scholarly journals Tracing devastating fires in Portugal to a snow archive in the Swiss Alps: a case study

2020 ◽  
Author(s):  
Dimitri Osmont ◽  
Sandra Brugger ◽  
Anina Gilgen ◽  
Helga Weber ◽  
Michael Sigl ◽  
...  
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Swiss Alps ◽  
Natural Phenomenon ◽  
Burned Area ◽  
Research Station ◽  
Test Bed ◽  
Fire Event ◽  
Carbonaceous Particles ◽  
Microscopic Charcoal

Abstract. Recent large wildfires, such as those in Portugal in 2017, have devastating impacts on societies, economy, ecosystems and environments. However, wildfires are a natural phenomenon, which has been exacerbated by land use during the past millennia. Ice cores are one of the archives preserving information on fire occurrences over these timescales. A difficulty is that emission sensitivity of ice cores is often unknown, which constitutes a source of uncertainty in the interpretation of such archives. Information from specific and well-documented case studies is therefore useful to better understand the spatial representation of ice-core burning records. The wildfires near Pedrógão Grande in Central Portugal in 2017 provided a test bed to link a fire event to its footprint left in a high-alpine snowpack considered a surrogate for high-alpine ice-core sites. Here, we (1) analyzed black carbon (BC) and microscopic charcoal particles deposited in the snowpack close to the high-alpine research station Jungfraujoch in the Swiss Alps, (2) calculated backward trajectories based on ERA-Interim reanalysis data and simulated the transport of these carbonaceous particles using a global aerosol-climate model, and (3) analyzed the fire spread, its spatial and temporal extent, as well as its intensity, with remote sensing (e.g. MODIS) active fire and burned area products. A peak of atmospheric equivalent BC (eBC) observed at the Jungfraujoch research station on 22nd June, with elevated eBC levels until the 25th June, is in correspondence with a peak in refractory BC (rBC) and microscopic charcoal observed in the snow layer. rBC was mainly scavenged by wet deposition and we obtained scavenging ratios ranging from 81 to 91. Unlike for microscopic charcoal, the model did not well reproduce the observed rBC signal. Our study reveals that microscopic charcoal can be transported over long distances (1500 km), and that snow and ice archives are much more sensitive to distant events than sedimentary archives, for which the signal is dominated by local fires. Microscopic charcoal concentrations were exceptionally high since this single outstanding event deposited as many charcoal particles per day as during an average year in ice cores. This study unambiguously links the fire tracers in the snow with the highly intensive fires in Portugal, where a total burned area of 501 km2 was observed on the basis of satellite fire products. According to our simulations, this fire event emitted at least 203.5 tons of BC.

scholarly journals Tracing devastating fires in Portugal to a snow archive in the Swiss Alps: a case study

2020 ◽  
Vol 14 (11) ◽  
pp. 3731-3745
Author(s):  
Dimitri Osmont ◽  
Sandra Brugger ◽  
Anina Gilgen ◽  
Helga Weber ◽  
Michael Sigl ◽  
...  
Keyword(s):  
Climate Model ◽  
Ice Core ◽  
Ice Cores ◽  
Swiss Alps ◽  
Natural Phenomenon ◽  
Burned Area ◽  
Research Station ◽  
Carbonaceous Particles ◽  
Backward Trajectories ◽  
Microscopic Charcoal

