Atmospheric Measurement Techniques Discussions

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EISSN : 1867-8610
Current Publisher: Copernicus GmbH (10.5194)
Total articles ≅ 2,463
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Hongming Yi, Mathieu Cazaunau, Aline Gratien, Vincent Michoud, Edouard Pangui, ,
Atmospheric Measurement Techniques Discussions pp 1-27; doi:10.5194/amt-2021-19-rc2

Abstract:
We report on applications of ultraviolet light emitted diode based incoherent broadband cavity enhanced absorption spectroscopy (UV-LED-IBBCEAS) technique for optical monitoring of HONO, NO2 and CH2O in a simulation chamber. Performance intercomparison of the UV-LED-IBBCEAS with a wet chemistry-based NitroMAC sensor and a FTIR spectrometer has been carried out on real time simultaneous measurement of HONO, NO2 and CH2O concentrations during the reaction of NO2 with H2O vapor in the CESAM atmospheric simulation chamber. 1-σ (SNR = 1) detection limits of 200 pptv for NO2, 100 pptv for HONO and 5 ppbv for CH2O over 120 s were found for the UV-LED-IBBCEAS measurement. On the contrary to many set-ups where cavities are installed outside the simulation chamber, we describe here an original in-situ permanent installation. The intercomparison results demonstrate that IBBCEAS is a very well suitable technique for in situ simultaneous measurements of multiple chemically reactive species with high sensitivity and high precision even if the absorption bands of these species are overlapped. It offers excellent capacity to non-invasive optical monitoring of chemical reaction without any perturbation. For the application to simulation chamber, it has the advantage to provide a spatially integrated measurement across the reactor and hence to avoid point sampling related artefact.
Hao Yang, Zhiyuan Fang, Cheng Li, Xu Deng, Kunming Xing, Chenbo Xie
Atmospheric Measurement Techniques Discussions pp 1-14; doi:10.5194/amt-2021-55-rc1

Abstract:
From August 4th to 30th, 2020 and from November 27th to December 25th, 2020, a self-developed radiosonde balloon system was used to observe high-altitude atmospheric optical turbulence at three sites in northwestern China, and an improved model based on the observational data was established. Through comparative analysis of the observational data and the improved model, the distribution characteristics of atmospheric optical turbulence under the combined action of different meteorological parameters and different landform features in different seasons were obtained. The improved model can show the variation of the detailed characteristics of turbulence with the height distribution, and the degree of correlation with the measured values is above 0.82. The improved model can provide a theoretical basis and supporting data for turbulence estimation and forecasting in northwestern China.
Michel Attoui, Silvia G. Danelli, Marco Brunoldi, , Franco Parodi, Virginia Vernocchi, Paolo Prati
Atmospheric Measurement Techniques Discussions pp 1-18; doi:10.5194/amt-2020-490-rc2

Abstract:
The interplay of bio-aerosol dispersion and impact, meteorology, air quality is gaining increasing interest in the wide spectrum of atmospheric science. Experiments conducted inside confined artificial environments, such as the Atmospheric Simulations Chambers (ASCs), where atmospheric conditions and composition are controlled, can provide valuable information on bio-aerosol viability, dispersion, and impact. We focus here on the reproducible aerosolization and injection of viable microorganisms into an ASC, the first and crucial step of any experimental protocol to expose bio-aerosol at different atmospheric conditions. We compare the performance of three nebulizers specifically designed for bioaerosol applications: the Collison nebulizer, the Blaustein Atomizing Modules (BLAM) and the Sparging Liquid Aerosol Generator (SLAG), all manufactured and commercialized by CH TECHNOLOGIES. The comparison refers to operating conditions and the concentration of viable bacteria at the nebulizer outlet, with the final goal to measure the reproducibility of the nebulization procedure and assess the application in experiments at ASCs. A typical bacterial test model, Escherichia coli (ATCC® 25922™), was selected for such characterization. Bacteria suspensions, with a concentration around 108 CFU ml−1, were first aerosolized at different air pressures and collected by a Liquid Impinger, to obtain a correlation curve between airflow and nebulized bacteria, for each generator. Afterwards, bacteria were aerosolized inside the atmospheric simulation chamber ChAMBRe (Chamber for Aerosol Modelling and Bio-aerosol Research) to measure the reproducibility of the whole procedure. An overall reproducibility of 11 % was obtained with each nebulizer through a set of baseline experiments.
Jing Wang, Silvia G. Danelli, Marco Brunoldi, , Franco Parodi, Virginia Vernocchi, Paolo Prati
Atmospheric Measurement Techniques Discussions pp 1-18; doi:10.5194/amt-2020-490-rc3

