The effect of the wintertime Arctic Oscillation on springtime vegetation over the northern high latitude region   总被引：1，自引：0，他引：1  

Mee-Hyun Cho  Gyu-Ho Lim  Hyo-Jong Song 《Asia-Pacific Journal of Atmospheric Sciences》2014,50(1):567-573

The winter Arctic Oscillation (AO), a major source of climate variability in the Northern Hemisphere, affects winter and the subsequent spring climate over northern high latitude. Such effects are evident even in the 1st eigenmode of the normalized difference vegetation index (NDVI). The impacts of the winter AO is a dipole pattern between Eurasia and North America; positive (negative) values of the winter AO induce warmer (cooler) and high (low) vegetation activity in the following spring over Eurasia (North America). Regarding the time-lagged response of vegetation, the sea surface temperature (SST) and snow cover contribute to maintaining the large-scale circulation anomaly associated with the AO.  相似文献   

Distribution and characteristics of marine habitats in a subpolar bay based on hydroacoustics and bed shear stress estimates—Potter Cove,King George Island,Antarctica     

Anne-Cathrin Wölfl  Chai Heng Lim  H. Christian Hass  Sebastian Lindhorst  Gabriela Tosonotto  Karsten Alexander Lettmann  Gerhard Kuhn  Jörg-Olaf Wolff  Doris Abele 《Geo-Marine Letters》2014,34(5):435-446

Marine habitats worldwide are increasingly pressurized by climate change, especially along the Antarctic Peninsula. Well-studied areas in front of rapidly retreating tidewater glaciers like Potter Cove are representative for similar coastal environments and, therefore, shed light on habitat formation and development on not only a local but also regional scale. The objective of this study was to provide insights into habitat distribution in Potter Cove, King George Island, Antarctica, and to evaluate the associated environmental processes. Furthermore, an assessment concerning the future development of the habitats is provided. To describe the seafloor habitats in Potter Cove, an acoustic seabed discrimination system (RoxAnn) was used in combination with underwater video images and sediment samples. Due to the absence of wave and current measurements in the study area, bed shear stress estimates served to delineate zones prone to sediment erosion. On the basis of the investigations, two habitat classes were identified in Potter Cove, namely soft-sediment and stone habitats that, besides influences from sediment supply and coastal morphology, are controlled by sediment erosion. A future expansion of the stone habitat is predicted if recent environmental change trends continue. Possible implications for the Potter Cove environment, and other coastal ecosystems under similar pressure, include changes in biomass and species composition.  相似文献   

Projected changes in meteorological drought over East Africa inferred from bias-adjusted CMIP6 models     

Ayugi  Brian  Shilenje  Zablon Weku  Babaousmail  Hassen  Lim Kam Sian  Kenny T. C.  Mumo  Richard  Dike  Victor Nnamdi  Iyakaremye  Vedaste  Chehbouni  Abdelghani  Ongoma  Victor 《Natural Hazards》2022,113(2):1151-1176

Natural Hazards - The ongoing global warming has caused unprecedented changes in the climate system, leading to an increase in the intensity and frequency of weather and climate extremes. This...  相似文献   

EChO payload electronics architecture and SW design     

M. Focardi  A. M. Di Giorgio  M. Farina  M. Pancrazzi  R. Ottensamer  T. L. Lim  S. Pezzuto  G. Micela  E. Pace 《Experimental Astronomy》2015,40(2-3):813-839

EChO is a three-modules (VNIR, SWIR, MWIR), highly integrated spectrometer, covering the wavelength range from 0.55 μ m to 11.0 μ m. The baseline design includes the goal wavelength extension to 0.4 μ m while an optional LWIR module extends the range to the goal wavelength of 16.0 μ m. An Instrument Control Unit (ICU) is foreseen as the main electronic subsystem interfacing the spacecraft and collecting data from all the payload spectrometers modules. ICU is in charge of two main tasks: the overall payload control (Instrument Control Function) and the housekeepings and scientific data digital processing (Data Processing Function), including the lossless compression prior to store the science data to the Solid State Mass Memory of the Spacecraft. These two main tasks are accomplished thanks to the Payload On Board Software (P-OBSW) running on the ICU CPUs.  相似文献   

Ecosystem responses to climate change in a large on-river reservoir, Lake Paldang, Korea   总被引：3，自引：0，他引：3  

Hae-Kyung Park  Kang-Hyun Cho  Doo Hee Won  Jangho Lee  Dong-Soo Kong  Dong-Il Jung 《Climatic change》2013,120(1-2):477-489

The impact of climate change on a large river reservoir ecosystem was investigated. Long-term meteorological data showed that recent climate change, including warmer winters, increased precipitation intensity and extended dry periods, may have influenced the basin of Lake Paldang, the most downstream reservoir of a series of on-river reservoirs. Extreme hydrologic events and climate warming, acting independently and in combination, appear to be related to changes in the Lake Paldang ecosystem. A significant increase in chlorophyll a concentrations in early spring corresponded to the timing of ice break-up. An increase in winter temperatures, which resulted in a shorter time period of ice-cover and earlier ice break-up, appears to have stimulated phytoplankton growth in winter and early spring. Repeated intensive and extended influxes of turbid water, associated with more frequent extreme rainfall events, have increased concentration of suspended solids and may have influenced the biotic community structure of Lake Paldang. In the mid-2000s, the area vegetated by submerged hydrophytes, the abundance and biomass of the phylum Mollusca, as well as the abundance of fish from the subfamily Acheilognathinae, which spawn in the body of bivalve molluscs, was all smaller than in the late 1980s and early 1990s. Together, these results suggest that climate change may have contributed directly and indirectly to changes in each trophic level of the Lake Paldang ecosystem.  相似文献   