Abstract. Recent large wildfires, such as those in Portugal in 2017, have devastating impacts on societies, economy, ecosystems and environments. However, wildfires are a natural phenomenon, which has been exacerbated by land use during the past millennia. Ice cores are one of the archives preserving information on fire occurrences over these timescales. A difficulty is that emission sensitivity of ice cores is often unknown, which constitutes a source of uncertainty in the interpretation of such archives. Information from specific and well-documented case studies is therefore useful to better understand the spatial representation of ice-core burning records. The wildfires near Pedrógão Grande in central Portugal in 2017 provided a test bed to link a fire event to its footprint left in a high-alpine snowpack considered a surrogate for high-alpine ice-core sites. Here, we (1) analysed black carbon (BC) and microscopic charcoal particles deposited in the snowpack close to the high-alpine research station Jungfraujoch in the Swiss Alps; (2) calculated backward trajectories based on ERA-Interim reanalysis data and simulated the transport of these carbonaceous particles using a global aerosol-climate model; and (3) analysed the fire spread, its spatial and temporal extent, and its intensity with remote-sensing (e.g. MODIS) Active Fire and Burned Area products. According to modelled emissions of the FINN v1.6 database, the fire emitted a total amount of 203.5 t BC from a total burned area of 501 km2 as observed on the basis of satellite fire products. Backward trajectories unambiguously linked a peak of atmospheric-equivalent BC observed at the Jungfraujoch research station on 22 June – with elevated levels until 25 June – with the highly intensive fires in Portugal. The atmospheric signal is in correspondence with an outstanding peak in microscopic charcoal observed in the snow layer, depositing nearly as many charcoal particles as during an average year in other ice archives. In contrast to charcoal, the amount of atmospheric BC deposited during the fire episode was minor due to a lack of precipitation. Simulations with a global aerosol-climate model suggest that the observed microscopic charcoal particles originated from the fires in Portugal and that their contribution to the BC signal in snow was negligible. Our study revealed that microscopic charcoal can be transported over long distances (1500 km) and that snow and ice archives are much more sensitive to distant events than sedimentary archives, for which the signal is dominated by local fires. The findings are important for future ice-core studies as they document that, for BC as a fire tracer, the signal preservation depends on precipitation. Single events, like this example, might not be preserved due to unfavourable meteorological conditions.

scholarly journals Towards radiocarbon dating of ice cores

2009 ◽  
Vol 55 (194) ◽  
pp. 985-996 ◽  
Author(s):  
M. Sigl ◽  
T.M. Jenk ◽  
T. Kellerhals ◽  
S. Szidat ◽  
H.W. Gäggeler ◽  
...  
Keyword(s):  
Aerosol Particles ◽  
Ice Core ◽  
Ice Cores ◽  
Swiss Alps ◽  
Carbonaceous Aerosol ◽  
Polar Ice ◽  
Low Latitude ◽  
Bolivian Andes ◽  
Glacier Ice ◽  
Dating Method

AbstractA recently developed dating method for glacier ice, based on the analysis of radiocarbon in carbonaceous aerosol particles, is thoroughly investigated. We discuss the potential of this method to achieve a reliable dating using examples from a mid- and a low-latitude ice core. Two series of samples from Colle Gnifetti (4450 m a.s.l., Swiss Alps) and Nevado Illimani (6300 m a.s.l., Bolivian Andes) demonstrate that the 14C ages deduced from the water-insoluble organic carbon fraction represent the age of the ice. Sample sizes ranged between 7 and 100 μg carbon. For validation we compare our results with those from independent dating. This new method is thought to have major implications for dating non-polar ice cores in the future, as it provides complementary age information for time periods not accessible with common dating techniques.

The Anthropogenic Impact on Snow Chemistry at Colle Gnifetti, Swiss Alps

1988 ◽  
Vol 10 ◽  
pp. 183-187 ◽  
Author(s):  
D. Wagenbach ◽  
K.O. Münnich ◽  
U. Schotterer ◽  
H. Oeschger
Keyword(s):  
Chemical Analysis ◽  
Ice Core ◽  
Ice Cores ◽  
Summer Precipitation ◽  
Snow Accumulation ◽  
Swiss Alps ◽  
Saharan Dust ◽  
Water Conductivity ◽  
Air Masses ◽  
Melt Water

