T. Riess, K. F. Boersma, J. Vliet, W. Peters, M. Sneep, H. Eskes, J. Geffen
Abstract. TROPOMI measurements of tropospheric NO2 columns provide powerful information on emissions of air pollution by ships on open sea. This information is potentially useful for authorities to help determine the (non-)compliance of ships with increasingly stringent NOx emission regulations. We find that the information quality is improved further by recent upgrades in the TROPOMI cloud retrieval and an optimal data selection. We show that the superior spatial resolution of TROPOMI allows the detection of several lanes of NO2 pollution ranging from the Aegean Sea near Greece to the Skagerrak in Scandinavia, which have not been detected with other satellite instruments before. Additionally, we demonstrate that under conditions of sun glint TROPOMI's vertical sensitivity to NO2 in the marine boundary layer increases by up to 60 %. The benefits of sun glint are most prominent under clear-sky situations when sea surface winds are low, but slightly above zero (±2 m/s). Beyond spatial resolution and sun glint, we examine for the first time the impact of the recently improved cloud algorithm on the TROPOMI NO2 retrieval quality, both over sea and over land. We find that the new FRESCO+wide algorithm leads to 50 hPa lower cloud pressures, correcting a known high bias, and produces 1–4·1015 molec/cm2 higher retrieved NO2 columns, thereby at least partially correcting for the previously reported low bias in the TROPOMI NO2 product. By training an artificial neural network on the 4 available periods with standard and FRESCO+wide test-retrievals, we develop a historic, consistent TROPOMI NO2 data set spanning the years 2019 and 2020. This improved data set shows stronger (35–75 %) and sharper (10–35 %) shipping NO2 signals compared to co-sampled measurements from OMI. We apply our improved data set to investigate the impact of the COVID-19 pandemic on ship NO2 pollution over European seas and find indications that NOx emissions from ships reduced by 20–25 % during the pandemic. The reductions in ship NO2 pollution start in March–April 2020, in line with changes in shipping activity inferred from AIS data.
{"title":"Improved monitoring of shipping NO2 with TROPOMI: decreasing NOx emissions in European seas during the COVID-19 pandemic","authors":"T. Riess, K. F. Boersma, J. Vliet, W. Peters, M. Sneep, H. Eskes, J. Geffen","doi":"10.5194/amt-2021-321","DOIUrl":"https://doi.org/10.5194/amt-2021-321","url":null,"abstract":"Abstract. TROPOMI measurements of tropospheric NO2 columns provide powerful information on emissions of air pollution by ships on open sea. This information is potentially useful for authorities to help determine the (non-)compliance of ships with increasingly stringent NOx emission regulations. We find that the information quality is improved further by recent upgrades in the TROPOMI cloud retrieval and an optimal data selection. We show that the superior spatial resolution of TROPOMI allows the detection of several lanes of NO2 pollution ranging from the Aegean Sea near Greece to the Skagerrak in Scandinavia, which have not been detected with other satellite instruments before. Additionally, we demonstrate that under conditions of sun glint TROPOMI's vertical sensitivity to NO2 in the marine boundary layer increases by up to 60 %. The benefits of sun glint are most prominent under clear-sky situations when sea surface winds are low, but slightly above zero (±2 m/s). Beyond spatial resolution and sun glint, we examine for the first time the impact of the recently improved cloud algorithm on the TROPOMI NO2 retrieval quality, both over sea and over land. We find that the new FRESCO+wide algorithm leads to 50 hPa lower cloud pressures, correcting a known high bias, and produces 1–4·1015 molec/cm2 higher retrieved NO2 columns, thereby at least partially correcting for the previously reported low bias in the TROPOMI NO2 product. By training an artificial neural network on the 4 available periods with standard and FRESCO+wide test-retrievals, we develop a historic, consistent TROPOMI NO2 data set spanning the years 2019 and 2020. This improved data set shows stronger (35–75 %) and sharper (10–35 %) shipping NO2 signals compared to co-sampled measurements from OMI. We apply our improved data set to investigate the impact of the COVID-19 pandemic on ship NO2 pollution over European seas and find indications that NOx emissions from ships reduced by 20–25 % during the pandemic. The reductions in ship NO2 pollution start in March–April 2020, in line with changes in shipping activity inferred from AIS data.\u0000","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116219221","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}
Drew C. Pendergrass, D. Jacob, S. Zhai, Jhoon Kim, Ja-Ho Koo, Seoyoung Lee, M. Bae, Soontae Kim