The 69-μm forsterite band as a dust temperature indicator     

J. E.Bowey  M. J.Barlow  F. J.Molster  A. M.Hofmeister  C.Lee  C.Tucker  T.Lim  P. A. R.Ade  L. B. F. M.Waters 《Monthly notices of the Royal Astronomical Society》2002,331(1):L1-L6

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Geological overview and cratering model for the Haughton impact structure,Devon Island,Canadian High Arctic     

Gordon R. Osinski  Pascal Lee  John G. Spray  John Parnell  Darlene S. S. Lim  Theodore E. Bunch  Charles S. Cockell  Brian Glass 《Meteoritics & planetary science》2005,40(12):1759-1776

Abstract— The Haughton impact structure has been the focus of systematic, multi‐disciplinary field and laboratory research activities over the past several years. Regional geological mapping has refined the sedimentary target stratigraphy and constrained the thickness of the sedimentary sequence at the time of impact to ?1880 m. New ⁴⁰Ar–³⁹Ar dates place the impact event at ?39 Ma, in the late Eocene. Haughton has an apparent crater diameter of ?23 km, with an estimated rim (final crater) diameter of ?16 km. The structure lacks a central topographic peak or peak ring, which is unusual for craters of this size. Geological mapping and sampling reveals that a series of different impactites are present at Haughton. The volumetrically dominant crater‐fill impact melt breccias contain a calcite‐anhydrite‐silicate glass groundmass, all of which have been shown to represent impact‐generated melt phases. These impactites are, therefore, stratigraphically and genetically equivalent to coherent impact melt rocks present in craters developed in crystalline targets. The crater‐fill impactites provided a heat source that drove a post‐impact hydrothermal system. During this time, Haughton would have represented a transient, warm, wet microbial oasis. A subsequent episode of erosion, during which time substantial amounts of impactites were removed, was followed by the deposition of intra‐crater lacustrine sediments of the Haughton Formation during the Miocene. Present‐day intra‐crater lakes and ponds preserve a detailed paleoenvironmental record dating back to the last glaciation in the High Arctic. Modern modification of the landscape is dominated by seasonal regional glacial and niveal melting, and local periglacial processes. The impact processing of target materials improved the opportunities for colonization and has provided several present‐day habitats suitable for microbial life that otherwise do not exist in the surrounding terrain.  相似文献   

The effect of dissipation on the generation of density structure by magnetohydrodynamic waves     

A. J. Lim  S. A. E. G. Falle  T. W. Hartquist 《Monthly notices of the Royal Astronomical Society》2005,357(2):461-470

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Performance of Jacobi preconditioning in Krylov subspace solution of finite element equations     

F.‐H. Lee  K.K. Phoon  K.C. Lim  S.H. Chan 《国际地质力学数值与分析法杂志》2002,26(4):341-372

This paper examines the performance of the Jacobi preconditioner when used with two Krylov subspace iterative methods. The number of iterations needed for convergence was shown to be different for drained, undrained and consolidation problems, even for similar condition number. The differences were due to differences in the eigenvalue distribution, which cannot be completely described by the condition number alone. For drained problems involving large stiffness ratios between different material zones, ill‐conditioning is caused by these large stiffness ratios. Since Jacobi preconditioning operates on degrees‐of‐freedom, it effectively homogenizes the different spatial sub‐domains. The undrained problem, modelled as a nearly incompressible problem, is much more resistant to Jacobi preconditioning, because its ill‐conditioning arises from the large stiffness ratios between volumetric and distortional deformational modes, many of which involve the similar spatial domains or sub‐domains. The consolidation problem has two sets of degrees‐of‐freedom, namely displacement and pore pressure. Some of the eigenvalues are displacement dominated whereas others are excess pore pressure dominated. Jacobi preconditioning compresses the displacement‐dominated eigenvalues in a similar manner as the drained problem, but pore‐pressure‐dominated eigenvalues are often over‐scaled. Convergence can be accelerated if this over‐scaling is recognized and corrected for. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

ISO Observations of Symbiotic Stars     

S.P.S. Eyres  A. Evans  A. Salama  P. Barr  J. Clavel  N. Jenkins  K. Leech  M. Kessler  T. Lim  L. Metcalfe  B. Schulz 《Astrophysics and Space Science》1997,255(1-2):361-366

A number of symbiotic stars have been observed with ISO. In addition to a number of emission lines, SWS observations of the symbiotic novae RR Tel and V1016 Cyg reveal prominent, broad 10 & 18 μm silicate dust features. The 10 μm features are similar to the crystalline silicate profiles seen in classical novae. There is some evidence that the silicate brightness in V1016 Cyg varies with Mira-component phase. However, the silicate feature in RR Tel also showed some variation even though observations were made at very similar Mira-component phases. PHT observations of S-type symbiotic stars show the IR emission to be dominated by the red-giant component. However, an excess in the PHT-P filters from 10 to 15 μm is evident in all the stars, and there may be a broad 3.2 μm absorption feature or a broad 3.8 μm emission feature. At this time we have no adequate physical explanations for any of these features. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献