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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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18 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

Climate Induced Birch Mortality in Trans-Baikal Lake Region, Siberia

The Trans-Baikal (or Zabailkal'e) region includes the forest-steppe ecotones south and east of Lake Baikal in Russia and has experienced drought for several years. The decline and mortality of birch (Betula pendula) stands within the forest-steppe ecotone Trans-Baikal region was studied based on a temporal series of satellite data, ground measurements, and tree ring analysis. During the first decade of the 21st century birch stands decline and mortality were observed on )about 5% of the total area of stands within our 1250 km(exp 2 study area. Birch forest decline and mortality occurs mainly at the margins of stands, within the forest-steppe ecotone on slopes with direct insolation. During the first decade of the 21st century summer (June-August) precipitation was about 25% below normal. Soil water content measurements were lowest within dead stands and highest within healthy stands and intermediate within damaged stands. Drought impact on stands was amplified by an increase in summer air temperatures (+0.9 C) in comparison with the previous decade. Tree ring data of ''surviving'' and ''dead'' tree groups showed a positive correlation with summer/annual precipitation and negative correlation with summer air temperatures. Temperature and precipitation extreme anomalies tend to occur in the region with a period of about 27 years. The observed anomaly was the most severe since the beginning of meteorological observations in the year 1900. Data for the other sites showed a positive climate impact on the growth and expansion of Siberian forests. That is, the same species (B. pendula) showed considerable increase (1.4 times both in height and stem volume) during 20th-21st centuries as temperature increased but precipitation remained at adequate levels.

Forest die-off↗
NASA NTRS1992

Ice patterns and hydrothermal plumes, Lake Baikal, Russia - Insights from Space Shuttle hand-held photography

Earth photography from the Space Shuttle is used to examine the ice cover on Lake Baikal and correlate the patterns of weakened and melting ice with known hydrothermal areas in the Siberian lake. Particular zones of melted and broken ice may be surface expressions of elevated heat flow in Lake Baikal. The possibility is explored that hydrothermal vents can introduce local convective upwelling and disrupt a stable water column to the extent that the melt zones which are observed in the lake's ice cover are produced. A heat flow map and photographs of the lake are overlaid to compare specific areas of thinned or broken ice with the hot spots. The regions of known hydrothermal activity and high heat flow correlate extremely well with circular regions of thinned ice, and zones of broken and recrystallized ice. Local and regional climate data and other sources of warm water, such as river inlets, are considered.

Evans, Cynthia A.↗
NASA NTRS2016

Climate-Induced Mortality of Siberian Pine and Fir in the Lake Baikal Watershed, Siberia

Siberian pine (Pinus sibirica) and fir (Abies sibirica) (so called ''dark needle conifers", DNC) showed decreased radial growth increment within the Lake Baikal watershed since the 1980s with increasing mortality recorded since the year 2000. Tree ring width was strongly correlated with vapor pressure deficit, aridity and root zone moisture. Water stress from droughts made trees more susceptible to insect attacks causing mortality in about 10% of DNC stands within the Lake Baikal watershed. Within Siberia DNC mortality increased in the southern part of the DNC range. Biogeographically, tree mortality was located within the DNC - forest-steppes transition. Tree mortality was significantly correlated with drought and soil moisture anomalies. Within the interior of the DNC range mortality occurred within relief features with high water stress risk (i.e., steep convex south facing slopes with shallow well-drained soils). In general, DNC mortality in Siberia was induced by increased aridity and severe drought (inciting factors) in synergy with biotic attacks (contributing factor). In future climate scenarios with predicted increase in aridity DNC could be eliminated from the southern part of its current range and will be replaced by drought-resistant conifers and broadleaf species (e.g., Larix sibirica, Pinus silvestris, and Betula pubescence).

Conifer Mortality↗
NASA NTRS2016

Climate-Induced Mortality of Siberian Pine and Fir in the Lake Baikal Watershed, Siberia

Siberian pine (Pinus sibirica) and fir (Abies sibirica) (so called "dark needle conifers", DNC) showed decreased radial growth increment within the Lake Baikal watershed since the 1980s with increasing mortality recorded since the year 2000. Tree ring width was strongly correlated with vapor pressure deficit, aridity and root zone moisture. Water stress from droughts made trees more susceptible to insect attacks causing mortality in about 10% of DNC stands within the Lake Baikal watershed. Within Siberia DNC mortality increased in the southern part of the DNC range. Biogeographically, tree mortality was located within the DNC - forest-steppes transition. Tree mortality was significantly correlated with drought and soil moisture anomalies. Within the interior of the DNC range mortality occurred within relief features with high water stress risk (i.e., steep convex south facing slopes with shallow well-drained soils). In general, DNC mortality in Siberia was induced by increased aridity and severe drought (inciting factors) in synergy with biotic attacks (contributing factor). In future climate scenarios with predicted increase in aridity DNC could be eliminated from the southern part of its current range and will be replaced by drought-resistant conifers and broadleaf species (e.g., Larix sibirica, Pinus silvestris, and Betula pubescence).

