Abstract. This paper presents a new technique to derive thermospheric temperature from space-based disk observations of far ultraviolet airglow. The technique, guided by findings from principal component analysis of synthetic daytime LBH disk emissions, uses a ratio of the emissions in two spectral channels that together span the Lyman–Birge–Hopfield (LBH) (2,0) band to determine the change in band shape with respect to a change in the rotational temperature of N2. The benefits of the two-channel ratio approach include an elimination of representativeness error as absolute LBH intensities are not required in the derivation procedure and a reduced impact of systematic measurement error caused by variations in the instrumental performance across the LBH band system as a fully resolved system is also not required. It is shown that the derived temperature should, in general, be interpreted as a column-integrated property as opposed to a temperature at a specified altitude without utilization of a priori information of the thermospheric temperature profile. The two-channel ratio approach is demonstrated using NASA GOLD Level 1C disk emission data for the period of 2–8 November 2018 during which a small geomagnetic storm has occurred. Due to the lack of independent thermospheric temperature observations, the efficacy of the approach is validated through comparisons of the column-integrated temperature derived from GOLD Level 1C data with version 2 of the GOLD Level 2 temperature product as well as temperatures from first principle and empirical models. The storm-time thermospheric response manifested in the column-integrated temperature is also shown to corroborate well with hemispherically integrated Joule heating rates, ESA SWARM mass density at 460 km, and GOLD Level 2 column O / N2 ratio.
{"title":"Deriving column-integrated thermospheric temperature with the N2 Lyman–Birge–Hopfield (2,0) band","authors":"C. Cantrall, T. Matsuo","doi":"10.5194/AMT-2021-75","DOIUrl":"https://doi.org/10.5194/AMT-2021-75","url":null,"abstract":"Abstract. This paper presents a new technique to derive thermospheric temperature from space-based disk observations of far ultraviolet airglow. The technique, guided by findings from principal component analysis of synthetic daytime LBH disk emissions, uses a ratio of the emissions in two spectral channels that together span the Lyman–Birge–Hopfield (LBH) (2,0) band to determine the change in band shape with respect to a change in the rotational temperature of N2. The benefits of the two-channel ratio approach include an elimination of representativeness error as absolute LBH intensities are not required in the derivation procedure and a reduced impact of systematic measurement error caused by variations in the instrumental performance across the LBH band system as a fully resolved system is also not required. It is shown that the derived temperature should, in general, be interpreted as a column-integrated property as opposed to a temperature at a specified altitude without utilization of a priori information of the thermospheric temperature profile. The two-channel ratio approach is demonstrated using NASA GOLD Level 1C disk emission data for the period of 2–8 November 2018 during which a small geomagnetic storm has occurred. Due to the lack of independent thermospheric temperature observations, the efficacy of the approach is validated through comparisons of the column-integrated temperature derived from GOLD Level 1C data with version 2 of the GOLD Level 2 temperature product as well as temperatures from first principle and empirical models. The storm-time thermospheric response manifested in the column-integrated temperature is also shown to corroborate well with hemispherically integrated Joule heating rates, ESA SWARM mass density at 460 km, and GOLD Level 2 column O / N2 ratio.\u0000","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"344 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124243128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Fischer, M. Breitenlechner, E. Canaval, W. Scholz, M. Striednig, M. Graus, T. Karl, T. Petäjä, M. Kulmala, A. Hansel
Abstract. We present first eddy covariance flux measurements with the PTR3-TOF-MS, a novel proton-transfer-reaction mass-spectrometer (PTR-MS). During three weeks in spring 2016 the instrument recorded 10 Hz BVOC data on top of the SMEAR II tower in Hyytiälä, Finland. Flux and concentration data of isoprene, monoterpenes and sesquiterpenes were compared to the literature. Due to the improved instrument sensitivity and a customized “wall less” inlet design we could detect a number of fluxes of semi-volatile and low volatile organic compounds (SVOC and LVOC) with less than single digit picomol/m2/s values for the first time. These compounds include sesquiterpene oxidation products and diterpenes. Daytime diterpene fluxes were in the range of 0.05 to 0.15 picomol/m2/s, which amounts to about 0.25 % to 0.5 % of the daytime sesquiterpene flux above canopy.
