scholarly journals Mercury distribution in the upper troposphere and lower most stratosphere according to measurements by the IAGOS-CARIBIC observatory, 2014–2016

2018 ◽  
Author(s):  
Franz Slemr ◽  
Andreas Weigelt ◽  
Ralf Ebinghaus ◽  
Johannes Bieser ◽  
Carl A. M. Brenninkmeijer ◽  
...  
Keyword(s):  
Large Scale ◽  
Total Mercury ◽  
Trace Gases ◽  
Boreal Winter ◽  
Signal Integration ◽  
Upper Troposphere ◽  
Cloud Scavenging ◽  
Passenger Aircraft ◽  
North And South America ◽  
North And South

Abstract. Mercury was measured onboard the IAGOS-CARIBIC passenger aircraft since May 2005 until February 2016 during nearly monthly sequences of mostly four intercontinental flights from Germany to destinations in North and South America, Africa, and South and East Asia. Most of these mercury data were obtained using an internal default signal integration procedure of the Tekran instrument but since April 2014 more precise and accurate data were obtained using post-flight manual integration of the instrument raw signal. In this paper we use the latter data. Elevated upper tropospheric total mercury (TM) concentrations due to large scale biomass burning were observed in the upper troposphere (UT) at the equator and southern latitudes during the flights to Latin America and South Africa in boreal autumn (SON) and boreal winter (DJF). TM concentrations in the lowermost stratosphere (LMS) decrease with altitude above the thermal tropopause but the gradient is less steep than reported before. Seasonal variation of the vertical TM distribution in the UT and LMS is similar to that of other trace gases with surface sources and stratospheric sinks. Using speciation experiments, we show that nearly identical TM and gaseous elementary mercury (GEM) concentrations exist at and below the tropopause. Above the thermal tropopause GEM concentrations are almost always smaller than those of TM and the TM – GEM (i.e. Hg2+) difference increases up to ~ 40 % of TM at ~ 2 km and more above the thermal tropopause. Correlations with N2O as a reference tracer suggest stratospheric lifetimes of 72 ± 37 and 74 ± 27 yr for TM and GEM, respectively, comparable to the stratospheric lifetime of COS. This coincidence, combined with pieces of evidence from us and other researchers, corroborates the hypothesis that Hg2+ formed by oxidation in the stratosphere attaches to sulfate particles formed mainly by oxidation of COS and is removed with them from the stratosphere by air mass exchange, gravitational sedimentation, and cloud scavenging processes.

scholarly journals Mercury distribution in the upper troposphere and lowermost stratosphere according to measurements by the IAGOS-CARIBIC observatory: 2014–2016

2018 ◽  
Vol 18 (16) ◽  
pp. 12329-12343 ◽  
Author(s):  
Franz Slemr ◽  
Andreas Weigelt ◽  
Ralf Ebinghaus ◽  
Johannes Bieser ◽  
Carl A. M. Brenninkmeijer ◽  
...  
Keyword(s):  
Large Scale ◽  
Total Mercury ◽  
Trace Gases ◽  
Boreal Winter ◽  
Signal Integration ◽  
Upper Troposphere ◽  
Cloud Scavenging ◽  
Passenger Aircraft ◽  
North And South America ◽  
North And South