By chemical analysis of the upper 40 m of a 124 m ice core from a high-altitude Alpine glacier (Colle Gnifetti, Swiss Alps; 4450 m a.s.l.), records of mineral dust, pH, melt-water conductivity, nitrate and sulfate are obtained. The characteristics of the drilling site are discussed, as derived from glacio-meteorological and chemical analysis. As a consequence of high snow-erosion rates (usually during the winter months), annual snow accumulation is dominated by summer precipitation. Clean-air conditions prevail even during summer; however, they are frequently interrupted by polluted air masses or by air masses which are heavily loaded with desert dust.Absolutely dated reference horizons for Saharan dust, together with the position of the broad nuclear-weapon tritium peak, provide the time-scale for the following statements:(1) Since at least the turn of the century the background melt-water conductivity has been rising steadily, as has the mean snow acidity. The trend of increasing background conductivity at Colle Gnifetti (1.9μS/cm around the beginning of this century, and at present 3.4 μS/cm) is found to be comparable with the records of mean melt-water conductivity reported from ice cores from the Canadian High Arctic.(2) Sulfate and nitrate concentrations are higher by a factor of 4–5 than they were at the beginning of the century. This is to be compared with the two- to three-fold rise in the concentrations in south Greenland during about the same time span.

scholarly journals The Anthropogenic Impact on Snow Chemistry at Colle Gnifetti, Swiss Alps

1988 ◽  
Vol 10 ◽  
pp. 183-187 ◽  
Author(s):  
D. Wagenbach ◽  
K.O. Münnich ◽  
U. Schotterer ◽  
H. Oeschger
Keyword(s):  
Chemical Analysis ◽  
Ice Core ◽  
Ice Cores ◽  
Summer Precipitation ◽  
Snow Accumulation ◽  
Swiss Alps ◽  
Saharan Dust ◽  
Water Conductivity ◽  
Air Masses ◽  
Melt Water

By chemical analysis of the upper 40 m of a 124 m ice core from a high-altitude Alpine glacier (Colle Gnifetti, Swiss Alps; 4450 m a.s.l.), records of mineral dust, pH, melt-water conductivity, nitrate and sulfate are obtained. The characteristics of the drilling site are discussed, as derived from glacio-meteorological and chemical analysis. As a consequence of high snow-erosion rates (usually during the winter months), annual snow accumulation is dominated by summer precipitation. Clean-air conditions prevail even during summer; however, they are frequently interrupted by polluted air masses or by air masses which are heavily loaded with desert dust. Absolutely dated reference horizons for Saharan dust, together with the position of the broad nuclear-weapon tritium peak, provide the time-scale for the following statements: (1) Since at least the turn of the century the background melt-water conductivity has been rising steadily, as has the mean snow acidity. The trend of increasing background conductivity at Colle Gnifetti (1.9μS/cm around the beginning of this century, and at present 3.4 μS/cm) is found to be comparable with the records of mean melt-water conductivity reported from ice cores from the Canadian High Arctic. (2) Sulfate and nitrate concentrations are higher by a factor of 4–5 than they were at the beginning of the century. This is to be compared with the two- to three-fold rise in the concentrations in south Greenland during about the same time span.

scholarly journals AMS and Microprobe Analysis of Combusted Particles in Ice and Snow

Radiocarbon ◽  
1997 ◽  
Vol 40 (1) ◽  
pp. 3-10 ◽  
Author(s):  
S. R. Biegalski ◽  
L. A. Currie ◽  
R. A. Fletcher ◽  
G. A. Klouda ◽  
Rolland Weissenbök
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Individual Particle ◽  
Total Carbon ◽  
The Arctic ◽  
Carbonaceous Particles ◽  
Range Transport ◽  
History Of ◽  
Combustion Processes