{"title":"First Eddy Covariance Flux Measurements of Semi Volatile Organic Compounds with the PTR3-TOF-MS","authors":"L. Fischer, M. Breitenlechner, E. Canaval, W. Scholz, M. Striednig, M. Graus, T. Karl, T. Petäjä, M. Kulmala, A. Hansel","doi":"10.5194/AMT-2021-117","DOIUrl":"https://doi.org/10.5194/AMT-2021-117","url":null,"abstract":"Abstract. We present first eddy covariance flux measurements with the PTR3-TOF-MS, a novel proton-transfer-reaction mass-spectrometer (PTR-MS). During three weeks in spring 2016 the instrument recorded 10 Hz BVOC data on top of the SMEAR II tower in Hyytiälä, Finland. Flux and concentration data of isoprene, monoterpenes and sesquiterpenes were compared to the literature. Due to the improved instrument sensitivity and a customized “wall less” inlet design we could detect a number of fluxes of semi-volatile and low volatile organic compounds (SVOC and LVOC) with less than single digit picomol/m2/s values for the first time. These compounds include sesquiterpene oxidation products and diterpenes. Daytime diterpene fluxes were in the range of 0.05 to 0.15 picomol/m2/s, which amounts to about 0.25 % to 0.5 % of the daytime sesquiterpene flux above canopy.","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"136 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121042987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. A great interest is growing about methods that combine measurements from two or more instruments that observe the same species either in different spectral regions or with different geometries. Recently, a method based on the Kalman filter has been proposed to combine IASI and TROPOMI methane products. We show that this method is equivalent to the Complete Data Fusion method. Therefore, the choice between these two methods is driven only by the advantages of the different implementations. From the comparison of the two methods a generalization of the Complete Data Fusion formula, which is valid also in the case that the noise error covariance matrices of the fused products are singular, is derived.
{"title":"Comment on “Synergetic use of IASI and TROPOMI space borne sensors for generating a tropospheric methane profile product”","authors":"S. Ceccherini","doi":"10.5194/AMT-2021-98","DOIUrl":"https://doi.org/10.5194/AMT-2021-98","url":null,"abstract":"Abstract. A great interest is growing about methods that combine measurements from two or more instruments that observe the same species either in different spectral regions or with different geometries. Recently, a method based on the Kalman filter has been proposed to combine IASI and TROPOMI methane products. We show that this method is equivalent to the Complete Data Fusion method. Therefore, the choice between these two methods is driven only by the advantages of the different implementations. From the comparison of the two methods a generalization of the Complete Data Fusion formula, which is valid also in the case that the noise error covariance matrices of the fused products are singular, is derived.","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123032877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jean-François Ribaud, M. Haeffelin, J. Dupont, M. Drouin, F. Toledo, S. Kotthaus
Abstract. An improved version of the near-real time decision tool PARAFOG (PFG2) is presented to retrieve pre-fog alert levels and to discriminate between radiation (RAD) and stratus lowering (STL) fog situations. PFG2 has two distinct modules to monitor the physical processes involved in RAD and STL fog formation and is evaluated at European sites. The modules are based on innovative fuzzy logic algorithms to retrieve fog alert levels (low, moderate, high) specific to RAD/STL conditions, minutes to hours prior to fog onset. The PFG2-RAD module assesses also the thickness of the fog. Both the PFG2-RAD and PFG2-STL modules rely on the combination of visibility observations and automatic lidar and ceilometer (ALC) measurements. The overall performance of the PFG2-RAD and -STL modules is evaluated based on 9 years of measurements at the SIRTA observatory near Paris and up to two fog seasons at the Paris-Roissy, Vienna, Munich and Zurich airports. At all sites, pre-fog alert levels retrieved by PFG2 are found to be consistent with the local weather analysis. The advanced PFG2 algorithm performs with a hit rate of about 100 % for both considered fog types, and presents a false alarm ratio on the order of 10 % (30 %) for RAD (STL) fog situations. Finally, the first high alerts that result in a subsequent fog event are found to occur for periods of time ranging from −120 minutes to fog onset, with first high alerts occurring earlier for RAD than STL cases.