Viacheslav I Kharuk↗
DOE OSTI2020

Variations in northeast Asian summer precipitation driven by the Atlantic multidecadal oscillation

By analysing a 113–year (1900–2012) observational dataset, it is shown in this work that the interdecadal fluctuation of the summer precipitation over Northeast Asia differs from that in central East Asia during the 20th century, and has experienced three interdecadal shifts in the 1920s, mid-1960s and late 1990s. That fluctuation coincides well with the multidecadal fluctuation of the sea surface temperature in the North Atlantic, known as the Atlantic Multidecadal Oscillation (AMO). The AMO affects Northeast Asia via a circumglobal teleconnection pattern extending from the North Atlantic to North America. Corresponding with the positive phase of this teleconnection pattern, a tripolar pattern emerges in the Asian–North Pacific sector, with anomalous low pressure over Northeast Asia and high pressure over Lake Baikal and the mid-latitude western North Pacific. These results suggest that the positive phase of the AMO favours the occurrence of cold vortex over Northeast Asia and anomalous highs over Lake Baikal and the mid-latitude western North Pacific in summer, which enhances the East Asian summer monsoon and southward intrusion of high-latitude cold air, and eventually increases the summer precipitation in Northeast Asia. Furthermore, initialized decadal prediction simulations using the CCSM4 model reproduce well the observed variations of the AMO and its associated atmospheric teleconnection but with slightly shifted geographic locations. The simulated anomalous Northeast Asia cold vortex and strong East Asian summer monsoon, lead to above-normal summer precipitation over Northeast Asia. The modelling results confirm that the multidecadal variability in the North Atlantic can cause the observed interdecadal variations of Northeast Asia summer precipitation. Our results suggest that to understand and predict interdecadal climate change over Northeast Asia, it is important to consider the key role of the AMO.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Data acquisition system for the Baikal-GVD neutrino telescope

The objective of the Baikal-GVD project is the construction of a km{sup 3}-scale neutrino telescope in Lake Baikal. The Gigaton Volume Detector consists of a large three-dimensional array of photo-multiplier tubes. The first GVD-cluster has been deployed and commissioned in April 2015. The data acquisition system (DAQ) of the detector takes care of the digitization of the photo-multiplier tube signals, data transmission, filtering and storage. The design and the implementation of the data acquisition system are described.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

High Energy Neutrino Astronomy: Where Do We Stand, Where Do We Go?

With the identification of a diffuse flux of astrophysical (“cosmic”) neutrinos in the TeV-PeV energy range, IceCube has opened a new window to the Universe. However, the corresponding cosmic landscape is still uncharted: so far, the observed flux does not show any clear association with known source classes. In the present talk, I sketch the way from Baikal-NT200 to IceCube and summarize IceCube’s recent astrophysics results. Finally, I describe the present projects to built even larger detectors: GVD in Lake Baikal, KM3NeT in the Mediterranean Sea and IceCube-Gen2 at the South Pole. These detectors will allow studying the high-energy neutrino sky in much more detail than the present arrays permit.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2011

LOSA-M2 aerosol Raman lidar

The scanning LOSA-M2 aerosol Raman lidar, which is aimed at probing atmosphere at wavelengths of 532 and 1064 nm, is described. The backscattered light is received simultaneously in two regimes: analogue and photon-counting. Along with the signals of elastic light scattering at the initial wavelengths, a 607-nm Raman signal from molecular nitrogen is also recorded. It is shown that the height range of atmosphere probing can be expanded from the near-Earth layer to stratosphere using two (near- and far-field) receiving telescopes, and analogue and photon-counting lidar signals can be combined into one signal. Examples of natural measurements of aerosol stratification in atmosphere along vertical and horizontal paths during the expeditions to the Gobi Desert (Mongolia) and Lake Baikal areas are presented.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

