In situ measurements of microphysical properties and trace gases in two cumulonimbus anvils over western Europe

1999 ◽  
Vol 104 (D10) ◽  
pp. 12221-12226 ◽  
Author(s):  
Johan Ström ◽  
Horst Fischer ◽  
Jos Lelieveld ◽  
Franz Schröder
Keyword(s):  
Western Europe ◽  
Trace Gases ◽  
In Situ Measurements ◽  
Microphysical Properties

scholarly journals Aerosol optical and microphysical retrievals from a hybrid multiwavelength lidar data set – DISCOVER-AQ 2011

2014 ◽  
Vol 7 (9) ◽  
pp. 3095-3112 ◽  
Author(s):  
P. Sawamura ◽  
D. Müller ◽  
R. M. Hoff ◽  
C. A. Hostetler ◽  
R. A. Ferrare ◽  
...  
Keyword(s):  
Remote Sensing ◽  
In Situ Measurements ◽  
Index Of Refraction ◽  
High Spectral Resolution ◽  
Lidar Data ◽  
Data Set ◽  
Microphysical Properties ◽  
Lidar Measurements ◽  
Multiwavelength Lidar

Abstract. Retrievals of aerosol microphysical properties (effective radius, volume and surface-area concentrations) and aerosol optical properties (complex index of refraction and single-scattering albedo) were obtained from a hybrid multiwavelength lidar data set for the first time. In July 2011, in the Baltimore–Washington DC region, synergistic profiling of optical and microphysical properties of aerosols with both airborne (in situ and remote sensing) and ground-based remote sensing systems was performed during the first deployment of DISCOVER-AQ. The hybrid multiwavelength lidar data set combines ground-based elastic backscatter lidar measurements at 355 nm with airborne High-Spectral-Resolution Lidar (HSRL) measurements at 532 nm and elastic backscatter lidar measurements at 1064 nm that were obtained less than 5 km apart from each other. This was the first study in which optical and microphysical retrievals from lidar were obtained during the day and directly compared to AERONET and in situ measurements for 11 cases. Good agreement was observed between lidar and AERONET retrievals. Larger discrepancies were observed between lidar retrievals and in situ measurements obtained by the aircraft and aerosol hygroscopic effects are believed to be the main factor in such discrepancies.

scholarly journals An Inverse Problem Approach for the Retrieval of Ice Particle Mass from In Situ Measurements

2017 ◽  
Vol 34 (11) ◽  
pp. 2457-2473 ◽  
Author(s):  
Pierre Coutris ◽  
Delphine Leroy ◽  
Emmanuel Fontaine ◽  
Alfons Schwarzenboeck
Keyword(s):  
Inverse Problem ◽  
Particle Size ◽  
Power Law ◽  
In Situ Measurements ◽  
Ice Cloud ◽  
Size Dependent ◽  
Microphysical Properties ◽  
Ice Water Content ◽  
Ice Water

AbstractMass–dimensional relationships have been published for decades to characterize the microphysical properties of ice cloud particles. Classical retrieval methods employ a simplifying assumption that restricts the form of the mass–dimensional relationship to a power law, an assumption that was proved inaccurate in recent studies. In this paper, a nonstandard approach that leverages optimal use of in situ measurements to remove the power-law constraint is presented. A model formulated as a linear system of equations relating ice particle mass to particle size distribution (PSD) and ice water content (IWC) is established, and the mass retrieval process consists of solving the inverse problem with numerical optimization algorithms. First, the method is applied to a synthetic crystal dataset in order to validate the selected algorithms and to tune the regularization strategy. Subsequently, the method is applied to in situ measurements collected during the High Altitude Ice Crystal–High Ice Water Content field campaigns. Preliminary results confirm the method is efficient at retrieving size-dependent masses from real data despite a significant amount of noise: the IWC values calculated from the retrieved masses are in good agreement with reference IWC measurements (errors on the order of 10%–15%). The possibility to retrieve ice particle size–dependent masses combined with the flexibility left for sorting datasets as a function of parameters such as cloud temperature, cloud type, or convective index makes this approach well suited for studying ice cloud microphysical properties.