{"title":"PARAFOG v2.0: a near real-time decision tool to support nowcasting fog formation events at local scales","authors":"Jean-François Ribaud, M. Haeffelin, J. Dupont, M. Drouin, F. Toledo, S. Kotthaus","doi":"10.5194/AMT-2021-99","DOIUrl":"https://doi.org/10.5194/AMT-2021-99","url":null,"abstract":"Abstract. An improved version of the near-real time decision tool PARAFOG (PFG2) is presented to retrieve pre-fog alert levels and to discriminate between radiation (RAD) and stratus lowering (STL) fog situations. PFG2 has two distinct modules to monitor the physical processes involved in RAD and STL fog formation and is evaluated at European sites. The modules are based on innovative fuzzy logic algorithms to retrieve fog alert levels (low, moderate, high) specific to RAD/STL conditions, minutes to hours prior to fog onset. The PFG2-RAD module assesses also the thickness of the fog. Both the PFG2-RAD and PFG2-STL modules rely on the combination of visibility observations and automatic lidar and ceilometer (ALC) measurements. The overall performance of the PFG2-RAD and -STL modules is evaluated based on 9 years of measurements at the SIRTA observatory near Paris and up to two fog seasons at the Paris-Roissy, Vienna, Munich and Zurich airports. At all sites, pre-fog alert levels retrieved by PFG2 are found to be consistent with the local weather analysis. The advanced PFG2 algorithm performs with a hit rate of about 100 % for both considered fog types, and presents a false alarm ratio on the order of 10 % (30 %) for RAD (STL) fog situations. Finally, the first high alerts that result in a subsequent fog event are found to occur for periods of time ranging from −120 minutes to fog onset, with first high alerts occurring earlier for RAD than STL cases.\u0000","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"262 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124281129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Using data from the Infrared Atmospheric Sounding Interferometer (IASI) measurements of volcanic ash clouds and radiative transfer calculations, we identify the optimal refractive index model for simulating the measured brightness temperature spectrum of volcanic ash material. We assume that the optimal refractive index model has the smallest root mean square of the brightness temperature difference between measurements and simulations for channels in the wavenumber range of 750–1400 cm−1 and compare 21 refractive index models for optical properties of ash particles, including recently published models. From the results of numerical simulations for 164 pixels of IASI measurements for ash clouds from 11 volcanoes, we found that the measured brightness temperature spectrum could be well simulated using certain newly established refractive index models. In the cases of Eyjafjallajökull and Grímsvötn ash clouds, the optimal refractive index models determined through numerical simulation correspond to those deduced from the chemical composition of ash samples for the same volcanic eruption events. This finding suggests that infrared sounder measurement of volcanic ash clouds is an effective approach to estimating the optimal refractive index model. However, discrepancies between the estimated refractive index models based on satellite measurements and the associated volcanic rock types were observed for some volcanic events.
