Studies on pneumatic transport of ice cores in reverse circulation air drilling

2019 ◽  
Vol 356 ◽  
pp. 50-59
Author(s):  
Pinlu Cao ◽  
Hongyu Cao ◽  
Jine Cao ◽  
Miaomiao Liu ◽  
Baoyi Chen
Keyword(s):  
Ice Cores ◽  
Pneumatic Transport ◽  
Air Drilling ◽  
Reverse Circulation

scholarly journals Air reverse circulation at the hole bottom in ice-core drilling

2019 ◽  
Vol 65 (249) ◽  
pp. 149-156 ◽  
Author(s):  
ZHENGYI HU ◽  
PAVEL TALALAY ◽  
ZHICHUAN ZHENG ◽  
PINLU CAO ◽  
GUITAO SHI ◽  
...  
Keyword(s):  
High Efficiency ◽  
Ice Core ◽  
Ice Cores ◽  
Test Results ◽  
Core Drilling ◽  
Low Energy Consumption ◽  
Reverse Circulation ◽  
Drilling System ◽  
Conventional Drilling ◽  
Hole Bottom

ABSTRACTIce-core drilling to depths of 200–300 m is an important part of research studies concerned with paleoclimate reconstruction and anthropogenic climate change. However, conventional drilling methods face difficulties due to firn permeability. We have developed an electromechanical ice-core drill with air reverse circulation at the hole bottom. We believe that the new drilling system will recover ice cores faster than shallow auger drills, with high efficiency and low energy consumption. The theoretically estimated up-hole speed of the airflow should be not <7.7 m s−1 to allow proper removal of ice cuttings from the borehole bottom. The computer simulation and test results showed that the design of the new ice-coring drill is feasible. The maximum allowed penetration rate depends by square law on airflow.

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

1997 ◽  
Vol 43 (143) ◽  
pp. 138-151 ◽  
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.

scholarly journals Spatial variations of local climate at Taylor Dome, Antarctica: implications for paleoclimate from ice cores

1994 ◽  
Vol 20 ◽  
pp. 219-225 ◽  
Author(s):  
E.D. Waddington ◽  
D.L. Morse
Keyword(s):  
Spatial Variability ◽  
Source Region ◽  
Ice Core ◽  
Ice Cores ◽  
Temperature Inversion ◽  
Related Factors ◽  
Local Climate ◽  
Air Masses ◽  
Air Temperatures ◽  
Inversion Strength

10m firn temperatures are commonly used on the Antarctic plateau to estimate mean annual air temperatures. 10m firn temperatures measured at Taylor Dome (also referred to as McMurdo Dome in the literature), Antarctica, are influenced by a factor other than altitude and latitude that varies systematically across Taylor Dome. Some inter-related factors possibly contributing to the modern temperature variability are differences in sensible heat from warm or cold air masses, differences in wind strength and source region, differences in temperature inversion strength and differences in cloudiness. Our preliminary data are compatible with spatially variable katabatic winds that could control the winter temperature inversion strength to provide a large part of the signal. This has implications for paleoclimate studies.(1) Variations of the stable isotopes δ18O and δD from ice cores are a proxy for paleotemperature. The isotope thermometer is calibrated by comparing local isotope ratios with corresponding measured temperatures. In order to derive a useful isotope-temperature calibration, we must understand the processes that control the modern spatial variability of temperature. (2) In order to quantify past changes in local climate, we must understand processes that influence local spatial variability. If those processes differed in the past, ice-core climate reconstruction would be affected in two ways: through alteration of the geochemical record and through alteration of deep ice and firn temperatures.

scholarly journals Apparatus for routine measurements of the thermal conductivity of ice cores

1999 ◽  
Vol 29 ◽  
pp. 151-154 ◽  
Author(s):  
Crescenzo Festa ◽  
Aristide Rossi
Keyword(s):  
Thermal Conductivity ◽  
Ice Cores ◽  
Maximum Temperature ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Standard Samples ◽  
Experimental Conditions ◽  
Heating Source ◽  
Central Segment ◽  
Wire Method

AbstractAn apparatus is described for measuring the thermal conductivity of ice by the transient hot-wire method. Thermal conductivity A, is determined by tracking the thermal pulse induced in the sample by a heating source consisting of a platinum resistor. A central segment of the same platinum heating resistor acts also as a thermal sensor. A heat pulse transferred to the ice for a period of 40s gives a maximum temperature increment of about 7-14°C. In good experimental conditions, the expected reproducibility of the measurements is within ±3%. The accuracy of the method depends on whether the instrument has been calibrated by reliable standard samples, certified by absolute methods.

scholarly journals A Synoptic Scale Perspective on Greenland Ice Core δ18O Variability and Related Teleconnection Patterns