scholarly journals An indirect-calibration method for non-target quantification of trace gases applied to a time series of fourth-generation synthetic halocarbons at the Taunus Observatory (Germany)

2021 ◽  
Vol 14 (6) ◽  
pp. 4669-4687
Author(s):  
Fides Lefrancois ◽  
Markus Jesswein ◽  
Markus Thoma ◽  
Andreas Engel ◽  
Kieran Stanley ◽  
...  
Keyword(s):  
Stratospheric Ozone ◽  
Trace Gases ◽  
Mass Range ◽  
Calibration Method ◽  
In Situ Measurements ◽  
Atmospheric Composition ◽  
Fourth Generation ◽  
Calibration Gas ◽  
Tof Ms

Abstract. Production and use of many synthetic halogenated trace gases are regulated internationally due to their contribution to stratospheric ozone depletion or climate change. In many applications they have been replaced by shorter-lived compounds, which have become measurable in the atmosphere as emissions increased. Non-target monitoring of trace gases rather than targeted measurements of well-known substances is needed to keep up with such changes in the atmospheric composition. We regularly deploy gas chromatography (GC) coupled to time-of-flight mass spectrometry (TOF-MS) for analysis of flask air samples and in situ measurements at the Taunus Observatory, a site in central Germany. TOF-MS acquires data over a continuous mass range that enables a retrospective analysis of the dataset, which can be considered a type of digital air archive. This archive can be used if new substances come into use and their mass spectrometric fingerprint is identified. However, quantifying new replacement halocarbons can be challenging, as mole fractions are generally low, requiring high measurement precision and low detection limits. In addition, calibration can be demanding, as calibration gases may not contain sufficiently high amounts of newly measured substances or the amounts in the calibration gas may have not been quantified. This paper presents an indirect data evaluation approach for TOF-MS data, where the calibration is linked to another compound which could be quantified in the calibration gas. We also present an approach to evaluate the quality of the indirect calibration method, select periods of stable instrument performance and determine well suited reference compounds. The method is applied to three short-lived synthetic halocarbons: HFO-1234yf, HFO-1234ze(E), and HCFO-1233zd(E). They represent replacements for longer-lived hydrofluorocarbons (HFCs) and exhibit increasing mole fractions in the atmosphere. The indirectly calibrated results are compared to directly calibrated measurements using data from TOF-MS canister sample analysis and TOF-MS in situ measurements, which are available for some periods of our dataset. The application of the indirect calibration method on several test cases can result in uncertainties of around 6 % to 11 %. For hydro(chloro-)fluoroolefines (denoted H(C)FOs), uncertainties up to 23 % are achieved. The indirectly calculated mole fractions of the investigated H(C)FOs at Taunus Observatory range between measured mole fractions at urban Dübendorf and Jungfraujoch stations in Switzerland.

scholarly journals Validation of MODIS cloud microphysical properties with in situ measurements over the Southeast Pacific

2012 ◽  
Vol 12 (1) ◽  
pp. 1419-1449 ◽  
Author(s):  
Q. Min ◽  
E. Joseph ◽  
Y. Lin ◽  
L. Min ◽  
B. Yin ◽  
...  
Keyword(s):  
Number Concentration ◽  
Effective Radius ◽  
In Situ Measurements ◽  
Liquid Water Path ◽  
Cloud Drop ◽  
Microphysical Properties ◽  
Satellite Retrievals ◽  
Drop Number ◽  
Cloud Liquid Water Path

