The HD(CP)2 Observational Prototype Experiment (HOPE) was performed as a major 2-month field experiment in Jülich, Germany, in April and May 2013, followed by a smaller campaign in Melpitz, Germany, ...in September 2013. HOPE has been designed to provide an observational dataset for a critical evaluation of the new German community atmospheric icosahedral non-hydrostatic (ICON) model at the scale of the model simulations and further to provide information on land-surface–atmospheric boundary layer exchange, cloud and precipitation processes, as well as sub-grid variability and microphysical properties that are subject to parameterizations. HOPE focuses on the onset of clouds and precipitation in the convective atmospheric boundary layer. This paper summarizes the instrument set-ups, the intensive observation periods, and example results from both campaigns. HOPE-Jülich instrumentation included a radio sounding station, 4 Doppler lidars, 4 Raman lidars (3 of them provide temperature, 3 of them water vapour, and all of them particle backscatter data), 1 water vapour differential absorption lidar, 3 cloud radars, 5 microwave radiometers, 3 rain radars, 6 sky imagers, 99 pyranometers, and 5 sun photometers operated at different sites, some of them in synergy. The HOPE-Melpitz campaign combined ground-based remote sensing of aerosols and clouds with helicopter- and balloon-based in situ observations in the atmospheric column and at the surface. HOPE provided an unprecedented collection of atmospheric dynamical, thermodynamical, and micro- and macrophysical properties of aerosols, clouds, and precipitation with high spatial and temporal resolution within a cube of approximately 10 × 10 × 10 km3. HOPE data will significantly contribute to our understanding of boundary layer dynamics and the formation of clouds and precipitation. The datasets have been made available through a dedicated data portal. First applications of HOPE data for model evaluation have shown a general agreement between observed and modelled boundary layer height, turbulence characteristics, and cloud coverage, but they also point to significant differences that deserve further investigations from both the observational and the modelling perspective.
Air quality measurements usually consist of ground-based instrumentation at fixed locations. However, vertical profiles of pollutants are of interest for understanding processes, distribution, ...dilution and concentration. Therefore, a multicopter system has been developed to investigate the vertical distribution of the concentration of aerosol particles, black carbon, ozone, nitrogen oxides (NOx) and carbon monoxide and the meteorological parameters of temperature and humidity. This article presents the requirements by different users, the setup of the quadrocopter system, the instrumentation and the results of first applications. The vertical distribution of particulate matter next to a highway was strongly related to atmospheric stratification, with different concentrations below and above the temperature inversion present in the morning. After the qualification phase described in this article, two identically equipped multicopters will be used upwind and downwind of line or diffuse sources such as highways or urban areas to quantify the influence of their emissions on the local air quality.
A unique data set derived from remote sensing, airborne, and
ground-based in situ measurements is presented. This measurement report
highlights the known complexity of comparing multiple aerosol ...optical
parameters examined with different approaches considering different states
of humidification and atmospheric aerosol concentrations. Mie-theory-based
modeled aerosol optical properties are compared with the respective results of airborne and ground-based in situ measurements and remote sensing (lidar and photometer) performed at the rural central European observatory at Melpitz, Germany. Calculated extinction-to-backscatter ratios (lidar ratios) were in the range of previously reported values. However, the lidar ratio is a function of the aerosol type and the relative humidity. The particle lidar ratio (LR) dependence on relative humidity was quantified and followed the trend found in previous studies. We present a fit function for the lidar wavelengths of 355, 532, and 1064 nm with an underlying equation of fLR(RH, γ(λ))=fLR(RH=0,λ)×(1-RH)-γ(λ), with the derived estimates of γ(355 nm) = 0.29 (±0.01), γ(532 nm) = 0.48 (±0.01), and γ(1064 nm) = 0.31 (±0.01) for central European aerosol. This parameterization might be used in the data analysis of elastic-backscatter lidar observations or lidar-ratio-based aerosol typing efforts. Our study shows that the used aerosol model could reproduce the in situ measurements of the aerosol particle light extinction coefficients (measured at dry conditions) within 13 %. Although the model reproduced the in situ measured aerosol particle light absorption coefficients within a reasonable range, we identified many sources for significant uncertainties in the simulations, such as the unknown aerosol mixing state, brown carbon (organic material) fraction, and the unknown aerosol mixing state wavelength-dependent refractive index. The modeled ambient-state aerosol particle light extinction and backscatter coefficients were smaller than the measured ones. However, depending on the prevailing aerosol conditions, an overlap of the uncertainty ranges of both approaches was achieved.
