scholarly journals Glaciological Investigations of the Tropical Quelccaya Ice Cap, Peru

1980 ◽  
Vol 25 (91) ◽  
pp. 69-84 ◽  
Author(s):  
Lonnie G. Thompson
Keyword(s):  
Rainy Season ◽  
Ice Core ◽  
Ice Cores ◽  
Dry Season ◽  
Radioactive Material ◽  
Polar Regions ◽  
Near Surface ◽  
Ice Cap ◽  
Activity Measurements ◽  
Quelccaya Ice Cap

AbstractGlaciological results of the continuing investigations of the Quelccaya ice cap located at lat. 13° 56’ S., long. 70° 50’ W., in the Cordillera Oriental of southern Peru are presented. Ice cores to a depth of 15 m have been retrieved from the summit dome (5650 m), middle dome (5543 m), and south dome (5480 m) and sampled in detail for microparticle, oxygen-isotope, and total-β-activity measurements. Results of these core analyses indicate that although the summit of this ice cap is only 300 m above the annual snow line and the firn is temperate, an interpretable stratigraphic record is preserved. The marked seasonal ice stratigraphy is produced by the marked seasonal variation in regional precipitation. High concentrations of microparticles and β- radioactive material occur during the dry season (May-August). Microparticles deposited during the rainy season are larger than those deposited during the dry season. On the Quelccaya ice cap the most negative δ18O values occur during the warmer rainy season (the opposite occurs in polar regions). The near-surface mean δ value of – 21‰ is remarkably low for this tropical site where the measured mean annual air temperature is – 3°C The seasonality of the microparticles, total β activity, and isotope ratios offers the prospect of a climatic ice-core record from this tropical ice cap.

scholarly journals Glaciological Investigations of the Tropical Quelccaya Ice Cap, Peru

1980 ◽  
Vol 25 (91) ◽  
pp. 69-84 ◽  
Author(s):  
Lonnie G. Thompson
Keyword(s):  
Rainy Season ◽  
Ice Core ◽  
Ice Cores ◽  
Dry Season ◽  
Radioactive Material ◽  
Polar Regions ◽  
Near Surface ◽  
Ice Cap ◽  
Activity Measurements ◽  
Quelccaya Ice Cap

AbstractGlaciological results of the continuing investigations of the Quelccaya ice cap located at lat. 13° 56’ S., long. 70° 50’ W., in the Cordillera Oriental of southern Peru are presented. Ice cores to a depth of 15 m have been retrieved from the summit dome (5650 m), middle dome (5543 m), and south dome (5480 m) and sampled in detail for microparticle, oxygen-isotope, and total-β-activity measurements. Results of these core analyses indicate that although the summit of this ice cap is only 300 m above the annual snow line and the firn is temperate, an interpretable stratigraphic record is preserved. The marked seasonal ice stratigraphy is produced by the marked seasonal variation in regional precipitation. High concentrations of microparticles andβ- radioactive material occur during the dry season (May-August). Microparticles deposited during the rainy season are larger than those deposited during the dry season. On the Quelccaya ice cap the most negativeδ18O values occur during the warmer rainy season (the opposite occurs in polar regions). The near-surface meanδvalue of – 21‰ is remarkably low for this tropical site where the measured mean annual air temperature is –3°CThe seasonality of the microparticles, totalβactivity, and isotope ratios offers the prospect of a climatic ice-core record from this tropical ice cap.

scholarly journals Apparent discrepancy of Tibetan ice core <i>δ</i><sup>18</sup>O records may be attributed to misinterpretation of chronology

2019 ◽  
Vol 13 (6) ◽  
pp. 1743-1752 ◽  
Author(s):  
Shugui Hou ◽  
Wangbin Zhang ◽  
Hongxi Pang ◽  
Shuang-Ye Wu ◽  
Theo M. Jenk ◽  
...  
Keyword(s):  
High Resolution ◽  
Ice Core ◽  
Ice Cores ◽  
Warming Trend ◽  
The Tibetan Plateau ◽  
Apparent Discrepancy ◽  
Ice Cap ◽  
Guliya Ice Core ◽  
Cooling Trend ◽  
Instrumental Period