Abstract. Utilizing the unique characteristics of the cloud over the Southeast Pacific (SEP) off the coast of Chile during the VOCALS field campaign, we validated satellite remote sensing of cloud microphysical properties against in situ data from multi-aircraft observations, and studied the extent to which these retrieved properties are sufficiently constrained and consistent to reliably quantify the influence of aerosol loading on cloud droplet sizes. After constraining the spatial-temporal coincidence between satellite retrievals and in situ measurements, we selected 17 non-drizzle comparison pairs. For these cases the mean aircraft profiling times were within one hour of Terra overpass at both projected and un-projected (actual) aircraft positions for two different averaging domains of 5 km and 25 km. Retrieved quantities that were averaged over a larger domain of 25 km compared better statistically with in situ observations than averages over a smaller domain of 5 km. Validation at projected aircraft positions was slightly better than un-projected aircraft positions for some parameters. Overall, both MODIS-retrieved effective radius and LWP were larger but highly correlated with the in situ measured effective radius and LWP. The observed effective radius difference between the two decreased with increasing cloud drop number concentration, and increased with increasing cloud geometrical thickness. Also, MODIS retrievals for adiabatic clouds agreed better with the in situ measurements than for sub-adiabatic clouds. Our validation and sensitivity analysis of simulated retrievals demonstrate that both cloud geometrical thickness and cloud adiabaticity are important factors in satellite retrievals of effective radius and cloud drop number concentration. The large variabilities in cloud geometric thickness and adiabaticity, the dependencies of cloud microphysical properties on both quantities (as demonstrated in our sensitivity study of simulated retrievals), and the inability to accurately account for either of them in retrievals lead to substantial uncertainties and biases in satellite retrieved cloud effective radius, cloud liquid water path, and cloud drop number concentration. However, strong correlations between satellite retrievals and in situ measurements suggest that satellite retrievals of cloud effective radius, cloud liquid water path, and cloud drop number concentration can be used to investigate aerosol indirect effects qualitatively.

scholarly journals Aerosol profiling during the large scale field campaign CINDI-2

2018 ◽  
Vol 176 ◽  
pp. 10005
Author(s):  
Arnoud Apituley ◽  
Michel Van Roozendael ◽  
Andreas Richter ◽  
Thomas Wagner ◽  
Udo Friess ◽  
...  
Keyword(s):  
Large Scale ◽  
Trace Gases ◽  
Raman Lidar ◽  
Proper Understanding ◽  
Passive Remote Sensing ◽  
Microphysical Properties ◽  
Large Scale Field ◽  
Independent Observations ◽  
Remote Sensing Techniques

For the validation of space borne observations of NO2 and other trace gases from hyperspectral imagers, ground based instruments based on the MAXDOAS technique are an excellent choice, since they rely on similar retrieval techniques as the observations from orbit. To ensure proper traceability of the MAXDOAS observations, a thorough validation and intercomparison is mandatory. Advanced MAXDOAS observation and retrieval techniques enable inferring vertical structure of trace gases and aerosols. These techniques and their results need validation by e.g. lidar techniques. For the proper understanding of the results from passive remote sensing techniques, independent observations are needed that include parameters needed to understand the light paths, i.e. in-situ aerosol observations of optical and microphysical properties, and essential are in particular the vertical profiles of aerosol optical properties by (Raman) lidar. The approach used in the CINDI-2 campaign held in Cabauw in 2016 is presented in this paper and the results will be discussed in the presentation at the conference.

Das ACTRIS-Kalibrierzentrum für Stickoxid-Messungen am Forschungszentrum Jülich

2021 ◽  
Author(s):  
Max Gerrit Adam ◽  
Robert Wegener ◽  
Franz Rohrer ◽  
Ralf Tillmann ◽  
Astrid Kiendler-Scharr ◽  
...  
Keyword(s):  
Phase Shift ◽  
Diode Laser ◽  
Trace Gases ◽  
In Situ Measurements ◽  
Tunable Diode Laser ◽  
Research Infrastructure ◽  
Aerosol Cloud ◽  
Reactive Trace Gases