Airborne observations of vertical aerosol particle distributions are crucial
for detailed process studies and model improvements. Tethered balloon
systems represent a less expensive alternative to ...aircraft to probe shallow
atmospheric boundary layers (ABLs). This study presents the newly developed
cubic aerosol measurement platform (CAMP) for balloon-borne observations of
aerosol particle microphysical properties. With an edge length of 35 cm and a weight of 9 kg, the cube is an environmentally robust instrument platform intended for measurements at low temperatures, with a particular focus on applications in cloudy Arctic ABLs. The aerosol instrumentation on board CAMP
comprises two condensation particle counters with different lower detection
limits, one optical particle size spectrometer, and a miniaturized
absorption photometer. Comprehensive calibrations and characterizations of
the instruments were performed in laboratory experiments. The first field
study with a tethered balloon system took place at the Leibniz Institute for Tropospheric Research (TROPOS) station in Melpitz, Germany, in the winter of 2019. At ambient temperatures between −8 and 15 ∘C, the platform was operated up to a 1.5 km height on 14 flights under both clear-sky and cloudy conditions. The continuous aerosol observations at the ground station served as a reference for evaluating the CAMP measurements.
Exemplary profiles are discussed to elucidate the performance of the system
and possible process studies. Based on the laboratory instrument
characterizations and the observations during the field campaign, CAMP
demonstrated the capability to provide comprehensive aerosol particle
measurements in cold and cloudy ABLs.
This paper examines the representativeness of ground-based in situ measurements for the planetary boundary layer (PBL) and conducts a closure study between airborne in situ and ground-based lidar ...measurements up to an altitude of 2300 m. The related measurements were carried out in a field campaign within the framework of the High-Definition Clouds and Precipitation for Advancing Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE) in September 2013 in a rural background area of central Europe.The helicopter-borne probe ACTOS (Airborne Cloud and Turbulence Observation System) provided measurements of the aerosol particle number size distribution (PNSD), the aerosol particle number concentration (PNC), the number concentration of cloud condensation nuclei (CCN-NC), and meteorological atmospheric parameters (e.g., temperature and relative humidity). These measurements were supported by the ground-based 3+2 wavelength polarization lidar system PollyXT, which provided profiles of the particle backscatter coefficient (σbsc) for three wavelengths (355, 532, and 1064 nm). Particle extinction coefficient (σext) profiles were obtained by using a fixed backscatter-to-extinction ratio (also lidar ratio, LR). A new approach was used to determine profiles of CCN-NC for continental aerosol. The results of this new approach were consistent with the airborne in situ measurements within the uncertainties.In terms of representativeness, the PNSD measurements on the ground showed a good agreement with the measurements provided with ACTOS for lower altitudes. The ground-based measurements of PNC and CCN-NC are representative of the PBL when the PBL is well mixed. Locally isolated new particle formation events on the ground or at the top of the PBL led to vertical variability in the cases presented here and ground-based measurements are not entirely representative of the PBL. Based on Mie theory (Mie, 1908), optical aerosol properties under ambient conditions for different altitudes were determined using the airborne in situ measurements and were compared with the lidar measurements. The investigation of the optical properties shows that on average the airborne-based particle light backscatter coefficient is 50.1 % smaller for 1064 nm, 27.4 % smaller for 532 nm, and 29.5 % smaller for 355 nm than the measurements of the lidar system. These results are quite promising, since in situ measurement-based Mie calculations of the particle light backscattering are scarce and the modeling is quite challenging. In contrast, for the particle light extinction coefficient we found a good agreement. The airborne-based particle light extinction coefficient was just 8.2 % larger for 532 nm and 3 % smaller for 355 nm, for an assumed LR of 55 sr. The particle light extinction coefficient for 1064 nm was derived with a LR of 30 sr. For this wavelength, the airborne-based particle light extinction coefficient is 5.2 % smaller than the lidar measurements. For the first time, the lidar ratio of 30 sr for 1064 nm was determined on the basis of in situ measurements and the LR of 55 sr for 355 and 532 nm wavelength was reproduced for European continental aerosol on the basis of this comparison. Lidar observations and the in situ based aerosol optical properties agree within the uncertainties. However, our observations indicate that a determination of the PNSD for a large size range is important for a reliable modeling of aerosol particle backscattering.
