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41.
Cloud profiling from active lidar and radar in the A-train satellite constellation has significantly advanced our understanding of clouds and their role in the climate system. Nevertheless, the response of clouds to a warming climate remains one of the largest uncertainties in predicting climate change and for the development of adaptions to change. Both observation of long-term changes and observational constraints on the processes responsible for those changes are necessary. We review recent progress in our understanding of the cloud feedback problem. Capabilities and advantages of active sensors for observing clouds are discussed, along with the importance of active sensors for deriving constraints on cloud feedbacks as an essential component of a global climate observing system. 相似文献
42.
Leanne Fernandes Jon Day Brigid Kerrigan Dan Breen Glenn De'ath Bruce Mapstone Rob Coles Terry Done Helene Marsh Ian Poiner Trevor Ward David Williams Richard Kenchington 《Ocean & Coastal Management》2009,52(8):439-447
In the absence of consensus on the quantity and level of zoning protection required for coral reef and lagoon ecosystems, which process can guide decision makers? The Great Barrier Reef Marine Park Authority (GBRMPA) worked with experts in a collaborative process to develop a set of Biophysical Operational Principles to guide the design of a network of no-take areas. First, 82 expert scientists were asked to provide data and advice on the physical, biological and ecological dimensions of the Great Barrier Reef ecosystem. They recommended that an independent Scientific Steering Committee (the Committee) was set up. How this Committee worked successfully with the GBRMPA staff is detailed here in a manner to enable other resource managers to adopt the process if they are working in data-limited marine environments. 相似文献
43.
Thibaut Caley Bruno Malaizé Franck Bassinot Steven C. Clemens Nicolas Caillon Rossignol Linda Karine Charlier Helene Rebaubier 《Quaternary Research》2011,76(2):285-293
Previous studies have suggested that Marine Isotope Stage (MIS) 13, recognized as atypical in many paleoclimate records, is marked by the development of anomalously strong summer monsoons in the northern tropical areas. To test this hypothesis, we performed a multi-proxy study on three marine records from the tropical Indian Ocean in order to reconstruct and analyse changes in the summer Indian monsoon winds and precipitations during MIS 13. Our data confirm the existence of a low-salinity event during MIS 13 in the equatorial Indian Ocean but we argue that this event should not be considered as “atypical”. Taking only into account a smaller precession does not make it possible to explain such precipitation episode. However, when considering also the larger obliquity in a more complete orbitally driven monsoon “model,” one can successfully explain this event. In addition, our data suggest that intense summer monsoon winds, although not atypical in strength, prevailed during MIS 13 in the western Arabian Sea. These strong monsoon winds, transporting important moisture, together with the effect of insolation and Eurasian ice sheet, are likely one of the factors responsible for the intense monsoon precipitation signal recorded in China loess, as suggested by model simulations. 相似文献
44.
Ben Burningham Tim Naylor S. P. Littlefair R. D. Jeffries 《Monthly notices of the Royal Astronomical Society》2005,356(4):1583-1591
We present radial velocities for 38 low-mass candidate members of the σ Orionis young group. We have measured their radial velocities by cross-correlation of high-resolution ( R ≈ 6000) AF2/Wide Field Fibre Optical Spectrograph (WYFFOS) spectra of the gravity-sensitive Na i doublet at 8183, 8195 Å. The total sample contained 117 objects, of which 54 have sufficient signal-to-noise ratio to detect Na i at an equivalent width of 3 Å; however, we only detect Na i in 38 of these. This implies that very low-mass members of this young group display weaker Na i absorption than similarly aged objects in the Upper Scorpius OB association. We develop a technique to assess membership using radial velocities with a range of uncertainties that does not bias the selection when large uncertainties are present. The resulting membership probabilities are used to assess the issue of exclusion in photometric selections, and we find that very few members are likely to be excluded by such techniques. We also assess the level of contamination in the expected pre-main-sequence region of colour–magnitude space brighter than I = 17 . We find that contamination by non-members in the expected pre-main-sequence region of the colour–magnitude diagram is small. We conclude that although radial velocity alone is insufficient to confirm membership, high signal-to-noise ratio observations of the Na i doublet provide the opportunity to use the strength of Na i absorption in concert with radial velocities to asses membership down to the lowest masses, where lithium absorption no longer distinguishes youth. 相似文献
45.