Abstract. We use 2011–2019 aerosol optical depth (AOD) observations from the Geostationary Ocean Color Imager (GOCI) instrument over East Asia to infer 24-h daily surface fine particulate matter (PM2.5) concentrations at continuous 6x6 km2 resolution over eastern China, South Korea, and Japan. This is done with a random forest (RF) algorithm applied to the gap-filled GOCI AODs and other data and trained with PM2.5 observations from the three national networks. The predicted 24-h PM2.5 concentrations for sites entirely withheld from training in a ten-fold crossvalidation procedure correlate highly with network observations (R2 = 0.89) with single-value precision of 26–32 % depending on country. Prediction of annual mean values has R2 = 0.96 and single-value precision of 12 %. The RF algorithm is only moderately successful for diagnosing local exceedances of the National Ambient Air Quality Standard (NAAQS) because these exceedances are typically within the single-value precisions of the RF, and also because of RF smoothing of extreme PM2.5 concentrations. The area-weighted and population-weighted trends of RF PM2.5 concentrations for eastern China, South Korea, and Japan show steady 2015–2019 declines consistent with surface networks, but the surface networks in eastern China and South Korea underestimate population exposure. Further examination of RF PM2.5 fields for South Korea identifies hotspots where surface network sites were initially lacking and shows 2015–2019 PM2.5 decreases across the country except for flat concentrations in the Seoul metropolitan area. Inspection of monthly PM2.5 time series in Beijing, Seoul, and Tokyo shows that the RF algorithm successfully captures observed seasonal variations of PM2.5 even though AOD and PM2.5 often have opposite seasonalities. Application of the RF algorithm to urban pollution episodes in Seoul and Beijing demonstrates high skill in reproducing the observed day-to-day variations in air quality as well as spatial patterns on the 6 km scale. Comparison to a CMAQ simulation for the Korean peninsula demonstrates the value of the continuous RF PM2.5 fields for testing air quality models, including over North Korea where they offer a unique resource.
{"title":"Continuous mapping of fine particulate matter (PM2.5) air quality in East Asia at daily 6×6 km2 resolution by application of a random forest algorithm to 2011–2019 GOCI geostationary satellite data","authors":"Drew C. Pendergrass, D. Jacob, S. Zhai, Jhoon Kim, Ja-Ho Koo, Seoyoung Lee, M. Bae, Soontae Kim","doi":"10.5194/amt-2021-273","DOIUrl":"https://doi.org/10.5194/amt-2021-273","url":null,"abstract":"Abstract. We use 2011–2019 aerosol optical depth (AOD) observations from the Geostationary Ocean Color Imager (GOCI) instrument over East Asia to infer 24-h daily surface fine particulate matter (PM2.5) concentrations at continuous 6x6 km2 resolution over eastern China, South Korea, and Japan. This is done with a random forest (RF) algorithm applied to the gap-filled GOCI AODs and other data and trained with PM2.5 observations from the three national networks. The predicted 24-h PM2.5 concentrations for sites entirely withheld from training in a ten-fold crossvalidation procedure correlate highly with network observations (R2 = 0.89) with single-value precision of 26–32 % depending on country. Prediction of annual mean values has R2 = 0.96 and single-value precision of 12 %. The RF algorithm is only moderately successful for diagnosing local exceedances of the National Ambient Air Quality Standard (NAAQS) because these exceedances are typically within the single-value precisions of the RF, and also because of RF smoothing of extreme PM2.5 concentrations. The area-weighted and population-weighted trends of RF PM2.5 concentrations for eastern China, South Korea, and Japan show steady 2015–2019 declines consistent with surface networks, but the surface networks in eastern China and South Korea underestimate population exposure. Further examination of RF PM2.5 fields for South Korea identifies hotspots where surface network sites were initially lacking and shows 2015–2019 PM2.5 decreases across the country except for flat concentrations in the Seoul metropolitan area. Inspection of monthly PM2.5 time series in Beijing, Seoul, and Tokyo shows that the RF algorithm successfully captures observed seasonal variations of PM2.5 even though AOD and PM2.5 often have opposite seasonalities. Application of the RF algorithm to urban pollution episodes in Seoul and Beijing demonstrates high skill in reproducing the observed day-to-day variations in air quality as well as spatial patterns on the 6 km scale. Comparison to a CMAQ simulation for the Korean peninsula demonstrates the value of the continuous RF PM2.5 fields for testing air quality models, including over North Korea where they offer a unique resource.\u0000","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129561595","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. The AirCore is a long coiled tube that acts as a “tape recorder” of the composition of air as it is slowly filled or flushed. When launched by balloon with one end of the tube open and the other closed, the initial fill air flows out during ascent as the outside air pressure drops. During descent atmospheric air flows back in. We describe how we can associate the position of an air parcel in the tube with the altitude it came from by modeling the dynamics of the fill process. The conditions that need to be satisfied for the model to be accurate are derived. The extent of mixing of air parcels that enter at different times is calculated, so that we know how many independent samples are in the tube upon landing, and later when the AirCore is analyzed.