Ice cores and snow pits of the cryosphere contain particles that detail the history of past atmospheric air compositions. Some of these particles result from combustion processes and have undergone long-range transport to arrive in the Arctic. Recent research has focused on the separation of particulate matter from ice and snow, as well as the subsequent analysis of the separated particles for 14C with accelerator mass spectrometry (AMS) and for individual particle compositions with laser microprobe mass analysis (LAMMA). The very low particulate concentrations in Arctic samples make these measurements a challenge. The first task is to separate the particles from the ice core. Two major options exist to accomplish this separation. One option is to melt the ice and then filter the meltwater. A second option is to sublimate the ice core directly, depositing the particles onto a surface. This work demonstrates that greater control is obtained through sublimation. A suite of analytical methods has been used for the measurement of the carbon in snow and ice. Total carbon was analyzed with a carbon/nitrogen/hydrogen (CHN) analyzer. AMS was used for the determination of carbon isotopes. Since source identification of the carbonaceous particles is of primary importance here, the use of LAMMA was incorporated to link individual particle molecular-structural patterns to the same group of particles that were measured by the other techniques. Prior to this study, neither AMS nor LAMMA had been applied to particles contained in snow. This paper discusses the development and limitations of the methodology required to make these measurements.

scholarly journals A new thermal drilling system for high-altitude or temperate glaciers

2014 ◽  
Vol 55 (68) ◽  
pp. 131-136 ◽  
Author(s):  
Margit Schwikowski ◽  
Theo M. Jenk ◽  
Dieter Stampfli ◽  
Felix Stampfli
Keyword(s):  
Melting Point ◽  
Liquid Water ◽  
Ice Core ◽  
Ice Cores ◽  
High Elevation ◽  
Swiss Alps ◽  
Ice Melting ◽  
Thermal Drilling ◽  
Drilling System ◽  
Core Production

AbstractFor ice-core drilling on high-elevation glaciers, lightweight and modular electromechanical (EM) drills are used to allow for transportation by porters or pack animals. However, application of EM drills is constrained to glaciers with temperatures well below the ice melting point. When drilling into temperate ice, liquid water accumulates in the borehole, hindering chip transport, filling the chip barrel and finally blocking the drill. Drilling into near-temperate ice is also problematic as pressure-induced melting can cause refreezing of meltwater on the drill which then easily gets stuck in the borehole. We developed a thermal drill compatible with the Fast Electromechanical Lightweight Ice Coring System (FELICS). The melting element consists of a coil heater, molded in an aluminum crown. Using the combined mechanical and thermal drill we obtained a 101 m surface-to-bedrock ice core from temperate Silvrettagletscher, Swiss Alps. The borehole with temperatures around 0°C was filled with meltwater. Power was supplied by two 2kW gasoline generators consuming a total of 70 L of alkylate fuel. Ice-core production rate was 1.8 mh−1. The drill produced non-fractured ice cores of excellent quality with a length of 70 cm and a diameter of 75–80 mm.

scholarly journals Extraction of Dissolved Organic Carbon from Glacier Ice for Radiocarbon Analysis

Radiocarbon ◽  
2019 ◽  
Vol 61 (03) ◽  
pp. 681-694 ◽  
Author(s):  
L Fang ◽  
J Schindler ◽  
T M Jenk ◽  
C Uglietti ◽  
S Szidat ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Working Conditions ◽  
Irradiation Time ◽  
Ice Core ◽  
Ice Cores ◽  
Swiss Alps ◽  
Carbonaceous Aerosols ◽  
Core Samples ◽  
Reported Data

ABSTRACTAlpine glaciers are valuable archives for the reconstruction of human impact on the environment. Besides dating purposes, measurement of radiocarbon (14C) content provides a powerful tool for long-term source apportionment studies on the carbonaceous aerosols incorporated in ice cores. In this work, we present an extraction system for 14C analyses of dissolved organic carbon (DOC) in ice cores. The setup can process ice samples of up to 350 g mass and offers ultra-clean working conditions for all extraction steps. A photo-oxidation method is applied by means of external UV irradiation of the sample. For an irradiation time of 30 min with catalyzation by addition of Fe2+ and H2O2, we achieve an efficiency of 96 ± 6% on average. Inert gas working conditions and stringent decontamination procedures enable a low overall blank of 1.9 ± 1.6 μg C with a F14C value of 0.68 ± 0.13. This makes it possible to analyze the DOC in ice samples with a carbon content of as low as 25 μg C kg−1 ice. For a first validation, the new method was applied to ice core samples from the Swiss Alps. The average DOC concentration and F14C values for the Fiescherhorn ice core samples show good agreement with previously reported data for the investigated period of 1925–1936 AD.

