Abstract. A ground-based 110 GHz radiometer was designed to measure the stratospheric ozone vertical profile by observing the 110.836 GHz ozone emission spectrum and the instrument has been operational at Sookmyung Women’s University (37.54° N, 126.97° E) in Seoul, Korea. In this paper, we detail the instrumental design, calibration procedures, correction methods, and the retrieved ozone vertical profile. The instrument is a heterodyne total power radiometer. It down-converts the observed 110.836 GHz ozone frequency to 0.609 GHz, with a frequency resolution of 61 kHz and a bandwidth of 800 MHz. The spectral intensity is digitized using a fast Fourier transform spectrometer. For hot-cold calibration, we use microwave absorbers at room temperature and liquid nitrogen as calibration targets. Tropospheric opacity is corrected using the continuous tipping curve calibration. The measured opacities were compared with simulated values from the Korea Local Analysis and Prediction System (KLAPS) data. Additionally, since 2016, the stratospheric ozone profiles over Seoul have been demonstrated for the vertical range of 100 hPa – 0.3 hPa (16 km–70 km) with validation performed by comparing them to the ozone profiles from the MLS on AURA satellite.
{"title":"SORAS, A ground-based 110 GHz microwave radiometer for measuring the stratospheric ozone vertical profile in Seoul","authors":"Soohyun Ka, Jung Jin Oh","doi":"10.5194/amt-2024-108","DOIUrl":"https://doi.org/10.5194/amt-2024-108","url":null,"abstract":"<strong>Abstract.</strong> A ground-based 110 GHz radiometer was designed to measure the stratospheric ozone vertical profile by observing the 110.836 GHz ozone emission spectrum and the instrument has been operational at Sookmyung Women’s University (37.54° N, 126.97° E) in Seoul, Korea. In this paper, we detail the instrumental design, calibration procedures, correction methods, and the retrieved ozone vertical profile. The instrument is a heterodyne total power radiometer. It down-converts the observed 110.836 GHz ozone frequency to 0.609 GHz, with a frequency resolution of 61 kHz and a bandwidth of 800 MHz. The spectral intensity is digitized using a fast Fourier transform spectrometer. For hot-cold calibration, we use microwave absorbers at room temperature and liquid nitrogen as calibration targets. Tropospheric opacity is corrected using the continuous tipping curve calibration. The measured opacities were compared with simulated values from the Korea Local Analysis and Prediction System (KLAPS) data. Additionally, since 2016, the stratospheric ozone profiles over Seoul have been demonstrated for the vertical range of 100 hPa – 0.3 hPa (16 km–70 km) with validation performed by comparing them to the ozone profiles from the MLS on AURA satellite.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"7 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198353","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 : 2024-09-03DOI: 10.5194/amt-17-5029-2024
Monica Campanelli, Victor Estellés, Gaurav Kumar, Teruyuki Nakajima, Masahiro Momoi, Julian Gröbner, Stelios Kazadzis, Natalia Kouremeti, Angelos Karanikolas, Africa Barreto, Saulius Nevas, Kerstin Schwind, Philipp Schneider, Iiro Harju, Petri Kärhä, Henri Diémoz, Rei Kudo, Akihiro Uchiyama, Akihiro Yamazaki, Anna Maria Iannarelli, Gabriele Mevi, Annalisa Di Bernardino, Stefano Casadio
Abstract. To retrieve columnar intensive aerosol properties from sun–sky photometers, both irradiance and radiance calibration factors are needed. For the irradiance the solar calibration constant, V0, which denotes the instrument counts for a direct normal solar flux extrapolated to the top of the atmosphere, must be determined. The solid view angle, SVA, is a measure of the field of view of the instrument, and it is important for obtaining the radiance from sky diffuse irradiance measurements. Each of the three sun-photometer networks considered in the present study (SKYNET, AERONET, WMO GAW) adopts different protocols of calibration, and we evaluate the performance of the on-site calibration procedures, applicable to every kind of sun–sky photometer but tested in this analysis only on SKYNET Prede POM01 instruments, during intercomparison campaigns and laboratory calibrations held in the framework of the Metrology for Aerosol Optical Properties (MAPP) European Metrology Programme for Innovation and Research (EMPIR) project. The on-site calibration, performed as frequently as possible (ideally monthly) to monitor changes in the device conditions, allows operators to track and evaluate the calibration status on a continuous basis, considerably reducing the data gaps incurred by the periodic shipments for performing centralized calibrations. The performance of the on-site calibration procedures for V0 was very good at sites with low turbidity, showing agreement with a reference calibration between 0.5 % and 1.5 % depending on wavelengths. In the urban area, the agreement decreases between 1.7 % and 2.5 %. For the SVA the difference varied from a minimum of 0.03 % to a maximum of 3.46 %.