Measuring vertical profiles of the particle light-absorption coefficient by
using absorption photometers may face the challenge of fast changes in
relative humidity (RH). These absorption photometers ...determine the particle light-absorption coefficient due to a change in light attenuation through a
particle-loaded filter. The filter material, however, takes up or releases
water with changing relative humidity (RH in %), thus influencing the light
attenuation. A sophisticated set of laboratory experiments was therefore conducted to
investigate the effect of fast RH changes (dRH ∕ dt) on the particle light-absorption coefficient (σabs in Mm−1) derived with two
absorption photometers. The RH dependence was examined based on different
filter types and filter loadings with respect to loading material and
areal loading density. The Single Channel Tricolor Absorption Photometer (STAP)
relies on quartz-fiber filter, and the microAeth® MA200 is
based on a polytetrafluoroethylene (PTFE) filter band. Furthermore, three
cases were investigated: clean filters, filters loaded with black carbon (BC),
and filters loaded with ammonium sulfate. The filter areal loading densities
(ρ*) ranged from 3.1 to 99.6 mg m−2 in the case of the STAP and
ammonium sulfate and 1.2 to 37.6 mg m−2 in the case the MA200.
Investigating BC-loaded cases, ρBC* was in the range of 2.9 to
43.0 and 1.1 to 16.3 mg m−2 for the STAP and MA200, respectively. Both instruments revealed opposing responses to relative humidity changes
(ΔRH) with different magnitudes. The STAP shows a linear dependence on
relative humidity changes. The MA200 is characterized by a distinct
exponential recovery after its filter was exposed to relative humidity
changes. At a wavelength of 624 nm and for the default 60 s running
average output, the STAP reveals an absolute change in σabs per absolute change of RH (Δσabs∕ΔRH) of 0.14 Mm−1 %−1 in the clean case, 0.29 Mm−1 %−1 in the case of BC-loaded filters, and 0.21 Mm−1 %−1 in the case filters loaded
with ammonium sulfate. The 60 s running average of the particle light-absorption coefficient at 625 nm measured with the MA200 revealed a response
of around −0.4 Mm−1 %−1 for all three cases. Whereas the
response of the STAP varies over the different loading materials, in
contrast, the MA200 was quite stable. The response was, for the STAP, in the
range of 0.17 to 0.24 Mm−1 %−1 and,
in the case of ammonium sulfate loading and in the BC-loaded case, 0.17 to 0.62 Mm−1 %−1. In the
ammonium sulfate case, the minimum response shown by the MA200 was −0.42 with a maximum of −0.36 Mm−1 %−1 and a minimum of −0.42 and maximum −0.37 Mm−1 %−1 in the case of BC. A linear correction function for the STAP was developed here. It is provided
by correlating 1 Hz resolved recalculated particle light-absorption
coefficients and RH change rates. The linear response is estimated at 10.08 Mm−1 s−1 %−1. A correction approach for the MA200 is also
provided; however, the behavior of the MA200 is more complex. Further
research and multi-instrument measurements have to be conducted to fully
understand the underlying processes, since the correction approach resulted
in different correction parameters across various experiments. However, the
exponential recovery after the filter of the MA200 experienced a RH change
could be reproduced. However, the given correction approach has to be
estimated with other RH sensors as well, since each sensor has a different
response time. And, for the given correction approaches, the uncertainties
could not be estimated, which was mainly due to the response time of the RH sensor.
