1928 research outputs found
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Meteorite classification for building the Chinese Antarctic Meteorite Depository—Introduction of the classification of 500 Grove Mountains meteorites
Get PDFMeteorites provide an important window into the origins and evolution of the solar system. Since the first four meteorites were recovered in Grove Mountains, Antarctica, in 1998, a further total of 12665 meteorites have been collected over seven polar seasons in the Grove Mountains. All of these meteorites are owned and managed by the Chinese Antarctic Meteorite Depository (CAMD) at the Polar Research Institute of China (PRIC). In recent years, another 500 Antarctic meteorites have been classified and characterized based on mineralogy and petrology. In this work we examine four samples that have been identified as terrestrial, and a further 496 samples that have been confirmed as meteorites. These meteorites are further divided into different types:488 ordinary chondrites, one eucrite, one ureilite, one CM2 carbonaceous chondrite, one EH4 enstatite chondrite, one mesosiderite and three iron meteorites. The classification of meteorites not only provides an abundance of fundamental scientific data, but is also significant for introducing meteorites and related scientific knowledge to the public, particularly via the website of Chinese Resource-sharing Platform of Polar Samples for scientific research and education
Climate and meteorological processes of the East Antarctic ice sheet between Zhongshan and Dome-A
Get PDFThe 1228 km over-snow traverse route between the Chinese Zhongshan Station, on the coast of Prydz Bay, and Dome-A, at 4091 m elevation the highest point of the East Antarctic ice sheet, has been the focus of CHINARE surface meteorological and climate studies since 2002. A network of seven Automatic Weather Stations has been deployed along this section, including at Dome-A itself, and some of these have now provided nearly-hourly data for over a decade. Atmospheric boundary layer turbulence and radiation observations have been made over the near-coastal ice sheet inland of Zhongshan and surface turbulence measurements using an ultrasonic anemometer system have also been made in the deep interior of the ice sheet. Summer GPS radiosonde soundings of the atmospheric boundary layer have been made at Kunlun Station, near Dome-A. In this paper these observations are combined to provide a comprehensive overview of the meteorological regime of this region of the ice sheet, its climate variability, and as a reference for future study of climate change. This includes investigation of the variation of surface climate features with elevation and distance from the coast, the height and structure of the boundary layer over the ice sheet, and seasonal and regional changes in ice/snow–air interactions, including turbulent and radiative energy fluxes. The air temperature and snow temperature between the coastal Zhongshan and Dome-A on the inland plateau have not changed significantly in the past decade compared with the inter-annual variability
Sources of organic matter and paleo-environmental implications inferred from carbon isotope compositions of lacustrine sediments at Inexpressible Island, Ross Sea, Antarctica
Get PDFThe carbon isotopic composition of organic matter (δ13Corg) was determined in two sediment cores (IIL1 and IIL9) recovered from Inexpressible Island, Ross Sea, Antarctica, and analyzed to identify the sources of that organic matter. The δ13Corg values of sediments of IIL9 were found to vary between −14.6‰ and −11.6‰, with a mean of −13.4‰ (n=48). These values were significantly higher than those of IIL1 sediments which varied between −23.2‰ and −20.4‰, with a mean of −21.8‰ (n=55). The variation in δ13Corg values in these two sediment cores indicate different sources of organic matter. The relatively high δ13Corg values in IIL9 are in accordance with a source from algae, while the low δ13Corg values in IIL1 evince significant influence from penguin guano with algae as the secondary source. Compared with the reference data from other high-latitude lake sediments and plants, the δ13Corg values in IIL9 were extremely high, a result likely related to intense competition for CO2 assimilation among algal species during the growing season in this relatively shallow pond. These results indicate that sedimentary δ13Corg is a reliable proxy for paleo-primary productivity in ponds at Inexpressible Island
A preliminary dayglow model for summer auroral images from Polar/UVI
Get PDFIn this study, we developed a summer dayglow model using auroral emissions acquired by the ultraviolet imager (UVI) onboard the Polar satellite. In the summer polar region, dayglow varies as a cosine-like function of the solar zenith angle (SZA). The shape of this function can be characterized by its amplitude (Amp) and phase (Phi) factors. We first obtained the hourly Amp and Phi factors in summers from 1996 to 2000, and then investigated the universal time (UT) and solar activity variations of these two shape factors. It was found that both factors were non-linearly dependent on the solar flux for all years, and the Amp factor showed clear UT variations under both low and high solar flux years. Thus, a dayglow model was constructed to consider the above dependencies. After the dayglow was removed automatically from the original UVI images via our model, the remaining auroral precipitation energy flux was in good agreement with previously reported magnetic local time–latitude (MLT–MLAT) patterns. Our model provides a fast way to statistically process summer auroral precipitation of Polar/UVI and its variations
Page21 - Policy Paper
Get PDFDuring the past few decades climate change has become the major environmental issue of our time. Not only scientists, but also the general public and the politicians that represent them, are increasingly faced with the effects of climate change on our planet. Observations show that the impacts of climate change are felt more rapidly in the Arctic than over the rest of the globe. Initially, it was the melting polar ice sheets and the retreat of the sea ice in the Arctic Ocean that captured the most interest, but now the thawing of the permafrost layer is also seen as an increasingly important issue, with serious consequences on climate feedbacks. Today, climate warming and the consequent reactivation of the immense currently frozen carbon reservoir in the permafrost, have become one of the main topics in climate research.
Traditionally in Europe, permafrost research mostly concentrated on mountainous areas. The increasing interest in global warming, however, has resulted in geographically broader EUfunded initiatives, of which the latest is the PAGE21 project. PAGE21, “Changing permafrost in the Arctic and its Global Effects in the 21st Century” brought together all major European permafrost research institutes as well as leading North American and Asian permafrost research groups. This grouping makes the project one of the first truly circumpolar permafrost research initiatives.
