Isotopic signatures for natural versus anthropogenic Pb in high-altitude Mt. Everest ice cores during the past 800years

2011 ◽  
Vol 412-413 ◽  
pp. 194-202 ◽  
Author(s):  
Khanghyun Lee ◽  
Soon Do Hur ◽  
Shugui Hou ◽  
Laurie J. Burn-Nunes ◽  
Sungmin Hong ◽  
...  
Keyword(s):  
High Altitude ◽  
Ice Cores ◽  
Isotopic Signatures ◽  
The Past

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.

Effect of Variations in Weight or Normal Acceleration on the Ceiling of Jet-Propelled Aircraft

1955 ◽  
Vol 59 (534) ◽  
pp. 435-437
Author(s):  
P. L. Sutcliffe
Keyword(s):  
High Altitude ◽  
Normal Force ◽  
Control Surface ◽  
Military Aircraft ◽  
Longitudinal Control ◽  
The Past ◽  
Normal Acceleration

The ability to manoeuvre at high altitude has become one of the main requirements in the design of modern military aircraft. Ability to manoeuvre enables the fighter pilot to execute tight turns during the attack on a bomber and the bomber pilot to perform evasive manoeuvres and so make the task of the fighter more difficult.Normally the main manoeuvre considered is the application of increased normal acceleration, or g, and if we assume that (a) there is sufficient pitching power available from the longitudinal control surface to increase the wing incidence to give the necessary increase in normal force, and (b) that the new wing incidence is below the stalling incidence of the wing, then the degree of manoeuvrability available is a function of thrust and drag alone. In the past the manoeuvrability required at a given altitude has been expressed in terms of the rate of climb available at that altitude and thus we have such definitions as “ the 1,000 ft./min. ceiling ” and so on.

United States Army Research Institute of Environmental Medicine: Warfighter research focusing on the past 25 years

2011 ◽  
Vol 35 (4) ◽  
pp. 353-360 ◽  
Author(s):  
Kent B. Pandolf ◽  
Ralph Francesconi ◽  
Michael N. Sawka ◽  
Allen Cymerman ◽  
Reed W. Hoyt ◽  
...  
Keyword(s):  
United States ◽  
Environmental Medicine ◽  
High Altitude ◽  
United States Army ◽  
50Th Anniversary ◽  
The United States ◽  
The Past ◽  
Army Research Institute ◽  
Efficient Planning ◽  
Research Institute

The United States Army Research Institute of Environmental Medicine (USARIEM) celebrated its 50th anniversary on July 1, 2011. This article reviews its history, evolution, and transition of its research programs as well as its scientific and military accomplishments, emphasizing the past 25 yr. During the 1990s, USARIEM published a series of pocket guides providing guidance for sustaining Warfighter health and performance in Southwest Asia, Somalia, the former Republic of Yugoslavia, Rwanda, and Haiti. Issues identified during Operation Desert Storm elicited research that improved nutritional guidelines for protracted desert operations; safer use of nuclear, chemical, and biological protective clothing; equipment, development, and fielding of efficient microclimate cooling systems; and effective evaluation of pharmaceuticals to protect soldiers from chemical and biological threats. During the first decade of the 21st century, USARIEM and the Department of the Army published official medical/performance doctrines for operations in the heat and cold and at high altitude. The current Global War on Terrorism focused research to improve doctrines for hot, cold, and high-altitude operations, reduce musculoskeletal training injuries, provide improved field nutrition, more efficient planning for operational water requirements, and improve both military clothing and materiel. This article also describes the critically important interactions and communications between USARIEM and deployed units and the benefits to Warfighters from this association. This report presents USARIEM's unique and world-class facilities, organizational changes, scientific and support personnel, and major research accomplishments, including the publication of 2,200 scientific papers over the past 25 yr.

An echo from the past: Building a Doppler repository for big data in diving research

2021 ◽  
pp. 57-58
Author(s):  
Virginie Papadopoulou ◽  
◽  
Peter Lindholm ◽  
Keyword(s):  
Big Data ◽  
High Altitude ◽  
Decompression Sickness ◽  
Non Invasive ◽  
The Past ◽  
Subject Variability ◽  
Decompression Stress

Decompression sickness (DCS) remains a major operational concern for diving operations, submarine escape and high-altitude jumps. Aside from DCS symptoms, venous gas emboli (VGE) detected with ultrasound post-dive are often used as a marker of decompression stress in humans, with a specificity of 100% even though the sensitivity is poor [1]. Being non-invasive, portable and non-ionizing, ultrasound is particularly suited to regular and repeated monitoring. It could help elucidate inter- and intra-subject variability in VGE and DCS susceptibility, but analyzing these recordings remains a cumbersome task [2].

scholarly journals Long-term evolution of the heliospheric magnetic field inferred from cosmogenic 44Ti activity in meteorites

