly available <em>K<sub>DP</sub></em> estimation methods implemented in open-source libraries such as PyArt and Wradlib, and the method used in the Vaisala weather radars. To benchmark these methods, we employ a polarimetric self-consistency approach that relates <em>K<sub>DP</sub></em> to reflectivity and differential reflectivity in rain, providing a reference self-consistency <em>K<sub>DP </sub></em> (K<em style=\"position: relative;\"><sub>DP</sub><sup style=\"position: absolute; top: 0px; left: 2px;\">SC</sup> </em>) for comparison. This approach allows for the construction of the reference <em>K<sub>DP</sub></em> observations that can be used to assess the accuracy and robustness of the studied <em>K<sub>DP</sub></em> estimation methods. We assess each method by quantifying uncertainties using C-band weather radar observations where the reflectivity values ranged between 20 and 50 dBZ. Using the proposed evaluation framework we could define optimized parameter settings for the methods that have user-configurable parameters. Most of such methods showed significant reduction in the estimation errors after the optimization with respect to the default settings. We have found significant differences in the performances of the studied methods, where the best performing methods showed smaller normalized biases in the high reflectivity values (i.e., ≥ 40 dBZ) and overall smaller normalized root mean squared errors across the range of reflectivity values.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"52 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250477","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 : 2024-09-18DOI: 10.5194/egusphere-2024-1910
Louis Jaffeux, Jan Breiner, Pierre Coutris, Alfons Schwarzenböck
Abstract. The convolutional network methodology is applied to train classification tools for hydrometeor images from optical array probes. Two models were developed in a previous article for the PIP and 2DS and are further tested. Three additional models are presented: for the CIP, HVPS, and a global model trained on a data set that includes all available data from all four instruments. A methodology to retrieve morphology-specific size distributions from the OAP data is provided. Size distributions for each morphological class, obtained with the specific or global classification models, are compared for the ICE GENESIS data set, where all four probes were used simultaneously. The reliability and coherence of these newly obtained machine learning classification tools are demonstrated clearly. The analysis shows significant advantages of using the global model over the specific ones, in terms of compatibility of the size distributions. The obtained morphology-specific size distributions effectively reduce OAP data to a level of detail pertinent to systematically identify microphysical processes. This study emphasizes the potential to improve insights in ice and mixed-phase microphysics based on hydrometeor morphological classification from machine learning algorithms.
{"title":"Ice crystal images from optical array probes. Compatibility of morphology specific size distributions, retrieved with specific and global Convolutional Neural Networks for HVPS, PIP, CIP, and 2DS","authors":"Louis Jaffeux, Jan Breiner, Pierre Coutris, Alfons Schwarzenböck","doi":"10.5194/egusphere-2024-1910","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1910","url":null,"abstract":"<strong>Abstract.</strong> The convolutional network methodology is applied to train classification tools for hydrometeor images from optical array probes. Two models were developed in a previous article for the PIP and 2DS and are further tested. Three additional models are presented: for the CIP, HVPS, and a global model trained on a data set that includes all available data from all four instruments. A methodology to retrieve morphology-specific size distributions from the OAP data is provided. Size distributions for each morphological class, obtained with the specific or global classification models, are compared for the ICE GENESIS data set, where all four probes were used simultaneously. The reliability and coherence of these newly obtained machine learning classification tools are demonstrated clearly. The analysis shows significant advantages of using the global model over the specific ones, in terms of compatibility of the size distributions. The obtained morphology-specific size distributions effectively reduce OAP data to a level of detail pertinent to systematically identify microphysical processes. This study emphasizes the potential to improve insights in ice and mixed-phase microphysics based on hydrometeor morphological classification from machine learning algorithms.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"54 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250479","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 : 2024-09-18DOI: 10.5194/egusphere-2024-2764
Bavo Langerock, Martine De Mazière, Filip Desmet, Pauli Heikkinen, Rigel Kivi, Mahesh Kumar Sha, Corinne Vigouroux, Minqiang Zhou, Gopala Khrisna Darbha, Mohmmed Talib
Abstract. For atmospheric trace gas columns retrievals obtained from ground based Fourier-transform interferometer spectra we study the sensitivity of the retrieval processing chain to changes in the number of points in the recorded interferograms. Shortening an interferogram will alter the leakage pattern in the associated spectrum and we demonstrate that the removal of a relatively small number of points from the interferogram edges creates a beat pattern in the difference of the associated spectra obtained from the original and shortened interferogram. For low-resolution interferometers the beat pattern in the spectra may exceed the noise level and the effect on atmospheric gas column retrievals may be large. Sensitivity of the retrieval algorithm to the length of the underlying interferogram can be reduced by applying a non-trivial apodization such as Norton-Beer. A case study shows the effect on formaldehyde retrievals obtained from low-resolution spectra in Sodankylä and Kolkata.