The project adopted an inter-disciplinary approach towards data collection and analyses,
combining field measurements with remotely sensed satellite data and global climate models. The output from the analyses helps us to advance understanding of permafrost processes at multiple scales, resulting in improvements in global climate modelling and the ensuing future climate projections.
It has been a great pleasure to lead this research consortium and I am very proud of the advancement the project has been able to make in permafrost, and more broadly, in climate science. The rapid changes that are occurring in the Arctic require a flexible and responsive research community. I believe that PAGE21 is an excellent example of the dynamic approach needed to respond to the developing research agenda in European permafrost research
ICARPIII Final report
Get PDFRapid transformations occurring in the Arctic are
affecting the entire Earth system, its climate and weather
extremes through increased temperatures and the continuing
loss of sea ice cover, glacier retreat and changing snow
and permafrost conditions. In addition, emerging economic
and geopolitical interests in the Arctic have established
the region as a larger player within the global context, with
potentially significant local effects. It is important to consider
the existence of ‘multiple Arctics’ in the context of
these changes. While there are many common challenges
and priorities facing the Arctic region as a whole, local contexts,
including political and governance regimes, socioeconomic
conditions, and cultures can vary substantially
within and across Arctic regions
Fact Sheet: First Arctic Science Ministerial
Get PDFScience Ministers from 25 governments and the European Union gathered at the White House to discuss Arctic research priorities and sign a Joint Statement on increased international collaboration on Arctic science and inclusion of Indigenous peoples in understanding and responding to changes in the Arcti
Considerable increase in bowhead, blue, humpback and fin whales numbers in the Greenland Sea and Fram Strait between 1979 and 2014
Get PDFIn the frame of our long-term study of cetacean abundance and distribution in polar marine ecosystems begun in 1979, a drastic increase in the bowhead Balaena mysticetus North Atlantic “stock” was observed from 2005 on, by a factor 30 and more: from 0.0002 per count between 1979 and 2003 (one individual, n=5430 counts) to 0.06 per count from 2005 to 2014 (34 individuals, n=6000 counts); the most significant part of the increase occurred from 2007 on. Other large whale species (Mysticeti) showed a similar pattern, mainly blue Balaenoptera musculus, humpback Megaptera novaeangliae and fin whales Balaenoptera physalus. This large and abrupt increase cannot logically be due to population growth, nor to survival of a hidden “relic” population, nor to a changing geographical distribution within the European Arctic, taking into account the importance of the coverage during this study. Our interpretation is that individuals passed through the Northwest and/ or Northeast Passages from the larger Pacific stock into the almost depleted North Atlantic populations coinciding with a period of very low ice coverage — at the time the lowest ever recorded. In contrast, no clear evolution was detected neither for sperm whale Physeter macrocephalus nor for Minke whale Balaenoptera acusrostrata
Outflow from under the Pine Island Bay Ice Shelf: finescale structure and its temporal variability
Get PDFThe water column structure of the ice shelf cavity outflow from under Pine Island Glacier and its temporal variability were investigated using a hourly time series of yo-yo CTD and LADCP data collected over ~24 h at the southern end of the ice shelf front. The primary water types present over the continental shelf off Pine Island Bay were Circumpolar Deep Water (CDW), modified Circumpolar Deep Water (mCDW), Shelf Water (SW), and Ice Shelf Water (ISW). As CDW transited the shelf, it transitioned into cooler, mCDW. In the upper 200 m, ISW dominated within 100 km of the ice shelf and SW further offshore. Within Pine Island Bay, the water column was partitioned into two primary layers based on their behavior: an upper outflowing layer from 100 m to 450 m composed of ISW with a significant meltwater component, 1%–2%, over an inflowing layer from ~550 m to the sea bed composed of mCDW. Due to the small cavity extent, the outflowing water was warmer than the seawater freezing point. The upper ISW layer was further split into upper ISW layer #1 (100–300 m) and upper ISW layer #2 (320–450 m) with the transition coinciding with the ice shelf draft. Small step-like features with heights from 1–50 m existed within both the ISW layers and were more prominent in upper ISW layer #1. A baroclinic signal at the semidiurnal frequency existed within both primary layers with the strongest signal, ~ 10 cm·s-1, propagating vertically in the upper ISW layer
Expression analysis of heat-shock protein gene Hsp845 in the Antarctic psychrotrophic bacterium Psychrobacter sp. G under temperature and salinity stress
Get PDFHeat shock proteins (Hsps), produced by organisms under high temperature stimulation, play important roles in protein folding, translocation, and refolding/degradation. In this study, we investigated the expression level of the GrpE Hsp gene Hsp845 of Psychrobacter sp. G under different temperature and salinity stresses by quantitative real-time PCR and western blotting, respectively. At both transcriptional and translational levels, Hsp845 gene expression was induced by high temperature (30°C) and inhibited by low temperatures (0°C and 10°C). Hsp845 expression was also induced both by the absence of salt (0‰) and high salinity (90‰ and 120‰) at the transcriptional level, but was only induced by high salinity (90‰ and 120‰) at the translational level. In a combined stress treatment, Hsp845 was more sensitive to high temperature than to salinity at both transcriptional and translational levels. The increase in the translational-level expression of Hsp845 lagged behind that at the transcriptional level, and Hsp845 maximum expression was also higher at the transcriptional than at the translational level. In the absence of salt, transcriptional- and translational-level expressions exhibited opposite patterns, suggesting that the underlying mechanism requires further study