Abstract. Ice cores from the Tibetan Plateau (TP) are widely used for reconstructing past climatic and environmental conditions that extend beyond the instrumental period. However, challenges in dating and interpreting ice core records often lead to inconsistent results. The Guliya ice core drilled from the northwestern TP suggested a cooling trend during the mid-Holocene based on its decreasing δ18O values, which is not observed in other Tibetan ice cores. Here we present a new high-resolution δ18O record of the Chongce ice cores drilled to bedrock ∼30 km away from the Guliya ice cap. Our record shows a warming trend during the mid-Holocene. Based on our results as well as previously published ice core data, we suggest that the apparent discrepancy between the Holocene δ18O records of the Guliya and the Chongce ice cores may be attributed to a possible misinterpretation of the Guliya ice core chronology.

scholarly journals Characterization and formation of melt layers in polar snow: observations and experiments from West Antarctica

2005 ◽  
Vol 51 (173) ◽  
pp. 307-312 ◽  
Author(s):  
Sarah B. Das ◽  
Richard B. Alley
Keyword(s):  
Field Experiments ◽  
Preferential Flow ◽  
Ice Core ◽  
Ice Cores ◽  
West Antarctica ◽  
Near Surface ◽  
Fine Grained ◽  
Ice Core Record ◽  
Temperature Records ◽  
Polar Snow

AbstractSurface melting rarely occurs across most of the Antarctic ice sheet, away from the warmer coastal regions. Nonetheless, isolated melt features are preserved in the firn and ice in response to infrequent and short-lived melting events. An understanding of the formation and occurrence of these melt layers will help us to interpret records of past melt occurrences from polar ice cores such as the Siple Dome ice-core record from West Antarctica. A search in the near-surface firn in West Antarctica found that melt features are extremely rare, and consist of horizontal, laterally continuous, one to a few millimeter thick, ice layers with few air bubbles. The melt layers found date from the 1992/93 and 1991/92 summers. Field experiments to investigate changes in stratigraphy taking place during melt events reproduced melt features as seen in the natural stratigraphy. Melting conditions of varying intensity were created by passively heating the near-surface air for varying lengths of time inside a clear plastic hotbox. Melt layers formed due entirely to preferential flow and subsequent refreezing of meltwater from the surface into near-surface, fine-grained, crust layers. Continuous melt layers were formed experimentally when positive-degree-day values exceeded 1ºC-day, a value corresponding well with air-temperature records from automatic weather station sites where melt layers formed in the recent past.

scholarly journals Some comments on climatic reconstructions from ice cores drilled in areas of high melt

1997 ◽  
Vol 43 (143) ◽  
pp. 90-97 ◽  
Author(s):  
Roy M. Koerner
Keyword(s):  
Time Scales ◽  
Ice Core ◽  
Ice Cores ◽  
The Holocene ◽  
Ice Caps ◽  
Ice Cap ◽  
Thermal Maximum ◽  
Devon Ice Cap ◽  
Seasonal Signals ◽  
Cross Correlations

AbstractPoor consideration has been given in many Arctic circum-polar ice-core studies to the effect of summer snow melt on chemistry, stable-isotope concentrations and time-scales. Many of these corps are drilled close to the firn line where melt is intense. Some come from below the firn line where accumulation is solely in the form of super-imposed ice. In all cases, seasonal signals are reduced or removed and, in some, time gaps develop during periods of excessive melting which situate the drill site in the ablation zone. Consequently, cross correlations of assumed synchronous events among the cores are invalid, so that time-scales along the same cores differ between authors by factors of over 2. Many so-called climatic signals are imaginary rather than real. By reference to published analyses of cores from the superimposed ice zone on Devon Ice Cap (Koerner, 1970) and Meighen Ice Cap (Koerner and Paterson, 1974), it is shown how melt affects all the normally well-established ice-core proxies and leads to their misinterpretation. Despite these limitations, the cores can give valuable low-resolution records for all or part of the Holocene. They show that the thermal maximum in the circum-polar Arctic occurred in the early Holocene. This maximum, effected negative balances on all the ice caps and removed the smaller ones. Cooler conditions in the second half of the Holocene have caused the regrowth of these same ice caps.

