scholarly journals Tropospheric mercury vertical profiles between 500 and 10 000 m in central Europe

2016 ◽  
Vol 16 (6) ◽  
pp. 4135-4146 ◽  
Author(s):  
Andreas Weigelt ◽  
Ralf Ebinghaus ◽  
Nicola Pirrone ◽  
Johannes Bieser ◽  
Jan Bödewadt ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Vertical Distribution ◽  
Vertical Profile ◽  
Mixed Boundary ◽  
Atmospheric Mercury ◽  
Observation System ◽  
Vertical Profiles ◽  
Free Troposphere ◽  
Airborne Measurements ◽  
The Vertical Distribution

Abstract. The knowledge of the vertical distribution of atmospheric mercury (Hg) plays an important role in determining the transport and cycling of mercury. However, measurements of the vertical distribution are rare, because airborne measurements are expensive and labour intensive. Consequently, only a few vertical Hg profile measurements have been reported since the 1970s. Besides the Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container (CARIBIC) observations, the latest vertical profile over Europe was measured in 1996. Within the Global Mercury Observation System (GMOS) project, four vertical profiles were taken on board research aircraft (CASA-212) in August 2013 in background air over different locations in Slovenia and Germany. Each vertical profile consists of at least seven 5 min horizontal flight sections from 500 m above ground to 3000 m a.s.l. Gaseous elemental mercury (GEM) and total gaseous mercury (TGM) were measured with Tekran 2537X and Tekran 2537B analysers. In addition to the mercury measurements, SO2, CO, O3, NO, and NO2, basic meteorological parameters (pressure, temperature, relative humidity) have been measured. Additional ground-based mercury measurements at the GMOS master site in Waldhof, Germany and measurements onboard the CARIBIC passenger aircraft were used to extend the profile to the ground and upper troposphere respectively. No vertical gradient was found inside the well-mixed boundary layer (variation of less than 0.1 ng m−3) at different sites, with GEM varying from location to location between 1.4 and 1.6 ng m−3 (standard temperature and pressure, STP: T  =  273.15 K, p  =  1013.25 hPa). At all locations GEM dropped to 1.3 ng m−3 (STP) when entering the free troposphere and remained constant at higher altitudes. The combination of the vertical profile, measured on 21 August 2013 over Leipzig, Germany, with the CARIBIC measurements during ascent and descent to Frankfurt Airport, Germany, taken at approximately the same time, provide a unique central European vertical profile from inside the boundary layer (550 m a.s.l) to the upper free troposphere (10 500 m a.s.l.) and show a fairly constant free-tropospheric TGM concentration of 1.3 ng m−3 (STP).

scholarly journals Tropospheric mercury vertical profiles between 500 and 10 000 m in central Europe

2015 ◽  
Vol 15 (20) ◽  
pp. 28217-28247 ◽  
Author(s):  
A. Weigelt ◽  
R. Ebinghaus ◽  
N. Pirrone ◽  
J. Bieser ◽  
J. Bödewadt ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Vertical Profile ◽  
Mixed Boundary ◽  
Elemental Mercury ◽  
Vertical Gradient ◽  
Atmospheric Mercury ◽  
Observation System ◽  
Vertical Profiles ◽  
Free Troposphere ◽  
Airborne Measurements

