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排序方式: 共有249条查询结果,搜索用时 234 毫秒
31.
Peer Helmke Susanne Neuer Michael W. Lomas Maureen Conte Tim Freudenthal 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(2):213-227
We compared in-situ and satellite-derived measures of the biological carbon pump efficiency at the two seemingly similar subtropical North Atlantic gyre time series sites, the Bermuda time series (BATS, Bermuda Atlantic time-series study and OFP, ocean flux program) in the western gyre and the ESTOC time series (European station for time-series in the ocean, Canary Islands) in the eastern gyre. Satellite-derived surface chlorophyll a was slightly lower at Bermuda compared to ESTOC (annual average of 0.10±0.04 vs. 0.14±0.05-mg-m?3), as was satellite-derived primary production (annual average of 380±77 vs. 440±80-mg C-m?2 d?1). However, export production normalized to primary production (export ratio) was higher at Bermuda by a factor of 2–3 when estimated using mesopelagic traps moored at 500-m depth and by a factor of 3–4 when estimated using surface-tethered drifting traps. When averaged seasonally, flux at BATS was highest in spring (March, April, May) at all depths followed by summer (June, July, August) and decreasing towards fall, but this seasonality was less visible at ESTOC. Seasonal comparison showed the fastest flux attenuation at Bermuda in winter and spring, coinciding with the highest POC flux. POC/PIC ratios derived from the moored traps were significantly higher at BATS than at ESTOC in fall and winter, but this difference was not significant in spring (p>0.05). This study shows that while the western and eastern Atlantic subtropical gyres have similar rates of primary production, the biological carbon pump differs between the two provinces. Higher new nutrient input observed at Bermuda compared to ESTOC might explain part of the difference in export ratio but alone is insufficient. Greater winter mixed-layer depths and higher mesoscale eddy activity at Bermuda resulting in pulsed production events of labile organic matter might explain both the higher export flux and export ratios found at Bermuda. 相似文献
32.
Rita Loidl Josef Hron Susanne Höfner Uffe G. ørgensen Bernhard Aringer Franz Kerschbaum 《Astrophysics and Space Science》1997,251(1-2):243-246
Exploratory synthetic spectra were computed for carbon-rich long-period variables. We used dynamic model atmospheres of Höfner &; Dorfi (1997) and calculated partial pressures, absorption- and scattering coefficients as input for the spectral synthesis code of Jørgensen et al. (1992). First ISO SWS-observations of the carbon-Mira T Dra are compared with our synthetic spectra. 相似文献
33.
34.
Julia Scharwächter Andreas Eckart Susanne Pfalzner Jens Zuther Melanie Krips Eva Schinnerer Johannes Staguhn 《Astrophysics and Space Science》2005,295(1-2):101-106
I Zw 1 and 3C 48 are two neighboring template objects at a later stage of the hypothesized merger-driven evolutionary sequence from ultra-luminous infrared galaxies (ULIRGs) to quasi-stellar objects (QSOs). Since galaxy mergers are assumed to trigger the evolution, it is important to confirm the merger properties of transitionary objects. Using multi-wavelength observations and N-body simulations, the merger histories of I Zw 1 and 3C 48 have been investigated in two separate case studies. Here, the results from both studies are compared and their relevance for the evolutionary hypothesis is discussed.This research is partly based on observations with ISAAC at the Very Large Telescope (VLT) of the European Southern Observatory (ESO) under projects 67.B-0009 and 67.B-0019. 相似文献
35.
Alan B. Binder Manfred A. Lange Heinz-Jürgen Brandt Susanne Kähler 《Earth, Moon, and Planets》1980,23(4):445-481
A synthesis of the majority of the available mare basalt data shows that basalts and glasses came from 28 different volcanic units. The compositions of the magmas of 12 of these units can be calculated with a high degree of confidence. Reasonable estimates can be made for the compositions of nine of the remaining units. In addition, the compositions of three general magma types can be obtained from data derived from the Luna 16, Luna 24, and Apollo 17 fines. The compositional data presented provide a firm basis for the further study of the characteristics of the mare basalt magma source region. 相似文献
36.
Julia Scharwächter Andreas Eckart Susanne Pfalzner Johannes Staguhn Eva Schinnerer 《Astrophysics and Space Science》2003,284(2):507-510
We address current theories of research on morphology, environment and evolution of active galaxies in the form of a detailed
case study of the nearby QSO host I Zw 1. This study is based on sub-kpc resolution 12CO(1-0) observations with the BIMA mm-interferometer and on near-infrared imaging with ISAAC at the VLT. The 12CO(1-0) maps reveal a circumnuclear molecular gas ring with a radius of 0.9 kpc. The imaging data in the J-band are analyzed
with respect to a disk-bulge decomposition. Together with a model of the gas rotation curve, the radial profile of the dynamical
J-band mass-to-light ratio (M/L) is discussed. The J-band images give new evidence for an interaction between I Zw 1 and its
nearby companion. First results from a sequence of N-body simulations for an extensive test of the parameter space of the
interaction are presented.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
37.