{"title":"Evaluation of on-site calibration procedures for SKYNET Prede POM sun–sky photometers","authors":"Monica Campanelli, Victor Estellés, Gaurav Kumar, Teruyuki Nakajima, Masahiro Momoi, Julian Gröbner, Stelios Kazadzis, Natalia Kouremeti, Angelos Karanikolas, Africa Barreto, Saulius Nevas, Kerstin Schwind, Philipp Schneider, Iiro Harju, Petri Kärhä, Henri Diémoz, Rei Kudo, Akihiro Uchiyama, Akihiro Yamazaki, Anna Maria Iannarelli, Gabriele Mevi, Annalisa Di Bernardino, Stefano Casadio","doi":"10.5194/amt-17-5029-2024","DOIUrl":"https://doi.org/10.5194/amt-17-5029-2024","url":null,"abstract":"Abstract. To retrieve columnar intensive aerosol properties from sun–sky photometers, both irradiance and radiance calibration factors are needed. For the irradiance the solar calibration constant, V0, which denotes the instrument counts for a direct normal solar flux extrapolated to the top of the atmosphere, must be determined. The solid view angle, SVA, is a measure of the field of view of the instrument, and it is important for obtaining the radiance from sky diffuse irradiance measurements. Each of the three sun-photometer networks considered in the present study (SKYNET, AERONET, WMO GAW) adopts different protocols of calibration, and we evaluate the performance of the on-site calibration procedures, applicable to every kind of sun–sky photometer but tested in this analysis only on SKYNET Prede POM01 instruments, during intercomparison campaigns and laboratory calibrations held in the framework of the Metrology for Aerosol Optical Properties (MAPP) European Metrology Programme for Innovation and Research (EMPIR) project. The on-site calibration, performed as frequently as possible (ideally monthly) to monitor changes in the device conditions, allows operators to track and evaluate the calibration status on a continuous basis, considerably reducing the data gaps incurred by the periodic shipments for performing centralized calibrations. The performance of the on-site calibration procedures for V0 was very good at sites with low turbidity, showing agreement with a reference calibration between 0.5 % and 1.5 % depending on wavelengths. In the urban area, the agreement decreases between 1.7 % and 2.5 %. For the SVA the difference varied from a minimum of 0.03 % to a maximum of 3.46 %.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"74 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198344","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 : 2024-09-03DOI: 10.5194/amt-17-5071-2024
Philippe Ricaud, Pierre Durand, Paolo Grigioni, Massimo Del Guasta, Giuseppe Camporeale, Axel Roy, Jean-Luc Attié, John Bognar
Abstract. Clouds in Antarctica are key elements that affect radiative forcing and thus Antarctic climate evolution. Although the vast majority of clouds are composed of ice crystals, a non-negligible fraction constitutes supercooled liquid water (SLW; water held in liquid form below 0 °C). Numerical weather prediction models have great difficulty in forecasting SLW clouds over Antarctica, favouring ice at the expense of liquid water and therefore incorrectly estimating the cloud radiative forcing. Remote-sensing observations of SLW clouds have been carried out for several years at Concordia Station (75° S, 123° E; 3233 m above mean sea level), combining active lidar measurements (SLW cloud detection) and passive HAMSTRAD microwave measurements (liquid water path, LWP). The present project aimed at in situ observations of SLW clouds using sondes developed by the company Anasphere, specifically designed for SLW content (SLWC) measurements. These SLWC sondes were coupled to standard meteorological pressure–temperature–humidity sondes from Vaisala and released under meteorological balloons. During the 2021–2022 summer campaign, 15 launches were made, of which 7 were scientifically exploitable above a height of 400 m above ground level, a threshold height imposed by the time the SLWC sonde takes to stabilize after launch. The three main outcomes from our analyses are as follows: (a) the first in situ observations so far of SLW clouds in Antarctica with SLWC sondes; (b) on average, the consistency of SLW cloud heights as observed by in situ sondes and remote-sensing lidar; and (c) the liquid water path (vertically integrated SLWC) deduced by the sondes being generally equal to or greater than the LWP remotely sensed by HAMSTRAD. In general, the SLW clouds were observed in a layer close to saturation (U > 80 %) or saturated (U ∼ 100 %–105 %) just below or at the lowermost part of the entrainment zone, or capping inversion zone, which exists at the top of the planetary boundary layer and is characterized by an inflection point in the potential temperature vertical profile. Our results are consistent with the theoretical view that SLW clouds form and remain at the top of the planetary boundary layer.