Therefore, we do not recommend using the given approaches. But they
point in the right direction, and despite the imperfections, they are useful for at least estimating the measurement uncertainties due to relative humidity changes. Due to our findings, we recommend using an aerosol dryer upstream of
absorption photometers to reduce the RH effect significantly. Furthermore, when absorption photometers are used in vertical measurements, the ascending or
descending speed through layers of large relative humidity gradients has to be low to
minimize the observed RH effect. But this is simply not possible in some
scenarios, especially in unmixed layers or clouds. Additionally, recording
the RH of the sample stream allows correcting for the bias during post-processing of the data. This data correction leads to reasonable results,
according to the given example in this study.
The HD - an overview Macke, Andreas; Seifert, Patric; Baars, Holger ...
Atmospheric chemistry and physics,
04/2017, Letnik:
17, Številka:
7
Journal Article
Recenzirano
The HD(CP).sup.2 Observational Prototype Experiment (HOPE) was performed as a major 2-month field experiment in Jülich, Germany, in April and May 2013, followed by a smaller campaign in Melpitz, ...Germany, in September 2013. HOPE has been designed to provide an observational dataset for a critical evaluation of the new German community atmospheric icosahedral non-hydrostatic (ICON) model at the scale of the model simulations and further to provide information on land-surface-atmospheric boundary layer exchange, cloud and precipitation processes, as well as sub-grid variability and microphysical properties that are subject to parameterizations. HOPE focuses on the onset of clouds and precipitation in the convective atmospheric boundary layer. This paper summarizes the instrument set-ups, the intensive observation periods, and example results from both campaigns. HOPE-Jülich instrumentation included a radio sounding station, 4Â Doppler lidars, 4Â Raman lidars (3Â of them provide temperature, 3Â of them water vapour, and all of them particle backscatter data), 1 water vapour differential absorption lidar, 3Â cloud radars, 5Â microwave radiometers, 3Â rain radars, 6Â sky imagers, 99Â pyranometers, and 5Â sun photometers operated at different sites, some of them in synergy. The HOPE-Melpitz campaign combined ground-based remote sensing of aerosols and clouds with helicopter- and balloon-based in situ observations in the atmospheric column and at the surface. HOPE provided an unprecedented collection of atmospheric dynamical, thermodynamical, and micro- and macrophysical properties of aerosols, clouds, and precipitation with high spatial and temporal resolution within a cube of approximately 10 Ã 10 Ã 10 km.sup.3 . HOPE data will significantly contribute to our understanding of boundary layer dynamics and the formation of clouds and precipitation. The datasets have been made available through a dedicated data portal. First applications of HOPE data for model evaluation have shown a general agreement between observed and modelled boundary layer height, turbulence characteristics, and cloud coverage, but they also point to significant differences that deserve further investigations from both the observational and the modelling perspective.
Aerosol particles directly influence the radiative transfer within the atmosphere by scattering and absorption of solar radiation and indirectly in their role as cloud condensation nuclei (CCN). The ...influence is subject to uncertainties, which can be reduced by a better understanding of their vertical distribution. The vertical aerosol distribution can be determined by airborne in-situ measurements, e.g., helicopter-borne probes, and ground-based remote sensing methods, e.g., lidar. Using algorithms with underlying assumptions and simplifications, physical and optical aerosol properties can be retrieved from lidar measurements. These derived aerosol properties, such as the CCN number concentration (NCCN), can be validated using direct in-situ measurements. In addition, the optical properties underlying the retrieval algorithms can be validated using Mie theory-based modeling. However, here the ambient humidity of the aerosol must be considered since the hygroscopic growth of the aerosol particles changes their optical properties.