{"title":"Fill dynamics and sample mixing in the AirCore ","authors":"P. Tans","doi":"10.5194/amt-2021-254","DOIUrl":"https://doi.org/10.5194/amt-2021-254","url":null,"abstract":"Abstract. The AirCore is a long coiled tube that acts as a “tape recorder” of the composition of air as it is slowly filled or flushed. When launched by balloon with one end of the tube open and the other closed, the initial fill air flows out during ascent as the outside air pressure drops. During descent atmospheric air flows back in. We describe how we can associate the position of an air parcel in the tube with the altitude it came from by modeling the dynamics of the fill process. The conditions that need to be satisfied for the model to be accurate are derived. The extent of mixing of air parcels that enter at different times is calculated, so that we know how many independent samples are in the tube upon landing, and later when the AirCore is analyzed.\u0000","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130133700","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}
Patrick Weber, A. Petzold, O. Bischof, B. Fischer, Marcel Berg, A. Freedman, T. Onasch, U. Bundke
Abstract. Aerosol intensive optical properties like the Ångström exponents for aerosol light extinction, scattering and absorption, or the single-scattering albedo are indicators for aerosol size distributions, chemical composition and radiative behaviour and contain also source information. The observation of these parameters requires the measurement of aerosol optical properties at multiple wavelengths which usually implies the use of several instruments. Our study aims to quantify the uncertainties of the determination of multiple-wavelengths intensive properties by an optical closure approach, using different test aerosols. In our laboratory study, we measured the full set of aerosol optical properties for a range of light-absorbing aerosols with different properties, mixed externally with ammonium sulphate to generate aerosols of controlled single-scattering albedo. The investigated aerosol types were: fresh combustion soot emitted by an inverted flame soot generator (SOOT, fractal aggregates), Aquadag (AQ, spherical shape), Cabot industrial soot (BC, compact clusters), and an acrylic paint (Magic Black, MB). One focus was on the validity of the Differential Method (DM: absorption = extinction minus scattering) for the determination of Ångström exponents for different particle loads and mixtures of light-absorbing aerosol with ammonium sulphate, in comparison to data obtained from single instruments. The instruments used in this study were two CAPS PMssa (Cavity Attenuated Phase Shift Single Scattering Albedo, λ = 450, 630 nm) for light extinction and scattering coefficients, one Integrating Nephelometer (λ = 450, 550, 700 nm) for light scattering coefficient and one Tricolour Absorption Photometer (TAP, λ = 467, 528, 652 nm) for filter-based light absorption coefficient measurement. Our key finding is that the coefficients of light absorption σap, scattering σsp and extinction σep from the Differential Method agree with data from single reference instruments, and the slopes of regression lines equal unity within the precision error. We found, however, that the precision error for the DM suppresses 100 % for σap values lower than 10–20 Mm−1 for atmospheric relevant single scattering albedo. This increasing uncertainty with decreasing σap yields an absorption Ångström exponent (AAE) that is too uncertain for measurements in the range of atmospheric aerosol loadings. We recommend using DM only for measuring AAE values for σap > 50 Mm−1. Ångström exponents for scattering and extinction are reliable for extinction coefficients from 20 up to 1000 Mm−1 and stay within 10 % deviation from reference instruments, regardless of the chosen method. Single-scattering albedo (SSA) values for 450 nm and 630 nm wavelengths agree with values from the reference method σsp (NEPH)/σep (CAPS PMSSA) with less than 10 % uncertainty for all instrument combinations and sampled aerosol types which fulfil the proposed goal for measurement uncertainty of 10 % proposed
{"title":"Relative errors of derived multi-wavelengths intensive aerosol optical properties using CAPS_SSA, Nephelometer and TAP measurements","authors":"Patrick Weber, A. Petzold, O. Bischof, B. Fischer, Marcel Berg, A. Freedman, T. Onasch, U. Bundke","doi":"10.5194/amt-2021-284","DOIUrl":"https://doi.org/10.5194/amt-2021-284","url":null,"abstract":"Abstract. Aerosol intensive optical properties like the Ångström exponents for aerosol light extinction, scattering and absorption, or the single-scattering albedo are indicators for aerosol size distributions, chemical composition and radiative behaviour and contain also source information. The observation of these parameters requires the measurement of aerosol optical properties at multiple wavelengths which usually implies the use of several instruments. Our study aims to quantify the uncertainties of the determination of multiple-wavelengths intensive properties by an optical closure approach, using different test aerosols. In our laboratory study, we measured the full set of aerosol optical properties for a range of light-absorbing aerosols with different properties, mixed externally with ammonium sulphate to generate aerosols of controlled single-scattering albedo. The investigated aerosol types were: fresh combustion soot emitted by an inverted flame soot generator (SOOT, fractal aggregates), Aquadag (AQ, spherical shape), Cabot industrial soot (BC, compact clusters), and an acrylic paint (Magic Black, MB). One focus was on the validity of the Differential Method (DM: absorption = extinction minus scattering) for the determination of Ångström exponents for different particle loads and mixtures of light-absorbing aerosol with ammonium sulphate, in comparison to data obtained from single instruments. The instruments used in this study were two CAPS PMssa (Cavity Attenuated Phase Shift Single Scattering Albedo, λ = 450, 630 nm) for light extinction and scattering coefficients, one Integrating Nephelometer (λ = 450, 550, 700 nm) for light scattering coefficient and one Tricolour Absorption Photometer (TAP, λ = 467, 528, 652 nm) for filter-based light absorption coefficient measurement. Our key finding is that the coefficients of light absorption σap, scattering σsp and extinction σep