scholarly journals Inferring paleo-accumulation records from ice-core data by an adjoint method: application to James Ross Island's ice core

2014 ◽  
Vol 10 (5) ◽  
pp. 3821-3845 ◽  
Author(s):  
C. Martín ◽  
R. Mulvaney ◽  
G. H. Gudmundsson ◽  
H. Corr
Keyword(s):  
Vertical Velocity ◽  
Adjoint Method ◽  
Ice Core ◽  
Synthetic Data ◽  
Ice Cores ◽  
Snow Accumulation ◽  
Polar Regions ◽  
History Of ◽  
Climatic Record ◽  
Accumulation History

Abstract. Ice cores contain a record of snow precipitation that includes information about past atmospheric circulation and mass imbalance in the polar regions. We present a novel adjoint method to reconstruct a climatic record by both optimally dating an ice-core and deriving from it a detailed accumulation history. The motivation of our work is the recent application of phase sensitive radar which measures the vertical velocity of an ice column. The velocity is dependent on the history of subsequent snow accumulation, compaction and compression; and in our inverse formulation of this problem, measured vertical velocity profiles can be utilized directly thereby reducing the uncertainty introduced by ice flow modelling. We first apply our method to synthetic data in order to study its capability and the effect of noise and gaps in the data on retrieved accumulation history. The method is then applied to the ice core retrieved from James Ross Island, Antarctica. We show that the method is robust and that the results depend on quality of the age-depth observations and the derived flow regime around the core site. The method facilitates the incorporation of increasing detail provided by ice-core analysis together with observed full-depth velocity in order to construct a complete climatic record of the polar regions.

scholarly journals Multi-model comparison of the volcanic sulfate deposition from the 1815 eruption of Mt. Tambora

2017 ◽  
Author(s):  
Lauren Marshall ◽  
Anja Schmidt ◽  
Matthew Toohey ◽  
Ken S. Carslaw ◽  
Graham W. Mann ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Model Comparison ◽  
Ice Core ◽  
Ice Cores ◽  
Sulfate Aerosol ◽  
Polar Regions ◽  
Polar Ice ◽  
Climatic Effects ◽  
Sulfate Deposition ◽  
Ice Core Records

Abstract. The eruption of Mt. Tambora in 1815 was the largest volcanic eruption of the past 500 years. The eruption had significant climatic impacts, leading to the 1816 Year Without a Summer and remains a valuable event from which to understand the climatic effects of large stratospheric volcanic sulfur dioxide injections. The eruption also resulted in one of the strongest and most easily identifiable volcanic signals in polar ice cores, which are widely used to reconstruct the timing and atmospheric sulfate loading of past eruptions. As part of the Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP), four state-of-the-art global aerosol models simulated this eruption. We analyse both simulated background (no Tambora) and volcanic (with Tambora) sulfate deposition to polar regions and compare to ice core records. Background sulfate deposition is of similar magnitude across all models and compares well to ice core records. However, volcanic sulfate deposition varies in timing, spatial pattern and magnitude between the models. Mean simulated deposited sulfate on Antarctica ranges from 19 to 264 kg km−2, and on Greenland from 31 to 194 kg km−2, as compared to the mean ice core-derived estimates of roughly 40–50 kg km−2, for both Greenland and Antarctica. The ratio of the hemispheric atmospheric sulfate aerosol burden after the eruption to the average ice sheet deposited sulfate varies between models by up to a factor of 15. Sources of this inter-model variability include differences in both the formation and the transport of sulfate aerosol. Our results highlight the uncertainties and difficulties in deriving historic volcanic aerosol radiative forcing of climate, based on measured volcanic sulfate in polar ice cores.

scholarly journals Community change of microorganisms in the Muztagata and Dunde glacier and climatic and environmental implications

2016 ◽  
Author(s):  
Yong Chen ◽  
Xiang-Kai Li ◽  
Jing Si ◽  
Guang-Jian WU ◽  
Li-De Tian ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Cell Density ◽  
Ice Core ◽  
Ice Cores ◽  
Community Change ◽  
Rrna Gene ◽  
Environmental Implications ◽  
Depth Profiles ◽  
Ice Cap ◽  
Glacier Ice