{"title":"Optimal ash particle refractive index model for simulating the brightness temperature spectrum of volcanic ash clouds from satellite infrared sounder measurements","authors":"H. Ishimoto, M. Hayashi, Y. Mano","doi":"10.5194/AMT-2021-103","DOIUrl":"https://doi.org/10.5194/AMT-2021-103","url":null,"abstract":"Abstract. Using data from the Infrared Atmospheric Sounding Interferometer (IASI) measurements of volcanic ash clouds and radiative transfer calculations, we identify the optimal refractive index model for simulating the measured brightness temperature spectrum of volcanic ash material. We assume that the optimal refractive index model has the smallest root mean square of the brightness temperature difference between measurements and simulations for channels in the wavenumber range of 750–1400 cm−1 and compare 21 refractive index models for optical properties of ash particles, including recently published models. From the results of numerical simulations for 164 pixels of IASI measurements for ash clouds from 11 volcanoes, we found that the measured brightness temperature spectrum could be well simulated using certain newly established refractive index models. In the cases of Eyjafjallajökull and Grímsvötn ash clouds, the optimal refractive index models determined through numerical simulation correspond to those deduced from the chemical composition of ash samples for the same volcanic eruption events. This finding suggests that infrared sounder measurement of volcanic ash clouds is an effective approach to estimating the optimal refractive index model. However, discrepancies between the estimated refractive index models based on satellite measurements and the associated volcanic rock types were observed for some volcanic events.\u0000","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"213 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116489094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Feofilov, H. Chepfer, V. Noel, R. Guzman, Cyprien Gindre, M. Chiriaco
Abstract. The spaceborne active sounders have been contributing invaluable vertically resolved information of atmospheric optical properties since the launch of CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) in 2006. To ensure the continuity of climate studies and monitoring the global changes, one has to understand the differences between lidars operating at different wavelengths, flying at different orbits, and utilizing different observation geometries, receiving paths, and detectors. In this article, we show the results of an intercomparison study of ALADIN (Atmospheric Laser Doppler INstrument) and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) lidars using their scattering ratio (SR) products for the period of 28/06/2019−31/12/2019. We suggest an optimal set of collocation criteria (Δdist < 1º; Δtime < 6 h), which would give a representative set of collocated profiles and we show that for such a pair of instruments the theoretically achievable cloud detection agreement for the data collocated with aforementioned criteria is 0.77 ± 0.17. The analysis of a collocated database consisting of ~78000 pairs of collocated nighttime SR profiles revealed the following: (a) in the cloud-free area, the agreement is good indicating low frequency of false positive cloud detections by both instruments; (b) the cloud detection agreement is better for the lower layers. Above ~7 km, the ALADIN product demonstrates lower sensitivity because of lower backscatter at 355 nm and because of lower signal-to-noise ratio; (c) in 50 % of the analyzed cases when ALADIN reported a low cloud not detected by CALIOP, the middle level cloud hindered the observations and perturbed the ALADIN’s retrieval indicating the need for quality flag refining for such scenarios; (d) large sensitivity to lower clouds leads to skewing the ALADIN’s cloud peaks down by ~0.5 ± 0.4 km, but this effect does not alter the polar stratospheric cloud peak heights; (e) temporal evolution of cloud agreement quality does not reveal any anomaly for the considered period, indicating that hot pixels and laser degradation effects in ALADIN have been mitigated at least down to the uncertainties in the following cloud detection agreement values: 61 ± 16 %, 34 ± 18 % 24 ± 10 %, 26 ± 10 %, and 22 ± 12 % at 0.75 km, 2.25 km, 6.75 km, 8.75 km, and 10.25 km, respectively.