Abstract. Mercury was measured onboard the IAGOS-CARIBIC passenger aircraft from May 2005 until February 2016 during near monthly sequences of mostly four intercontinental flights from Germany to destinations in North and South America, Africa and South and East Asia. Most of these mercury data were obtained using an internal default signal integration procedure of the Tekran instrument but since April 2014 more precise and accurate data were obtained using post-flight manual integration of the instrument raw signal. In this paper we use the latter data.Increased upper tropospheric total mercury (TM) concentrations due to large scale biomass burning were observed in the upper troposphere (UT) at the equator and southern latitudes during the flights to Latin America and South Africa in boreal autumn (SON) and boreal winter (DJF). TM concentrations in the lowermost stratosphere (LMS) decrease with altitude above the thermal tropopause but the gradient is less steep than reported before. Seasonal variation of the vertical TM distribution in the UT and LMS is similar to that of other trace gases with surface sources and stratospheric sinks. Speciation experiments suggest comparable TM and gaseous elementary mercury (GEM) concentrations at and below the tropopause leaving little space for Hg2+ (TM − GEM) being the dominating component of TM here. In the stratosphere significant GEM concentrations were found to exist up to 4 km altitude above the thermal tropopause. Correlations with N2O as a reference tracer suggest stratospheric lifetimes of 72±37 and 74±27 years for TM and GEM, respectively, comparable to the stratospheric lifetime of COS. This coincidence, combined with pieces of evidence from us and other researchers, corroborates the hypothesis that Hg2+ formed by oxidation in the stratosphere attaches to sulfate particles formed mainly by oxidation of COS and is removed with them from the stratosphere by air mass exchange, gravitational sedimentation and cloud scavenging processes.

“Stay and Starve, Or Go and Prosper!” Juvenile Emigration from Great Britain in the Nineteenth Century

1985 ◽  
Vol 9 (2) ◽  
pp. 145-166
Author(s):  
Thomas E. Jordan
Keyword(s):  
Nineteenth Century ◽  
South America ◽  
Large Scale ◽  
Western Europe ◽  
Equable Climate ◽  
Strategic Location ◽  
The World ◽  
English Speaking ◽  
North And South America ◽  
North And South

The nineteenth century saw the beginning of large-scale migration of population from western Europe to various countries of the world. North and South America had proven hospitable in previous centuries and the southern tip of Africa presented an equable climate as well as strategic location. The islands of the southern seas reached by Cook and Van Diemen proved equally attractive if more remote. In retrospect it seems inevitable that, with the exception of South America, they were bound to be English-speaking. Even South America had its British farming colonists at one stage. In 1826 just under two hundred Highland Scots embarked for Topo in the highlands of Colombia (United Kingdom, 1827). Significantly, one hundred and two of them were under fourteen years of age.

scholarly journals The influence of deep convection on HCHO and H<sub>2</sub>O<sub>2</sub> in the upper troposphere over Europe

2017 ◽  
Vol 17 (19) ◽  
pp. 11835-11848 ◽  
Author(s):  
Heiko Bozem ◽  
Andrea Pozzer ◽  
Hartwig Harder ◽  
Monica Martinez ◽  
Jonathan Williams ◽  
...  
Keyword(s):  
Large Scale ◽  
Deep Convection ◽  
Trace Gases ◽  
Cloud Droplets ◽  
Data Set ◽  
Transport Efficiency ◽  
Upper Troposphere ◽  
Secondary Formation

Abstract. Deep convection is an efficient mechanism for vertical trace gas transport from Earth's surface to the upper troposphere (UT). The convective redistribution of short-lived trace gases emitted at the surface typically results in a C-shaped profile. This redistribution mechanism can impact photochemical processes, e.g. ozone and radical production in the UT on a large scale due to the generally longer lifetimes of species like formaldehyde (HCHO) and hydrogen peroxide (H2O2), which are important HOx precursors (HOx =  OH + HO2 radicals). Due to the solubility of HCHO and H2O2 their transport may be suppressed as they are efficiently removed by wet deposition. Here we present a case study of deep convection over Germany in the summer of 2007 within the framework of the HOOVER II project. Airborne in situ measurements within the in- and outflow regions of an isolated thunderstorm provide a unique data set to study the influence of deep convection on the transport efficiency of soluble and insoluble trace gases. Comparing the in- and outflow indicates an almost undiluted transport of insoluble trace gases from the boundary layer to the UT. The ratios of out : inflow of CO and CH4 are 0.94 ± 0.04 and 0.99 ± 0.01, respectively. For the soluble species HCHO and H2O2 these ratios are 0.55 ± 0.09 and 0.61 ± 0.08, respectively, indicating partial scavenging and washout. Chemical box model simulations show that post-convection secondary formation of HCHO and H2O2 cannot explain their enhancement in the UT. A plausible explanation, in particular for the enhancement of the highly soluble H2O2, is degassing from cloud droplets during freezing, which reduces the retention coefficient.