from the Differential Method agree with data from single reference instruments, and the slopes of regression lines equal unity within the precision error. We found, however, that the precision error for the DM suppresses 100 % for σap values lower than 10–20 Mm−1 for atmospheric relevant single scattering albedo. This increasing uncertainty with decreasing σap yields an absorption Ångström exponent (AAE) that is too uncertain for measurements in the range of atmospheric aerosol loadings. We recommend using DM only for measuring AAE values for σap > 50 Mm−1. Ångström exponents for scattering and extinction are reliable for extinction coefficients from 20 up to 1000 Mm−1 and stay within 10 % deviation from reference instruments, regardless of the chosen method. Single-scattering albedo (SSA) values for 450 nm and 630 nm wavelengths agree with values from the reference method σsp (NEPH)/σep (CAPS PMSSA) with less than 10 % uncertainty for all instrument combinations and sampled aerosol types which fulfil the proposed goal for measurement uncertainty of 10 % proposed ","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"113 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131376609","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}
E. Sánchez-García, Javier Gorroño, I. Irakulis-Loitxate, D. Varon, L. Guanter
Abstract. The detection of methane emissions from industrial activities has been identified as an effective climate change mitigation strategy. These industrial emissions, such as from oil and gas (O&G) extraction and coal mining, typically occur as large plumes of highly concentrated gas. Different satellite missions have recently shown potential to map such methane plumes from space. In this work, we report on the great potential of the WorldView-3 (WV-3) satellite mission for methane mapping. This relies on its unique very high spatial resolution (up to 3.7 m) data in the shortwave infrared part of the spectrum, which is complemented by a good spectral sampling of the methane absorption feature at 2300 nm and a high signal to noise ratio. The proposed retrieval methodology is based on the calculation of methane concentration enhancements from pixel-wise estimates of methane transmittance at WV-3 SWIR band 7 (2235–2285 nm), which is positioned at a highly-sensitive methane absorption region. A sensitivity analysis based on end-to-end simulations has helped to understand retrieval errors and detection limits. The results have shown the good performance of WV-3 for methane mapping, especially over bright and homogeneous areas. The potential of WV-3 for methane mapping has been further tested with real data, which has led to the detection of 26 independent point emissions over different methane hotspot regions such as the O&G extraction fields in Algeria and Turkmenistan, and the Shanxi coal mining region in China. In particular, the detection of very small leaks (< 100 kg/h) from oil pipelines in Turkmenistan shows the game-changing potential of WV-3 to map industrial methane emissions from space.
{"title":"Mapping methane plumes at very high spatial resolution with the WorldView-3 satellite","authors":"E. Sánchez-García, Javier Gorroño, I. Irakulis-Loitxate, D. Varon, L. Guanter","doi":"10.5194/amt-2021-238","DOIUrl":"https://doi.org/10.5194/amt-2021-238","url":null,"abstract":"Abstract. The detection of methane emissions from industrial activities has been identified as an effective climate change mitigation strategy. These industrial emissions, such as from oil and gas (O&G) extraction and coal mining, typically occur as large plumes of highly concentrated gas. Different satellite missions have recently shown potential to map such methane plumes from space. In this work, we report on the great potential of the WorldView-3 (WV-3) satellite mission for methane mapping. This relies on its unique very high spatial resolution (up to 3.7 m) data in the shortwave infrared part of the spectrum, which is complemented by a good spectral sampling of the methane absorption feature at 2300 nm and a high signal to noise ratio. The proposed retrieval methodology is based on the calculation of methane concentration enhancements from pixel-wise estimates of methane transmittance at WV-3 SWIR band 7 (2235–2285 nm), which is positioned at a highly-sensitive methane absorption region. A sensitivity analysis based on end-to-end simulations has helped to understand retrieval errors and detection limits. The results have shown the good performance of WV-3 for methane mapping, especially over bright and homogeneous areas. The potential of WV-3 for methane mapping has been further tested with real data, which has led to the detection of 26 independent point emissions over different methane hotspot regions such as the O&G extraction fields in Algeria and Turkmenistan, and the Shanxi coal mining region in China. In particular, the detection of very small leaks (< 100 kg/h) from oil pipelines in Turkmenistan shows the game-changing potential of WV-3 to map industrial methane emissions from space.\u0000","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134420662","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}
D. Cholleton, E. Bialic, A. Dumas, P. Kaluzny, P. Rairoux, A. Miffre
Abstract. Pollens are nowadays recognized as one of the main atmospheric particles affecting public human health as well as the Earth's climate. In this context, an important issue concerns our ability to detect and differentiate among the existing pollen taxa. In this paper, the potential differences that may exist in light scattering by four of the most common pollen taxa, namely ragweed, birch, pine and ash, are analysed in the framework of the scattering matrix formalism at two wavelengths simultaneously (532 and 1064 nm). Interestingly, our laboratory experimental error bars are precise enough to show that these four pollens, when embedded in ambient air, exhibit different spectral and polarimetric light scattering characteristics, in the form of ten scattering matrix elements (five per wavelength), which allow identifying each separately. To end with, a simpler light scattering criterion is proposed for classifying among the four considered pollens by performing a principal component (PC) analysis, that still accounts for more than 99 % of the observed variance. We thus believe this work may open new insights for future atmospheric pollen detection.