TAIGA Gamma Observatory: Status and Prospects

Over the past few years, the TAIGA (Tunka Advanced Instrument for cosmic ray physics and Gamma-ray Astronomy) observatory has been being deployed in the Tunka Valley, Republic of Buryatia. It is designed for studying gamma rays of energy above 30 TeV and performing searches for sources of galactic cosmic rays with energies in the vicinity of 1 PeV, which is an energy region around the classic knee in the cosmic-ray energy spectrum. The first phase of the observatory will be situated at a distance of about 50 km from Lake Baikal at the site of the Tunka-133 array. The TAIGA gamma observatory will include a network of 500 wide-angle (0.6 sr) Cherenkov detectors (TAIGA-HiSCORE array) and up to 16 atmospheric Cherenkov telescopes (ACT) designed for analyzing the EAS images (imaging atmospheric Cherenkov telescopes, or IACT) and positioned within an area of 5 km{sup 2}. The observatory will also include muon detectors of total area 2000 m{sup 2} distributed over an area of 1 km{sup 2}. Within the next three years, it is planned to enhance the area of the TAIGA-HiSCORE array by a factor of four—from 0.25 km{sup 2} to 1 km{sup 2}; to supplement the existing IACT with two new ones; and to deploy new muon detectors with a total coverage of 200 m{sup 2}. The structure of the new observatory is described along with the data analysis techniques used. The most interesting physical results are presented, and the research program for the future is discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

The TAIGA Experiment: From Cosmic Ray Physics to Gamma Astronomy in the Tunka Valley

The article presents the relevance and advantages of the new gamma observatory TAIGA (Tunka Advanced Instrument for cosmic ray physics and Gamma Astronomy), which is being constructed in the Tunka Valley 50 km from Lake Baikal. Various detectors of the six TAIGA gamma observatory arrays register the Cherenkov and radio radiation, as well as the electron and muon components of EAS. The primary objective of the TAIGA gamma observatory is to study the high-energy part of the gamma-ray spectrum, in particular, in order to search for Galactic PeVatrons. The energy, direction, and position of the EAS axis are reconstructed in the observatory based on the data of the wide-angle Cherenkov detectors of the TAIGA-HiSCORE experiment. Taking into account this information, the gamma quanta are distinguished from the hadron background using the data obtained by the muon detectors and telescopes that register the EAS image in the Cherenkov light. In this hybrid mode of operation, the atmospheric Cherenkov telescopes can operate in the mono-mode, and the distance between them can be increased to 800–1000 m, which makes it possible to construct an array with an area of 5 km{sup 2} and more at relatively low cost and in a short time. By 2019, the first stage of the gamma observatory with an area of 1 km{sup 2} will be constructed; its expected integral sensitivity for detecting the gamma radiation with an energy of 100 TeV at observation of the source for 300 hours will be approximately 2×5 10{sup –13} TeV cm{sup –2}s{sup –1}.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Dark matter constraints from an observation of dSphs and the LMC with the Baikal NT200

We have analyzed the neutrino events recoded in the deep-water neutrino experiment NT200 in Lake Baikal in five years of observations toward dark dwarf spheroidal galaxies (dSphs) in the southern hemisphere and the Large Magellanic Cloud (LMC). This analysis completes the series of works based on NT200 data in the search for a dark matter annihilation signal in astrophysical objects. We have found no significant excess in the number of observed events relative to the expected background from atmospheric neutrinos in all tested directions, in 22 dSphs and the LMC. For a sample of five selected dwarf galaxies we have performed a joint analysis of the data by the maximum likelihood method. We have obtained a correspondence of the observational data to the null hypothesis about the presence of only background events and established 90% confidence-level upper limits for the annihilation cross sections of dark matter particles with a mass from 30 GeV to 10 TeV in several annihilation channels both in the joint analysis of the selected sample of galaxies and in the analysis toward the LMC. The strongest constraints at a level of 7 × 10{sup –21} cm{sup 3} s{sup –1} have been obtained for the direction toward the LMC in the channel of annihilation into a pair of neutrinos.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1984

SEASAT altimetry for surface height of inland seas

The capability of spaceborne altimetry to record the level, or monitor changes in the level, of inland seas was assessed. SEASAT altimetry data from Lake Baikal in Siberia; the Caspian, Black, and Aral Seas in the southern Soviet Union; the Great Salt Lake in the United States; lakes and reservoirs in northwestern and central China; and snow cover in northwestern India and on the Tibetan Plateau were examined.

Welker, J. E.↗
DOE OSTI2015

Status and recent results of the BAIKAL-GVD project

The Prototyping phase of the BAIKAL-GVD project has been started in April 2011 with the deployment of first autonomous engineering array which comprises all basic elements and systems of the Gigaton Volume Detector (GVD) in Lake Baikal. The prototyping phase will be concluded with deployment of the GVD demonstration cluster “DUBNA” in 2015, which will comprise 192 light sensors arranged at 8 strings. The first stage of the GVD demonstration cluster which consists of three strings was deployed in April 2013 and successfully operated up to February 2014. We review the prototyping phase of the BAIKAL-GVD project and describe the configuration and design of the 2013 engineering array.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1993

Earth observations during Space Shuttle Mission STS-42 - Discovery's mission to planet earth

The noteworthy imagery acquired during Space Shuttle Mission STS-42 is documented. Attention is given to frozen Tibetan lakes, Merapi Volcano in Java, Mt. Pinatubo in the Philippines, the coastline east of Tokyo Japan, land use in southern India, and the Indus River Delta. Observations of Kamchatka Peninsula, Lake Baikal, Moscow, Katmai National Park and Mt. Augustine, Alaska, the Alaskan coast by the Bering Sea, snow-covered New York, the Rhone River valley, the Strait of Gibraltar, and Mt. Ararat, Turkey, are also reported.