Abstract:
The interplay of bio-aerosol dispersion and impact, meteorology, air quality is gaining increasing interest in the wide spectrum of atmospheric science. Experiments conducted inside confined artificial environments, such as the Atmospheric Simulations Chambers (ASCs), where atmospheric conditions and composition are controlled, can provide valuable information on bio-aerosol viability, dispersion, and impact. We focus here on the reproducible aerosolization and injection of viable microorganisms into an ASC, the first and crucial step of any experimental protocol to expose bio-aerosol at different atmospheric conditions. We compare the performance of three nebulizers specifically designed for bioaerosol applications: the Collison nebulizer, the Blaustein Atomizing Modules (BLAM) and the Sparging Liquid Aerosol Generator (SLAG), all manufactured and commercialized by CH TECHNOLOGIES. The comparison refers to operating conditions and the concentration of viable bacteria at the nebulizer outlet, with the final goal to measure the reproducibility of the nebulization procedure and assess the application in experiments at ASCs. A typical bacterial test model, Escherichia coli (ATCC® 25922™), was selected for such characterization. Bacteria suspensions, with a concentration around 108 CFU ml−1, were first aerosolized at different air pressures and collected by a Liquid Impinger, to obtain a correlation curve between airflow and nebulized bacteria, for each generator. Afterwards, bacteria were aerosolized inside the atmospheric simulation chamber ChAMBRe (Chamber for Aerosol Modelling and Bio-aerosol Research) to measure the reproducibility of the whole procedure. An overall reproducibility of 11 % was obtained with each nebulizer through a set of baseline experiments.
Alexey B. Tikhomirov, Glen Lesins, James R. Drummond
Atmospheric Measurement Techniques Discussions pp 1-27; doi:10.5194/amt-2020-515-cc1

Abstract:
The absence of sunlight during the winter in the High Arctic results in a strong surface-based atmospheric temperature inversion especially during clear skies and light surface wind conditions. The inversion suppresses turbulent heat transfer between the ground and the boundary layer. As a result the difference between the surface air temperature, measured at a height of 2 m, and the ground skin temperature can exceed several degrees Celsius. Such inversions occur very frequently in polar regions and are of interest to understand the mechanisms responsible for surface-atmosphere heat, mass and momentum exchanges and are critical for satellite validation studies. In this paper we present the results of operations of two commercial remotely piloted aircraft systems, or drones, at the Polar Environment Atmospheric Research Laboratory (PEARL), Eureka, Nunavut, Canada, at 80° N latitude. The drones are the Matrice 100 and M210-RTK quad-copters manufactured by DJI and were flown over Eureka during the February–March field campaigns in 2017 and 2020. They were equipped with a temperature measurement system built on a Raspberry Pi single-board computer, three platinum wire temperature sensors, GNSS receiver, and a pressure sensor. We demonstrate that the drones can be effectively used in the High Arctic to measure vertical temperature profiles up to 60 m of the ground and sea ice surface. Our results indicate that the inversion lapse rates within 0–10 m altitude range above the ground can reach the values of ~0.1–0.3 °C/m (~100–300 °C/km). The results are in a good agreement with the coincident temperatures measured at 2, 6 and 10 m levels at the National Oceanic and Atmospheric Administration flux tower at PEARL. Above 10 m a weaker inversion with an order of magnitude smaller lapse rates is recorded by the drone. The inversion strength agrees well with one obtained from the radiosonde temperature measurements. Above the sea ice, drone temperature profiles are found to have an isothermal layer above a surface based layer of instability which is attributed to the sensible heat flux through the sea ice. With the drones we were able to evaluate the influence of local topography on the surface-based inversion structure above the ground and to measure extremely cold temperatures of air that can pool in topographic depressions. The unique technical challenges of conducting drone campaigns in the winter High Arctic are highlighted in the paper.
Piet Stammes, Jia Su, M. Patrick McCormick, Matthew S. Johnson, , Michael J. Newchurch, Timothy A. Berkoff, ,
Atmospheric Measurement Techniques Discussions pp 1-24; doi:10.5194/amt-2020-449-ec1

