Mass balance of three Svalbard glaciers reconstructed back to 1948     

L. A. Rasmussen  & J. Kohler 《Polar research》2007,26(2):168-174

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广东清远早、晚稻稻田甲烷排放的观测研究   总被引：1，自引：0，他引：1  

许黎  任万辉  杨宁  王天龙  刘锦銮  M A K Khalil  R A Rasmussen  M J Shearer 《气象》2007,33(3):19-27

分析了2003、2004年广东省清远市郊区早、晚稻稻田甲烷（CH4）的排放通量，结果表明：广东清远早、晚稻稻田CH4排放通量的几何平均值2003年为4，38mg·m^-2·h^-1和6．09mg·m^-2·h^-1；2004年为5．17mg·m^-2·h^-1和8．3mg·m^-2·h^-1，土壤有机质含量是造成2003和2004年CH4排放差异的原因之一。水稻品种的不同，CH4排放通量也有所不同，实验表明，水稻品种“七丝尖”的排放通量比品种“金优99”高1．08mg·m^-2·h^-1，产量却只有64％。此外，与相关的测量结果进行初步比较。  相似文献   

Use of discriminant analysis for classification of strata in sedimentary successions     

Douglas M. Hawkins  Stephen E. Rasmussen 《Mathematical Geology》1973,5(2):163-177

The technique of instrumental neutron activation analysis (INAA) has been used to analyze chip samples of geological material for 12 elements. Discriminant analysis has been used to classify the unknown chip samples to the correct stratum in a sedimentary succession.  相似文献   

Quaternary interaction of cryospheric and oceanographic processes along the central‐east Greenland margin     

Lara F. Prez  Tove Nielsen  Tine L. Rasmussen  Monica Winsborrow 《Boreas: An International Journal of Quaternary Research》2019,48(1):72-91

The east Greenland margin has been influenced by oceanographic and cryospheric processes since the late Miocene, when the southwards flow of the East Greenland Current (EGC) initiated and ice sheets first advanced across the margin. However, the relative importance of these processes, and their influence on the sedimentation of the margin through time remains poorly understood. High‐resolution single‐channel seismic, chirp sub‐bottom profiles and swath bathymetry data were acquired along the middle/lower slope and proximal basinal area off Liverpool Land, central‐east Greenland margin. In this study, seismic‐stratigraphical and morphological analyses allowed us to distinguish between the major sedimentary processes that influenced this margin during the Quaternary. The stratigraphical architecture reveals mass transport deposits (MTDs) related to glacially influenced down‐slope sedimentation. These are intercalated with buried contourite systems associated with bottom‐current controlled along‐slope sedimentation. The distribution of the MTDs suggests the influence of two distinct ice‐stream systems. Initial phases of down‐slope deposition during the early‐middle Quaternary appears to be related to distal deposition fed by an ice stream from the Scoresby Sund area in the south. Shallow sedimentary processes, together with morphological analysis of the sea floor, show that the most recent activity of down‐slope processes during the latest Quaternary has occurred in the north, linked to an ice stream from the Kong Oscar Fjord area. These observations document a temporal shift in the relative dominance of the Scoresby Sund and Kong Oscar Fjord ice‐stream systems. The glacial influence on the margin has been interrupted by periods of stronger activity of along‐slope bottom‐current flow, demonstrating that the EGC periodically controlled sedimentation on the continental margin.  相似文献   

Tree survey and allometric models for tiger bush in northern Senegal and comparison with tree parameters derived from high resolution satellite data     

Mads Olander Rasmussen  Frank-M. Göttsche  Doudou Diop  Cheikh Mbow  Folke-S. Olesen  Rasmus Fensholt  Inge Sandholt 《International Journal of Applied Earth Observation and Geoinformation》2011

A tree survey and an analysis of high resolution satellite data were performed to characterise the woody vegetation within a 10 × 10 km² area around a site located close to the town of Dahra in the semi-arid northern part of Senegal. The surveyed parameters were tree species, height, tree crown radius, and diameter at breast height (DBH), for which allometric models were determined. An object-based classification method was used to determine tree crown cover (TCC) from Quickbird data. The average TCC from the tree survey and the respective TCC from remote sensing were both about 3.0%. For areas beyond the surveyed areas TCC varied between 3.0% and 4.5%. Furthermore, an empirical correction factor for tree clumping was obtained, which considerably improved the estimated number of trees and the estimated average tree crown area and radius. An allometric model linking TCC to tree stem crosssectional area (CSA) was developed, which allows to estimate tree biomass from remote sensing. The allometric models for the three main tree species found performed well and had r²-values of about 0.7–0.8.  相似文献   