In the frame of this dissertation, three peer-reviewed scientific papers were published. The goals were to validate lidar-retrieval-based aerosol properties like NCCN, identify sources of uncertainty in Mie theory-based validation studies, and improve the quality of in-situ measurements, such as those of the aerosol particle light absorption coefficient conducted with filter-based absorption photometers.
To this end, a Mie theory-based model was developed to calculate aerosol particles' optical properties in the dry and ambient states. The model input parameters were determined with sophisticated instrumentation deployed on the ground and within airborne measurement platforms during three conducted field campaigns. Lidar-based NCCN and the model were compared with corresponding direct in-situ measurements of aerosol optical and microphysical properties with satisfactory results. Sources of deviations concerning the modeled aerosol particle light absorption were identified; among others, the assumed aerosol mixing state and the consideration of light-absorbing organic aerosol components are key parameters. In addition, the representation of aerosol hygroscopicity in the model was investigated based on different measurement techniques. Possible further sources of uncertainty regarding the comparison with aerosol optical properties measured by lidar were discussed.
Regarding the aerosol particle light extinction-to-backscatter ratio, also known as the lidar ratio, the dependence on the ambient relative humidity is shown for the first time by employing in-situ measurements and the developed Mie model. A corresponding parameterization was determined. Previous theoretical considerations from other studies were qualitatively confirmed. In addition, the lidar ratio was determined for the first time based on airborne in-situ measurements for the light of wavelength 1064 nm.
Also, employing a laboratory study, the influence of rapid changes in relative humidity on filter-based absorption photometers was quantified. Surprisingly, an opposite effect was observed for two different filter materials. First approaches to correct the observed humidity effect were provided using two parameterizations. The findings are crucial, especially in environments with low aerosol particle light absorption, because the effect can exceed the measured values.
The results of this work are an important contribution to the improvement, interpretation, and application of the vertical measurement of aerosol properties.:List of Figures I
List of Tables I
List of Acronyms II
List of Symbols IV
1 Introduction 1
2 Theoretical background 5
2.1 Aerosol particles 5
2.1.1 Microphysical properties 5
2.1.2 Aerosol optical properties 8
2.1.3 Aerosol particles under humidified conditions 11
2.2 Lidar theory 11
2.3 Filter-based aerosol particle light absorption measurements and eBC mass concentration 15
2.4 Mie theory 17
3 Methodology 19
3.1 Measurement site 19
3.2 Mie-model 20
3.3 Field campaign instrumentation 20
3.3.1 Aerosol microphysical properties 22
3.3.2 Aerosol Hygroscopicity and complex refractive index 22
3.3.3 Aerosol optical properties 24
3.4 Filter-based particle light absorption measurements and RH 24
4 Results and Discussion 27
4.1 First publication 27
4.1.1 Re-usage of parts of Master thesis 27
4.1.2 Helicopter-borne observations of continental background aerosol in combination with remote sensing and ground-based measurements 27
4.2 Second publication 57
4.2.1 The effect of rapid relative humidity changes on filter-based aerosol-particle light-absorption measurements: uncertainties and correction schemes 57