{"title":"Comparing scattering ratio products retrieved from ALADIN/Aeolus and CALIOP/CALIPSO observations: sensitivity, comparability, and temporal evolution","authors":"A. Feofilov, H. Chepfer, V. Noel, R. Guzman, Cyprien Gindre, M. Chiriaco","doi":"10.5194/AMT-2021-96","DOIUrl":"https://doi.org/10.5194/AMT-2021-96","url":null,"abstract":"Abstract. The spaceborne active sounders have been contributing invaluable vertically resolved information of atmospheric optical properties since the launch of CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) in 2006. To ensure the continuity of climate studies and monitoring the global changes, one has to understand the differences between lidars operating at different wavelengths, flying at different orbits, and utilizing different observation geometries, receiving paths, and detectors. In this article, we show the results of an intercomparison study of ALADIN (Atmospheric Laser Doppler INstrument) and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) lidars using their scattering ratio (SR) products for the period of 28/06/2019−31/12/2019. We suggest an optimal set of collocation criteria (Δdist < 1º; Δtime < 6 h), which would give a representative set of collocated profiles and we show that for such a pair of instruments the theoretically achievable cloud detection agreement for the data collocated with aforementioned criteria is 0.77 ± 0.17. The analysis of a collocated database consisting of ~78000 pairs of collocated nighttime SR profiles revealed the following: (a) in the cloud-free area, the agreement is good indicating low frequency of false positive cloud detections by both instruments; (b) the cloud detection agreement is better for the lower layers. Above ~7 km, the ALADIN product demonstrates lower sensitivity because of lower backscatter at 355 nm and because of lower signal-to-noise ratio; (c) in 50 % of the analyzed cases when ALADIN reported a low cloud not detected by CALIOP, the middle level cloud hindered the observations and perturbed the ALADIN’s retrieval indicating the need for quality flag refining for such scenarios; (d) large sensitivity to lower clouds leads to skewing the ALADIN’s cloud peaks down by ~0.5 ± 0.4 km, but this effect does not alter the polar stratospheric cloud peak heights; (e) temporal evolution of cloud agreement quality does not reveal any anomaly for the considered period, indicating that hot pixels and laser degradation effects in ALADIN have been mitigated at least down to the uncertainties in the following cloud detection agreement values: 61 ± 16 %, 34 ± 18 % 24 ± 10 %, 26 ± 10 %, and 22 ± 12 % at 0.75 km, 2.25 km, 6.75 km, 8.75 km, and 10.25 km, respectively.\u0000","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126513985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yun He, Yunfei Zhang, Fuchao Liu, Zhenping Yin, Yang Yi, Yifan Zhan, F. Yi
Abstract. The POLIPHON (Polarization Lidar Photometer Networking) method is a powerful pathway to retrieve the height profiles of dust-related particle mass and ice-nucleating particles (INP) concentrations. The conversion factors fitted from the sun photometer observation data are the major part of the POLIPHON computations, which can convert the polarization-lidar-derived dust extinction coefficients into the dust-related particle mass and INP concentrations. For a central China megacity Wuhan (30.5° N, 114.4° E), located at the downstream area several thousands of kilometers far away from the source regions of Asian dust, dust particles always mix with other aerosols from local emission. Therefore, very few dust case data sets can be available when using the column-integrated Angstrom exponent (for 440–870 nm) 0.1 recorded by sun photometer as the filtering criteria. Instead, we present another dust-case data-set screening scheme that applies the simultaneous polarization lidar observation to verify the occurrence of dust. Based on the 33 dust-intrusion days identified during 2011–2013, the extinction-to-volume (cv,d) and extinction-to-large particle (with radius > 250 nm) number concentration (c250,d) conversion factors are determined to be 0.52 × 10−12 Mm m3 m−3 and 0.11 Mm cm−3, respectively. They are both smaller than those observed at Lanzhou SACOL (36.0° N, 104.1° E), a site closer to the Gobi Desert, due to the partial dust sedimentation during transport. The conversion factors are applied in a dust event in Wuhan to reveal the typical dust-related INP concentration over East Asia city. The proposed dust-case data-set screening scheme may potentially be extended to the other polluted city sites more influenced by mixed dust.