Analysing the advantages of high temporal resolution geostationary MSG SEVIRI data compared to Polar Operational Environmental Satellite data for land surface monitoring in Africa     

R. Fensholt  A. Anyamba  S. Huber  S.R. Proud  C.J. Tucker  J. Small  E. Pak  M.O. Rasmussen  I. Sandholt  C. Shisanya 《International Journal of Applied Earth Observation and Geoinformation》2011

Since 1972, satellite remote sensing of the environment has been dominated by polar-orbiting sensors providing useful data for monitoring the earth's natural resources. However their observation and monitoring capacity are inhibited by daily to monthly looks for any given ground surface which often is obscured by frequent and persistent cloud cover creating large gaps in time series measurements. The launch of the Meteosat Second Generation (MSG) satellite into geostationary orbit has opened new opportunities for land surface monitoring. The Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument on-board MSG with an imaging capability every 15 min which is substantially greater than any temporal resolution that can be obtained from existing Polar Operational Environmental Satellite (POES) systems currently in use for environmental monitoring. Different areas of the African continent were affected by droughts and floods in 2008 caused by periods of abnormally low and high rainfall, respectively. Based on the effectiveness of monitoring these events from Earth Observation (EO) data the current analyses show that the new generation of geostationary remote sensing data can provide higher temporal resolution cloud-free (<5 days) measurements of the environment as compared to existing POES systems. SEVIRI MSG 5-day continental scale composites will enable rapid assessment of environmental conditions and improved early warning of disasters for the African continent such as flooding or droughts. The high temporal resolution geostationary data will complement existing higher spatial resolution polar-orbiting satellite data for various dynamic environmental and natural resource applications of terrestrial ecosystems.  相似文献   

A miniature laser anemometer for measurement of wind speed and dust suspension on Mars     

J.P. Merrison  H.P. Gunnlaugsson  J. Jensen  K. Kinch  P. Nørnberg  K.R. Rasmussen 《Planetary and Space Science》2004,52(13):1177-1186

Suspended dust is a dominant component of the Martian environment. It has a major influence on atmospheric circulation and it is deposited widely over the planetary surface causing a serious hazard to instrumentation. In order to study dust transport, quantification of the wind flow and dust concentration are vital. A simple laser-based anemometer system is presented that is able to measure suspended dust grain velocity and turbulence from a landed spacecraft. This system has advantages over other techniques of wind speed determination in being insensitive to contamination or atmospheric conditions such as temperature, pressure or composition. For the first time it would allow direct measurement of the suspended dust concentration on Mars. A prototype instrument has been constructed and successfully tested in a wind tunnel facility under simulated Martian conditions. The optics are simple in design, light weight and the instrument has low power consumption. It is also robust and the output signal is easily interpreted, producing only a small data volume. Future improvements will be discussed, specifically modification to measure wind direction, the possibility of obtaining information about dust grain size and the construction of a flight model.  相似文献   

Bivariate frequency analysis: discussion of some useful concepts in hydrological application     

Sheng Yue  Peter Rasmussen 《水文研究》2002,16(14):2881-2898

Basic concepts such as conditional probability distributions, conditional return periods, and joint return periods are important to understand and to interpret multivariate hydrological events such as floods and storms. However, these concepts are not well documented in the open literature. This paper assembles and clarifies these concepts, and illustrates their practical utility. Relationships between joint return periods and univariate return periods are also derived. These concepts and relationships are demonstrated by applying a bivariate extreme value distribution to represent the joint distribution of flood peak and volume from an actual basin. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

XMM–Newton observations of two X-ray-bright galaxy groups – pushing out to r₅₀₀     

J. Rasmussen  T. J. Ponman 《Monthly notices of the Royal Astronomical Society》2004,349(2):722-734

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The Chandra view of NGC 1800 and the X-ray scaling properties of dwarf starbursts     

J. Rasmussen  I. R. Stevens  T. J. Ponman 《Monthly notices of the Royal Astronomical Society》2004,354(1):259-274

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