{"title":"In situ observations of supercooled liquid water clouds over Dome C, Antarctica, by balloon-borne sondes","authors":"Philippe Ricaud, Pierre Durand, Paolo Grigioni, Massimo Del Guasta, Giuseppe Camporeale, Axel Roy, Jean-Luc Attié, John Bognar","doi":"10.5194/amt-17-5071-2024","DOIUrl":"https://doi.org/10.5194/amt-17-5071-2024","url":null,"abstract":"Abstract. Clouds in Antarctica are key elements that affect radiative forcing and thus Antarctic climate evolution. Although the vast majority of clouds are composed of ice crystals, a non-negligible fraction constitutes supercooled liquid water (SLW; water held in liquid form below 0 °C). Numerical weather prediction models have great difficulty in forecasting SLW clouds over Antarctica, favouring ice at the expense of liquid water and therefore incorrectly estimating the cloud radiative forcing. Remote-sensing observations of SLW clouds have been carried out for several years at Concordia Station (75° S, 123° E; 3233 m above mean sea level), combining active lidar measurements (SLW cloud detection) and passive HAMSTRAD microwave measurements (liquid water path, LWP). The present project aimed at in situ observations of SLW clouds using sondes developed by the company Anasphere, specifically designed for SLW content (SLWC) measurements. These SLWC sondes were coupled to standard meteorological pressure–temperature–humidity sondes from Vaisala and released under meteorological balloons. During the 2021–2022 summer campaign, 15 launches were made, of which 7 were scientifically exploitable above a height of 400 m above ground level, a threshold height imposed by the time the SLWC sonde takes to stabilize after launch. The three main outcomes from our analyses are as follows: (a) the first in situ observations so far of SLW clouds in Antarctica with SLWC sondes; (b) on average, the consistency of SLW cloud heights as observed by in situ sondes and remote-sensing lidar; and (c) the liquid water path (vertically integrated SLWC) deduced by the sondes being generally equal to or greater than the LWP remotely sensed by HAMSTRAD. In general, the SLW clouds were observed in a layer close to saturation (U > 80 %) or saturated (U ∼ 100 %–105 %) just below or at the lowermost part of the entrainment zone, or capping inversion zone, which exists at the top of the planetary boundary layer and is characterized by an inflection point in the potential temperature vertical profile. Our results are consistent with the theoretical view that SLW clouds form and remain at the top of the planetary boundary layer.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"171 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198345","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 : 2024-09-03DOI: 10.5194/amt-17-5015-2024
Witali Krochin, Axel Murk, Gunter Stober
Abstract. In recent decades, theoretical studies and numerical models of thermal tides have gained attention. It has been recognized that tides have a significant influence on the dynamics of the middle and upper atmosphere; as they grow in amplitude and propagate upward, they transport energy and momentum from the lower to the upper atmosphere, contributing to the vertical coupling between atmospheric layers. The superposition of tides with other atmospheric waves leads to non-linear wave–wave interactions. However, direct measurements of thermal tides in the middle atmosphere are challenging and are often limited to satellite measurements in the tropics and at low latitudes. Due to orbit geometry, such observations provide only a reduced insight into the short-term variability in atmospheric tides. In this paper, we present tidal analysis from 5 years of continuous observations of middle-atmospheric temperatures. The measurements were performed with the ground-based temperature radiometer TEMPERA (TEMPErature RAdiometer), which was developed at the University of Bern in 2013 and was located in Bern (46.95° N, 7.45° E) and Payerne (46.82° N, 6.94° E). TEMPERA achieves a temporal resolution of 1–3 h and covers the altitude range between 25–50 km. Using an adaptive spectral filter with a vertical regularization (ASF2D) for the tidal analysis, we found maximum amplitudes for the diurnal tide of approximately 2.4 K, accompanied by seasonal variability. The maximum amplitude was reached on average at an altitude of 43 km, which also reflected some seasonal characteristics. We demonstrate that TEMPERA is suitable for providing continuous temperature soundings in the stratosphere and lower mesosphere with a sufficient cadence to infer tidal amplitudes and phases for the dominating tidal modes. Furthermore, our measurements exhibit a dominating diurnal tide and smaller amplitudes for the semidiurnal and terdiurnal tides in the stratosphere.
