Linking pollen deposition and snow accumulation on the Alto dell'Ortles glacier (South Tyrol, Italy) for sub-seasonal dating of a firn temperate core

Abstract. Dating of ice cores from temperate non-polar glaciers is challenging and often problematic. However, a proper timescale is essential for a correct interpretation of the proxies measured in the cores. Here, we introduce a new method developed to obtain a sub-seasonal timescale relying on statistically measured similarities between pollen spectra obtained from core samples and daily airborne pollen monitoring samples collected in the same area. This approach was developed on a 10 m core retrieved from the temperate-firn portion of Alto dell'Ortles glacier (Eastern Italian Alps), for which a 5-year annual/seasonal timescale already exists. The aim was to considerably improve this timescale, reaching the highest possible temporal resolution and testing the efficiency and limits of pollen as a chronological tool. A test of the new timescale was performed by comparing our results to the output (date of layer formation) of the mass balance model EISModel, during the period encompassed by the timescale. The correspondence of the results supports the new sub-seasonal timescale based on pollen analysis. This comparison also allows us to draw important conclusions on the post-depositional effects of meltwater percolation on the pollen content of the firn core as well as on the climatic interpretation of the pollen signal.

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Linking pollen deposition, snow accumulation and isotopic composition on the Alto dell'Ortles glacier (South Tyrol, Italy) for sub-seasonal dating of a firn temperate core

10.5194/tc-2016-221 ◽

2016 ◽

Author(s):

Daniela Festi ◽

Luca Carturan ◽

Werner Kofler ◽

Giancarlo dalla Fontana ◽

Fabrizio de Blasi ◽

...

Keyword(s):

Meteorological Parameters ◽

Airborne Pollen ◽

Ice Cores ◽

Snow Accumulation ◽

Balance Model ◽

Pollen Deposition ◽

Layer Formation ◽

Italian Alps ◽

Pollen Monitoring ◽

Pollen Content

Abstract. Dating of ice cores from temperate non-polar glaciers is challenging and often problematic. Yet, a proper timescale is essential for a correct interpretation of the proxies measured in the cores. Here, we introduce a new method developed to obtain a sub-seasonal timescale relying on statistically measured similarities between pollen spectra obtained from core samples, and daily airborne pollen monitoring samples collected in the same area. This approach was developed on a 10 m core retrieved from the temperate firn portion of Alto dell'Ortles glacier (Eastern Italian Alps), for which a five-year annual/seasonal timescale already exists. The aim was to considerably improve this timescale, reaching the highest possible temporal resolution, and testing the efficiency and limits of pollen as a chronological tool. A test of the new timescale was performed by comparing our results to the output (date of layer formation) of the mass balance model EISModel, during the period encompassed by the timescale. The correspondence of the results supports the new sub-seasonal timescale based on pollen analysis. This comparison also allows to draw important conclusions on the post depositional effects of meltwater percolation on the pollen content of the firn core, as well as on the climatic interpretation of the pollen signal. Finally, we provide an example of useful application of the timescale related to the direct comparison of measured meteorological parameters and the stable isotopes composition of the core.

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Stratigraphic Studies and Surface-Layer Formation. A Case Study: Eastern Wilkes Land, East Antarctica (Abstract)

Annals of Glaciology ◽

10.1017/s0260305500006790 ◽

1988 ◽

Vol 11 ◽

pp. 216

Author(s):

I. D. Goodwin

Keyword(s):

Surface Layer ◽

Oxygen Isotope ◽

Snow Accumulation ◽

Katabatic Wind ◽

Late Winter ◽

Layer Formation ◽

Annual Layer ◽

Wilkes Land ◽

Firn Core ◽

Surface Layer Formation

This paper presents the results of a detailed study on the geomorphic and diagenetic processes of surface-layer formation and its subsequent preservation in the stratigraphic record. The study supplemented stratigraphic studies carried out along a 750 km ANARE traverse route along the 69 °S parallel between 112° and 131 °E (which approximately follows the 2000 m contour) in the katabatic wind zone of eastern Wilkes Land. A 100 cane farm was established at GD03 (69 °S, 115°E; 1835 m a.s.l.), adjacent to a 30 m deep firn-core drill site. The cane farm was used to monitor seasonal changes in snow accumulation and the type, size, distribution and orientation of the surface micro-relief. The annual snow accumulation at GD03 is equivalent to 300 kg m−2 of water. This annual layer is visibly marked by a multi-layered ice crust, typically 1–2 mm thick, which is formed in autumn during a hiatus in snow supply. Within the annual layer, single-layered thin ice crusts were observed. These correspond to short hiatus periods, of the order of 2–3 weeks, during late winter–early spring, and radiation glazes formed during summer. Density and oxygen-isotope–depth profiles display annual cyclicity within the snow-pack. Considerable horizontal variation was found in a single annual-layer thickness, with respect to ice-crust thickness, snow-density and oxygen-isotope values, and depth-hoar development, when traced in 21 2 m cores drilled at 5 m horizontal spacing. The observed changes in surface micro-relief distributions over the cane farm have enabled a greater understanding of vertical variations between annual layers observed in the 30 m firn core.