Atmosphere ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 294
Author(s):  
Norel Rimbu ◽  
Monica Ionita ◽  
Gerrit Lohmann
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Synoptic Scale ◽  
Local Climate ◽  
Rossby Wave Breaking ◽  
Weather Patterns ◽  
Teleconnection Patterns ◽  
Climate Anomalies ◽  
The North ◽  
Oxygen Isotope Ratios

The variability of stable oxygen isotope ratios (δ18O) from Greenland ice cores is commonly linked to changes in local climate and associated teleconnection patterns. In this respect, in this study we investigate ice core δ18O variability from a synoptic scale perspective to assess the potential of such records as proxies for extreme climate variability and associated weather patterns. We show that positive (negative) δ18O anomalies in three southern and central Greenland ice cores are associated with relatively high (low) Rossby Wave Breaking (RWB) activity in the North Atlantic region. Both cyclonic and anticyclonic RWB patterns associated with high δ18O show filaments of strong moisture transport from the Atlantic Ocean towards Greenland. During such events, warm and wet conditions are recorded over southern, western and central part of Greenland. In the same time the cyclonic and anticyclonic RWB patterns show enhanced southward advection of cold polar air masses on their eastern side, leading to extreme cold conditions over Europe. The association between high δ18O winters in Greenland ice cores and extremely cold winters over Europe is partly explained by the modulation of the RWB frequency by the tropical Atlantic sea surface temperature forcing, as shown in recent modeling studies. We argue that δ18O from Greenland ice cores can be used as a proxy for RWB activity in the Atlantic European region and associated extreme weather and climate anomalies.

Influence of Late Holocene climate on Lake Eggers hydrology, McMurdo Sound

2021 ◽  
pp. 1-13
Author(s):  
E.J. Chamberlain ◽  
A.J. Christ ◽  
R.W. Fulweiler
Keyword(s):  
Late Holocene ◽  
Ross Sea ◽  
Regional Climate ◽  
Ice Cores ◽  
Lake Ice ◽  
Mcmurdo Sound ◽  
Ice Accumulation ◽  
History Of ◽  
Ground Penetrating ◽  
Western Ross Sea

Abstract Ice-covered lakes in Antarctica preserve records of regional hydroclimate and harbour extreme ecosystems that may serve as terrestrial analogues for exobiotic environments. Here, we examine the impacts of hydroclimate and landscape on the formation history of Lake Eggers, a small ice-sealed lake, located in the coastal polar desert of McMurdo Sound, Antarctica (78°S). Using ground penetrating radar surveys and three lake ice cores we characterize the ice morphology and chemistry. Lake ice geochemistry indicates that Lake Eggers is fed primarily from local snowmelt that accreted onto the lake surface during runoff events. Radiocarbon ages of ice-encased algae suggest basal ice formed at least 735 ± 20 calibrated years before present (1215 C.E.). Persisting through the Late Holocene, Lake Eggers alternated between periods of ice accumulation and sublimation driven by regional climate variability in the western Ross Sea. For example, particulate organic matter displayed varying δ15N ratios with depth, corresponding to sea ice fluctuations in the western Ross Sea during the Late Holocene. These results suggest a strong climatic control on the hydrologic regime shifts shaping ice formation at Lake Eggers.

scholarly journals Improved estimates of preindustrial biomass burning reduce the magnitude of aerosol climate forcing in the Southern Hemisphere

2021 ◽  
Vol 7 (22) ◽  
pp. eabc1379
Author(s):  
Pengfei Liu ◽  
Jed O. Kaplan ◽  
Loretta J. Mickley ◽  
Yang Li ◽  
Nathan J. Chellman ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Radiative Forcing ◽  
Ice Core ◽  
Ice Cores ◽  
Terrestrial Ecosystems ◽  
Rapid Expansion ◽  
Past Century ◽  
Fire Emissions ◽  
The Past ◽  
Fire Activity

Fire plays a pivotal role in shaping terrestrial ecosystems and the chemical composition of the atmosphere and thus influences Earth’s climate. The trend and magnitude of fire activity over the past few centuries are controversial, which hinders understanding of preindustrial to present-day aerosol radiative forcing. Here, we present evidence from records of 14 Antarctic ice cores and 1 central Andean ice core, suggesting that historical fire activity in the Southern Hemisphere (SH) exceeded present-day levels. To understand this observation, we use a global fire model to show that overall SH fire emissions could have declined by 30% over the 20th century, possibly because of the rapid expansion of land use for agriculture and animal production in middle to high latitudes. Radiative forcing calculations suggest that the decreasing trend in SH fire emissions over the past century largely compensates for the cooling effect of increasing aerosols from fossil fuel and biofuel sources.

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