A. C. Day-Jones † D. J. Pinfield R. Napiwotzki B. Burningham J. S. Jenkins H. R. A. Jones S. L. Folkes D. J. Weights J. R. A. Clarke 《Monthly notices of the Royal Astronomical Society》2008,388(2):838-848
We present the discovery of the widest known ultracool dwarf–white dwarf binary. This binary is the first spectroscopically confirmed widely separated system from our target sample. We have used the Two-Micron All-Sky Survey (2MASS) and SuperCOSMOS archives in the southern hemisphere, searching for very widely separated ultracool dwarf–white dwarf binaries, and find one common proper motion system, with a separation of 3650–5250 au at an estimated distance of 41–59 pc, making it the widest known system of this type. Spectroscopy reveals 2MASS J0030−3740 is a DA white dwarf with T eff = 7600 ± 100 K, log( g ) = 7.79–8.09 and M WD = 0.48–0.65 M⊙ . We spectroscopically type the ultracool dwarf companion (2MASS J0030−3739) as M9 ± 1 and estimate a mass of 0.07–0.08 M⊙ , T eff = 2000–2400 K and log( g ) = 5.30–5.35 , placing it near the mass limit for brown dwarfs. We estimate the age of the system to be >1.94 Gyr (from the white dwarf cooling age and the likely length of the main-sequence lifetime of the progenitor) and suggest that this system and other such wide binaries can be used as benchmark ultracool dwarfs. 相似文献
46.
Jaromír Janský Vladimír Plicka Helene Lyon-Caen Oldřich Novotný 《Journal of Seismology》2007,11(2):199-204
We determine the velocities in an upper crustal model, composed of three homogeneous layers, for one subregion of the western
part of the Gulf of Corinth, NE of the town of Aigion, Greece. We have used local events that occurred there in the year 2001
and were recorded by the Corinth Rift Laboratory Network. Weighted P and S arrival time residuals are minimized using the Neighbourhood Algorithm of Sambridge (1999), combined with the grid search
for source locations. The resolution of the inversion is tested by delete-one jackknifing. The model obtained is compared
with some other models derived or applied to the subregion. A fast velocity increase between depths of 5 and 7 km is confirmed
as the major structural element. 相似文献
47.
Bjrn E. Berglund Svante Bjrck Geoffrey Lemdahl Helene Bergsten Kjell Nordberg Else Kolstrup 《第四纪科学杂志》1994,9(2):127-132
A synthesis is presented of the envronmental and climatic variations that are inferred to have occurred in southern Sweden (up to latitude 59°N) and Denmark during the Weichselian Late-glacial (14-9 ka BP). The chronology and characteristics of the main phases of deglaciation, sea-level change, periglacial activity, soil development, vegetation cover and climate change are summarised. A curve representing the main changes in temperature, including quantitative estimates based upon beetle data and using the ‘mutual climatic range’ method, is presented. 相似文献
48.
James J. Bock Andrew E. Lange T. Matsumoto Peter B. Eisenhardt Perry B. Hacking Helene R. Schember 《Experimental Astronomy》1994,3(1-4):119-120
The high sensitivity of large format InSb arrays can be used to obtain deep images of the sky at 3–5 m. In this spectral range cool or highly redshifted objects (e.g. brown dwarfs and protogalaxies) which are not visible at shorter wavelengths may be observed. Sensitivity at these wavelengths in ground-based observations is severely limited by the thermal flux from the telescope and from the earth's atmosphere. The Near Infrared Faint-Object Telescope Experiment (NIFTE), a 50 cm cooled rocket-borne telescope combined with large format, high performance InSb arrays, can reach a limiting flux < 1 Jy (1) over a large field-of-view in a single flight. In comparison, ISO will require days of observation to reach a sensitivity more than one order of magnitude worse over a similar area of the sky. The deep 3–5 m images obtained by the rocket-borne telescope will assist in determining the nature of faint red objects detected by ground-based telescopes at 2 m, and by ISO at wavelengths longer than 5 m. 相似文献
49.
Abu El-Enen Mahrous M. Lorenz Joachim Ali Kamal A. von Seckendorff Volker Okrusch Martin Schüssler Ulrich Brätz Helene Schmitt Ralf-Thomas 《International Journal of Earth Sciences》2018,107(7):2393-2408
International Journal of Earth Sciences - Imperial Porphyry, a famous dimension stone of spectacular purple color, was quarried in the Mons Porphyrites area north of Jabal Dokhan in the Eastern... 相似文献
50.
Digital technologies, including participatory Internet mapping, social media and smartphones, provide new avenues for research in outdoor recreation and tourism. The potential to reach a greater audience and collect visitation data on a broader scale, with less costs than traditional paper surveys, are key advantages that have increased the use of these novel technologies. Using of mobile apps for data collection is still at the experimental stage. We evaluate previous attempts to use apps for monitoring recreation and tourism in protected areas, as an alternative to other in situ or online methods. We present a pilot study implemented in Jotunheimen National Park (Norway), where we developed a mobile app for visitor monitoring and real-time mapping of values and experiences. We present the lessons learned, give suggestions on how and for what apps can be used, and discuss the advantages and limitations of using smartphones for visitor monitoring in protected areas. 相似文献