{"title":"Thermal tides in the middle atmosphere at mid-latitudes measured with a ground-based microwave radiometer","authors":"Witali Krochin, Axel Murk, Gunter Stober","doi":"10.5194/amt-17-5015-2024","DOIUrl":"https://doi.org/10.5194/amt-17-5015-2024","url":null,"abstract":"Abstract. In recent decades, theoretical studies and numerical models of thermal tides have gained attention. It has been recognized that tides have a significant influence on the dynamics of the middle and upper atmosphere; as they grow in amplitude and propagate upward, they transport energy and momentum from the lower to the upper atmosphere, contributing to the vertical coupling between atmospheric layers. The superposition of tides with other atmospheric waves leads to non-linear wave–wave interactions. However, direct measurements of thermal tides in the middle atmosphere are challenging and are often limited to satellite measurements in the tropics and at low latitudes. Due to orbit geometry, such observations provide only a reduced insight into the short-term variability in atmospheric tides. In this paper, we present tidal analysis from 5 years of continuous observations of middle-atmospheric temperatures. The measurements were performed with the ground-based temperature radiometer TEMPERA (TEMPErature RAdiometer), which was developed at the University of Bern in 2013 and was located in Bern (46.95° N, 7.45° E) and Payerne (46.82° N, 6.94° E). TEMPERA achieves a temporal resolution of 1–3 h and covers the altitude range between 25–50 km. Using an adaptive spectral filter with a vertical regularization (ASF2D) for the tidal analysis, we found maximum amplitudes for the diurnal tide of approximately 2.4 K, accompanied by seasonal variability. The maximum amplitude was reached on average at an altitude of 43 km, which also reflected some seasonal characteristics. We demonstrate that TEMPERA is suitable for providing continuous temperature soundings in the stratosphere and lower mesosphere with a sufficient cadence to infer tidal amplitudes and phases for the dominating tidal modes. Furthermore, our measurements exhibit a dominating diurnal tide and smaller amplitudes for the semidiurnal and terdiurnal tides in the stratosphere.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"13 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198346","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 : 2024-09-03DOI: 10.5194/egusphere-2024-2243
Johanna Schäfer, Anja Beschnitt, François Burgay, Thomas Singer, Margit Schwikowski, Thorsten Hoffmann
Abstract. Glaciers are valuable environmental archives that preserve organic compounds from atmospheric aerosols that can be used as marker species for their respective emission sources. Most environmental studies do not distinguish between the enantiomers of chiral compounds, although these compounds, mostly from biogenic sources, are very common in the atmosphere. We have developed a two-dimensional liquid chromatography (mLC-LC) method that allows the simultaneous determination of the chiral ratios of the monoterpene oxidation products cis-pinic acid and cis-pinonic acid in ice-core samples. The method combines a reversed-phase column in the first dimension and a chiral column in the second dimension in a simple instrumental setup with only one additional six-port valve. This novel method was successfully applied to selected ice-core samples from the Belukha glacier in the Siberian Altai spread over the period 1870–1970 CE. The chiral ratio of cis-pinic acid showed fluctuating values, while the chiral ratio of cis-pinonic acid remained more constant with an excess of the (–)-enantiomer.
{"title":"Method development and application for the analysis of chiral organic marker species in ice-cores","authors":"Johanna Schäfer, Anja Beschnitt, François Burgay, Thomas Singer, Margit Schwikowski, Thorsten Hoffmann","doi":"10.5194/egusphere-2024-2243","DOIUrl":"https://doi.org/10.5194/egusphere-2024-2243","url":null,"abstract":"<strong>Abstract.</strong> Glaciers are valuable environmental archives that preserve organic compounds from atmospheric aerosols that can be used as marker species for their respective emission sources. Most environmental studies do not distinguish between the enantiomers of chiral compounds, although these compounds, mostly from biogenic sources, are very common in the atmosphere. We have developed a two-dimensional liquid chromatography (mLC-LC) method that allows the simultaneous determination of the chiral ratios of the monoterpene oxidation products cis-pinic acid and cis-pinonic acid in ice-core samples. The method combines a reversed-phase column in the first dimension and a chiral column in the second dimension in a simple instrumental setup with only one additional six-port valve. This novel method was successfully applied to selected ice-core samples from the Belukha glacier in the Siberian Altai spread over the period 1870–1970 CE. The chiral ratio of cis-pinic acid showed fluctuating values, while the chiral ratio of cis-pinonic acid remained more constant with an excess of the (–)-enantiomer.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"69 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-30DOI: 10.5194/amt-17-4979-2024
Julia Danzer, Magdalena Pieler, Gottfried Kirchengast
Abstract. Globally available and highly vertically resolved wind fields are crucial for the analysis of atmospheric dynamics for the benefit of climate studies. Most observation techniques have problems to fulfill these requirements. Especially in the tropics and in the Southern Hemisphere more wind data are required. In this study, we investigate the potential of radio-occultation (RO) data for climate-oriented wind field monitoring in the tropics, with a specific focus on the equatorial band within ± 5° latitude. In this region, the geostrophic balance breaks down, due to the Coriolis force term approaching zero, and the equatorial-balance equation becomes relevant. One aim is to understand how the individual wind components of the geostrophic-balance and equatorial-balance approximations bridge across the Equator and where each component breaks down. Our central aim focuses on the equatorial-balance approximation, testing its quality by comparison with ERA5 reanalysis data. The analysis of the zonal and meridional wind components showed that while the zonal wind was well reconstructed, it was difficult to estimate the meridional wind from the approximation. However, we still found a somewhat better agreement from including both components in the zonal-mean total wind speed in the troposphere. In the stratosphere, the meridional wind component is close to zero for physical reasons and has no relevant impact on the total wind speed. In general, the equatorial-balance approximation works best in the stratosphere. As a second aim, we investigated the systematic data bias between using the RO and ERA5 data and find it smaller than the bias resulting from the approximations. We also inspected the monthly-mean RO wind data over the full example year of 2009. The bias in the core region of highest quality of RO data, which is the upper troposphere and lower stratosphere, was generally smaller than ± 2 m s−1. This is in line with the wind field requirements of the World Meteorological Organization. Overall, the study encourages the use of RO wind fields for regional-scale climate monitoring over the entire globe, including the equatorial region, and also showed a small improvement in the troposphere when including the meridional wind component in the zonal-mean total wind speed.