Cluster analysis of organic molecules in an alpine ice core: the transition from the pre-industrial to the industrial era

2020 ◽  
Author(s):  
Franziska Bachmeier ◽  
Alexander L. Vogel ◽  
Anja Lauer ◽  
Ling Fang ◽  
Katarzyna Arturi ◽  
...  
Keyword(s):  
Cluster Analysis ◽  
Chemical Composition ◽  
Atmospheric Aerosol ◽  
Organic Molecules ◽  
Solid Phase ◽  
Ice Core ◽  
Ice Cores ◽  
Aerosol Concentration ◽  
Swiss Alps ◽  
Organic Carbon Concentration

<p>The effects of atmospheric aerosol particles on the Earth’s radiative balance are a major source of uncertainty in global climate models. A distinction and quantification between natural and anthropogenic atmospheric aerosol concentration and their sources has to be made to reduce this uncertainty. Therefore, the natural pre-industrial aerosol concentration of the atmosphere must be determined. Ice cores are climate archives that enable the reconstruction of past atmospheric composition changes.</p><p>For such a reconstruction, an ice core from the Swiss Alps, which covers the years from 1682-1985, was examined for secondary organic aerosol (SOA) compounds. A non-target analysis (NTA) was used to determine the chemical composition of small organic molecules in the ice. The analytical method of the melted ice samples is based on solid-phase extraction, liquid chromatography and high-resolution mass spectrometry. The result of the NTA showed more than 630 features statistically different from the blank. A hierarchical cluster analysis was performed, in which compounds with a similar trend over time were grouped (clustered) together. The cluster analysis separated the considered features into two main groups. The first cluster showed a good correlation with the dissolved organic carbon concentration (DOC) of non-fossil origin (R = 0.75) while the second main group correlated excellently with the fossil DOC (R = 0.95), attributed based on the radiocarbon content. This leads to the presumption that compounds represented in the first cluster originated from biogenic sources while compounds in the second cluster are anthropogenic emissions or SOA formed by anthropogenically emitted precursors. This hypothesis is supported by the temporal trend of the two groups. The potential biogenic compounds show a relative stable behavior throughout time.  At the beginning of the 20th century a decrease of biogenic SOA is recorded. No compounds from the anthropogenic cluster were detected in pre-industrial times, they increase slowly from 1800 and more and more from 1900. Based on the division into the two main clusters, a detailed graphical evaluation of their chemical composition was performed. We show that the suspected biogenic cluster consists mainly of oxidation products of volatile organic compounds (VOC). The presumed anthropogenic cluster consists mainly of organosulfates, nitrooxy-organosulfate, aromatic compounds and mono- and dinitroaromatics.</p>

scholarly journals Acoustic velocity measurements for detecting the crystal orientation fabrics of a temperate ice core

2021 ◽  
Vol 15 (7) ◽  
pp. 3507-3521
Author(s):  
Sebastian Hellmann ◽  
Melchior Grab ◽  
Johanna Kerch ◽  
Henning Löwe ◽  
Andreas Bauder ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Crystal Orientation ◽  
Ice Core ◽  
Point Contact ◽  
Ice Cores ◽  
Swiss Alps ◽  
Mechanical Anisotropy ◽  
Similar Amount ◽  
Core Samples ◽  
Ultrasonic Measurements