4.3 Third publication 75
4.3.1 Measurement report: Comparison of airborne, in situ measured, lidar-based, and modeled aerosol optical properties in the central European background – identifying sources of deviations 75
4.3.2 Supplementary material of “Measurement report: Comparison of airborne, in situ measured, lidar-based, and modeled aerosol optical properties in the central European background – identifying sources of deviations” 105
5 Summary, Conclusions, and Outlook 117
Appendix A 121
Bibliography 123
Acknowledgments i
Declaration of Independence iii
Aerosolpartikel beeinflussen den Strahlungstransport in der Atmosphäre durch Streuung und Absorption von solarer Strahlung direkt und indirekt in ihrer Wirkung als Wolkenkondensationskerne (CCN, cloud condensation nuclei). Der Einfluss ist mit Unsicherheiten behaftet, welche unter anderem durch ein besseres Verständnis über deren vertikale Verteilung reduziert werden kann. Die vertikale Verteilung der Aerosole kann mittels luftgetragener in-situ Messungen, z.B. mit helikoptergetragenen Sonden, und bodengebundener Fernerkundungsmethoden, z.B. Lidar, bestimmt werden. Mittels verschiedener Algorithmen, denen jedoch diverse Annahmen und Vereinfachungen zu Grunde liegen, können aus Lidarmessungen mikrophysikalische und optische Aerosoleigenschaften abgeleitet werden. Mittels direkter Messungen können diese abgeleiteten Aerosoleigenschaften, wie z.B. die CCN Anzahlkonzentration (NCCN), überprüft werden. Zudem können die, den Ableitungsalgorithmen zu Grunde liegenden, optischen Eigenschaften mittels Mie-Theorie basierter Modellierung validiert werden. Die Umgebungsfeuchte des Aerosols muss dabei jedoch berücksichtig werden, da auf Grund des hygroskopischen Wachstums die optischen Eigenschaften von Aerosolpartikeln verändert werden.
Im Rahmen dieser Dissertation wurden drei begutachteten wissenschaftlichen Artikel publiziert. Die Ziele waren aus Lidarretrievals abgeleitete Aerosolgrößen wie z.B. NCCN zu validieren, Unsicherheitsquellen in Mie-Theorie basierten Validierungsstudien zu identifizieren und die Qualität von in-situ Messungen, wie z.B. die des Lichtabsorptionskoeffizienten von Aerosolpartikeln mittels filterbasierter Absorptionsphotometern, zu steigern.
Dazu wurde ein Mie-Theorie basiertes Model entwickelt, welches die optischen Eigenschaften von Aerosolpartikeln im trockenen und Umgebungszustand berechnen kann. Dessen Eingangsparameter wurden mit hochqualitativen Messungen am Boden und in der Luft während dreier Feldkampagnen ermittelt. Korrespondierende in-situ Messungen am Boden und in der Luft verifizierten neben Lidar-basierten NCCN die Modelqualität mit zufriedenstellendem Resultat. Bezüglich der Aerosolpartikellichtabsorption konnte die Wichtigkeit des angenommen Aerosolmischungszustandes und der Berücksichtigung von lichtabsorbierenden organischen Aerosolkomponenten identifiziert werden. Zudem wurde die Repräsentierung der Aerosolhygroskopizität im Model auf Grundlage von verschiedenen Messtechniken untersucht. Mögliche weitere Unsicherheitsquellen bezüglich des Vergleiches mit den von Lidar gemessenen optischen Aerosoleigenschaften wurden diskutiert.
Bezüglich des Lichtextinktions-zu-Rückstreuverhältnisses von Aerosolpartikeln, auch Lidarverhältnis (LR), konnte erstmals mit in-situ Messungen und dem entwickelten Mie-Model die Abhängigkeit dieses Parameters gegenüber der relativen Umgebungsfeuchte gezeigt und parametrisiert werden. Theoretische Betrachtungen aus vorherigen Studien wurden qualitativ bestätigt. Auf Basis von luftgetragenen in-situ Messungen konnte erstmalig das LR für Licht der Wellenlänge 1064 nm bestimmt werden.