2018 ◽  
Vol 610 ◽  
pp. A28 ◽  
Author(s):  
S. Mancuso ◽  
C. Taricco ◽  
P. Colombetti ◽  
S. Rubinetti ◽  
N. Sinha ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Ice Cores ◽  
Long Term Evolution ◽  
Galactic Cosmic Rays ◽  
Sunspot Activity ◽  
Cosmogenic Isotopes ◽  
Heliospheric Magnetic Field ◽  
The Past ◽  
Term Evolution

Typical reconstructions of historic heliospheric magnetic field (HMF) BHMF are based on the analysis of the sunspot activity, geomagnetic data or on measurement of cosmogenic isotopes stored in terrestrial reservoirs like trees (14C) and ice cores (10Be). The various reconstructions of BHMF are however discordant both in strength and trend. Cosmogenic isotopes, which are produced by galactic cosmic rays impacting on meteoroids and whose production rate is modulated by the varying HMF convected outward by the solar wind, may offer an alternative tool for the investigation of the HMF in the past centuries. In this work, we aim to evaluate the long-term evolution of BHMF over a period covering the past twenty-two solar cycles by using measurements of the cosmogenic 44Ti activity (τ1∕2 = 59.2 ± 0.6 yr) measured in 20 meteorites which fell between 1766 and 2001. Within the given uncertainties, our result is compatible with a HMF increase from 4.87-0.30+0.24 nT in 1766 to 6.83-0.11+0.13 nT in 2001, thus implying an overall average increment of 1.96-0.35+0.43 nT over 235 years since 1766 reflecting the modern Grand maximum. The BHMF trend thus obtained is then compared with the most recent reconstructions of the near-Earth HMF strength based on geomagnetic, sunspot number, and cosmogenic isotope data.

scholarly journals Volcanic synchronization of Dome Fuji and Dome C Antarctic deep ice cores over the past 216 kyr

2015 ◽  
Vol 11 (10) ◽  
pp. 1395-1416 ◽  
Author(s):  
S. Fujita ◽  
F. Parrenin ◽  
M. Severi ◽  
H. Motoyama ◽  
E. W. Wolff
Keyword(s):  
Age Differences ◽  
Flow Model ◽  
Ice Cores ◽  
Ice Flow ◽  
Surface Mass ◽  
The Past ◽  
The One ◽  
Mis 5E ◽  
Age Constraints ◽  
Mis 5

Abstract. Two deep ice cores, Dome Fuji (DF) and EPICA Dome C (EDC), drilled at remote dome summits in Antarctica, were volcanically synchronized to improve our understanding of their chronologies. Within the past 216 kyr, 1401 volcanic tie points have been identified. DFO2006 is the chronology for the DF core that strictly follows O2 / N2 age constraints with interpolation using an ice flow model. AICC2012 is the chronology for five cores, including the EDC core, and is characterized by glaciological approaches combining ice flow modelling with various age markers. A precise comparison between the two chronologies was performed. The age differences between them are within 2 kyr, except at Marine Isotope Stage (MIS) 5. DFO2006 gives ages older than AICC2012, with peak values of 4.5 and 3.1 kyr at MIS 5d and MIS 5b, respectively. Accordingly, the ratios of duration (AICC2012 / DFO2006) range between 1.4 at MIS 5e and 0.7 at MIS 5a. When making a comparison with accurately dated speleothem records, the age of DFO2006 agrees well at MIS 5d, while the age of AICC2012 agrees well at MIS 5b, supporting their accuracy at these stages. In addition, we found that glaciological approaches tend to give chronologies with younger ages and with longer durations than age markers suggest at MIS 5d–6. Therefore, we hypothesize that the causes of the DFO2006–AICC2012 age differences at MIS 5 are (i) overestimation in surface mass balance at around MIS 5d–6 in the glaciological approach and (ii) an error in one of the O2 / N2 age constraints by ~ 3 kyr at MIS 5b. Overall, we improved our knowledge of the timing and duration of climatic stages at MIS 5. This new understanding will be incorporated into the production of the next common age scale. Additionally, we found that the deuterium signals of ice, δDice, at DF tends to lead the one at EDC, with the DF lead being more pronounced during cold periods. The lead of DF is by +710 years (maximum) at MIS 5d, −230 years (minimum) at MIS 7a and +60 to +126 years on average.

scholarly journals Climate dependent contrast in surface mass balance in East Antarctica over the past 216 ka

2016 ◽  
Vol 62 (236) ◽  
pp. 1037-1048 ◽  
Author(s):  
F. PARRENIN ◽  
S. FUJITA ◽  
A. ABE-OUCHI ◽  
K. KAWAMURA ◽  
V. MASSON-DELMOTTE ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Core ◽  
Ice Cores ◽  
East Antarctica ◽  
Surface Mass Balance ◽  
Last Interglacial ◽  
Surface Mass ◽  
The Past ◽  
Water Stable Isotope ◽  
Global Mean Sea Level