Abstract. The crystal orientation fabric (COF) in ice cores provides detailed information, such as grain size and distribution and the orientation of the crystals in relation to the large-scale glacier flow. These data are relevant for a profound understanding of the dynamics and deformation history of glaciers and ice sheets. The intrinsic, mechanical anisotropy of the ice crystals causes an anisotropy of the polycrystalline ice of glaciers and affects the velocity of acoustic waves propagating through the ice. Here, we employ such acoustic waves to obtain the seismic anisotropy of ice core samples and compare the results with calculated acoustic velocities derived from COF analyses. These samples originate from an ice core from Rhonegletscher (Rhone Glacier), a temperate glacier in the Swiss Alps. Point-contact transducers transmit ultrasonic P waves with a dominant frequency of 1 MHz into the ice core samples and measure variations in the travel times of these waves for a set of azimuthal angles. In addition, the elasticity tensor is obtained from laboratory-measured COF, and we calculate the associated seismic velocities. We compare these COF-derived velocity profiles with the measured ultrasonic profiles. Especially in the presence of large ice grains, these two methods show significantly different velocities since the ultrasonic measurements examine a limited volume of the ice core, whereas the COF-derived velocities are integrated over larger parts of the core. This discrepancy between the ultrasonic and COF-derived profiles decreases with an increasing number of grains that are available within the sampling volume, and both methods provide consistent results in the presence of a similar amount of grains. We also explore the limitations of ultrasonic measurements and provide suggestions for improving their results. These ultrasonic measurements could be employed continuously along the ice cores. They are suitable to support the COF analyses by bridging the gaps between discrete measurements since these ultrasonic measurements can be acquired within minutes and do not require an extensive preparation of ice samples when using point-contact transducers.

scholarly journals The transport history of two Saharan dust events archived in an Alpine ice core

2005 ◽  
Vol 5 (4) ◽  
pp. 7497-7545 ◽  
Author(s):  
H. Sodemann ◽  
A. S. Palmer ◽  
C. Schwierz ◽  
M. Schwikowski ◽  
H. Wernli
Keyword(s):  
Phytoplankton Bloom ◽  
Ice Core ◽  
Ice Cores ◽  
Swiss Alps ◽  
Saharan Dust ◽  
Back Trajectory ◽  
Second Phase ◽  
The Alps ◽  
The Mediterranean ◽  
Dust Events

Abstract. Mineral dust from the Saharan desert can be transported across the Mediterranean towards the Alpine region several times a year. Occasionally, the dust is deposited with snowfall on Alpine glaciers and appears then as yellow or red layers in ice cores. Two such significant dust events were identified in an ice core drilled at the high-accumulation site Piz Zupó in the Swiss Alps (46°22' N, 9°55' E, 3850 m a.s.l.). From stable oxygen isotopes and major ion concentrations, the events were approximately dated as October and March 2000. In order to link the dust record in the ice core to the meteorological situation that led to the dust events, a novel methodology based on back-trajectory analysis was developed. It allowed for the identification of source regions, the atmospheric transport pathways, and wet deposition periods for both dust events. Furthermore, differences in the chemical signature of the two dust events could be interpreted with respect to contributions from the dust sources and aerosol scavenging during the transport. The dust deposition during the October event took place during 13–16 October 2000. Mobilisation areas of dust were mainly identified in the Algerian and Libyan deserts. A combination of an upper-level potential vorticity streamer and a midlevel jet across Algeria first brought moist Atlantic air and later mixed air from the tropics and Saharan desert across the Mediterranean towards the Alps. The March event consisted of two different deposition phases which took place during 18–20 and 23–26 March 2000. The first phase was associated with an exceptional transport pattern past Iceland and towards the Alps from northerly directions. The second phase was similar to the October event. A significant peak of methanesulphonic acid associated with the March dust event was most likely caused by incorporation of biogenic aerosol while passing through the marine boundary layer of the western Mediterranean during a local phytoplankton bloom. From this study, we conclude that the whole sequence of mobilisation, transport, and deposition of mineral aerosol should be considered for a detailed understanding of the chemical signal recorded in the ice core at Piz Zupó.

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