Abstract:
The conventional two-wavelength Differential Absorption Lidar (DIAL) has measured air pollutants such as nitrogen dioxide (NO2). However, high concentrations of aerosol within the planetary boundary layer (PBL) can cause significant retrieval errors using only a two-wavelength DIAL technique to measure NO2. We proposed a new technique to obtain more accurate measurements of NO2 using a three-wavelength DIAL technique based on an Optical Parametric Oscillator (OPO) laser. This study derives the three-wavelength DIAL retrieval equations necessary to retrieve vertical profiles of NO2 in the troposphere. Additionally, two rules to obtain the optimum choice of the three wavelengths applied in the retrieval are designed to help increase the differences of the NO2 absorption cross sections and reduce aerosol interference. NO2 retrieval relative uncertainties caused by aerosol extinction, molecular extinction, absorption of gases other than the gas of interest and backscattering are calculated using two-wavelength DIAL (438 nm and 439.5 nm) and three-wavelength DIAL (438 nm, 439.5 nm and 441 nm) techniques. The retrieval uncertainties of aerosol extinction using the three-wavelength DIAL technique are reduced to less than 2 % of using the two-wavelength DIAL technique. Moreover, the retrieval uncertainty analysis indicates that the three-wavelength DIAL technique can reduce more fluctuation caused by aerosol backscattering than two-wavelength DIAL technique. This study presents NO2 concentration profiles which were obtained using the HU (Hampton University) three-wavelength OPO DIAL. As a first step to assess the accuracy of the HU lidar NO2 profiles we compared the retrievals to simulated data from WRF-Chem model. This comparison suggests that the NO2 profiles retrieved with the three-wavelength DIAL technique have similar vertical structure, and magnitudes typically within ±0.1 ppb, of modeled profiles.
Dhiraj K. Singh, Spencer Donovan, ,
Atmospheric Measurement Techniques Discussions pp 1-27; doi:10.5194/amt-2021-44-rc1

Abstract:
The Differential Emissivity Imaging Disdrometer (DEID) is a new evaporation-based optical and thermal instrument designed to measure the mass, size, density, and type of individual hydrometeors and their bulk properties. Hydrometeor spatial dimensions are measured on a heated metal plate using an infrared camera by exploiting the much higher thermal emissivity of water compared with metal. As a melted hydrometeor evaporates, its mass can be directly related to the loss of heat from the hotplate assuming energy conservation across the hydrometeor. The heat-loss required to evaporate a hydrometeor is found to be independent of environmental conditions including ambient wind velocity, moisture level, and temperature. The difference in heat loss for snow versus rain for a given mass offers a method for discriminating precipitation phase. The DEID measures hydrometeors at sampling frequencies up to 1 Hz with masses and effective diameters greater than 1 µg and 200 µm, respectively, determined by the size of the hotplate and the thermal camera specifications. Measurable snow water equivalent (SWE) precipitation rates range from 0.001 to 200 mm h−1, as validated against a standard weighing bucket. Preliminary field-experiment measurements of snow and rain from the winters of 2019 and 2020 provided continuous automated measurements of precipitation rate, snow density, and visibility. Measured hydrometeor size distributions agree well with canonical results described in the literature.
, , Patrick Konjari, , Tatiana Nomokonova, Ana Radovan, David Strack, Arantxa M. Triana-Gómez, , , et al.
Atmospheric Measurement Techniques Discussions pp 1-36; doi:10.5194/amt-2020-491-ac1