{"title":"Laboratory evaluation of the scattering matrix of ragweed, ash, birch and pine pollens towards pollen classification","authors":"D. Cholleton, E. Bialic, A. Dumas, P. Kaluzny, P. Rairoux, A. Miffre","doi":"10.5194/amt-2021-272","DOIUrl":"https://doi.org/10.5194/amt-2021-272","url":null,"abstract":"Abstract. Pollens are nowadays recognized as one of the main atmospheric particles affecting public human health as well as the Earth's climate. In this context, an important issue concerns our ability to detect and differentiate among the existing pollen taxa. In this paper, the potential differences that may exist in light scattering by four of the most common pollen taxa, namely ragweed, birch, pine and ash, are analysed in the framework of the scattering matrix formalism at two wavelengths simultaneously (532 and 1064 nm). Interestingly, our laboratory experimental error bars are precise enough to show that these four pollens, when embedded in ambient air, exhibit different spectral and polarimetric light scattering characteristics, in the form of ten scattering matrix elements (five per wavelength), which allow identifying each separately. To end with, a simpler light scattering criterion is proposed for classifying among the four considered pollens by performing a principal component (PC) analysis, that still accounts for more than 99 % of the observed variance. We thus believe this work may open new insights for future atmospheric pollen detection.\u0000","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"218 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131455929","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. Beck, S. Schobesberger, V. Kerminen, M. Kulmala
Abstract. Sulfuric acid (H2SO4, SA) is the key compound in atmospheric new particle formation. Therefore, it is crucial to observe its concentration with sensitive instrumentation, such as chemical ionisation inlets coupled to Atmospheric Pressure interface Time-of-Flight mass spectrometers (CI-APi-TOF). However, there are environmental conditions and physical reasons when chemical ionisation cannot be used, for example in certain remote places or flight measurements with limitations regarding chemicals. In these cases, it is important to estimate the SA concentration based on ambient ion composition and concentration measurements that are achieved by APi-TOF alone. Here we derive a theoretical expression to estimate SA concentration and validate it with accurate CI-APi-TOF observations. The developed estimate works very well during daytime and with SA concentrations above 2⋅106 cm-3.
{"title":"Estimation of sulfuric acid concentrations using ambient ion composition and concentration data obtained by ion mass spectrometry measurements (APi-TOF)","authors":"L. Beck, S. Schobesberger, V. Kerminen, M. Kulmala","doi":"10.5194/amt-2021-259","DOIUrl":"https://doi.org/10.5194/amt-2021-259","url":null,"abstract":"Abstract. Sulfuric acid (H2SO4, SA) is the key compound in atmospheric new particle formation. Therefore, it is crucial to observe its concentration with sensitive instrumentation, such as chemical ionisation inlets coupled to Atmospheric Pressure interface Time-of-Flight mass spectrometers (CI-APi-TOF). However, there are environmental conditions and physical reasons when chemical ionisation cannot be used, for example in certain remote places or flight measurements with limitations regarding chemicals. In these cases, it is important to estimate the SA concentration based on ambient ion composition and concentration measurements that are achieved by APi-TOF alone. Here we derive a theoretical expression to estimate SA concentration and validate it with accurate CI-APi-TOF observations. The developed estimate works very well during daytime and with SA concentrations above 2⋅106 cm-3.\u0000","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123524668","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}
F. Mei, S. Spielman, S. Hering, Jian Wang, M. Pekour, Gregory S. Lewis, B. Schmid, J. Tomlinson, Maynard Havlicek
Abstract. Capturing the vertical profiles and horizontal variations of atmospheric aerosols often requires accurate airborne measurements. With the advantage of avoiding health and safety concerns related to the use of butanol or other chemicals, a water-based condensation particle counter (wCPC) has emerged to provide measurements under various environments. However, the airborne deployment of wCPC is relatively rare due to the lack of characterization of wCPC performance. This study investigates the performance of a commercial "versatile" water CPC (vWCPC Model 3789, TSI) under low-pressure conditions. The effect of conditioner temperature on wCPC performance at low pressure is examined through numerical simulation and laboratory experiments. We show that the default instrument temperature setting of 30 °C for the conditioner is not suitable for airborne measurement and that the optimal conditioner temperature for low-pressure operation is 27 °C. Additionally, we show that insufficient droplet growth becomes more significant under the low-pressure operation. The variation in the chemical composition can contribute up to 20 % uncertainty in the counting efficiency of the wCPC, but this variation is independent of pressure.