{"title":"Closing the gap in the tropics: the added value of radio-occultation data for wind field monitoring across the Equator","authors":"Julia Danzer, Magdalena Pieler, Gottfried Kirchengast","doi":"10.5194/amt-17-4979-2024","DOIUrl":"https://doi.org/10.5194/amt-17-4979-2024","url":null,"abstract":"Abstract. Globally available and highly vertically resolved wind fields are crucial for the analysis of atmospheric dynamics for the benefit of climate studies. Most observation techniques have problems to fulfill these requirements. Especially in the tropics and in the Southern Hemisphere more wind data are required. In this study, we investigate the potential of radio-occultation (RO) data for climate-oriented wind field monitoring in the tropics, with a specific focus on the equatorial band within ± 5° latitude. In this region, the geostrophic balance breaks down, due to the Coriolis force term approaching zero, and the equatorial-balance equation becomes relevant. One aim is to understand how the individual wind components of the geostrophic-balance and equatorial-balance approximations bridge across the Equator and where each component breaks down. Our central aim focuses on the equatorial-balance approximation, testing its quality by comparison with ERA5 reanalysis data. The analysis of the zonal and meridional wind components showed that while the zonal wind was well reconstructed, it was difficult to estimate the meridional wind from the approximation. However, we still found a somewhat better agreement from including both components in the zonal-mean total wind speed in the troposphere. In the stratosphere, the meridional wind component is close to zero for physical reasons and has no relevant impact on the total wind speed. In general, the equatorial-balance approximation works best in the stratosphere. As a second aim, we investigated the systematic data bias between using the RO and ERA5 data and find it smaller than the bias resulting from the approximations. We also inspected the monthly-mean RO wind data over the full example year of 2009. The bias in the core region of highest quality of RO data, which is the upper troposphere and lower stratosphere, was generally smaller than ± 2 m s−1. This is in line with the wind field requirements of the World Meteorological Organization. Overall, the study encourages the use of RO wind fields for regional-scale climate monitoring over the entire globe, including the equatorial region, and also showed a small improvement in the troposphere when including the meridional wind component in the zonal-mean total wind speed.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"73 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-30DOI: 10.5194/egusphere-2024-1695
Jiangman Xu, Ang Li, Min Qin, Zhaokun Hu, Hairong Zhang
Abstract. This study investigates a multi-elevation Fast Synchronous Multi-Axis Differential Optical Absorption Spectroscopy (FS MAX-DOAS) observation system that can rapidly acquire trace gas profiles. It modifies the conventional MAX-DOAS method by sequentially scanning at elevation angles using motors. The new system incorporates a two-dimensional area array Charge Coupled Device (CCD) grating spectrometer, small field-of-view telescopes (<1°), a high-speed shutter switching module, and a multi-mode multi-core fiber to enable multi-channel spectroscopy and significantly enhance the time resolution of the collected spectra (one elevation cycle within two minutes). When selecting the spectrometer grating, the impact of spectral resolution on the detection of nitrigen dioxide (NO2) and formaldehyde (HCHO) by FS MAX-DOAS was simulated and analyzed. The optimal resolution range was determined to be 0.3–0.6 nm. The selection of the number of binning rows in the acquisition settings considers the signal-to-noise ratio of the pixels in each row to enhance the quality of the spectral data. Two-step acquisition is used for low-elevation angles within one cycle to overcome the influence of variations in light intensity. A comparative test was conducted on outfield NO2 and HCHO measurements using differential optical absorption spectroscopy. Compared with the differential slant column densities(dSCDs) at each elevation angle measured by the MAX-DOAS system, the Pearson correlation coefficient of NO2 reached 0.9, while for HCHO it ranged mostly between 0.76 and 0.85. The results of the slant column concentration inversion indicate that the root mean square (RMS) of the FS MAX-DOAS spectrum inversion can consistently be lower than that of MAX-DOAS over an extended period. The profile results show that the diurnal variation trend of the two systems was consistent, and because of the enhanced time resolution, the gas profile obtained by the former system can provide more detailed information. Compared with the near-ground NO2 concentration measured by the long-path DOAS system, the daily variation trend shows a characteristic of being high in the morning and starting to decrease at noon, and the correlation coefficient between FS MAX-DOAS and LP -DOAS is higher (R = 0.880). The FS MAX-DOAS system can quickly and simultaneously obtain the vertical distribution profiles of NO2 and HCHO with high accuracy, providing a basis for mobile MAX-DOAS to achieve gas profile inversion.