{"title":"Robustness of atmospheric trace gas retrievals obtained from low spectral resolution Fourier-transform infrared absorption spectra","authors":"Bavo Langerock, Martine De Mazière, Filip Desmet, Pauli Heikkinen, Rigel Kivi, Mahesh Kumar Sha, Corinne Vigouroux, Minqiang Zhou, Gopala Khrisna Darbha, Mohmmed Talib","doi":"10.5194/egusphere-2024-2764","DOIUrl":"https://doi.org/10.5194/egusphere-2024-2764","url":null,"abstract":"<strong>Abstract.</strong> For atmospheric trace gas columns retrievals obtained from ground based Fourier-transform interferometer spectra we study the sensitivity of the retrieval processing chain to changes in the number of points in the recorded interferograms. Shortening an interferogram will alter the leakage pattern in the associated spectrum and we demonstrate that the removal of a relatively small number of points from the interferogram edges creates a beat pattern in the difference of the associated spectra obtained from the original and shortened interferogram. For low-resolution interferometers the beat pattern in the spectra may exceed the noise level and the effect on atmospheric gas column retrievals may be large. Sensitivity of the retrieval algorithm to the length of the underlying interferogram can be reduced by applying a non-trivial apodization such as Norton-Beer. A case study shows the effect on formaldehyde retrievals obtained from low-resolution spectra in Sodankylä and Kolkata.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"11 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250839","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 : 2024-09-18DOI: 10.5194/egusphere-2024-2752
Hendrik Fuchs, Aaron Stainsby, Florian Berg, René Dubus, Michelle Färber, Andreas Hofzumahaus, Frank Holland, Kelvin H. Bates, Steven S. Brown, Matthew M. Coggon, Glenn S. Diskin, Georgios I. Gkatzelis, Christopher M. Jernigan, Jeff Peischl, Michael A. Robinson, Andrew W. Rollins, Nell B. Schafer, Rebecca H. Schwantes, Chelsea E. Stockwell, Patrick R. Veres, Carsten Warneke, Eleanor M. Waxman, Lu Xu, Kristen Zuraski, Andreas Wahner, Anna Novelli
Abstract. Hydroxyl radical OH reactivity, which is the inverse lifetime of the OH radical, provides information on the burden of air pollutants, since almost all air pollutants react with OH. OH reactivity measurements from field experiments can help to identify gaps in the measurement of individual reactants and serve as a proxy for the potential formation of secondary pollutants, including ozone and particles. However, OH reactivity is not regularly measured specifically on airborne platforms due to the technical complexity of the instruments and/or the need for careful instrumental characterisation to apply accurate correction factors to account for secondary chemistry in the instruments. The method used in this work, based on the time-resolved measurement of OH radicals produced by laser flash photolysis in a flow tube, does not require corrections as secondary chemistry in the instrument is negligible for typical atmospheric conditions. However, the detection of OH radicals by laser-induced fluorescence is challenging. In this work, an OH reactivity instrument has been further developed specifically for airborne measurements. The laser system used to detect the OH radicals has been simplified compared to previous setups, thereby significantly reducing the need for user interaction. The improved sensitivity allows measurements to be made with high time resolution on the order of seconds with a measurements precision of 0.3 s−1. The OH reactivity measurements were validated by using a propane gas standard, which allowed the determination of the reaction rate constant of the OH reaction with propane. The values are in excellent agreement with literature recommendations within a range of 4 to 8 %. Deviations are well within the combined uncertainties. The accuracy of the OH reactivity measurements is mainly limited by the determination of the instrumental zero, which has a typical maximum uncertainty of 0.5 s−1. The high sensitivity of the improved instrument facilitates the data acquisition on board an aircraft as demonstrated by its deployment during the AEROMMA campaign in 2023.