Abstract:
Water vapor is an important component in the water and energy cycle of the Arctic. Especially in the light of Arctic amplification, changes of water vapor are of high interest but are difficult to observe due to the data sparsity of the region. The ACLOUD/PASCAL campaign performed in May/June 2017 in the Arctic North Atlantic sector offers the opportunity to investigate the quality of various satellite and reanalysis products. Compared to reference measurements at R/V Polarstern frozen into the ice (around 82° N, 10° E) and at Ny-Ålesund, the Integrated Water Vapor (IWV) from IASI shows the best performance among all satellite products. Using all radiosonde stations within the region indicates some differences that might relate to different radiosonde types used. Though the region is well sampled by polar orbiting satellites daily means can deviate by up to 50 % due to strong spatio-temporal IWV variability associated with atmospheric river events. For monthly mean values, this weather induced variability cancels out but systematic differences dominate which particularly appear over different surface types, e.g. ocean, sea ice. In the data sparse central Arctic above 84° N, strong differences of 30 % in IWV monthly means between satellite products occur in the month of June which likely results from the difficulties to consider the complex and changing surface characteristics of the melting ice within the retrieval algorithms. There is hope that the detailed surface characterization performed as part of the recently finished Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) will foster the improvement of future retrieval algorithms.
, , Patrick Konjari, , Tatiana Nomokonova, Ana Radovan, David Strack, Arantxa M. Triana-Gómez, , , et al.
Atmospheric Measurement Techniques Discussions pp 1-36; doi:10.5194/amt-2020-491-ac2

Abstract:
Water vapor is an important component in the water and energy cycle of the Arctic. Especially in the light of Arctic amplification, changes of water vapor are of high interest but are difficult to observe due to the data sparsity of the region. The ACLOUD/PASCAL campaign performed in May/June 2017 in the Arctic North Atlantic sector offers the opportunity to investigate the quality of various satellite and reanalysis products. Compared to reference measurements at R/V Polarstern frozen into the ice (around 82° N, 10° E) and at Ny-Ålesund, the Integrated Water Vapor (IWV) from IASI shows the best performance among all satellite products. Using all radiosonde stations within the region indicates some differences that might relate to different radiosonde types used. Though the region is well sampled by polar orbiting satellites daily means can deviate by up to 50 % due to strong spatio-temporal IWV variability associated with atmospheric river events. For monthly mean values, this weather induced variability cancels out but systematic differences dominate which particularly appear over different surface types, e.g. ocean, sea ice. In the data sparse central Arctic above 84° N, strong differences of 30 % in IWV monthly means between satellite products occur in the month of June which likely results from the difficulties to consider the complex and changing surface characteristics of the melting ice within the retrieval algorithms. There is hope that the detailed surface characterization performed as part of the recently finished Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) will foster the improvement of future retrieval algorithms.
Kevin B. Fischer, Giuseppe A. Petrucci
Atmospheric Measurement Techniques Discussions pp 1-26; doi:10.5194/amt-2021-35-rc1

Abstract:
Secondary organic aerosol (SOA), formed through oxidation of volatile organic compounds (VOCs), display complex viscosity and phase behaviors influenced by temperature, relative humidity (RH), and chemical composition. Here, the efficacy of a multi-stage electrical low pressure impactor (ELPI) for indirect water uptake measurements was studied for ammonium sulfate (AS) aerosol, sucrose aerosol, and α-pinene derived SOA. All three aerosol systems were subjected to greater than 90 % chamber relative humidity, with subsequent analysis indicating persistence of particle bounce for sucrose 10 aerosol of 70 nm (initial dry diameter) and α-pinene derived SOA of number geometric mean diameters between 39 nm and 136 nm (initial dry diameter). On the other hand, sucrose aerosol of 190 nm (initial dry diameter) and AS aerosol down to 70 nm (initial dry diameter) exhibited no particle bounce at elevated RH. Partial drying of aerosol within the lower diameter ELPI impaction stages, where inherent and significant RH reductions occur, is proposed as one explanation for particle bounce persistence.
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