Topography and morphodynamics in the German Bight using SAR and optical remote sensing data 总被引:3,自引:0,他引:3
Morphological changes in coastal areas, especially in river estuaries, are of high interest in many parts of the world. Satellite
data from both optical and radar sensors can help to monitor and investigate these changes. Data from both kinds of sensors
being available for up to 30 years now, allow examinations over large timescales, while high resolution sensors developed
within the last decade allow increased accuracy. So the creation of digital elevation models (DEMs) of, for example, the wadden
sea from a series of satellite images is already possible. ENVISAT, successfully launched on March 1, 2002, continues the
line of higher resolution synthetic aperture radar (SAR) imaging sensors with its ASAR instrument and now also allows several
polarization modes for better separation of land and water areas. This article gives an overview of sensors and algorithms
for waterline determination as well as several applications. Both optical and SAR images are considered. Applications include
morphodynamic monitoring studies and DEM generation.
相似文献
Andreas NiedermeierEmail: |
38.
The atmospheres and circumstellar envelopes of AGB stars are characterized by complex physical phenomena like shock waves
caused by stellar pulsation or formation of molecules and dust which often lead to a heavy mass loss and have a strong influence
on IR properties as observed by ISO. To allow a physical interpretation of various observations we have constructed improved
dynamical model atmospheres of long-period variables. In this contribution we mainly investigate the dependence of the atmospheric
structure and its variability on stellar pulsation, molecular opacities and time-dependent dust formation. IR spectra resulting
from our models are discussed in detail by Loidl et al. (1997b) and compared to ISO-SWS spectra obtained by Hron et al. (1997).
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
39.
Evaluation of an ensemble of Arctic regional climate models: spatiotemporal fields during the SHEBA year 总被引:1,自引:1,他引:0
A.?RinkeEmail author K.?Dethloff J.?J.?Cassano J.?H.?Christensen J.?A.?Curry P.?Du E.?Girard J.-E.?Haugen D.?Jacob C.?G.?Jones M.?K?ltzow R.?Laprise A.H.?Lynch S.?Pfeifer M.?C.?Serreze M.?J.?Shaw M.?Tjernstr?m K.?Wyser M.??agar 《Climate Dynamics》2006,26(5):459-472
Simulations of eight different regional climate models (RCMs) have been performed for the period September 1997–September
1998, which coincides with the Surface Heat Budget of the Arctic Ocean (SHEBA) project period. Each of the models employed
approximately the same domain covering the western Arctic, the same horizontal resolution of 50 km, and the same boundary
forcing. The models differ in their vertical resolution as well as in the treatments of dynamics and physical parameterizations.
Both the common features and differences of the simulated spatiotemporal patterns of geopotential, temperature, cloud cover,
and long-/shortwave downward radiation between the individual model simulations are investigated. With this work, we quantify
the scatter among the models and therefore the magnitude of disagreement and unreliability of current Arctic RCM simulations.
Even with the relatively constrained experimental design we notice a considerable scatter among the different RCMs. We found
the largest across-model scatter in the 2 m temperature over land, in the surface radiation fluxes, and in the cloud cover
which implies a reduced confidence level for these variables.
An erratum to this article can be found at 相似文献
40.
Darren Ruddell Sharon L. Harlan Susanne Grossman-Clarke Gerardo Chowell 《Climatic change》2012,111(3-4):581-607
Understanding public perceptions of climate is critical for developing an effective strategy to mitigate the effects of human activity on the natural environment and reduce human vulnerability to the impacts of climate change. While recent climate assessments document change among various physical systems (e.g., increased temperature, sea level rise, shrinking glaciers), environmental perceptions are relatively under-researched despite the fact that there is growing skepticism and disconnect between climate science and public opinion. This study utilizes a socio-ecological research framework to investigate how public perceptions compared with environmental conditions in one urban center. Specifically, air temperature during an extreme heat event was examined as one characteristic of environmental conditions by relating simulations from the Weather Research and Forecast (WRF) atmospheric model with self-reported perceptions of regional and neighborhood temperatures from a social survey of Phoenix, AZ (USA) metropolitan area residents. Results indicate that: 1) human exposure to high temperatures varies substantially throughout metropolitan Phoenix; 2) public perceptions of temperature are more strongly correlated with proximate environmental conditions than with distal conditions; and 3) perceptions of temperature are related to social characteristics and situational variables. The social constructionist paradigm explains public perceptions at the regional scale, while experience governs attitude formation at the neighborhood scale. 相似文献