{"title":"Advances in OH reactivity instruments for airborne field measurements","authors":"Hendrik Fuchs, Aaron Stainsby, Florian Berg, René Dubus, Michelle Färber, Andreas Hofzumahaus, Frank Holland, Kelvin H. Bates, Steven S. Brown, Matthew M. Coggon, Glenn S. Diskin, Georgios I. Gkatzelis, Christopher M. Jernigan, Jeff Peischl, Michael A. Robinson, Andrew W. Rollins, Nell B. Schafer, Rebecca H. Schwantes, Chelsea E. Stockwell, Patrick R. Veres, Carsten Warneke, Eleanor M. Waxman, Lu Xu, Kristen Zuraski, Andreas Wahner, Anna Novelli","doi":"10.5194/egusphere-2024-2752","DOIUrl":"https://doi.org/10.5194/egusphere-2024-2752","url":null,"abstract":"<strong>Abstract.</strong> Hydroxyl radical OH reactivity, which is the inverse lifetime of the OH radical, provides information on the burden of air pollutants, since almost all air pollutants react with OH. OH reactivity measurements from field experiments can help to identify gaps in the measurement of individual reactants and serve as a proxy for the potential formation of secondary pollutants, including ozone and particles. However, OH reactivity is not regularly measured specifically on airborne platforms due to the technical complexity of the instruments and/or the need for careful instrumental characterisation to apply accurate correction factors to account for secondary chemistry in the instruments. The method used in this work, based on the time-resolved measurement of OH radicals produced by laser flash photolysis in a flow tube, does not require corrections as secondary chemistry in the instrument is negligible for typical atmospheric conditions. However, the detection of OH radicals by laser-induced fluorescence is challenging. In this work, an OH reactivity instrument has been further developed specifically for airborne measurements. The laser system used to detect the OH radicals has been simplified compared to previous setups, thereby significantly reducing the need for user interaction. The improved sensitivity allows measurements to be made with high time resolution on the order of seconds with a measurements precision of 0.3 s<sup>−1</sup>. The OH reactivity measurements were validated by using a propane gas standard, which allowed the determination of the reaction rate constant of the OH reaction with propane. The values are in excellent agreement with literature recommendations within a range of 4 to 8 %. Deviations are well within the combined uncertainties. The accuracy of the OH reactivity measurements is mainly limited by the determination of the instrumental zero, which has a typical maximum uncertainty of 0.5 s<sup>−1</sup>. The high sensitivity of the improved instrument facilitates the data acquisition on board an aircraft as demonstrated by its deployment during the AEROMMA campaign in 2023.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"6 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250478","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 : 2024-09-18DOI: 10.5194/egusphere-2024-2625
Erlend Øydvin, Renaud Gaban, Jafet Andersson, Remco van de Beek, Mareile Astrid Wolff, Nils-Otto Kitterød, Christian Chwala, Vegard Nilsen
Abstract. Differentiating between snow and rainfall is crucial for hydrological modeling and understanding. Commercial Microwave Links (CMLs) can provide accurate rainfall estimates for liquid precipitation, but show minimal signal attenuation during dry snow events, causing the CML time series during these periods to resemble non-precipitation periods. Weather radars can detect precipitation also for dry snow, yet, they struggle to accurately differentiate between precipitation types. This study introduces a new approach to improve rainfall and dry snow classification by combining weather radar precipitation detection with CML signal attenuation. Specifically, events where the radar detects precipitation, but the CML does not, are classified as dry snow. As a reference method we use weather radar, with the precipitation type identified by the dew point temperature at the CML location. Both methods were evaluated using ground measurements from disdrometers within 8 km of a CML, analysing data from 550 CMLs in December 2021 and 435 CMLs in June 2022. Our results show that using CMLs can enhance the classification of dry snow and rainfall, presenting an advantage over the reference method. Further, our research provides valuable insights into how precipitation at temperatures around zero degrees, such as sleet or wet snow, can affect CMLs, contributing to a better understanding of CML applications in colder climates.
{"title":"Combining commercial microwave links and weather radar for classification of dry snow and rainfall","authors":"Erlend Øydvin, Renaud Gaban, Jafet Andersson, Remco van de Beek, Mareile Astrid Wolff, Nils-Otto Kitterød, Christian Chwala, Vegard Nilsen","doi":"10.5194/egusphere-2024-2625","DOIUrl":"https://doi.org/10.5194/egusphere-2024-2625","url":null,"abstract":"<strong>Abstract.</strong> Differentiating between snow and rainfall is crucial for hydrological modeling and understanding. Commercial Microwave Links (CMLs) can provide accurate rainfall estimates for liquid precipitation, but show minimal signal attenuation during dry snow events, causing the CML time series during these periods to resemble non-precipitation periods. Weather radars can detect precipitation also for dry snow, yet, they struggle to accurately differentiate between precipitation types. This study introduces a new approach to improve rainfall and dry snow classification by combining weather radar precipitation detection with CML signal attenuation. Specifically, events where the radar detects precipitation, but the CML does not, are classified as dry snow. As a reference method we use weather radar, with the precipitation type identified by the dew point temperature at the CML location. Both methods were evaluated using ground measurements from disdrometers within 8 km of a CML, analysing data from 550 CMLs in December 2021 and 435 CMLs in June 2022. Our results show that using CMLs can enhance the classification of dry snow and rainfall, presenting an advantage over the reference method. Further, our research provides valuable insights into how precipitation at temperatures around zero degrees, such as sleet or wet snow, can affect CMLs, contributing to a better understanding of CML applications in colder climates.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"13 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142250840","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}
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