Abstract. Measurements of the vertical distribution of atmospheric mercury (Hg) are rare, because airborne measurements are expensive and labour intensive. Consequently, only a few vertical Hg profile measurements have been reported since the 1970s. Besides the CARIBIC passenger aircraft observations, the latest vertical profile over Europe was measured in 1996. Within the Global Mercury Observation System (GMOS) project four vertical profiles were taken on board research aircraft (CASA-212) in August 2013 in background air over different locations in Slovenia and Germany. Each vertical profile consists of at least seven 5 min horizontal flight sections from 500 m above ground to 3000 m a.s.l. Gaseous elemental mercury (GEM) was measured with a Tekran 2537X analyser and a Lumex RA-915-AM. Total gaseous mercury (TGM) was measured using a Tekran 2537B analyser and gaseous oxidized mercury (GOM) was sampled onto 8 denuders for post flight analysis (one for each profile, three during the transfer flights, and two blanks). In addition to the mercury measurements, SO2, CO, O3, NO, NO2, as well as basic meteorological parameters (pressure, temperature, relative humidity) have been measured. Additional ground based speciated mercury measurements at the GMOS master site in Waldhof (Germany) were used to extend the profile to the ground. No vertical gradient was found inside the well mixed boundary layer (variation by less than 0.1 ng m-3) at different sites with GEM varying from location to location between 1.4 and 1.6 ng m-3 (STP; standard conditions: p = 1013.25 hPa, T = 273.15 K). At all locations GEM dropped to 1.3 ng m-3 (STP) when entering the free troposphere and remained constant at higher altitudes. The combination of the vertical profile, measured on 21 August 2013, over Leipzig (Germany) with the CARIBIC measurements during ascent and descent to Frankfurt airport (Germany) at approximately the same time provide a unique central European vertical profile from inside the boundary layer (550 m a.s.l.) to the upper free troposphere (10 500 m a.s.l.) and shows a fairly constant free tropospheric TGM concentration of 1.3 ng m-3 (STP). The highest GOM concentrations of up to 60 pg m-3 (STP, denuder samples) were found above the boundary layer during the transfer flights.

scholarly journals Vertical profile observations of water vapor deuterium excess in the lower troposphere

2019 ◽  
Author(s):  
Olivia E. Salmon ◽  
Lisa R. Welp ◽  
Michael Baldwin ◽  
Kristian Hajny ◽  
Brian H. Stirm ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Water Vapor ◽  
Case Studies ◽  
Vertical Profile ◽  
Inversion Layer ◽  
Vertical Profiles ◽  
Free Troposphere ◽  
Deuterium Excess ◽  
Airborne Measurements

Abstract. We use H2Ov isotopic vertical profile measurements and complementary meteorological observations to examine how boundary layer, cloud, and mixing processes influence the vertical structure of deuterium-excess (d-excess = δD – 8 × δ18O) in the boundary layer, inversion layer, and lower free troposphere. Airborne measurements of water vapor (H2Ov) stable isotopologues were conducted around two continental U.S. cities in February–March 2016. Nine research flights were designed to characterize the δD, δ18O, and d-excess vertical profiles extending from the surface to ≤ 2 km. We examine observations from three unique case study flights in detail. One case study shows H2Ov isotopologue vertical profiles that are consistent with Rayleigh isotopic distillation theory coinciding with clear skies, dry adiabatic lapse rates within the boundary layer, and relatively constant vertical profiles of wind speed and wind direction. The two remaining case studies show that H2Ov isotopic signatures above the boundary layer are sensitive to cloud processes and complex air mass mixing patterns. These two case studies indicate anomalies in the d-excess signature relative to Rayleigh theory, such as low d-excess values at the interface of the inversion layer and the free troposphere, which is possibly indicative of cloud evaporation. We discuss possible explanations for the observed d-excess anomalies, such as cloud evaporation, wind shear, and vertical mixing. In situ H2Ov stable isotope measurements, and d-excess in particular, could be useful for improving our understanding of moisture processing and transport mixing occurring between the boundary layer, inversion layer, and free troposphere.

Black Carbon profiles from tethered balloon flights over the Southeastern Tibetan Plateau

2020 ◽  
Author(s):  
Mo Wang ◽  
Baiqing Xu ◽  
Song Yang ◽  
Jing Gao ◽  
Taihua Zhang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Relative Humidity ◽  
Tibetan Plateau ◽  
Vertical Distribution ◽  
Biomass Burning ◽  
Vertical Profile ◽  
Mass Concentration ◽  
Maximum Height ◽  
Free Troposphere ◽  
Tethered Balloon

