Aerosol and Cloud Changes during the Corona Lockdown in 2020 – First highlights from the BLUESKY campaign

2021 ◽  
Author(s):  
Christiane Voigt ◽  
Jos Lelieveld ◽  
Hans Schlager ◽  
Johannes Schneider ◽  
Daniel Sauer ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Composition ◽  
Data Set ◽  
The North ◽  
Aerosol Mass ◽  
Trace Species ◽  
Research Aircraft ◽  
Fine Mode ◽  
Cloud Modeling ◽  
Fine Mode Aerosol

<p>Worldwide regulations to control the COVID-19 pandemic caused significant reductions in ground and airborne transportation in spring 2020. This unprecedented situation provided the unique opportunity to directly measure the less perturbed atmosphere, notably near the tropopause, and derive the effects of anthropogenic emissions on atmospheric composition, aerosol, clouds and climate. These changes were investigated during the BLUESKY experiment by the two research aircraft HALO and the DLR Falcon, satellite observations and models. From 16 May to 9 June 2020, the two research aircraft performed 20 flights over Europe and the North Atlantic. Profiles of trace species were measured with an advanced in-situ trace gas, aerosol and cloud payload from the boundary layer to 14 km altitude. Here, we present an overview and selected highlights of the BLUESKY experiment. Continental aerosol profiles show significant reductions in aerosol mass in the boundary layer. The reduced aerosol optical thickness above Germany has also been detected by MODIS and its impact on the colour of the sky is investigated. A specific focus was the detection of aerosol and cirrus changes caused by up to 90% reductions in air traffic. We find reductions in fine mode aerosol in the UTLS at various levels compared to CARIBIC data. In addition, we derive reductions in contrail and cirrus cover using passive and active remote sensing from satellite combined with cloud modeling. The comprehensive data set acquired during the 2020 lockdown period allows better understanding and constraining the anthropogenic influence on the composition of the atmosphere and its impacts on air quality and climate.</p>

scholarly journals The North Atlantic Marine Boundary Layer Experiment(NAMBLEX). Overview of the campaign held at Mace Head, Ireland, in summer 2002

2006 ◽  
Vol 6 (8) ◽  
pp. 2241-2272 ◽  
Author(s):  
D. E. Heard ◽  
K. A. Read ◽  
J. Methven ◽  
S. Al-Haider ◽  
W. J. Bloss ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
Numerical Models ◽  
Measurement Data ◽  
Air Mass ◽  
The North ◽  
Trace Species ◽  
Wide Range ◽  
The North Atlantic

Abstract. The North Atlantic Marine Boundary Layer Experiment (NAMBLEX), involving over 50 scientists from 12 institutions, took place at Mace Head, Ireland (53.32° N, 9.90° W), between 23 July and 4 September 2002. A wide range of state-of-the-art instrumentation enabled detailed measurements of the boundary layer structure and atmospheric composition in the gas and aerosol phase to be made, providing one of the most comprehensive in situ studies of the marine boundary layer to date. This overview paper describes the aims of the NAMBLEX project in the context of previous field campaigns in the Marine Boundary Layer (MBL), the overall layout of the site, a summary of the instrumentation deployed, the temporal coverage of the measurement data, and the numerical models used to interpret the field data. Measurements of some trace species were made for the first time during the campaign, which was characterised by predominantly clean air of marine origin, but more polluted air with higher levels of NOx originating from continental regions was also experienced. This paper provides a summary of the meteorological measurements and Planetary Boundary Layer (PBL) structure measurements, presents time series of some of the longer-lived trace species (O3, CO, H2, DMS, CH4, NMHC, NOx, NOy, PAN) and summarises measurements of other species that are described in more detail in other papers within this special issue, namely oxygenated VOCs, HCHO, peroxides, organo-halogenated species, a range of shorter lived halogen species (I2, OIO, IO, BrO), NO3 radicals, photolysis frequencies, the free radicals OH, HO2 and (HO2+Σ RO2), as well as a summary of the aerosol measurements. NAMBLEX was supported by measurements made in the vicinity of Mace Head using the NERC Dornier-228 aircraft. Using ECMWF wind-fields, calculations were made of the air-mass trajectories arriving at Mace Head during NAMBLEX, and were analysed together with both meteorological and trace-gas measurements. In this paper a chemical climatology for the duration of the campaign is presented to interpret the distribution of air-mass origins and emission sources, and to provide a convenient framework of air-mass classification that is used by other papers in this issue for the interpretation of observed variability in levels of trace gases and aerosols.