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Intercomparison of firn core and meteorological data

Antarctic Science ◽

10.1017/s0954102001000463 ◽

2001 ◽

Vol 13 (3) ◽

pp. 329-337 ◽

Cited By ~ 19

Author(s):

Alison J. McMorrow ◽

Mark A.J. Curran ◽

Tas D. Van Ommen ◽

Vin Morgan ◽

Michael J. Pook ◽

...

Keyword(s):

High Resolution ◽

Abrupt Change ◽

Meteorological Data ◽

Chemical Species ◽

Ice Cores ◽

Snow Accumulation ◽

Meteorological Conditions ◽

Depth Range ◽

High Accumulation ◽

Firn Core

High resolution firn core records of the oxygen isotope ratio (δ18O) and trace chemical species were extracted from a high accumulation site on Law Dome, East Antarctica. Inter-core comparisons were conducted and regional events identified in cores 5 km apart. High resolution dating of one of the firn cores was established using a co-located Automatic Weather Station (AWS) equipped with a snow accumulation sensor, allowing dating of individual precipitation events in the firn core record. Variations in the δ18O and trace chemical records were compared with meteorological conditions at the mesoscale and the synoptic-scale. Particular focus was given to an abrupt change in sea salt concentrations and δ18O within a depth range that appears from AWS accumulation data to have been deposited over a 24 hour period. The abrupt change in the firn core record was found to be consistent with an abrupt change in meteorological conditions. Direct comparisons between high resolution firn core records and meteorological conditions will greatly facilitate the interpretation of signals preserved in deep ice cores.

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Firn accumulation records for the past 1000 years on the basis of dielectric profiling of six cores from Dronning Maud Land, Antarctica

Journal of Glaciology ◽

10.3189/172756504781830169 ◽

2004 ◽

Vol 50 (169) ◽

pp. 279-291 ◽

Cited By ~ 26

Author(s):

Coen M. Hofstede ◽

S.W van de Wal Roderik ◽

Karsten A. Kaspers ◽

Michiel R. van den Broeke ◽

Lars Karlöf ◽

...

Keyword(s):

20Th Century ◽

Accumulation Rate ◽

Ice Cores ◽

Snow Accumulation ◽

The Past ◽

Medium Length ◽

Dronning Maud Land ◽

The Mean ◽

Firn Core ◽

Past 1000 Years

AbstractThis paper presents an overview of firn accumulation in Dronning Maud Land (DML), Antarctica, over the past 1000 years. It is based on a chronology established with dated volcanogenic horizons detected by dielectric profiling of six medium-length firn cores. In 1998 the British Antarctic Survey retrieved a medium-length firn core from western DML. During the Nordic EPICA (European Project for Ice Coring in Antarctica) traverse of 2000/01, a 160 m long firn core was drilled in eastern DML. Together with previously published data from four other medium-length ice cores from the area, these cores yield 50 possible volcanogenic horizons. All six firn cores cover a mutual time record until the 29th eruption. This overlapping period represents a period of approximately 1000 years, with mean values ranging between 43 and 71 mm w.e. The cores revealed no significant trend in snow accumulation. Running averages over 50 years, averaged over the six cores, indicate temporal variations of5%. All cores display evidence of a minimum in the mean annual firn accumulation rate around AD 1500 and maxima around AD 1400 and 1800. The mean increase over the early 20th century was the strongest increase, but the absolute accumulation rate was not much higher than around AD 1400. In eastern DML a 13% increase is observed for the second half of the 20th century.

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Stratigraphic Studies and Surface-Layer Formation. A Case Study: Eastern Wilkes Land, East Antarctica (Abstract)

Annals of Glaciology ◽

10.3189/s0260305500006790 ◽

1988 ◽

Vol 11 ◽

pp. 216-216

Author(s):

I. D. Goodwin

Keyword(s):