<p>Black carbon (BC) can change the energy budget of the earth system by strongly absorbing solar radiation: both suspended in the atmosphere, incorporated into cloud droplets, or deposited onto high-albedo surfaces. BC’s direct radiative forcing is highly dependent on its vertical distribution. However, due to large variabilities and the small number of vertical profile measurements, there is still large uncertainty in this forcing value. Moreover, the vertical profile of BC and its relative elevation to clouds determine BC’s lifetime in the atmosphere and its transport and removal processes. In November-December 2017, a series of tethered balloon flights was launched at the Southeast Tibet Observation and Research Station for the Alpine Environment of the Chinese Academy of Sciences. A cylindrical balloon with a diameter of 7.9 m and maximum volume of 1250 m<sup>3</sup> was used. A 7-channel Aethalometer was installed in the gondola attached to the balloon, together with several other instruments including a GPS for altitude, and sensors for temperature and relative humidity. The airborne Aethalometer measured BC mass concentration (ng/m<sup>3</sup>) on a on a 1-second timebase at 7 wavelengths ranging from 370 nm to 950 nm. Meanwhile, another Aethalometer was used to monitor BC mass concentration near the surface, at a height of about 10 m above the ground. From the tethered balloon flights, we derived three profiles designated as ‘F1’, ‘F3-ASC’, and ‘F3-DES’. The maximum height for the F1 flight was 500 m a.g.l., namely 3800 m a.s.l.; while the maximum height for the F3 flight was 1950 m a.g.l., namely 5250 m a.s.l. Based on the potential temperature and relative humidity data, the profiles were divided into three layers: the stable boundary layer (SBL), the residual layer (RL), and the free troposphere (FT). The vertical distribution of BC shows a prominent peak within the SBL. The mean BC concentration in SBL (1000±750 ng/m<sup>3</sup>) was one order of magnitude higher than in RL and FT, which were 140±40 ng/m<sup>3</sup> and 120±40 ng/m<sup>3</sup>, respectively. The BC concentration measured in the present study in FT over the southeastern Tibetan Plateau is comparable to measurements in Arctic regions, but lower than values in South Asia. Analysis of the wavelength dependence of the data yields an estimate of the biomass burning contribution. This showed a maximum value in SBL of 44±37%, and was 16±6% in RL and 13±5% in FT. Analysis of 24-hour isentropic back trajectories showed that BC in SBL and RL was dominated by local sources, while in the FT, BC is mainly influenced by mid- to long-distant transport by the westerlies. In addition, analysis of the variations of BC concentration and biomass burning contribution on a high-resolution time scale showed that BC concentrations and the nature of their sources are largely influenced by air mass origins and transport. To our knowledge, this is the first ever in situ measurement of BC concentration over the Tibetan Plateau in the atmospheric boundary layer and free troposphere up to 5000 m a.s.l.</p>

scholarly journals Airborne DOAS limb measurements of tropospheric trace gas profiles: case studies on the profile retrieval of O<sub>4</sub> and BrO

2011 ◽  
Vol 4 (6) ◽  
pp. 1241-1260 ◽  
Author(s):  
C. Prados-Roman ◽  
A. Butz ◽  
T. Deutschmann ◽  
M. Dorf ◽  
L. Kritten ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Vertical Distribution ◽  
Vertical Profile ◽  
Trace Gases ◽  
Trace Gas ◽  
Vertical Profiles ◽  
Cloud Particle ◽  
Upper Troposphere ◽  
Mixing Ratios ◽  
Tropospheric Aerosol

Abstract. A novel limb scanning mini-DOAS spectrometer for the detection of UV/vis absorbing radicals (e.g., O3, BrO, IO, HONO) was deployed on the DLR-Falcon (Deutsches Zentrum für Luft- und Raumfahrt) aircraft and tested during the ASTAR 2007 campaign (Arctic Study of Tropospheric Aerosol, Clouds and Radiation) that took place at Svalbard (78° N) in spring 2007. Our main objectives during this campaign were to test the instrument, and to perform spectral and profile retrievals of tropospheric trace gases, with particular interest on investigating the distribution of halogen compounds (e.g., BrO) during the so-called ozone depletion events (ODEs). In the present work, a new method for the retrieval of vertical profiles of tropospheric trace gases from tropospheric DOAS limb observations is presented. Major challenges arise from modeling the radiative transfer in an aerosol and cloud particle loaded atmosphere, and from overcoming the lack of a priori knowledge of the targeted trace gas vertical distribution (e.g., unknown tropospheric BrO vertical distribution). Here, those challenges are tackled by a mathematical inversion of tropospheric trace gas profiles using a regularization approach constrained by a retrieved vertical profile of the aerosols extinction coefficient EM. The validity and limitations of the algorithm are tested with in situ measured EM, and with an absorber of known vertical profile (O4). The method is then used for retrieving vertical profiles of tropospheric BrO. Results indicate that, for aircraft ascent/descent observations, the limit for the BrO detection is roughly 1.5 pptv (pmol mol−1), and the BrO profiles inferred from the boundary layer up to the upper troposphere and lower stratosphere have around 10 degrees of freedom. For the ASTAR 2007 deployments during ODEs, the retrieved BrO vertical profiles consistently indicate high BrO mixing ratios (∼15 pptv) within the boundary layer, low BrO mixing ratios (&amp;leq;1.5 pptv) in the free troposphere, occasionally enhanced BrO mixing ratios (∼1.5 pptv) in the upper troposphere, and increasing BrO mixing ratios with altitude in the lowermost stratosphere. These findings agree reasonably well with satellite and balloon-borne soundings of total and partial BrO atmospheric column densities.