<p>Langzeitmessungen der atmosphärischen Zusammensetzung sind von zentraler Bedeutung, um die Atmosphärenchemie und den Klimawandel zu verstehen. ACTRIS (Aerosol, Cloud and Trace Gases Research Infrastructure) hat sich zum Ziel gesetzt, ein europaweites Netzwerk von Beobachtungsstationen aufzubauen, die qualitativ hochwertige Daten und Informationen zu kurzlebigen atmosphärischen Bestandteilen liefern und für Nutzer auf der ganzen Welt offen zugänglich machen. Stickstoffmonoxid (NO) und Stickstoffdioxid (NO<sub>2</sub>), die sogenannten Stickoxide (NO<sub>x</sub>), spielen eine Schlüsselrolle in der Atmosphärenchemie, da sie zur Bildung von troposphärischem Ozon, Smog und saurem Regen beitragen. Darüber hinaus ist die kurz- und langfristige Exposition mit NO<sub>2</sub> mit negativen Auswirkungen auf das menschliche Atmungssystem in Verbindung gebracht worden. Die Hauptquellen von NO<sub>x</sub> in bewohnten Gebieten sind Verbrennungsprozesse, z.B. von Fahrzeugen und bei industriellen Aktivitäten. NO<sub>x</sub>-Messungen werden derzeit meist indirekt über Chemilumineszenz-Instrumente durchgeführt, die Korrekturen für Feuchte und Ozon erfordern. Jüngste technologische Fortschritte (z. B. Cavity Attenuated Phase Shift, CAPS, oder Tunable Diode Laser Systeme) erlauben die direkte Detektion von NO<sub>x</sub>-Komponenten, was Interferenzen vermeidet, die durch die Umwandlung von NO<sub>2</sub> in NO hervorgerufen werden. Messvergleiche zeigen aber, dass auch hier neben bekannten Problemen wie Reaktionen in den Einlassleitungen auch unerwartete Artefakte beobachtet werden können. Messvergleiche aber zeigen auch hier, dass neben bekannten Problemen wie Reaktionen in den Einlassleitungen auch unerwartete auftreten können. Um genaue und präzise NO<sub>x</sub> Messungen mit einer Vielzahl von NO<sub>x</sub>-Messsystemen in verschiedenen Stationen sicherzustellen, müssen neben der Standardisierung von Messprotokollen und Kalibrierungsverfahren auch an zentraler Stelle durch Messvergleiche und Auditierungen Unterschiede der verschiedenen Messverfahren dokumentiert werden.</p> <p>ACTRIS setzt sich aus central facilities (CFs) und national facilities (NFs) zusammen. Die NFs bilden den explorativen und beobachtenden Teil der Forschungsinfrastruktur. Die CFs sind von grundlegender Bedeutung für die Bereitstellung von harmonisierten und hochpräzisen Daten und stellen eine Vielzahl von Dienstleistungen zur Verfügung. Eines der CFs ist das Reactive Trace Gases In Situ Measurements (CiGas), das für die Überwachung der Datenqualität reaktiver Spurengase verantwortlich ist. Für die Qualitätssicherung (QA) und Qualitätskontrolle (QC) der Stickoxidmessungen an den NFs innerhalb von CiGas ist das Forschungszentrum Jülich (FZJ) zuständig, das auch das World Calibration Center (WCC) für Stickoxide im Global Atmosphere Watch (GAW) Netzwerk beheimatet. Seine Aufgaben umfassen i) die Verbindung von Spurengasmessungen von ACTRIS mit denen anderer Netzwerke, ii) die Beratung und Organisation von Schulungen, iii) die Bereitstellung von Mess- und Auswerteverfahren, iv) das Labelling und die Auditierung von NFs, v) die Implementierung neuer wissenschaftlicher und technologischer Entwicklungen.</p> <p>Es ist vorgesehen, bis 2025 ein zertifiziertes und funktionsfähiges Netzwerk von ACTRIS-Stationen aufzubauen. Es soll der wissenschaftlichen Gemeinschaft qualitativ hochwertige Daten liefern, die die Grundlage für fundierte Entscheidungen der politischen Entscheidungsträger bilden können.</p>

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