scholarly journals Ammonia in the summertime Arctic marine boundary layer: sources, sinks, and implications

2016 ◽  
Vol 16 (4) ◽  
pp. 1937-1953 ◽  
Author(s):  
Gregory R. Wentworth ◽  
Jennifer G. Murphy ◽  
Betty Croft ◽  
Randall V. Martin ◽  
Jeffrey R. Pierce ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Transport Model ◽  
Canadian Arctic ◽  
Atmospheric Composition ◽  
Chemical Transport Model ◽  
Data Set ◽  
Baffin Bay ◽  
Melt Ponds ◽  
Ambient Nh3 ◽  
The Impact

Abstract. Continuous hourly measurements of gas-phase ammonia (NH3(g)) were taken from 13 July to 7 August 2014 on a research cruise throughout Baffin Bay and the eastern Canadian Arctic Archipelago. Concentrations ranged from 30 to 650 ng m−3 (40–870 pptv) with the highest values recorded in Lancaster Sound (74°13′ N, 84°00′ W). Simultaneous measurements of total ammonium ([NHx]), pH and temperature in the ocean and in melt ponds were used to compute the compensation point (χ), which is the ambient NH3(g) concentration at which surface–air fluxes change direction. Ambient NH3(g) was usually several orders of magnitude larger than both χocean and χMP (< 0.4–10 ng m3) indicating these surface pools are net sinks of NH3. Flux calculations estimate average net downward fluxes of 1.4 and 1.1 ng m−2 s−1 for the open ocean and melt ponds, respectively. Sufficient NH3(g) was present to neutralize non-sea-salt sulfate (nss-SO42−) in the boundary layer during most of the study. This finding was corroborated with a historical data set of PM2.5 composition from Alert, Nunavut (82°30′ N, 62°20′ W) wherein the median ratio of NH4+/nss-SO42− equivalents was greater than 0.75 in June, July and August. The GEOS-Chem chemical transport model was employed to examine the impact of NH3(g) emissions from seabird guano on boundary-layer composition and nss-SO42− neutralization. A GEOS-Chem simulation without seabird emissions underestimated boundary layer NH3(g) by several orders of magnitude and yielded highly acidic aerosol. A simulation that included seabird NH3 emissions was in better agreement with observations for both NH3(g) concentrations and nss-SO42− neutralization. This is strong evidence that seabird colonies are significant sources of NH3 in the summertime Arctic, and are ubiquitous enough to impact atmospheric composition across the entire Baffin Bay region. Large wildfires in the Northwest Territories were likely an important source of NH3, but their influence was probably limited to the Central Canadian Arctic. Implications of seabird-derived N-deposition to terrestrial and aquatic ecosystems are also discussed.

scholarly journals Interannual and seasonal variations in aerosol optical depth of the atmosphere in two regions of Spitsbergen Archipelago (2002–2018)

2020 ◽  
Author(s):  
Dmitry M. Kabanov ◽  
Christoph Ritter ◽  
Sergey M. Sakerin
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Wave Spectrum ◽  
Short Wave ◽  
The Arctic ◽  
Data Set ◽  
Fine Mode ◽  
European Arctic ◽  
Highly Correlated ◽  
Fine Mode Aerosol

Abstract. In this work hourly averaged sun photometer data from the sites Barentsburg and Ny-Ålesund, both located in Spitsbergen in the European Arctic, are compared. Our data set comprises the years 2011 to 2017. We found for more turbid periods (aerosol optical depth τ0.5 > 0.1) that typically Barentsburg is more polluted than Ny-Ålesund, especially in the short wave spectrum. However, the diurnal variation of AOD is highly correlated. Next, τ was divided into a fine and coarse mode. It was found that generally the fine mode aerosol optical depth dominates and also shows a larger interannual as inner annual variation. Tau fine τf is in fact larger in spring during the Arctic Haze period. Overall the aerosol optical depth seems to decrease, although this is not statistically significant.

scholarly journals Closure study between chemical composition and hygroscopic growth of aerosol particles during TORCH2

2007 ◽  
Vol 7 (24) ◽  
pp. 6131-6144 ◽  
Author(s):  
M. Gysel ◽  
J. Crosier ◽  
D. O. Topping ◽  
J. D. Whitehead ◽  
K. N. Bower ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Aerosol Particles ◽  
Residence Times ◽  
Hygroscopic Growth ◽  
Data Set ◽  
Composition Data ◽  
The North ◽  
Aerosol Mass ◽  
Hygroscopic Properties ◽  
Evaporation Losses