scholarly journals Airborne DOAS limb measurements of tropospheric trace gas profiles: case study on the profile retrieval of O<sub>4</sub> and BrO

2010 ◽  
Vol 3 (4) ◽  
pp. 3925-3969 ◽  
Author(s):  
C. Prados-Roman ◽  
A. Butz ◽  
T. Deutschmann ◽  
M. Dorf ◽  
L. Kritten ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Vertical Distribution ◽  
Vertical Profile ◽  
Trace Gases ◽  
Trace Gas ◽  
Vertical Profiles ◽  
Cloud Particle ◽  
Upper Troposphere ◽  
Mixing Ratios ◽  
Tropospheric Aerosol

Abstract. A novel limb scanning mini-DOAS spectrometer for the detection of UV/vis absorbing radicals (e.g., O3, BrO, IO, HONO) was deployed on the DLR-Falcon (Deutsches Zentrum für Luft- und Raumfahrt) aircraft and tested during the ASTAR 2007 campaign (Arctic Study of Tropospheric Aerosol, Clouds and Radiation) that took place at Svalbard (78° N) in spring 2007. Our main objectives during this campaign were to test the instrument, and to perform spectral and profile retrievals of tropospheric trace gases, with particular interest on investigating the distribution of halogen compounds (e.g., BrO) during the so-called ozone depletion events (ODEs). In the present work, a new method for the retrieval of vertical profiles of tropospheric trace gases from tropospheric DOAS limb observations is presented. Major challenges arise from modeling the radiative transfer in an aerosol and cloud particle loaded atmosphere, and from overcoming the lack of a priori knowledge of the targeted trace gas vertical distribution (e.g., unknown tropospheric BrO vertical distribution). Here, those challenges are tackled by a mathematical inversion of tropospheric trace gas profiles using a regularization approach constrained by a retrieved vertical profile of the aerosols extinction coefficient εM. The validity and limitations of the algorithm are tested with in situ measured εM, and with an absorber of known vertical profile (O4). The method is then used for retrieving vertical profiles of tropospheric BrO. Results indicate that, for aircraft ascent/descent observations, the limit for the BrO detection is roughly 1.5 pptv (pmol/mol), and the BrO profiles inferred from the boundary layer up to the upper troposphere and lower stratosphere have around 10 degrees of freedom. For the ASTAR 2007 deployments during ODEs, the retrieved BrO vertical profiles consistently indicate high BrO mixing ratios (~15 pptv) within the boundary layer, low BrO mixing ratios (≤1.5 pptv) in the free troposphere, occasionally enhanced BrO mixing ratios (~1.5 pptv) in the upper troposphere, and increasing BrO mixing ratios with altitude in the lowermost stratosphere. These findings are well in agreement with satellite and balloon-borne soundings of total and partial BrO atmospheric column densities.

scholarly journals Vertical profile observations of water vapor deuterium excess in the lower troposphere