{"title":"Study of NO2 and HCHO vertical profile measurement based on Fast Synchronous MAX-DOAS","authors":"Jiangman Xu, Ang Li, Min Qin, Zhaokun Hu, Hairong Zhang","doi":"10.5194/egusphere-2024-1695","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1695","url":null,"abstract":"<strong>Abstract.</strong> This study investigates a multi-elevation Fast Synchronous Multi-Axis Differential Optical Absorption Spectroscopy (FS MAX-DOAS) observation system that can rapidly acquire trace gas profiles. It modifies the conventional MAX-DOAS method by sequentially scanning at elevation angles using motors. The new system incorporates a two-dimensional area array Charge Coupled Device (CCD) grating spectrometer, small field-of-view telescopes (<1°), a high-speed shutter switching module, and a multi-mode multi-core fiber to enable multi-channel spectroscopy and significantly enhance the time resolution of the collected spectra (one elevation cycle within two minutes). When selecting the spectrometer grating, the impact of spectral resolution on the detection of nitrigen dioxide (NO<sub>2</sub>) and formaldehyde (HCHO) by FS MAX-DOAS was simulated and analyzed. The optimal resolution range was determined to be 0.3–0.6 nm. The selection of the number of binning rows in the acquisition settings considers the signal-to-noise ratio of the pixels in each row to enhance the quality of the spectral data. Two-step acquisition is used for low-elevation angles within one cycle to overcome the influence of variations in light intensity. A comparative test was conducted on outfield NO<sub>2</sub> and HCHO measurements using differential optical absorption spectroscopy. Compared with the differential slant column densities(dSCDs) at each elevation angle measured by the MAX-DOAS system, the Pearson correlation coefficient of NO<sub>2</sub> reached 0.9, while for HCHO it ranged mostly between 0.76 and 0.85. The results of the slant column concentration inversion indicate that the root mean square (RMS) of the FS MAX-DOAS spectrum inversion can consistently be lower than that of MAX-DOAS over an extended period. The profile results show that the diurnal variation trend of the two systems was consistent, and because of the enhanced time resolution, the gas profile obtained by the former system can provide more detailed information. Compared with the near-ground NO<sub>2</sub> concentration measured by the long-path DOAS system, the daily variation trend shows a characteristic of being high in the morning and starting to decrease at noon, and the correlation coefficient between FS MAX-DOAS and LP -DOAS is higher (R = 0.880). The FS MAX-DOAS system can quickly and simultaneously obtain the vertical distribution profiles of NO<sub>2</sub> and HCHO with high accuracy, providing a basis for mobile MAX-DOAS to achieve gas profile inversion.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"3 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-30DOI: 10.5194/amt-17-4997-2024
Evgueni Kassianov, Connor J. Flynn, James C. Barnard, Brian D. Ermold, Jennifer M. Comstock
Abstract. A novel ground-based radiometer, referred to as the Shortwave Array Spectroradiometer-Hemispheric (SAS-He), is introduced. This radiometer uses the shadow-band technique to report total irradiance and its direct and diffuse components frequently (every 30 s) with continuous spectral coverage (350–1700 nm) and moderate spectral (∼ 2.5 nm ultraviolet–visible and ∼ 6 nm shortwave-infrared) resolution. The SAS-He's performance is evaluated using integrated datasets collected over coastal regions during three field campaigns supported by the US Department of Energy's Atmospheric Radiation Measurement (ARM) program, namely the (1) Two-Column Aerosol Project (TCAP; Cape Cod, Massachusetts), (2) Tracking Aerosol Convection Interactions Experiment (TRACER; in and around Houston, Texas), and (3) Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE; La Jolla, California). We compare (i) aerosol optical depth (AOD) and total optical depth (TOD) derived from the direct irradiance, as well as (ii) the diffuse irradiance and direct-to-diffuse ratio (DDR) calculated from two components of the total irradiance. As part of the evaluation, both AOD and TOD derived from the SAS-He direct irradiance are compared to those provided by a collocated Cimel sunphotometer (CSPHOT) at five (380, 440, 500, 675, 870 nm) and two (1020, 1640 nm) wavelengths, respectively. Additionally, the SAS-He diffuse irradiance and DDR are contrasted with their counterparts offered by a collocated multifilter rotating shadowband radiometer (MFRSR) at six (415, 500, 615, 675, 870, 1625 nm) wavelengths. Overall, reasonable agreement is demonstrated between the compared products despite the challenging observational conditions associated with varying aerosol loadings and diverse types of aerosols and clouds. For example, the AOD- and TOD-related values of root mean square error remain within 0.021 at 380, 440, 500, 675, 870, 1020, and 1640 nm wavelengths during the three field campaigns.