摘要捕捉大气气溶胶的垂直剖面和水平变化通常需要精确的机载测量。水基冷凝粒子计数器(wCPC)的优点是避免了与使用丁醇或其他化学品有关的健康和安全问题，可以在各种环境下进行测量。然而，由于缺乏对wCPC性能的表征，wCPC的空降部署相对较少。本研究考察了商用“多功能”水CPC (vWCPC Model 3789, TSI)在低压条件下的性能。通过数值模拟和室内实验研究了调理剂温度对低压下wCPC性能的影响。我们表明，空调的默认仪表温度设置为30°C不适合机载测量，低压运行的最佳空调温度为27°C。此外，我们还表明，在低压操作下，液滴生长不足变得更加明显。化学成分的变化可以对wCPC的计数效率造成高达20%的不确定性，但这种变化与压力无关。
{"title":"Simulation-aided characterization of a versatile water condensation particle counter for atmospheric airborne research","authors":"F. Mei, S. Spielman, S. Hering, Jian Wang, M. Pekour, Gregory S. Lewis, B. Schmid, J. Tomlinson, Maynard Havlicek","doi":"10.5194/amt-2021-266","DOIUrl":"https://doi.org/10.5194/amt-2021-266","url":null,"abstract":"Abstract. Capturing the vertical profiles and horizontal variations of atmospheric aerosols often requires accurate airborne measurements. With the advantage of avoiding health and safety concerns related to the use of butanol or other chemicals, a water-based condensation particle counter (wCPC) has emerged to provide measurements under various environments. However, the airborne deployment of wCPC is relatively rare due to the lack of characterization of wCPC performance. This study investigates the performance of a commercial \"versatile\" water CPC (vWCPC Model 3789, TSI) under low-pressure conditions. The effect of conditioner temperature on wCPC performance at low pressure is examined through numerical simulation and laboratory experiments. We show that the default instrument temperature setting of 30 °C for the conditioner is not suitable for airborne measurement and that the optimal conditioner temperature for low-pressure operation is 27 °C. Additionally, we show that insufficient droplet growth becomes more significant under the low-pressure operation. The variation in the chemical composition can contribute up to 20 % uncertainty in the counting efficiency of the wCPC, but this variation is independent of pressure.\u0000","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128322481","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}
C. Alberti, Q. Tu, F. Hase, M. Makarova, K. Gribanov, S. Foka, V. Zakharov, T. Blumenstock, M. Buchwitz, C. Diekmann, B. Ertl, Matthias M. Frey, H. Imhasin, D. Ionov, F. Khosrawi, S. Osipov, M. Reuter, M. Schneider, T. Warneke
Abstract. This work employs ground- and space-based observations, together with model data to study columnar abundances of atmospheric trace gases (XH2O, XCO2, XCH4, and XCO) in two high-latitude Russian cities, St. Petersburg and Yekaterinburg. Two portable COllaborative Column Carbon Observing Network (COCCON) spectrometers were used for continuous measurements at these locations during 2019 and 2020. Additionally, a subset of data of special interest (a strong gradient in XCH4 and XCO was detected) collected in the framework of a mobile city campaign performed in 2019 using both instruments is investigated. All studied satellite products (TROPOMI, OCO-2, GOSAT, MUSICA IASI) show generally good agreement with COCCON observations. Satellite and ground-based observations at high latitude are much sparser than at low or mid latitude, which makes direct coincident comparisons between remote-sensing observations more difficult. Therefore, a method of scaling continuous CAMS model data to the ground-based observations is developed and used for creating virtual COCCON observations. These adjusted CAMS data are then used for satellite validation, showing good agreement in both Peterhof and Yekaterinburg cities. The gradients between the two study sites (ΔXgas) are similar between CAMS and CAMS-COCCON data sets, indicating that the model gradients are in agreement with the gradients observed by COCCON. This is further supported by a few simultaneous COCCON and satellite ΔXgas measurements, which also agree with the model gradient. With respect to the city campaign observations recorded in St. Petersburg, the downwind COCCON station measured obvious enhancements for both XCH4 (10.6 ppb) and XCO (9.5 ppb), which is nicely reflected by TROPOMI observations, which detect city-scale gradients of the order 9.4 ppb for XCH4 and 12.5 ppb XCO, respectively.