Surface Layer ◽

Oxygen Isotope ◽

Snow Accumulation ◽

Katabatic Wind ◽

Late Winter ◽

Layer Formation ◽

Annual Layer ◽

Wilkes Land ◽

Firn Core ◽

Surface Layer Formation

This paper presents the results of a detailed study on the geomorphic and diagenetic processes of surface-layer formation and its subsequent preservation in the stratigraphic record. The study supplemented stratigraphic studies carried out along a 750 km ANARE traverse route along the 69 °S parallel between 112° and 131 °E (which approximately follows the 2000 m contour) in the katabatic wind zone of eastern Wilkes Land.A 100 cane farm was established at GD03 (69 °S, 115°E; 1835 m a.s.l.), adjacent to a 30 m deep firn-core drill site. The cane farm was used to monitor seasonal changes in snow accumulation and the type, size, distribution and orientation of the surface micro-relief.The annual snow accumulation at GD03 is equivalent to 300 kg m−2 of water. This annual layer is visibly marked by a multi-layered ice crust, typically 1–2 mm thick, which is formed in autumn during a hiatus in snow supply. Within the annual layer, single-layered thin ice crusts were observed. These correspond to short hiatus periods, of the order of 2–3 weeks, during late winter–early spring, and radiation glazes formed during summer.Density and oxygen-isotope–depth profiles display annual cyclicity within the snow-pack. Considerable horizontal variation was found in a single annual-layer thickness, with respect to ice-crust thickness, snow-density and oxygen-isotope values, and depth-hoar development, when traced in 21 2 m cores drilled at 5 m horizontal spacing.The observed changes in surface micro-relief distributions over the cane farm have enabled a greater understanding of vertical variations between annual layers observed in the 30 m firn core.

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Firn changes at Colle Gnifetti revealed with a high-resolution process-based physical model approach

The Cryosphere ◽

10.5194/tc-15-3181-2021 ◽

2021 ◽

Vol 15 (7) ◽

pp. 3181-3205

Author(s):

Enrico Mattea ◽

Horst Machguth ◽

Marlene Kronenberg ◽

Ward van Pelt ◽

Manuela Bassi ◽

...

Keyword(s):

High Resolution ◽

Distributed Simulation ◽

Meteorological Data ◽

Ice Core ◽

Ice Cores ◽

Snow Accumulation ◽

Balance Model ◽

Monte Rosa ◽

Fully Coupled

Abstract. Our changing climate is expected to affect ice core records as cold firn progressively transitions to a temperate state. Thus, there is a need to improve our understanding and to further develop quantitative process modeling, to better predict cold firn evolution under a range of climate scenarios. Here we present the application of a distributed, fully coupled energy balance model, to simulate cold firn at the high-alpine glaciated saddle of Colle Gnifetti (Swiss–Italian Alps) over the period 2003–2018. We force the model with high-resolution, long-term, and extensively quality-checked meteorological data measured in the closest vicinity of the firn site, at the highest automatic weather station in Europe (Capanna Margherita, 4560 m a.s.l.). The model incorporates the spatial variability of snow accumulation rates and is calibrated using several partly unpublished high-altitude measurements from the Monte Rosa area. The simulation reveals a very good overall agreement in the comparison with a large archive of firn temperature profiles. Our results show that surface melt over the glaciated saddle is increasing by 3–4 mm w.e. yr−2 depending on the location (29 %–36 % in 16 years), although with large inter-annual variability. Analysis of modeled melt indicates the frequent occurrence of small melt events (<4 mm w.e.), which collectively represent a significant fraction of the melt totals. Modeled firn warming rates at 20 m depth are relatively uniform above 4450 m a.s.l. (0.4–0.5 ∘C per decade). They become highly variable at lower elevations, with a marked dependence on surface aspect and absolute values up to 2.5 times the local rate of atmospheric warming. Our distributed simulation contributes to the understanding of the thermal regime and evolution of a prominent site for alpine ice cores and may support the planning of future core drilling efforts. Moreover, thanks to an extensive archive of measurements available for comparison, we also highlight the possibilities of model improvement most relevant to the investigation of future scenarios, such as the fixed-depth parametrized routine of deep preferential percolation.

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Airborne Pollen: A Unique Air Mass Tracer, Its Influx to the Canadian High Arctic

Annals of Glaciology ◽

10.3189/s0260305500006005 ◽

1985 ◽

Vol 7 ◽

pp. 109-116 ◽

Cited By ~ 4

Author(s):

J.C. Bourgeois ◽

R.M. Koerner ◽

B.T. Alt

Keyword(s):

Airborne Pollen ◽

Ice Cores ◽

High Arctic ◽

Pollen Grain ◽

The Arctic ◽

Pollen Deposition ◽

Tree Line ◽

Canadian High Arctic ◽

Deposition Rates ◽

The North

A study of pollen grain concentration in surface snow and ice cores at 15 sites in the Canadian high Arctic and one site near the tree line, together with published pollen deposition rates south of the tree line has shown long-range dispersal of pollen from the boreal forest to the limits of our area on the Arctic Ocean close to Svalbard and the North Pole. There are no discernible trends of deposition rates within the high Arctic which suggests extremely long trajectories with strong zonal components; some of the pollen may have an Eurasian source. We relate the trajectories to synoptic patterns in the mid- and high Arctic.