ABSTRACTDocumenting past changes in the East Antarctic surface mass balance is important to improve ice core chronologies and to constrain the ice-sheet contribution to global mean sea-level change. Here we reconstruct past changes in the ratio of surface mass balance (SMB ratio) between the EPICA Dome C (EDC) and Dome Fuji (DF) East Antarctica ice core sites, based on a precise volcanic synchronization of the two ice cores and on corrections for the vertical thinning of layers. During the past 216 000 a, this SMB ratio, denoted SMBEDC/SMBDF, varied between 0.7 and 1.1, being small during cold periods and large during warm periods. Our results therefore reveal larger amplitudes of changes in SMB at EDC compared with DF, consistent with previous results showing larger amplitudes of changes in water stable isotopes and estimated surface temperature at EDC compared with DF. Within the last glacial inception (Marine Isotope Stages, MIS-5c and MIS-5d), the SMB ratio deviates by up to 0.2 from what is expected based on differences in water stable isotope records. Moreover, the SMB ratio is constant throughout the late parts of the current and last interglacial periods, despite contrasting isotopic trends.

scholarly journals Fire in ice: two millennia of Northern Hemisphere fire history from the Greenland NEEM ice core

2014 ◽  
Vol 10 (1) ◽  
pp. 809-857 ◽  
Author(s):  
P. Zennaro ◽  
N. Kehrwald ◽  
J. R. McConnell ◽  
S. Schüpbach ◽  
O. Maselli ◽  
...  
Keyword(s):  
Black Carbon ◽  
Biomass Burning ◽  
Fire History ◽  
Global Climate ◽  
Ice Cores ◽  
Dominant Factor ◽  
The Past ◽  
Past 2000 Years ◽  
Isotopic Analyses ◽  
Fire Activity

Abstract. Biomass burning is a major source of greenhouse gases and influences regional to global climate. Pre-industrial fire-history records from black carbon, charcoal and other proxies provide baseline estimates of biomass burning at local to global scales, but there remains a need for broad-scale fire proxies that span millennia in order to understand the role of fire in the carbon cycle and climate system. We use the specific biomarker levoglucosan, and multi-source black carbon and ammonium concentrations to reconstruct fire activity from the North Greenland Eemian (NEEM) ice cores (77.49° N; 51.2° W, 2480 m a.s.l.) over the past 2000 years. Increases in boreal fire activity (1000–1300 CE and 1500–1700 CE) over multi-decadal timescales coincide with the most extensive central and northern Asian droughts of the past two millennia. The NEEM biomass burning tracers coincide with temperature changes throughout much of the past 2000 years except for during the extreme droughts, when precipitation changes are the dominant factor. Many of these multi-annual droughts are caused by monsoon failures, thus suggesting a connection between low and high latitude climate processes. North America is a primary source of biomass burning aerosols due to its relative proximity to the NEEM camp. During major fire events, however, isotopic analyses of dust, back-trajectories and links with levoglucosan peaks and regional drought reconstructions suggest that Siberia is also an important source of pyrogenic aerosols to Greenland.

Modern atmospheric monitoring using pollen analysis of ice cores: a case study from the Elbrus Western Plateau, Caucasus, Russia

2021 ◽  
Author(s):  
Vlada Batalova ◽  
Vladimir Mikhalenko ◽  
Stanislav Kutuzov ◽  
Lyudmila Shumilovskikh ◽  
Karim Shukurov
Keyword(s):  
High Altitude ◽  
Pollen Analysis ◽  
Anthropogenic Activities ◽  
Ice Core ◽  
Ice Cores ◽  
Testate Amoebae ◽  
Forest Belt ◽  
Russian Science ◽  
Flexible Tool ◽  
Atmospheric Monitoring

<p>The report highlights the results of first ice-core palynology studies from the Elbrus Western Plateau. The title of the highest point in Europe and the geographical location of Elbrus determine the diversity of natural conditions and, as a result, palynological spectra, which act as markers of seasonal vegetation, climate dynamics, fires and anthropogenic activities in the Mediterranean, southern European Russia, the Middle East, and North Africa.</p><p>The 24-m ice core from the Elbrus Western Plateau collected in 2017 (5115 m a.s.l., 43<sup>о</sup>20′53,9′′ N, 42<sup>о</sup>25′36′′ E) covers the period 2012-2017. Pollen analysis revealed a significant number of biological markers contained in the ice core, including pollen and spores, fungi, algae, testate amoebae, feather barbules, microcharcoal, and black carbon.</p><p>The obtained results show that taxonomic diversity and concentration of biomarkers in the ice core were determined by the seasons of the year and their inherent convective flows. Pollen assemblages are characterized by predominance of native Caucasian plant species. Among them pollen values of Picea forming the high-altitude forest belt in the Western Caucasus significantly exceed pollen frequency of Pinus growing near the upper timber line on Elbrus Mt in the Central Caucasus that suggests a westerlies of air masses and transfer of microparticles. A high abundance of non-pollen palynomorphs in pollen assemblages demonstrates a high potential for studying of human impact on mountain ecosystems. The first pollen data from the ice core evidences a promising resource of the high-altitude temperate glaciers as a flexible tool for atmospheric monitoring of microparticle transfer and fixing its seasonality and biotic relationships.</p><p>This work was supported by the Russian Science Foundation, project № 17-17-01270.</p>

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