{"title":"Investigation of space-borne trace gas products over St. Petersburg and Yekaterinburg, Russia by using COCCON observations","authors":"C. Alberti, Q. Tu, F. Hase, M. Makarova, K. Gribanov, S. Foka, V. Zakharov, T. Blumenstock, M. Buchwitz, C. Diekmann, B. Ertl, Matthias M. Frey, H. Imhasin, D. Ionov, F. Khosrawi, S. Osipov, M. Reuter, M. Schneider, T. Warneke","doi":"10.5194/amt-2021-237","DOIUrl":"https://doi.org/10.5194/amt-2021-237","url":null,"abstract":"Abstract. This work employs ground- and space-based observations, together with model data to study columnar abundances of atmospheric trace gases (XH2O, XCO2, XCH4, and XCO) in two high-latitude Russian cities, St. Petersburg and Yekaterinburg. Two portable COllaborative Column Carbon Observing Network (COCCON) spectrometers were used for continuous measurements at these locations during 2019 and 2020. Additionally, a subset of data of special interest (a strong gradient in XCH4 and XCO was detected) collected in the framework of a mobile city campaign performed in 2019 using both instruments is investigated. All studied satellite products (TROPOMI, OCO-2, GOSAT, MUSICA IASI) show generally good agreement with COCCON observations. Satellite and ground-based observations at high latitude are much sparser than at low or mid latitude, which makes direct coincident comparisons between remote-sensing observations more difficult. Therefore, a method of scaling continuous CAMS model data to the ground-based observations is developed and used for creating virtual COCCON observations. These adjusted CAMS data are then used for satellite validation, showing good agreement in both Peterhof and Yekaterinburg cities. The gradients between the two study sites (ΔXgas) are similar between CAMS and CAMS-COCCON data sets, indicating that the model gradients are in agreement with the gradients observed by COCCON. This is further supported by a few simultaneous COCCON and satellite ΔXgas measurements, which also agree with the model gradient. With respect to the city campaign observations recorded in St. Petersburg, the downwind COCCON station measured obvious enhancements for both XCH4 (10.6 ppb) and XCO (9.5 ppb), which is nicely reflected by TROPOMI observations, which detect city-scale gradients of the order 9.4 ppb for XCH4 and 12.5 ppb XCO, respectively.\u0000","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124450764","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. With the accumulation of data about biogenic volatile organic compounds (BVOCs) emissions from plants based on branch-scale enclosure measurements worldwide, it is vital to assure that measurements are conducted using well-characterized dynamic chambers with good transfer efficiencies and less disturbance on natural growing microenvironments. In this study, a self-made cylindrical semi-open dynamic chamber with Teflon-coated inner surface was characterized both in the lab with standard BVOC mixtures and in the field with typical broad-leaf and coniferous trees. The lab simulation with a constant flow of standard mixtures and online monitoring of BVOCs by proton transfer-time of flight-mass spectrometry (PTR-ToF-MS) revealed that lower real-time mixing ratios and shorter equilibrium times than theoretically predicted due to wall loss in the chamber, and larger flow rates (shorter residence times) can reduce the absorptive loss and improve the transfer efficiencies. However, even flow rates were raised to secure residence times less than 1 min, transfer efficiencies were still below 70 % for heavier BVOCs like α-pinene and β-caryophyllene. Relative humidity (RH) impacted the adsorptive loss of BVOCs less significantly when compared to flow rates, with compound specific patterns related to the influence of RH on their adsorption behavior. When the chamber was applied in the field to a branch of a mangifera indica tree, the enclosure-ambient temperature differences decreased from 4.5 ± 0.3 to 1.0 ± 0.2 °C and the RH differences decreased from 9.8 ± 0.5 % to 1.2 ± 0.1 % as flow rates increased from 3 L min−1 (residence time ~4.5 min) to 15 L min−1 (residence time ~0.9 min). At a medium flow rate of 9 L min−1 (residence time ~1.5 min), field tests with the dynamic chamber for Mangifera indica and Pinus massoniana branches revealed enclosure temperature increase within +2 °C and CO2 depletion within −50 ppm when compared to their ambient counterparts. The results suggested that substantially higher air circulating rates would benefit reducing equilibrium time, adsorptive loss and the ambient-enclosure temperature/RH differences. However, even under higher air circulating rates and with inert Teflon-coated inner surfaces, the transfer efficiencies for monoterpene and sesquiterpene species are not so satisfactory, implying that emission factors for these species might be underestimated if they are obtained by dynamic chambers without certified transfer efficiencies, and that further efforts are needed for field measurements to improve accuracies and narrow the uncertainties of the emission factors.