Lulla, Kamlesh P.↗
NASA NTRS1993

Global geologic applications of the Space Shuttle earth observations photography database

The advantages of the astronaut photography during Space Shuttle missions are briefly examined, and the scope and applications of the Space Shuttle earth observations photography database are discussed. The global and multidisciplinary nature of the data base is illustrated by several examples of geologic applications. These include the eruption of Mount Pinatubo (Philippine Islands), heat flow and ice cover on Lake Baikal in Siberia (Russia), and windblown dust in South America. It is noted that hand-held photography from the U.S. Space Shuttle provides unique remotely-sensed data for geologic applications because of the combination of varying perspectives, look angles, and illumination, and changing resolution resulting from different lenses and altitudes.

Lulla, Kamlesh↗
NASA NTRS2011

Fire Return Interval Within the Northern Boundary of the Larch Forest

Larch (Larix spp.) dominant forests compose a large proportion of the forests of Russia (i.e., about 40% of forested areas). These forests range from the Yenisei ridge on the west to the Pacific Ocean on the east, and from Lake Baikal on the south to the 73rd parallel in the north. Larch stands comprise the world s northern most forest at Ary-Mas (72 deg 28' N, 102 deg 15' E). Larch dominated forests occupy about 70% of the permafrost areas in Siberia. Larch forms high closure stands as well as open forests, and is found mainly over permafrost, where other tree species barely survive. Wildfires are typical for this territory with the majority occurring as ground fires due to low crown closure. Due to the thin active layer in permafrost soils and a dense lichen-moss cover, ground fires may cause stand mortality. The vast areas of larch-dominant forests is generally considered as a "carbon sink"; however, positive long-term temperature trends at higher latitudes are expected to result in an increase of fire frequency, and thus may convert this area to a source for greenhouse gases. There are recent observations regarding the increase of fire frequency within non-protected territories. Surprisingly, there are few publications on fire chronoseqences for the huge forested territory between the Ural Mountains and the Pacific Ocean. Also there is a general understanding that bimodal (late spring -- early summer and late summer-beginning of fall) fire seasonal distribution in the south becomes uni-modal (late spring -- early summer) in the north. The purpose of this study is to investigate the wildfire history at the northern edge of the zone of larch dominance.

Kharuk, V. I.↗
DOE OSTI2010

Fish Tales

This talk is about fishing and the friendships that have resulted in its pursuit. It is also about theoretical physics, and the relationship of imagination and fantasy to the establishment of ideas about nature. Fishermen, like theoretical physicists, are well known for their inventive imaginations. Perhaps neither are as clever as sailors, who conceived of the mermaid. If one doubts the power of this fantasy, one should remember the ghosts of the many sailors who drowned pursuing these young nymphs. An extraordinary painting by J. Waterhouse is shown as Fig. 1. The enchantment of a mermaid must reflect an extraordinary excess of imagination on the part of the sailor, perhaps together with an impractical turn of mind. A consummated relationship with a mermaid is after all, by its very nature a fantasy incapable of realization. To a theoretical physicist, she is symbolic of many ideas we develop. There are many truths known to fisherman in which one might also find parallels to the goals of scientists: (1) A fish is the only animal that keeps growing after its death; (2) Nothing makes a fish bigger than almost being caught; (3) ''...of all the liars among mankind, the fisherman is the most trustworthy.'' (William Sherwood Fox, in Silken Lines and Silver Hooks); and (4) Men and fish are alike. They both get into trouble when they open their mouths. These quotes may be interpreted as reflecting skepticism regarding the honesty of fisherman, and probably do not reflect adequate admiration for a creative imagination. Is it fair to criticize a person for believing a falsehood that he or she sincerely believes to be true? The fisherman simultaneously invents the lie, and believes in it himself. The parallel with theoretical physics is perhaps only approximate, although we physicists may invent stories that we come to believe, on some rare occasions our ideas actually correspond to a more or less true descriptions of nature. These minor philosophical differences are not really the central issue, however. It is more to the point that both fishermen and scientists enjoy creating a good story, and we also enjoy a story well told. The correct mixture of truth, lie, fantasy and excitement is a witches brew.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