Abstract. Measurements of aerosol properties were made in aged polluted and clean background air masses encountered at the North Norfolk (UK) coastline as part of the TORCH2 field campaign in May 2004. Hygroscopic growth factors (GF) at 90% relative humidity (RH) for D0=27–217 nm particles and size-resolved chemical composition were simultaneously measured using a Hygroscopicity Tandem Differential Mobility Analyser (HTDMA) and an Aerodyne aerosol mass spectrometer (Q-AMS), respectively. Both hygroscopic properties and chemical composition showed pronounced variability in time and with particles size. With this data set we could demonstrate that the Zdanovskii-Stokes-Robinson (ZSR) mixing rule combined with chemical composition data from the AMS makes accurate quantitative predictions of the mean GF of mixed atmospheric aerosol particles possible. In doing so it is crucial that chemical composition data are acquired with high resolution in both particle size and time, at least matching the actual variability of particle properties. The closure results indicate an ensemble GF of the organic fraction of ~1.20±0.10 at 90% water activity. Thus the organics contribute somewhat to hygroscopic growth, particularly at small sizes, however the inorganic salts still dominate. Furthermore it has been found that most likely substantial evaporation losses of NH4NO3 occurred within the HTDMA instrument, exacerbated by a long residence time of ~1 min. Such an artefact is in agreement with our laboratory experiments and literature data for pure NH4NO3, both showing similar evaporation losses within HTDMAs with residence times of ~1 min. Short residence times and low temperatures are hence recommended for HTDMAs in order to minimise such evaporation artefacts.

scholarly journals The North Atlantic Marine Boundary Layer Experiment (NAMBLEX). Overview of the campaign held at Mace Head, Ireland, in summer 2002

2005 ◽  
Vol 5 (6) ◽  
pp. 12177-12254 ◽  
Author(s):  
D. E. Heard ◽  
K. A. Read ◽  
J. Methven ◽  
S. Al-Haider ◽  
W. J. Bloss ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
Numerical Models ◽  
Measurement Data ◽  
Air Mass ◽  
The North ◽  
Trace Species ◽  
Wide Range ◽  
The North Atlantic

Abstract. The North Atlantic Marine Boundary Layer Experiment (NAMBLEX), involving over 50 scientists from 12 institutions, took place at Mace Head, Ireland (53.32° N, 9.90° W), between 23 July and 4 September 2002. A wide range of state-of-the-art instrumentation enabled detailed measurements of the boundary layer structure and atmospheric composition in the gas and aerosol phase to be made, providing one of the most comprehensive in situ studies of the marine boundary layer to date. This overview paper describes the aims of the NAMBLEX project in the context of previous field campaigns in the Marine Boundary Layer (MBL), the overall layout of the site, a summary of the instrumentation deployed, the temporal coverage of the measurement data, and the numerical models used to interpret the field data. Measurements of some trace species were made for the first time during the campaign, which was characterised by predominantly clean air of marine origin, but more polluted air with higher levels of NOx originating from continental regions was also experienced. This paper provides a summary of the meteorological measurements and Planetary Boundary Layer (PBL) structure measurements, presents time series of some of the longer-lived trace species (O3, CO, H2, DMS, CH4, NMHC, NOx, NOy, PAN) and summarises measurements of other species that are described in more detail in other papers within this special issue, namely oxygenated VOCs, HCHO, peroxides, organo-halogenated species, a range of shorter lived halogen species (I2, OIO, IO, BrO), NO3 radicals, photolysis frequencies, the free radicals OH, HO2 and (HO2+ΣRO2), as well as a summary of the aerosol measurements. NAMBLEX was supported by measurements made in the vicinity of Mace Head using the NERC Dornier-228 aircraft. Using ECMWF wind-fields, calculations were made of the air-mass trajectories arriving at Mace Head during NAMBLEX, and were analysed together with both meteorological and trace-gas measurements. In this paper a chemical climatology is presented to interpret the distribution of air-mass origins and emission sources, and to provide a convenient framework of air-mass classification that is used by other papers in this issue for the interpretation of observed variability in levels of trace gases and aerosols.