摘要偏振激光雷达光度计网络(POLIPHON)方法是获取尘埃相关粒子质量和冰核粒子(INP)浓度高度分布的有力途径。由太阳光度计观测数据拟合的转换因子是POLIPHON计算的主要部分，它可以将偏振激光雷达导出的尘埃消光系数转换为与尘埃有关的粒子质量和INP浓度。中国中部特大城市武汉(30.5°N, 114.4°E)位于距离亚洲沙尘源区数千公里的下游地区，沙尘颗粒经常与当地排放的其他气溶胶混合。因此，当使用太阳光度计记录的柱积分埃氏指数(440-870 nm) 0.1作为过滤标准时，可获得的沙尘数据集很少。相反，我们提出了另一种沙尘数据集筛选方案，该方案应用同步偏振激光雷达观测来验证沙尘的发生。基于2011-2013年的33个沙尘侵入日，确定了灭绝-体积(cv,d)和灭绝-大颗粒(半径> 250 nm)数浓度(c250,d)的转换因子分别为0.52 × 10−12 Mm m3 m−3和0.11 Mm cm−3。在靠近戈壁沙漠的兰州SACOL(36.0°N, 104.1°E)，由于运输过程中的部分沙尘沉降，两者都小于观测值。将转换因子应用于武汉的一次沙尘事件，揭示了东亚城市典型的沙尘相关INP浓度。建议的粉尘数据集筛选方案可能会推广到其他受混合粉尘影响较大的污染城市场地。
{"title":"Retrievals of dust-related particle mass and ice-nucleating particle concentration profiles with ground-based polarization lidar and sun photometer over a central China megacity","authors":"Yun He, Yunfei Zhang, Fuchao Liu, Zhenping Yin, Yang Yi, Yifan Zhan, F. Yi","doi":"10.5194/AMT-2021-83","DOIUrl":"https://doi.org/10.5194/AMT-2021-83","url":null,"abstract":"Abstract. The POLIPHON (Polarization Lidar Photometer Networking) method is a powerful pathway to retrieve the height profiles of dust-related particle mass and ice-nucleating particles (INP) concentrations. The conversion factors fitted from the sun photometer observation data are the major part of the POLIPHON computations, which can convert the polarization-lidar-derived dust extinction coefficients into the dust-related particle mass and INP concentrations. For a central China megacity Wuhan (30.5° N, 114.4° E), located at the downstream area several thousands of kilometers far away from the source regions of Asian dust, dust particles always mix with other aerosols from local emission. Therefore, very few dust case data sets can be available when using the column-integrated Angstrom exponent (for 440–870 nm) 0.1 recorded by sun photometer as the filtering criteria. Instead, we present another dust-case data-set screening scheme that applies the simultaneous polarization lidar observation to verify the occurrence of dust. Based on the 33 dust-intrusion days identified during 2011–2013, the extinction-to-volume (cv,d) and extinction-to-large particle (with radius > 250 nm) number concentration (c250,d) conversion factors are determined to be 0.52 × 10−12 Mm m3 m−3 and 0.11 Mm cm−3, respectively. They are both smaller than those observed at Lanzhou SACOL (36.0° N, 104.1° E), a site closer to the Gobi Desert, due to the partial dust sedimentation during transport. The conversion factors are applied in a dust event in Wuhan to reveal the typical dust-related INP concentration over East Asia city. The proposed dust-case data-set screening scheme may potentially be extended to the other polluted city sites more influenced by mixed dust.","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122008585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Boris Vansevenant, Ced́ric Louis, C. Ferronato, L. Fine, P. Tassel, P. Perret, E. Kostenidou, B. Temime-Roussel, B. d'Anna, K. Sartelet, V. Cerezo, Yao Liu
Abstract. Atmospheric particles have several impacts on health and environment, especially in urban areas. Part of those particles is not fresh, and has undergone atmospheric chemical and physical processes. Due to not representative experimental conditions, and experimental artifacts such as particle wall losses in chambers, there are uncertainties on the effects of physical processes (condensation, nucleation and coagulation) and how they act on particles from modern vehicles. This study develops a new method to correct wall losses, accounting for size dependence and experiment-to-experiment variations, and applies it to the evolution of fresh diesel exhaust particles to characterize the physical processes acting on them. The correction method is based on the black carbon decay and a size-dependent coefficient to correct particle distributions. Exhaust from 6 diesel passenger cars, Euro 3 to Euro 6, driven on a chassis dynamometer with Artemis Urban cold start and Artemis Motorway cycles, was injected in an 8 m3 chamber with Teflon walls. The physical evolution of particles was characterized during 6 to 10 hours. Condensation occurs even without photochemical reactions, due to the presence of intermediate volatility organic compounds and semi-volatile organic compounds which were quantified at emission, and induces a particle mass increase up to 17 %.h−1, mainly for the older vehicles (Euro 3 and Euro 4). Condensation is 4 times faster when the available particle surface if multiplied by 3. If initial particle number concentration is below [8–9] × 104 #.cm−3, it can increase up to 25 %.h−1 due to nucleation or condensation on particles below 14 nm. Above this threshold, particle number concentration decreases due to coagulation, up to −27 %.h−1.