{"title":"Shortwave Array Spectroradiometer-Hemispheric (SAS-He): design and evaluation","authors":"Evgueni Kassianov, Connor J. Flynn, James C. Barnard, Brian D. Ermold, Jennifer M. Comstock","doi":"10.5194/amt-17-4997-2024","DOIUrl":"https://doi.org/10.5194/amt-17-4997-2024","url":null,"abstract":"Abstract. A novel ground-based radiometer, referred to as the Shortwave Array Spectroradiometer-Hemispheric (SAS-He), is introduced. This radiometer uses the shadow-band technique to report total irradiance and its direct and diffuse components frequently (every 30 s) with continuous spectral coverage (350–1700 nm) and moderate spectral (∼ 2.5 nm ultraviolet–visible and ∼ 6 nm shortwave-infrared) resolution. The SAS-He's performance is evaluated using integrated datasets collected over coastal regions during three field campaigns supported by the US Department of Energy's Atmospheric Radiation Measurement (ARM) program, namely the (1) Two-Column Aerosol Project (TCAP; Cape Cod, Massachusetts), (2) Tracking Aerosol Convection Interactions Experiment (TRACER; in and around Houston, Texas), and (3) Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE; La Jolla, California). We compare (i) aerosol optical depth (AOD) and total optical depth (TOD) derived from the direct irradiance, as well as (ii) the diffuse irradiance and direct-to-diffuse ratio (DDR) calculated from two components of the total irradiance. As part of the evaluation, both AOD and TOD derived from the SAS-He direct irradiance are compared to those provided by a collocated Cimel sunphotometer (CSPHOT) at five (380, 440, 500, 675, 870 nm) and two (1020, 1640 nm) wavelengths, respectively. Additionally, the SAS-He diffuse irradiance and DDR are contrasted with their counterparts offered by a collocated multifilter rotating shadowband radiometer (MFRSR) at six (415, 500, 615, 675, 870, 1625 nm) wavelengths. Overall, reasonable agreement is demonstrated between the compared products despite the challenging observational conditions associated with varying aerosol loadings and diverse types of aerosols and clouds. For example, the AOD- and TOD-related values of root mean square error remain within 0.021 at 380, 440, 500, 675, 870, 1020, and 1640 nm wavelengths during the three field campaigns.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"57 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-29DOI: 10.5194/amt-17-4957-2024
Stuart Fox, Vinia Mattioli, Emma Turner, Alan Vance, Domenico Cimini, Donatello Gallucci
Abstract. Accurate gas absorption models at millimetre and sub-millimetre wavelengths are required to make best use of observations from instruments on board the next generation of EUMETSAT polar-orbiting weather satellites, including the Ice Cloud Imager (ICI), which measures at frequencies up to 664 GHz. In this study, airborne observations of clear-sky scenes between 89 and 664 GHz are used to perform radiative closure calculations for both upward- and downward-looking viewing directions in order to evaluate two state-of-the-art absorption models, both of which are integrated into the Atmospheric Radiative Transfer Simulator (ARTS). Differences of 20 K are seen in some individual comparisons, with the largest discrepancies occurring where the brightness temperature is highly sensitive to the atmospheric water vapour profile. However, these differences are within the expected uncertainty due to the observed water vapour variability, highlighting the importance of understanding the spatial and temporal distribution of water vapour when performing such comparisons. The errors can be significantly reduced by averaging across multiple flights, which reduces the impact of uncertainties in individual atmospheric profiles. For upward-looking views, which have the greatest sensitivity to the absorption model, the mean differences between observed and simulated brightness temperatures are generally close to, or within, the estimated spectroscopic uncertainty. For downward-looking views, which more closely match the satellite viewing geometry, the mean differences were generally less than 1.5 K, with the exception of window channels at 89 and 157 GHz, which are significantly influenced by surface properties. These results suggest that both of the absorption models considered are sufficiently accurate for use with ICI.