摘要随着全球范围内基于树枝尺度圈闭测量的植物生物源性挥发性有机化合物(BVOCs)排放数据的积累，确保测量使用具有良好传递效率和对自然生长微环境干扰较小的表征良好的动态室至关重要。本研究采用自制的内表面涂覆聚四氟乙烯的圆柱形半开式动态室，在标准BVOC混合物的实验室和典型阔叶树和针叶树的野外进行了表征。在恒定流动的标准混合物和质子转移时间飞行质谱(PTR-ToF-MS)在线监测BVOCs的实验室模拟中发现，由于腔室壁损失的影响，较低的实时混合比和较短的平衡时间比理论预测的要短，而较大的流量(较短的停留时间)可以减少吸收损失并提高转移效率。然而，即使提高流速使停留时间小于1 min，对于α-蒎烯和β-石竹烯等较重的BVOCs，转移效率仍低于70%。相对湿度(RH)对BVOCs吸附损失的影响不如流量显著，相对湿度对BVOCs吸附行为的影响具有复合特定模式。当将该实验箱应用于芒果树的一个分支上时，当流量从3 L min - 1(停留时间~4.5 min)增加到15 L min - 1(停留时间~0.9 min)时，箱体与环境的温差从4.5±0.3°C减小到1.0±0.2°C，相对湿度从9.8±0.5%减小到1.2±0.1%。在9 L min - 1的介质流速下(停留时间~1.5 min)，对Mangifera indica和Pinus massoniana枝条进行的动态室现场试验表明，与环境相比，封闭温度升高在+2°C以内，二氧化碳消耗在- 50 ppm以内。结果表明，大幅度提高空气循环速率有利于减少平衡时间、吸附损失和环境-封闭温度/RH差异。然而，即使在较高的空气循环率和惰性聚四氟乙烯包覆的内表面下，单萜和倍半萜的转移效率也不太令人满意，这意味着如果在没有经过认证的转移效率的情况下通过动态室获得这些物种的发射因子可能会被低估，并且需要进一步努力进行现场测量以提高精度并缩小发射因子的不确定性。
{"title":"Design and characterization of a semi-open dynamic chamber for measuring biogenic volatile organic compounds (BVOCs) emissions from plants","authors":"Jianqiang Zeng, Yanli Zhang, Huina Zhang, Wei Song, Zhenfeng Wu, Xinming Wang","doi":"10.5194/amt-2021-265","DOIUrl":"https://doi.org/10.5194/amt-2021-265","url":null,"abstract":"Abstract. With the accumulation of data about biogenic volatile organic compounds (BVOCs) emissions from plants based on branch-scale enclosure measurements worldwide, it is vital to assure that measurements are conducted using well-characterized dynamic chambers with good transfer efficiencies and less disturbance on natural growing microenvironments. In this study, a self-made cylindrical semi-open dynamic chamber with Teflon-coated inner surface was characterized both in the lab with standard BVOC mixtures and in the field with typical broad-leaf and coniferous trees. The lab simulation with a constant flow of standard mixtures and online monitoring of BVOCs by proton transfer-time of flight-mass spectrometry (PTR-ToF-MS) revealed that lower real-time mixing ratios and shorter equilibrium times than theoretically predicted due to wall loss in the chamber, and larger flow rates (shorter residence times) can reduce the absorptive loss and improve the transfer efficiencies. However, even flow rates were raised to secure residence times less than 1 min, transfer efficiencies were still below 70 % for heavier BVOCs like α-pinene and β-caryophyllene. Relative humidity (RH) impacted the adsorptive loss of BVOCs less significantly when compared to flow rates, with compound specific patterns related to the influence of RH on their adsorption behavior. When the chamber was applied in the field to a branch of a mangifera indica tree, the enclosure-ambient temperature differences decreased from 4.5 ± 0.3 to 1.0 ± 0.2 °C and the RH differences decreased from 9.8 ± 0.5 % to 1.2 ± 0.1 % as flow rates increased from 3 L min−1 (residence time ~4.5 min) to 15 L min−1 (residence time ~0.9 min). At a medium flow rate of 9 L min−1 (residence time ~1.5 min), field tests with the dynamic chamber for Mangifera indica and Pinus massoniana branches revealed enclosure temperature increase within +2 °C and CO2 depletion within −50 ppm when compared to their ambient counterparts. The results suggested that substantially higher air circulating rates would benefit reducing equilibrium time, adsorptive loss and the ambient-enclosure temperature/RH differences. However, even under higher air circulating rates and with inert Teflon-coated inner surfaces, the transfer efficiencies for monoterpene and sesquiterpene species are not so satisfactory, implying that emission factors for these species might be underestimated if they are obtained by dynamic chambers without certified transfer efficiencies, and that further efforts are needed for field measurements to improve accuracies and narrow the uncertainties of the emission factors.\u0000","PeriodicalId":441110,"journal":{"name":"Atmospheric Measurement Techniques Discussions","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126601249","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}
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：