{"title":"Evolution under dark conditions of particles from old and modern diesel vehicles, in a new environmental chamber characterized with fresh exhaust emissions","authors":"Boris Vansevenant, Ced́ric Louis, C. Ferronato, L. Fine, P. Tassel, P. Perret, E. Kostenidou, B. Temime-Roussel, B. d'Anna, K. Sartelet, V. Cerezo, Yao Liu","doi":"10.5194/AMT-2021-43","DOIUrl":"https://doi.org/10.5194/AMT-2021-43","url":null,"abstract":"Abstract. Atmospheric particles have several impacts on health and environment, especially in urban areas. Part of those particles is not fresh, and has undergone atmospheric chemical and physical processes. Due to not representative experimental conditions, and experimental artifacts such as particle wall losses in chambers, there are uncertainties on the effects of physical processes (condensation, nucleation and coagulation) and how they act on particles from modern vehicles. This study develops a new method to correct wall losses, accounting for size dependence and experiment-to-experiment variations, and applies it to the evolution of fresh diesel exhaust particles to characterize the physical processes acting on them. The correction method is based on the black carbon decay and a size-dependent coefficient to correct particle distributions. Exhaust from 6 diesel passenger cars, Euro 3 to Euro 6, driven on a chassis dynamometer with Artemis Urban cold start and Artemis Motorway cycles, was injected in an 8 m3 chamber with Teflon walls. The physical evolution of particles was characterized during 6 to 10 hours. Condensation occurs even without photochemical reactions, due to the presence of intermediate volatility organic compounds and semi-volatile organic compounds which were quantified at emission, and induces a particle mass increase up to 17 %.h−1, mainly for the older vehicles (Euro 3 and Euro 4). Condensation is 4 times faster when the available particle surface if multiplied by 3. If initial particle number concentration is below [8–9] × 104 #.cm−3, it can increase up to 25 %.h−1 due to nucleation or condensation on particles below 14 nm. Above this threshold, particle number concentration decreases due to coagulation, up to −27 %.h−1.\u0000","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127751140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Zuber, U. Köhler, L. Egli, Mario Ribnitzky, W. Steinbrecht, J. Gröbner
Abstract. In the 2019/2020 measurement campaign at Hohenpeisenberg (Germany) and Davos (Switzerland) we compared the well-established Dobson and Brewer spectrometers (single and double monochromator Brewer) with newer BTS array spectroradiometer based systems in terms of total ozone column (TOC) determination. The aim of this study is to validate the BTS performance in a longer-term TOC analysis over more than one year with seasonal and weather influences. Two different BTS setups have been used. A fibre coupled entrance optic version by PMOD/WRC called Koherent and a diffusor optic which proved to be simpler in terms of calibration from Gigahertz-Optik GmbH called BTS Solar. The array-spectrometer based BTS systems have been traceable calibrated to National Metrology Institutes (NMI) and the used TOC retrieval algorithms are based on spectral measurements in the range of 305 nm and 350 nm instead of single wavelength measurements as for Brewer or Dobson. The two BTS based systems, however, used fundamentally different retrieval algorithms for the TOC assessment, whereby the retrieval of the BTS solar turned out to achieve significantly smaller seasonal drifts. The intercomparison showed a deviation of the BTS Solar to Brewers of
{"title":"TOC intercomparison of Brewer, Dobson and BTS Solar at Hohenpeißenberg and Davos 2019/2020","authors":"R. Zuber, U. Köhler, L. Egli, Mario Ribnitzky, W. Steinbrecht, J. Gröbner","doi":"10.5194/AMT-2021-52","DOIUrl":"https://doi.org/10.5194/AMT-2021-52","url":null,"abstract":"Abstract. In the 2019/2020 measurement campaign at Hohenpeisenberg (Germany) and Davos (Switzerland) we compared the well-established Dobson and Brewer spectrometers (single and double monochromator Brewer) with newer BTS array spectroradiometer based systems in terms of total ozone column (TOC) determination. The aim of this study is to validate the BTS performance in a longer-term TOC analysis over more than one year with seasonal and weather influences. Two different BTS setups have been used. A fibre coupled entrance optic version by PMOD/WRC called Koherent and a diffusor optic which proved to be simpler in terms of calibration from Gigahertz-Optik GmbH called BTS Solar. The array-spectrometer based BTS systems have been traceable calibrated to National Metrology Institutes (NMI) and the used TOC retrieval algorithms are based on spectral measurements in the range of 305 nm and 350 nm instead of single wavelength measurements as for Brewer or Dobson. The two BTS based systems, however, used fundamentally different retrieval algorithms for the TOC assessment, whereby the retrieval of the BTS solar turned out to achieve significantly smaller seasonal drifts. The intercomparison showed a deviation of the BTS Solar to Brewers of","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117114745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-26DOI: 10.5194/AMT-14-2409-2021