scholarly journals Observations and hypotheses related to low to middle free tropospheric aerosol, water vapor and altocumulus cloud layers within convective weather regimes: a SEAC<sup>4</sup>RS case study

2019 ◽  
Vol 19 (17) ◽  
pp. 11413-11442
Author(s):  
Jeffrey S. Reid ◽  
Derek J. Posselt ◽  
Kathleen Kaku ◽  
Robert A. Holz ◽  
Gao Chen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Water Vapor ◽  
Atmospheric Composition ◽  
High Spectral Resolution ◽  
Aerosol Layer ◽  
In Situ Data ◽  
Tropospheric Aerosol ◽  
Entrainment Zone ◽  
Research Aircraft ◽  
Cumulus Congestus

Abstract. The NASA Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) project included goals related to aerosol particle life cycle in convective regimes. Using the University of Wisconsin High Spectral Resolution Lidar system at Huntsville, Alabama, USA, and the NASA DC-8 research aircraft, we investigate the altitude dependence of aerosol, water vapor and Altocumulus (Ac) properties in the free troposphere from a canonical 12 August 2013 convective storm case as a segue to a presentation of a mission-wide analysis. It stands to reason that any moisture detrainment from convection must have an associated aerosol layer. Modes of covariability between aerosol, water vapor and Ac are examined relative to the boundary layer entrainment zone, 0 ∘C level, and anvil, a region known to contain Ac clouds and a complex aerosol layering structure (Reid et al., 2017). Multiple aerosol layers in regions warmer than 0 ∘C were observed within the planetary boundary layer entrainment zone. At 0 ∘C there is a proclivity for aerosol and water vapor detrainment from storms, in association with melting level Ac shelves. Finally, at temperatures colder than 0 ∘C, weak aerosol layers were identified above Cumulus congestus tops (∼0 and ∼-20 ∘C). Stronger aerosol signals return in association with anvil outflow. In situ data suggest that detraining particles undergo aqueous-phase or heterogeneous chemical or microphysical transformations, while at the same time larger particles are being scavenged at higher altitudes leading to enhanced nucleation. We conclude by discussing hypotheses regarding links to aerosol emissions and potential indirect effects on Ac clouds.

scholarly journals ACE-FTS measurements of trace species in the characterization of biomass burning plumes

2011 ◽  
Vol 11 (23) ◽  
pp. 12169-12179 ◽  
Author(s):  
K. A. Tereszchuk ◽  
G. González Abad ◽  
C. Clerbaux ◽  
D. Hurtmans ◽  
P.-F. Coheur ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Atmospheric Composition ◽  
Fourier Transform Spectrometer ◽  
Free Troposphere ◽  
Convective Processes ◽  
Trace Species ◽  
Chemistry Experiment

Abstract. To further our understanding of the effects of biomass burning emissions on atmospheric composition, we report measurements of trace species in biomass burning plumes made by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) instrument on the SCISAT-1 satellite. An extensive set of 15 molecules, C2H2, C2H6, CH3OH, CH4, CO, H2CO, HCN, HCOOH, HNO3, NO, NO2, N2O5, O3, OCS and SF6 are used in our analysis. Even though most biomass burning smoke is typically confined to the boundary layer, some of these emissions are injected directly into the free troposphere via fire-related convective processes and transported away from the emission source. Further knowledge of the aging of biomass burning emissions in the free troposphere is needed. Tracer-tracer correlations are made between known pyrogenic species in these plumes in an effort to characterize them and follow their chemical evolution. Criteria such as age and type of biomass material burned are considered.

scholarly journals Interannual and seasonal variations in the aerosol optical depth of the atmosphere in two regions of Spitsbergen (2002–2018)

2020 ◽  
Vol 13 (10) ◽  
pp. 5303-5317
Author(s):  
Dmitry M. Kabanov ◽  
Christoph Ritter ◽  
Sergey M. Sakerin
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
The Arctic ◽  
Data Set ◽  
Arctic Haze ◽  
Fine Mode ◽  
European Arctic ◽  
Sun Photometer ◽  
Highly Correlated ◽  
Fine Mode Aerosol