Abstract. Microorganisms are continuously blown onto the glacier snow, and thus the glacial depth profiles provide excellent geographic archives of the microbial communities. However, it is uncertain about how the microbial communities respond to the climatic and environmental changes over the glacier ice. In the present study, the live microbial density, stable isotopic ratios, 18O/16O in the precipitation, and mineral particle concentrations along the glacial depth profiles were collected from ice cores from the Muztagata glacier and the Dunde ice cap. Six bacterial 16S rRNA gene clone libraries were established from the Dunde ice core. The Muztagata ice core presented seasonal response patterns for both live and total cell density with high cell density occurring in the warming spring and summer. Both ice core data showed a frequent association of dust and microorganisms in the ice. Genera Polaromas sp., Pedobacter sp, Flavobacterium sp., Cryobacteriium sp., and Propionibacterium/Blastococcus sp. frequently appeared at the six tested ice layers, and constituted the dominant species endemic to the Dunde ice cap, whereas some genera such as Rhodoferax sp., Variovorax sp., Sphingobacterium sp., Cyanobacterium sp., Knoellia sp., and Luteolibacter sp. rarely presented in the ice. In conclusion, data present a discrete increase of microbial cell density in the warming seasons and biogeography of the microbial communities associated with the predominance of a few endemic groups in the local glacial regions. This reinforces our hypothesis of dust-borne and post-deposition being the main agents interactively controlling microbial load in the glacier ice.

scholarly journals Technical details concerning development of a 1200 yr proxy index for global volcanism

2013 ◽  
Vol 5 (1) ◽  
pp. 187-197 ◽  
Author(s):  
T. J. Crowley ◽  
M. B. Unterman
Keyword(s):  
Climate Models ◽  
Ice Core ◽  
Growth Curves ◽  
Ice Cores ◽  
Simultaneous Occurrence ◽  
High Temporal Resolution ◽  
Polar Regions ◽  
Effective Particle ◽  
Global Volcanism ◽  
Technical Details

Abstract. This report describes details of developing a volcano forcing reconstruction (Crowley et al., 2008) for climate models that is based primarily on sulphate records in Antarctic and Greenland ice cores. The chronology of eruptions is considered accurate to within 1 yr for the interval AD 1104–2000 and about 2 yr for AD 800–1103. The reconstruction involves (1) calibration against satellite aerosol optical depth (AOD) estimates of the 1991 Pinatubo/Hudson eruptions; (2) partial validation against independent lunar estimates of AOD and global sulphate emissions; (3) partial assessment of uncertainties in AOD estimates; (4) assessment of possible tropical "false positives" in ice core reconstructions due to simultaneous occurrence of mid/high-latitude eruptions in each hemisphere; (5) identification of a new category of eruptions, termed "unipolar" tropical eruptions, in which the eruption plume penetrates mainly to polar regions in only the hemisphere of its eruption; (6) use of different growth curves for high- and low-latitude eruptions; (7) specification of 2/3 power shortwave scaling for eruptions larger than the 1991 Pinatubo eruption; (8) introduction of an estimate of effective particle size that affects lifetime and scattering properties of stratospheric aerosols; and (9) utilization of bimonthly-resolution electrical conductivity measurements to estimate the eruption date of the 1258/1259 eruption as 1257.7±0.2. The data, and a high-temporal resolution reconstruction for climate models, are available at: http://hurricane.ncdc.noaa.gov/pls/paleox/f?p=519:1:::::P1_STUDY_ID:14168.

scholarly journals Glacier ice archives fifteen-thousand-year-old viruses

2020 ◽  
Author(s):  
Zhi-Ping Zhong ◽  
Natalie E. Solonenko ◽  
Yueh-Fen Li ◽  
Maria C. Gazitúa ◽  
Simon Roux ◽  
...  
Keyword(s):  
In Silico ◽  
Ice Core ◽  
Ice Cores ◽  
Metagenomic Sequencing ◽  
Climate Conditions ◽  
Ice Cap ◽  
Glacier Ice ◽  
Viral Communities ◽  
Microbial Groups ◽  
Sampling Procedures