scholarly journals Pollution trace gas distributions and their transport in the Asian monsoon upper troposphere and lowermost stratosphere during the StratoClim campaign 2017

2020 ◽  
Author(s):  
Sören Johansson ◽  
Michael Höpfner ◽  
Oliver Kirner ◽  
Ingo Wohltmann ◽  
Silvia Bucci ◽  
...  
Keyword(s):  
Large Scale ◽  
Asian Summer Monsoon ◽  
Trace Gases ◽  
Local Maximum ◽  
Horizontal Resolution ◽  
Convective Transport ◽  
Trace Gas ◽  
Air Masses ◽  
Upper Troposphere ◽  
Simulation Results

Abstract. We present the first high resolution measurements of pollutant trace gases in the Asian Summer Monsoon Upper Troposphere and Lowermost Stratosphere (UTLS) from the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) during the StratoClim (Stratospheric and upper tropospheric processes for better climate predictions) campaign with base in Kathamandu, Nepal, 2017. Measurements of peroxyacetyl nitrate (PAN), acetylene (C2H2), and formic acid (HCOOH) show strong local enhancements up to altitudes of 16 km. More than 500 pptv of PAN, more than 200 pptv of C2H2, and more than 200 pptv of HCOOH are observed. An observed local maximum of PAN and C2H2 at altitudes up to 18 km, reaching to the lowermost stratosphere, instead has been transported for a longer time. A local minimum of HCOOH is correlated with a maximum of ammonia (NH3), which suggests different wash out efficiencies of these species in the same air masses. To study the influence of convective transport to the measured pollution trace gas occurrences in detail, a trajectory analysis of the models ATLAS and TRACZILLA examined backward trajectories, starting at geolocations of GLORIA measurements with enhanced pollution trace gases. Both trajectory schemes implemented advanced techniques for detection of convective events. These convective events along trajectories leading to GLORIA measurements with enhanced pollutants are located close to regions, where satellite measurements by OMI show enhanced tropospheric columns of nitrogen dioxide (NO2) in the days prior to the observation. As an application of these highly resolved measurements, a comparison to the atmospheric models CAMS and EMAC is performed. It is demonstrated that these simulation results are able to reproduce large scale structures of the pollution trace gas distributions if the convective influence on the measured air masses is captured by the meteorological fields used by these simulations. Both models do not have sufficient horizontal resolution to capture all the convective events that are necessary to reproduce the fine structures measured by GLORIA. To investigate the influence of the strength of non-methane volatile organic compounds (NMVOCs) emissions in the EMAC model, sensitivity studies with artificially enhanced NMVOC emissions are performed. With these enhanced emissions, the simulation results succeed to reproduce the measured peak values of the pollutants, but do not improve the comparison of spatial distributions.

The seasonal and zonal differences in the temperature, circulation and composition of the tropical upper troposphere and lower stratosphere due to the MJO

2020 ◽  
Author(s):  
Olga Tweedy ◽  
Luke Oman ◽  
Darryn Waugh
Keyword(s):  
Lower Stratosphere ◽  
Trace Gases ◽  
Trace Gas ◽  
Boreal Summer ◽  
Boreal Winter ◽  
Kelvin Wave ◽  
Upper Troposphere ◽  
Circulation Anomalies ◽  
Gas Response ◽  
Tropical Upper Troposphere

&lt;p&gt;The intraseasonal (20-90 day) variability of the tropical upper troposphere/lower stratosphere (UTLS)&amp;#160; is dominated by the Madden-Julian Oscillation (MJO). Previous studies showed a strong connection between the MJO and variability in the UTLS circulation and trace gases. However, seasonality of UTLS circulation and trace gas response to the MJO has received very little attention in the literature. In this study, we use observations of trace gases (ozone, carbon monoxide and water vapor) and temperature from the Microwave Limb Sounder (MLS, version 4) and meteorological fields from the Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) reanalyses to examine and explain the seasonal and zonal differences in the UTLS temperature, circulation, and trace gas anomalies associated with the MJO propagation. We find that the response of the UTLS during boreal summer months (June -September, JJAS) is different from the response during boreal winter months (November -February, NDJF). Ozone, temperature and circulation anomalies during JJAS are more zonally symmetric with a stronger Kelvin wave response than during NDJF. These differences are explained in terms of seasonal variations in vertically propagating Kelvin waves that strongly depend on the zonal structure of the climatological zonal winds. The trace gas response to the MJO is in agreement with circulation anomalies, showing strong seasonal differences. The analysis of MLS observations presented in this study may be useful for evaluation and validation of the MJO-related physical and dynamical processes in a hierarchy of models.&lt;/p&gt;