Abstract. In this work, hourly averaged sun photometer data from Barentsburg and Ny-Ålesund, both located on Spitsbergen in the European Arctic, are compared. Our data set comprises the years from 2002 to 2018 with overlapping measurements from both sites during the period from 2011 to 2018. For more turbid periods (aerosol optical depth, AOD, τ0.5>0.1), we found that Barentsburg is typically more polluted than Ny-Ålesund, especially in the shortwave spectrum. However, the diurnal variation in the AOD is highly correlated. Next, τ was divided into a fine and coarse mode. It was found that the fine-mode aerosol optical depth generally dominates and also shows a larger interannual than seasonal variation. The fine-mode optical depth is in fact largest in spring during the Arctic haze period. Overall the aerosol optical depth seems to decrease (at 500 nm the fine-mode optical depth decreased by 0.016 over 10 years), although this is hardly statistically significant.

scholarly journals A Study of the Forcing of the 22–25 June 2006 Coastally Trapped Wind Reversal Based on Numerical Simulations and Aircraft Observations

2008 ◽  
Vol 136 (12) ◽  
pp. 4687-4708 ◽  
Author(s):  
David A. Rahn ◽  
Thomas R. Parish
Keyword(s):  
Boundary Layer ◽  
Numerical Simulations ◽  
Marine Boundary Layer ◽  
Density Contrast ◽  
Maximum Speed ◽  
The North ◽  
Coastal Fog ◽  
Research Aircraft ◽  
Forcing Mechanisms ◽  
The University

Abstract Coastally trapped wind reversals (CTWRs) occur periodically in the lowest several hundred meters of the marine boundary layer west of California and disrupt the northerly flow that typically occurs during summer. South winds and coastal fog or low stratus accompany the CTWR, which propagates northward along the coast. A CTWR was observed off the California coast during late June 2006 that originated in the California Bight and propagated northward to Cape Mendocino during the subsequent 2-day period. This CTWR event was explored by the University of Wyoming King Air research aircraft to document the primary characteristics of the wind reversal. Numerical simulations of the CTWR event using the Weather Research and Forecast modeling system were conducted to compare with observations and to provide a broader picture of the CTWR structure and evolution. An analysis of the forcing mechanisms responsible for the June 2006 CTWR event is presented. It is demonstrated that the mature CTWR for this case is a density current propagating northward along the coast in response to the density gradient found to the north of the CTWR with maximum speed during the nighttime hours. Establishment of the density contrast is largely a result of cloud-top longwave radiative cooling of the stratus that accompanies the CTWR, which serves to cool and deepen the boundary layer during the night. Density contrast between the cloudy CTWR air and the ambient environment is enhanced by the persistent offshore flow to the north of the CTWR with attendant warming and a flattening of the horizontal pressure gradient in the marine layer.

scholarly journals Two-years of NO<sub>3</sub> radical observations in the boundary layer over the Eastern Mediterranean

2007 ◽  
Vol 7 (2) ◽  
pp. 315-327 ◽  
Author(s):  
M. Vrekoussis ◽  
N. Mihalopoulos ◽  
E. Gerasopoulos ◽  
M. Kanakidou ◽  
P. J. Crutzen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Marine Boundary Layer ◽  
Heterogeneous Reaction ◽  
Eastern Mediterranean ◽  
North Coast ◽  
Data Set ◽  
East Europe ◽  
Dinitrogen Pentoxide ◽  
Mixing Ratios ◽  
The North

Abstract. This is the first study that investigates the seasonal variability of nitrate (NO3) radicals in the marine boundary layer over the East Mediterranean Sea. An extensive data set of NO3 radical observations on the north coast of Crete for more than two years (June 2001–September 2003) is presented here. NO3 radicals follow a distinct seasonal dependency with the highest seasonally average mixing ratios in summer (5.6±1.2 pptv) and the lowest in winter (1.2±1.2 pptv). Episodes with high NO3 mixing ratios have been encountered mainly in polluted air masses originating from mainland Greece, Central and East Europe, and Turkey. Ancillary measurements of ozone, nitrogen dioxide (NO2) and meteorological parameters have been conducted and used to reveal possible relationship with the observed NO3 variability. The acquired NO2 nighttime observations provide the up-to-date most complete overview of NO2 temporal variability in the area. The data show correlations of the NO3 nighttime mixing ratios with temperature (positive), relative humidity (negative) and to a lesser extend with O3 (positive). As inferred from these observations, on average the major sink of NO3 radicals in the area is the heterogeneous reaction of dinitrogen pentoxide (N2O5) on aqueous particles whereas the homogeneous gas phase reactions of NO3 are most important during spring and summer. These observations support a significant contribution of NO3 nighttime chemistry to the oxidizing capacity of the troposphere.

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