AbstractWhile glacier ice cores provide climate information over tens to hundreds of thousands of years, study of microbes is challenged by ultra-low-biomass conditions, and virtually nothing is known about co-occurring viruses. Here we establish ultra-clean microbial and viral sampling procedures and apply them to two ice cores from the Guliya ice cap (northwestern Tibetan Plateau, China) to study these archived communities. This method reduced intentionally contaminating bacterial, viral, and free DNA to background levels in artificial-ice-core control experiments, and was then applied to two authentic ice cores to profile their microbes and viruses. The microbes differed significantly across the two ice cores, presumably representing the very different climate conditions at the time of deposition that is similar to findings in other cores. Separately, viral particle enrichment and ultra-low-input quantitative viral metagenomic sequencing from ∼520 and ∼15,000 years old ice revealed 33 viral populations (i.e., species-level designations) that represented four known genera and likely 28 novel viral genera (assessed by gene-sharing networks). In silico host predictions linked 18 of the 33 viral populations to co-occurring abundant bacteria, including Methylobacterium, Sphingomonas, and Janthinobacterium, indicating that viruses infected several abundant microbial groups. Depth-specific viral communities were observed, presumably reflecting differences in the environmental conditions among the ice samples at the time of deposition. Together, these experiments establish a clean procedure for studying microbial and viral communities in low-biomass glacier ice and provide baseline information for glacier viruses, some of which appear to be associated with the dominant microbes in these ecosystems.ImportanceThis study establishes ultra-clean microbial and viral sampling procedures for glacier ice, which complements prior in silico decontamination methods and expands, for the first time, the clean procedures to viruses. Application of these methods to glacier ice confirmed prior common microbiological findings for a new ice core climate record, and provides a first window into viral genomes and their ecology from glacier ice across two time horizons, and emphasizes their likely impact on abundant microbial groups. Together these efforts provide clean sampling approaches and foundational datasets that should enable simultaneous access to an archived virosphere in glacier ice.

scholarly journals Soluble Impurities In Ice Core D-1 Of Dunde Ice Cap, China, Over The Last 500 Years

1990 ◽  
Vol 14 ◽  
pp. 363
Author(s):  
Wu Xiaoling ◽  
Liu Jingsona ◽  
Yang Qinzhou
Keyword(s):  
Atmospheric Chemistry ◽  
Industrial Revolution ◽  
Environmental Changes ◽  
Ice Core ◽  
Ice Cores ◽  
Short Term ◽  
The Core ◽  
Ice Cap ◽  
National Foundation ◽  
Analysis Of Time Series

This paper gives the preliminary results of 26 trace element measurements of ice cores from Dunde Ice Cap, China. The chemical composition of soluble impurities along ice core D-1 covering the last 500 years B P., is reported and interpreted in terms of atmospheric contributions. The dust content in ice cores of Dunde Ice Cap is 36 times higher than in Byrd Station, Antarctica. Variations of soluble elements such as Ca, Mg, Κ and Na, in Dunde Ice cores are very sensitive to climatic and environmental changes. The 25 trace elements in ice core D-1 (K, Na, Ca, Mg, Cd, Cr, Co, Cu, Fe, Mn, Mo, Ni, Pb, Al, Sr, Ti, V, Zn, As, Ba, Β, Li, Ρ, S, Sn) were measured. Cationicions arranged in order of content are as follows: Ca &gt; Na &gt; Mg &gt; Κ &gt; Αl &gt; Fe &gt; Ζn &gt; Cu &gt; Μn &gt; Pb &gt; Cr &gt; Ni &gt; Co &gt; Cd etc. The content of soluble impurities has typical terrestrial features. Rock-forming elements such as Ca, Mg, Κ, Na, Si, Al, and Fe make up 99% in the core samples. Particular attention is given to the possible impact of the so-called “pre-Industrial Revolution period” and man’s influence on the atmospheric chemistry. The spectral analysis of time series for the variation of each of the 26 contributions show a 92 year cycle that is present in the variation of all 26 ions with depth. Short-term variations, such as 23, 31, 48, 81 year cycles, are also discussed. The ice-core research program has been supported by the Chinese National Foundation of Natural Science under Grant DO125-4860011.

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