2019 ◽  
Vol 19 (17) ◽  
pp. 11525-11543 ◽  
Author(s):  
Olivia E. Salmon ◽  
Lisa R. Welp ◽  
Michael E. Baldwin ◽  
Kristian D. Hajny ◽  
Brian H. Stirm ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Water Vapor ◽  
Inversion Layer ◽  
Lower Troposphere ◽  
Phase Changes ◽  
Vertical Profiles ◽  
Free Troposphere ◽  
Deuterium Excess ◽  
Airborne Measurements

Abstract. We use airborne measurements of water vapor (H2Ov) stable isotopologues and complementary meteorological observations to examine how boundary layer (BL) dynamics, cloud processing, and atmospheric mixing influence the vertical structure of δD, δ18O, and deuterium excess (d excess =δD–8×δ18O) in the BL, inversion layer (INV), and lower free troposphere (FT). Flights were conducted around two continental US cities in February–March 2016 and included vertical profiles extending from near the surface to ≤2 km. We examine observations from three unique case study flights in detail. One case study shows observations that are consistent with Rayleigh isotopic distillation theory coinciding with clear skies, dry adiabatic lapse rates within the boundary layer, and relatively constant vertical profiles of wind speed and wind direction. This suggests that the air mass retained the isotopic fingerprint of dehydration during moist adiabatic processes upwind of the study area. Also, observed d-excess values in the free troposphere were sometimes larger than Rayleigh theory predicts, which may indicate mixing of extremely dehydrated air from higher altitudes. The two remaining case studies show isotopic anomalies in the d-excess signature relative to Rayleigh theory and indicate cloud processes and complex boundary layer development. The most notable case study with stratocumulus clouds present had extremely low (negative) d-excess values at the interface of the inversion layer and the free troposphere, which is possibly indicative of cloud or rain droplet evaporation. We discuss how in situ H2Ov stable isotope measurements, and d excess in particular, could be useful for improving our understanding of water phase changes, transport, and mixing that occurs between the BL, INV, and FT.

scholarly journals The vertical distribution of aerosols, Saharan dust and cirrus clouds in Rome (Italy) in the year 2001

2004 ◽  
Vol 4 (2) ◽  
pp. 351-359 ◽  
Author(s):  
G. P. Gobbi ◽  
F. Barnaba ◽  
L. Ammannato
Keyword(s):  
Boundary Layer ◽  
Vertical Distribution ◽  
Cirrus Clouds ◽  
Saharan Dust ◽  
Vertical Profiles ◽  
Tropospheric Aerosol ◽  
Yearly Average ◽  
Seasonal Analysis ◽  
The Vertical Distribution ◽  
Good Agreement

Abstract. A set of 813 lidar profiles of tropospheric aerosol and cirrus clouds extinction and depolarization observed in Rome, Italy, between February 2001 and February 2002 is analyzed and discussed. The yearly record reveals a meaningful contribution of both cirrus clouds (38%) and Saharan dust (12%) to the total optical thickness (OT) of 0.26, at 532nm. Seasonal analysis shows the planetary boundary layer (PBL) aerosols to be confined below 2km in winter and 3.8km in summer, with relevant OT shifting from 0.08 to 0.16, respectively. Cirrus clouds maximise in spring and autumn, in both cases with average OT similar to the PBL aerosols one. With the exception of winter months, Saharan dust is found to represent an important third layer mostly residing between PBL aerosols and cirrus clouds, with yearly average OT0.03. Saharan dust and cirrus clouds were detected in 20% and in 45% of the observational days, respectively. Validation of the lidar OT retrievals against collocated sunphotometer observations show very good agreement. These results represent one of the few yearly records of tropospheric aerosol vertical profiles available in the literature.

scholarly journals Investigation of NO<sub>2</sub> vertical distribution using two DOAS retrievals for GOME-2A measurements in the UV and vis spectral range

2017 ◽  
Author(s):  
Lisa K. Behrens ◽  
Andreas Hilboll ◽  
Andreas Richter ◽  
Enno Peters ◽  
Henk Eskes ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Radiative Transfer ◽  
Vertical Distribution ◽  
Spectral Range ◽  
Biomass Burning ◽  
Vertical Profile ◽  
Lower Troposphere ◽  
Tropical Africa ◽  
Profile Shape ◽  
Spectral Ranges