{"title":"An evaluation of atmospheric absorption models at millimetre and sub-millimetre wavelengths using airborne observations","authors":"Stuart Fox, Vinia Mattioli, Emma Turner, Alan Vance, Domenico Cimini, Donatello Gallucci","doi":"10.5194/amt-17-4957-2024","DOIUrl":"https://doi.org/10.5194/amt-17-4957-2024","url":null,"abstract":"Abstract. Accurate gas absorption models at millimetre and sub-millimetre wavelengths are required to make best use of observations from instruments on board the next generation of EUMETSAT polar-orbiting weather satellites, including the Ice Cloud Imager (ICI), which measures at frequencies up to 664 GHz. In this study, airborne observations of clear-sky scenes between 89 and 664 GHz are used to perform radiative closure calculations for both upward- and downward-looking viewing directions in order to evaluate two state-of-the-art absorption models, both of which are integrated into the Atmospheric Radiative Transfer Simulator (ARTS). Differences of 20 K are seen in some individual comparisons, with the largest discrepancies occurring where the brightness temperature is highly sensitive to the atmospheric water vapour profile. However, these differences are within the expected uncertainty due to the observed water vapour variability, highlighting the importance of understanding the spatial and temporal distribution of water vapour when performing such comparisons. The errors can be significantly reduced by averaging across multiple flights, which reduces the impact of uncertainties in individual atmospheric profiles. For upward-looking views, which have the greatest sensitivity to the absorption model, the mean differences between observed and simulated brightness temperatures are generally close to, or within, the estimated spectroscopic uncertainty. For downward-looking views, which more closely match the satellite viewing geometry, the mean differences were generally less than 1.5 K, with the exception of window channels at 89 and 157 GHz, which are significantly influenced by surface properties. These results suggest that both of the absorption models considered are sufficiently accurate for use with ICI.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"217 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-28DOI: 10.5194/egusphere-2024-1651
Howard W. Barker, Jason N. S. Cole, Najda Villefranque, Zhipeng Qu, Almudena Velázquez Blázquez, Carlos Domenech, Shannon L. Mason, Robin J. Hogan
Abstract. Measurements made by three instruments aboard the EarthCARE satellite, plus data from auxiliary sources, will be used to synergistically retrieve estimates of cloud and aerosol properties. The ACMB-DF processor consists of a continuous radiative closure assessment of these retrievals and is both described and demonstrated in this study. The closure procedure begins with 3D radiative transfer models (RTMs) acting on retrieved and auxiliary data. These models yield upwelling shortwave and longwave broadband radiances commensurate with measurements made by EarthCARE’s multi-angle broadband radiometer (BBR). Measured and modelled radiances are averaged up to “assessment domains”, that measure ~21 km along-track by no more than 5 km across-track, centred on the retrieved cross-section of ~1 km profiles, and are then combined, by angular distributions models (ADMs), to produce “effective” upwelling fluxes at the top-of-atmosphere, denoted as FBBR and FRTM, respectively. Last, the probability 𝑝ΔF^ of |FRTM – FBBR| being less than ΔF^ W m-2 is estimated recognizing as many sources of, assumed normally distributed, uncertainties as possible. For historical/programmatic reasons, ΔF^ is set to 10 W m-2, but that might change during EarthCARE’s commissioning phase and with Sun angle. The closure process is demonstrated up to calculation of 𝑝ΔF^ using four 400 km-long portions of one of EarthCARE’s test frames for which simulated passive measurements were computed by 3D RTMs. Note that this study, like the ACMB-DF process with real EarthCARE observations, does not comment explicitly on performance of retrieval algorithms.
{"title":"Radiative Closure Assessment of Retrieved Cloud and Aerosol Properties for the EarthCARE Mission: The ACMB-DF Product","authors":"Howard W. Barker, Jason N. S. Cole, Najda Villefranque, Zhipeng Qu, Almudena Velázquez Blázquez, Carlos Domenech, Shannon L. Mason, Robin J. Hogan","doi":"10.5194/egusphere-2024-1651","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1651","url":null,"abstract":"<strong>Abstract.</strong> Measurements made by three instruments aboard the EarthCARE satellite, plus data from auxiliary sources, will be used to synergistically retrieve estimates of cloud and aerosol properties. The ACMB-DF processor consists of a continuous radiative closure assessment of these retrievals and is both described and demonstrated in this study. The closure procedure begins with 3D radiative transfer models (RTMs) acting on retrieved and auxiliary data. These models yield upwelling shortwave and longwave broadband radiances commensurate with measurements made by EarthCARE’s multi-angle broadband radiometer (BBR). Measured and modelled radiances are averaged up to “assessment domains”, that measure ~21 km along-track by no more than 5 km across-track, centred on the retrieved cross-section of ~1 km profiles, and are then combined, by angular distributions models (ADMs), to produce “effective” upwelling fluxes at the top-of-atmosphere, denoted as F<sub>BBR</sub> and F<sub>RTM</sub>, respectively. Last, the probability 𝑝<sub>ΔF<sup>^</sup></sub> of |F<sub>RTM</sub> – F<sub>BBR</sub>| being less than ΔF<sup>^</sup> W m<sup>-2</sup> is estimated recognizing as many sources of, assumed normally distributed, uncertainties as possible. For historical/programmatic reasons, ΔF<sup>^ </sup>is set to 10 W m<sup>-2</sup>, but that might change during EarthCARE’s commissioning phase and with Sun angle. The closure process is demonstrated up to calculation of 𝑝<sub>ΔF<sup>^ </sup></sub> using four 400 km-long portions of one of EarthCARE’s test frames for which simulated passive measurements were computed by 3D RTMs. Note that this study, like the ACMB-DF process with real EarthCARE observations, does not comment explicitly on performance of retrieval algorithms.","PeriodicalId":8619,"journal":{"name":"Atmospheric Measurement Techniques","volume":"101 1","pages":""},"PeriodicalIF":3.8,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198428","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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