scholarly journals The influence of deep convection on HCHO and H<sub>2</sub>O<sub>2</sub> in the upper troposphere over Europe

2017 ◽  
Author(s):  
Heiko Bozem ◽  
Andrea Pozzer ◽  
Hartwig Harder ◽  
Monica Martinez ◽  
Jonathan Williams ◽  
...  
Keyword(s):  
Large Scale ◽  
Deep Convection ◽  
Trace Gases ◽  
Cloud Droplets ◽  
Data Set ◽  
Transport Efficiency ◽  
Upper Troposphere ◽  
Secondary Formation

Abstract. Deep convection is an efficient mechanism for vertical trace gas transport from the Earth's surface to the upper troposphere (UT). The convective redistribution of short-lived trace gases emitted at the surface typically results in a C-shaped profile. This redistribution mechanism can impact photochemical processes, e.g. ozone and radical production in the UT on a large scale due to the generally longer lifetimes of species like formaldehyde (HCHO) and hydrogen peroxide (H2O2), which are important HOx precursors (HOx = OH + HO2 radicals). Due to the solubility of HCHO and H2O2 their transport may be suppressed as they are efficiently removed by wet deposition. Here we present a case study of deep convection over Germany in the summer of 2007 within the framework of the HOOVER II project. Airborne in-situ measurements within the in- and outflow regions of an isolated thunderstorm provide a unique data set to study the influence of deep convection on the transport efficiency of soluble and insoluble trace gases. Comparing the in- and outflow indicates almost undiluted transport of insoluble trace gases from the boundary layer to the UT. The ratios of out/inflow of CO and CH4 are 0.94 ± 0.04 and 0.99 ± 0.01, respectively. For the soluble species HCHO and H2O2 these ratios are 0.55 ± 0.09 and 0.61 ± 0.08, respectively, indicating partial scavenging and washout. Chemical box model simulations show that post-convection secondary formation of HCHO and H2O2 cannot explain their enhancement in the UT. A plausible explanation, in particular for the enhancement of the highly soluble H2O2, is degassing from cloud droplets during freezing, which reduces the retention coefficient.

Gerald H. Thayer's ornithological work in St Vincent and the Grenadines, Lesser Antilles

2018 ◽  
Vol 45 (1) ◽  
pp. 21-39 ◽  
Author(s):  
James W. Wiley
Keyword(s):  
New York ◽  
New York City ◽  
West Indies ◽  
The United States ◽  
Lesser Antilles ◽  
American Museum ◽  
The West ◽  
Comparative Zoology ◽  
North And South America ◽  
North And South

Gerald Handerson Thayer (1883–1939) was an artist, writer and naturalist who worked in North and South America, Europe and the West Indies. In the Lesser Antilles, Thayer made substantial contributions to the knowledge and conservation of birds in St Vincent and the Grenadines. Thayer observed and collected birds throughout much of St Vincent and on many of the Grenadines from January 1924 through to December 1925. Although he produced a preliminary manuscript containing interesting distributional notes and which is an early record of the region's ornithology, Thayer never published the results of his work in the islands. Some 413 bird and bird egg specimens have survived from his work in St Vincent and the Grenadines and are now housed in the American Museum of Natural History (New York City) and the Museum of Comparative Zoology (Cambridge, Massachusetts). Four hundred and fifty eight specimens of birds and eggs collected by Gerald and his father, Abbott, from other countries are held in museums in the United States.

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