Mittels einer Laborstudie konnte der Einfluss von schnellen Änderungen der relativen Feuchte auf filterbasierte Absorptionsphotometer quantifiziert werden. Überraschenderweise zeigten zwei verschieden Filtermaterialen ein gegensätzlicher Effekt. Erste Ansätze zu der Korrektur des Feuchteeffekts wurden mit zwei Parametrisierungen geliefert. Gerade in Umgebungen mit niedriger Lichtabsorption durch Aerosol kann dies wichtig sein, da der Effekt die Messwerte übersteigen kann.
Die Ergebnisse diese Arbeit sind ein wichtiger Beitrag zur Verbesserung, Interpretation und Anwendung vertikaler Messungen von Aerosoleigenschaften.:List of Figures I
List of Tables I
List of Acronyms II
List of Symbols IV
1 Introduction 1
2 Theoretical background 5
2.1 Aerosol particles 5
2.1.1 Microphysical properties 5
2.1.2 Aerosol optical properties 8
2.1.3 Aerosol particles under humidified conditions 11
2.2 Lidar theory 11
2.3 Filter-based aerosol particle light absorption measurements and eBC mass concentration 15
2.4 Mie theory 17
3 Methodology 19
3.1 Measurement site 19
3.2 Mie-model 20
3.3 Field campaign instrumentation 20
3.3.1 Aerosol microphysical properties 22
3.3.2 Aerosol Hygroscopicity and complex refractive index 22
3.3.3 Aerosol optical properties 24
3.4 Filter-based particle light absorption measurements and RH 24
4 Results and Discussion 27
4.1 First publication 27
4.1.1 Re-usage of parts of Master thesis 27
4.1.2 Helicopter-borne observations of continental background aerosol in combination with remote sensing and ground-based measurements 27
4.2 Second publication 57
4.2.1 The effect of rapid relative humidity changes on filter-base
Im Rahmen eines Forschungsvorhabens wurden die Einflüsse von Ozon und meteorologischen Bedingungen sowie verschiedenen Maßnahmen auf die NO2-Konzentrationen in der Außenluft an ausgewählten ...sächsischen Luftgüte-Messstationen untersucht. Für die statistische Analyse wurde das Verfahren „boosted regression trees“ angewendet. Die Broschüre richtet sich an Fachbehörden und Wissenschaftler, die sich mit der Analyse und Überwachung der Luftgüte beschäftigen.
Redaktionsschluss: 22.01.2020
Aim
Inflammation and calcification are hallmarks in the development of aortic valve stenosis (AVS). Ceramides mediate inflammation and calcification in the vascular tissue. The highly abundant ...d18:1,16:0 ceramide (C16) has been linked to increased cardiovascular mortality and obesity. In this study, we investigate the role of ceramide synthase 5 (CerS5), a critical enzyme for C16 ceramide synthesis, in the development of AVS, particularly in conjunction with a high‐fat/high‐cholesterol diet (Western diet, WD).
Methods
We used wild‐type (WT) and CerS5−/− mice on WD or normal chow in a wire injury model. We measured the peak velocity to determine AVS development and performed histological analysis of the aortic valve area, immune cell infiltration (CD68 staining), and calcification (von Kossa). In vitro experiments involved measuring the calcification of human aortic valvular interstitial cells (VICs) and evaluating cytokine release from THP‐1 cells, a human leukemia monocytic‐like cell line, following CerS5 knockdown.
Results
CerS5−/− mice showed a reduced peak velocity compared to WT only in the experiment with WD. Likewise, we observed reduced immune cell infiltration and calcification in the aortic valve of CerS5−/− mice, but only on WD. In vitro, calcification was reduced after knockdown of CerS5 in VICs, while THP‐1 cells exhibited a decreased inflammatory response following CerS5 knockdown.
Conclusion
We conclude that CerS5 is an important mediator for the development of AVS in mice on WD and regulates critical pathophysiological hallmarks of AVS formation. CerS5 is therefore an interesting target for pharmacological therapy and merits further investigation.
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