O. Peltola, K. Lapo, I. Martinkauppi, E. O'connor, Christoph K. Thomas, T. Vesala
Abstract. Suitability of fibre-optic distributed temperature sensing (DTS) technique to observe atmospheric mixing profiles within and above forest was quantified and these profiles were analysed. The spatially continuous observations were made at a 125 m tall mast in a boreal pine forest. Air flows near forest canopies diverge from typical boundary layer flows due to the influence of roughness elements (i.e. trees) on the flow. Ideally these complex flows should be studied with spatially continuous measurements, yet such measurements are not feasible with conventional micrometeorological measurements with e.g. sonic anemometers. Hence the suitability of DTS measurements for studying canopy flows was quantified. The DTS measurements were able to discern continuous profiles of turbulent fluctuations and mean values of air temperature along the mast providing information about mixing processes (e.g. canopy eddies, evolution of inversion layers at night) and up to third order turbulence statistics across the forest-atmosphere interface. Turbulence measurements with 3D sonic anemometers and Doppler lidar at the site were also utilised in this analysis. The continuous profiles for turbulence statistics were in line with prior studies made at wind tunnels and large eddy simulations for canopy flows. The DTS measurements contained a significant noise component which was however quantified and its effect on turbulence statistics was accounted for. Underestimation of air temperature fluctuations at high frequencies caused 20...30 % underestimation of temperature variance at typical flow conditions. Despite these limitations, the DTS measurements should prove useful also in other studies concentrating on flows near roughness elements and/or non-stationary periods, since the measurements revealed spatio-temporal patterns of the flow which were not possible to discern from single point measurements fixed in space.
{"title":"Suitability of fibre-optic distributed temperature sensing for revealing mixing processes and higher-order moments at the forest–air interface","authors":"O. Peltola, K. Lapo, I. Martinkauppi, E. O'connor, Christoph K. Thomas, T. Vesala","doi":"10.5194/AMT-14-2409-2021","DOIUrl":"https://doi.org/10.5194/AMT-14-2409-2021","url":null,"abstract":"Abstract. Suitability of fibre-optic distributed temperature sensing (DTS) technique to observe atmospheric mixing profiles within and above forest was quantified and these profiles were analysed. The spatially continuous observations were made at a 125 m tall mast in a boreal pine forest. Air flows near forest canopies diverge from typical boundary layer flows due to the influence of roughness elements (i.e. trees) on the flow. Ideally these complex flows should be studied with spatially continuous measurements, yet such measurements are not feasible with conventional micrometeorological measurements with e.g. sonic anemometers. Hence the suitability of DTS measurements for studying canopy flows was quantified. The DTS measurements were able to discern continuous profiles of turbulent fluctuations and mean values of air temperature along the mast providing information about mixing processes (e.g. canopy eddies, evolution of inversion layers at night) and up to third order turbulence statistics across the forest-atmosphere interface. Turbulence measurements with 3D sonic anemometers and Doppler lidar at the site were also utilised in this analysis. The continuous profiles for turbulence statistics were in line with prior studies made at wind tunnels and large eddy simulations for canopy flows. The DTS measurements contained a significant noise component which was however quantified and its effect on turbulence statistics was accounted for. Underestimation of air temperature fluctuations at high frequencies caused 20...30 % underestimation of temperature variance at typical flow conditions. Despite these limitations, the DTS measurements should prove useful also in other studies concentrating on flows near roughness elements and/or non-stationary periods, since the measurements revealed spatio-temporal patterns of the flow which were not possible to discern from single point measurements fixed in space.","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122992997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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