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Airborne Pollen: A Unique Air Mass Tracer, Its Influx to the Canadian High Arctic

Annals of Glaciology ◽

10.1017/s0260305500006005 ◽

1985 ◽

Vol 7 ◽

pp. 109-116 ◽

Cited By ~ 47

Author(s):

J.C. Bourgeois ◽

R.M. Koerner ◽

B.T. Alt

Keyword(s):

Airborne Pollen ◽

Ice Cores ◽

High Arctic ◽

Pollen Grain ◽

The Arctic ◽

Pollen Deposition ◽

Tree Line ◽

Canadian High Arctic ◽

Deposition Rates ◽

The North

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Seasonal variations in the properties and structural composition of sea ice and snow cover in the Bellingshausen and Amundsen Seas, Antarctica

Journal of Glaciology ◽

10.3189/s0022143000002902 ◽

1997 ◽

Vol 43 (143) ◽

pp. 138-151 ◽

Cited By ~ 2

Author(s):

M. O. Jeffries ◽

K. Morris ◽

W.F. Weeks ◽

A. P. Worby

Keyword(s):

Sea Ice ◽

Isotopic Composition ◽

Snow Cover ◽

Sea Water ◽

Ice Cores ◽

Ice Cover ◽

Snow Accumulation ◽

Ice Formation ◽

Frazil Ice ◽

Core Sets

AbstractSixty-three ice cores were collected in the Bellingshausen and Amundsen Seas in August and September 1993 during a cruise of the R.V. Nathaniel B. Palmer. The structure and stable-isotopic composition (18O/16O) of the cores were investigated in order to understand the growth conditions and to identify the key growth processes, particularly the contribution of snow to sea-ice formation. The structure and isotopic composition of a set of 12 cores that was collected for the same purpose in the Bellingshausen Sea in March 1992 are reassessed. Frazil ice and congelation ice contribute 44% and 26%, respectively, to the composition of both the winter and summer ice-core sets, evidence that the relatively calm conditions that favour congelation-ice formation are neither as common nor as prolonged as the more turbulent conditions that favour frazil-ice growth and pancake-ice formation. Both frazil- and congelation-ice layers have an av erage thickness of 0.12 m in winter, evidence that congelation ice and pancake ice thicken primarily by dynamic processes. The thermodynamic development of the ice cover relies heavily on the formation of snow ice at the surface of floes after sea water has flooded the snow cover. Snow-ice layers have a mean thickness of 0.20 and 0.28 m in the winter and summer cores, respectively, and the contribution of snow ice to the winter (24%) and summer (16%) core sets exceeds most quantities that have been reported previously in other Antarctic pack-ice zones. The thickness and quantity of snow ice may be due to a combination of high snow-accumulation rates and snow loads, environmental conditions that favour a warm ice cover in which brine convection between the bottom and top of the ice introduces sea water to the snow/ice interface, and bottom melting losses being compensated by snow-ice formation. Layers of superimposed ice at the top of each of the summer cores make up 4.6% of the ice that was examined and they increase by a factor of 3 the quantity of snow entrained in the ice. The accumulation of superimposed ice is evidence that melting in the snow cover on Antarctic sea-ice floes ran reach an advanced stage and contribute a significant amount of snow to the total ice mass.

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Neural networks for increased accuracy of allergenic pollen monitoring

Scientific Reports ◽

10.1038/s41598-021-90433-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Marcel Polling ◽

Chen Li ◽

Lu Cao ◽

Fons Verbeek ◽

Letty A. de Weger ◽

...

Keyword(s):

Neural Networks ◽

Airborne Pollen ◽

Pollen Grains ◽

Allergenic Pollen ◽

Herbarium Specimens ◽

Pollen Monitoring ◽

Pollen Concentrations ◽

Source Of Information ◽

Urticaceae Pollen

AbstractMonitoring of airborne pollen concentrations provides an important source of information for the globally increasing number of hay fever patients. Airborne pollen is traditionally counted under the microscope, but with the latest developments in image recognition methods, automating this process has become feasible. A challenge that persists, however, is that many pollen grains cannot be distinguished beyond the genus or family level using a microscope. Here, we assess the use of Convolutional Neural Networks (CNNs) to increase taxonomic accuracy for airborne pollen. As a case study we use the nettle family (Urticaceae), which contains two main genera (Urtica and Parietaria) common in European landscapes which pollen cannot be separated by trained specialists. While pollen from Urtica species has very low allergenic relevance, pollen from several species of Parietaria is severely allergenic. We collect pollen from both fresh as well as from herbarium specimens and use these without the often used acetolysis step to train the CNN model. The models show that unacetolyzed Urticaceae pollen grains can be distinguished with > 98% accuracy. We then apply our model on before unseen Urticaceae pollen collected from aerobiological samples and show that the genera can be confidently distinguished, despite the more challenging input images that are often overlain by debris. Our method can also be applied to other pollen families in the future and will thus help to make allergenic pollen monitoring more specific.

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