Abstract. In this study, we present a novel NO2 DOAS retrieval in the ultraviolet (UV) spectral range for satellite observations from the Global Ozone Monitoring Instrument 2 on board EUMETSAT’s MetOp-A (GOME-2A) satellite. We compare the results to those from an established NO2 retrieval in the visible (vis) spectral range from the same instrument and infer information about the NO2 vertical profile shape in the troposphere. As expected, radiative transfer calculations for satellite geometries show that the sensitivity close to the ground is higher in the vis than in the UV spectral range. Consequently, NO2 slant column densities (SCDs) in the vis are usually higher than in the UV, if the NO2 is close to the surface. Therefore, these differences in NO2 SCDs between the two spectral ranges contain information on the vertical distribution of NO2 in the troposphere. We combine these results with radiative transfer calculations and simulated NO2 fields from the TM5 chemistry transport model to evaluate the simulated NO2 vertical distribution. We investigate regions representative for both anthropogenic and biomass burning NO2 pollution. Anthropogenic air pollution is mostly located in the boundary layer close to the surface, which is reflected by the large differences between UV and vis SCDs of ~ 60 %. Biomass burning NO2 in contrast is often uplifted into elevated layers above the boundary layer. This is best seen in tropical Africa south of the equator, where the biomass burning NO2 is well observed in the UV, and the difference between the two spectral ranges is only ~ 36 %. In tropical Africa north of the equator, however, the biomass burning NO2 is located closer to the ground, reducing its visibility. While not enabling a full retrieval of the vertical NO2 profile shape in the troposphere, our results can help to constrain the vertical profile of NO2 in the lower troposphere and, when analyzed together with simulated NO2 fields, can help interpret the model output.

scholarly journals The vertical distribution of biomass burning pollution over tropical South America from aircraft in situ measurements during SAMBBA

2019 ◽  
Vol 19 (9) ◽  
pp. 5771-5790 ◽  
Author(s):  
Eoghan Darbyshire ◽  
William T. Morgan ◽  
James D. Allan ◽  
Dantong Liu ◽  
Michael J. Flynn ◽  
...  
Keyword(s):  
Air Quality ◽  
South America ◽  
Vertical Distribution ◽  
Biomass Burning ◽  
Mixing Layer ◽  
Free Troposphere ◽  
The West ◽  
The Vertical Distribution ◽  
Tropical South America

Abstract. We examine processes driving the vertical distribution of biomass burning pollution following an integrated analysis of over 200 pollutant and meteorological profiles measured in situ during the South AMerican Biomass Burning Analysis (SAMBBA) field experiment. This study will aid future work examining the impact of biomass burning on weather, climate and air quality. During the dry season there were significant contrasts in the composition and vertical distribution of haze between western and eastern regions of tropical South America. Owing to an active or residual convective mixing layer, the aerosol abundance was similar from the surface to ∼1.5 km in the west and ∼3 km in the east. Black carbon mass loadings were double as much in the east (1.7 µg m−3) than the west (0.85 µg m−3), but aerosol scattering coefficients at 550 nm were similar (∼120 Mm−1), as too were CO near-surface concentrations (310–340 ppb). We attribute these contrasts to the more flaming combustion of Cerrado fires in the east and more smouldering combustion of deforestation and pasture fires in the west. Horizontal wind shear was important in inhibiting mixed layer growth and plume rise, in addition to advecting pollutants from the Cerrado regions into the remote tropical forest of central Amazonia. Thin layers above the mixing layer indicate the roles of both plume injection and shallow moist convection in delivering pollution to the lower free troposphere. However, detrainment of large smoke plumes into the upper free troposphere was very infrequently observed. Our results reiterate that thermodynamics control the pollutant vertical distribution and thus point to the need for correct model representation so that the spatial distribution and vertical structure of biomass burning smoke is captured. We observed an increase of aerosol abundance relative to CO with altitude both in the background haze and plume enhancement ratios. It is unlikely associated with thermodynamic partitioning, aerosol deposition or local non-fire sources. We speculate it may be linked to long-range transport from West Africa or fire combustion efficiency coupled to plume injection height. Further enquiry is required to explain the phenomenon and explore impacts on regional climate and air quality.

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