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1.
全球气候变化下南海诸岛保护优先区识别分析 总被引:3,自引:1,他引:2
全球变化下,珊瑚礁保护区是保护生物多样性、增强珊瑚礁对气候变暖抵抗力的有效方式,而维持珊瑚礁弹性是其核心内容。针对珊瑚礁最具有威胁性的热压力因子,基于南海1982—2009年卫星观测海表面温度(SST)数据和CMIP5加拿大地球系统模式CanESM2模型预估的2006—2100年南海SST数据构建热压力强度模型,从维持珊瑚礁弹性的角度识别IPCC RCP 4.5和RCP 8.5情景下南海诸岛保护优先区。结果表明:RCP 4.5和RCP 8.5情景下13%左右的南海诸岛珊瑚礁识别为保护优先区。根据热压力强度与珊瑚抵抗力及避难所关系,西沙群岛七连屿和晋卿岛近年观测与未来预估的热压力强度均比较低,在保障其服务功能的基础上建议实施完全保护;东沙群岛东沙环礁和中沙环礁排洪滩近年观测急性热压力强度较高但未来预估热压力强度较低,建议实施50%禁止利用保护;中沙群岛黄岩岛近年观测和未来预估的急性热压力强度均比较低,建议实施50%多用途保护。南沙群岛有14%左右的珊瑚礁识别为保护优先区,根据其热压力强度可实施30%~100%禁止利用保护或30%~50%多用途保护。RCP 4.5和RCP 8.5情景下的南海诸岛保护优先区及保护对策,可为维持珊瑚礁生态弹性及应对全球气候变化提供重要的参考价值。 相似文献
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Andrea PATZER Jochen SCHLÜTER Ludolf SCHULTZ Dolores H. HILL William V. BOYNTON 《Meteoritics & planetary science》2005,40(6):869-879
Abstract— Mineralogical and chemical studies of Dar al Gani 983 show that this meteorite is a eucrite. Its texture is that of an impact breccia. It contains cumulate pyroxene and feldspar megacrysts, a variety of recrystallized melt clasts, clasts of subophitic basalt, and mesostasis. These components are embedded in a matrix of fragmental pyroxene and plagioclase. In addition, the entire rock is penetrated by glassy melt veins and patches, and displays features of strong shock. The mineralogical and chemical evidence obtained for DaG 983 indicates that this meteorite experienced a complex evolutionary history. The presence of cumulate silicate crystals implies substantial, large scale cratering events on the HED asteroid. As a result of these impacts, rocks from different intrusive bodies to extrusive surface layers were laterally and vertically transported to form a thoroughly mixed megaregolith. DaG 983 represents a sample of this megabreccia. 相似文献
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网络安全是近年来研究的热点,各种新技术不断涌现,身份认证是安全应用中最重要的一个问题,也是PKI的核心服务之一。PKI作为信息安全的基石经过几年的发展不断走向成熟,在许多领域发挥着重要的作用。针对目前对PKI中的重要部件RA的研究很少的状况,着重对RA的实现模型进行了探讨。 相似文献
6.
The inception and growth of the active Carpino-Le Piane Basin Fault System (CLPBFS; central-southern Apennines, Italy) was analysed with respect to the neighbouring Isernia and Surrounding (ISFS) and Boiano Basin (BBFS) extensional Fault Systems. 39Ar–40Ar dating showed that the BBFS was already active 649 ± 21 ka bp and that the ISFS was active at least 476 ±10 ka bp , whereas the activity of the CLPBFS started certainly later than 253 ± 22 ka bp , and very probably as recently as <28 ka bp . These ages, combined with structural data (geometry and kinematics of the fault systems), indicate that the inception and development of the CLPBFS could be strictly related to the stress changes caused by earthquakes occurring on the BBFS. 相似文献
7.
G. Palladino A. Basili G. Di Cocco T. Franceschini G. Landini S. Silvestri A. Barbini M. Galimberti L. A. Gizzi 《Experimental Astronomy》2006,21(3):169-187
This paper describes the design of a star sensor based upon a high dynamic range CCD in order to reach an arcsec-level attitude
determination in balloon-borne missions. A custom star identification software was developed and laboratory-tested on a prototype
assembled using commercial components. A set of numerical simulations have been carried out to study the dependence on the
pointing precision of the centroid position accuracy, the number of detected stars and the effect of the image focusing. Moreover,
the role of the electronic noise and the discrete pixel structure on the light signals is identified by the analysis of numerical
simulations. Laboratory tests confirm that the arcsec pointing accuracy with a 1 Hz update rate can be achieved with our combination
of custom-developed software and selected hardware components. 相似文献
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9.
Andrés E. Piatti Juan J. Clariá Andrea V. Ahumada 《Monthly notices of the Royal Astronomical Society》2003,346(2):390-402
Charge-coupled device (CCD) photometry in the Johnson V , Kron–Cousins I and Washington CMT 1 systems is presented in the field of the poorly known open cluster NGC 2627. Four independent Washington abundance indices yield a mean cluster metallicity of [Fe/H]=−0.12 ± 0.08 , which is compatible with the existence of a radial gradient in the Galactic disc. The resultant colour–magnitude diagrams indicate that the cluster is an intermediate-age object of 1.4 Gyr. Based on the best fits of the Geneva group's isochrones to the ( V , V − I ) and ( T 1 , C − T 1 ) diagrams, we estimate E ( V − I ) = 0.25 ± 0.05 and V − MV = 11.80 ± 0.25 for log t = 9.15 , and E ( C − T 1 ) = 0.23 ± 0.07 and T 1 − M T 1 = 11.85 ± 0.25 for log t = 9.10 , respectively, assuming solar metal content. The derived reddening value E ( C − T 1 ) implies E ( B − V ) = 0.12 ± 0.07 and a distance from the Sun of 2.0 ± 0.4 kpc . Using the WEBDA data base and the available literature, we re-examined the overall properties of all the open clusters with ages between 0.6 and 2.5 Gyr. We identified peaks of cluster formation at 0.7–0.8, 1.0–1.1, 1.6–1.7 and 2.0–2.1 Gyr, separated by relative quiescent epochs of ∼0.2–0.3 Gyr. We also estimated a radial abundance gradient of −0.08 ± 0.02 , which is consistent with the most recent determinations for the Galactic disc, but no clear evidence for a gradient perpendicular to the Galactic plane is found. 相似文献
10.
We present first observations of Mira stars obtained at the Very Large Telescope Interferometer (VLTI) at 2 microns, equipped
with the VINCI instrument, using different baselines with both the test siderostats and the 8.2 m unit telescopes. These observations,
collected in the course of the VLTI commissining program, have targeted so far about sixty cool giant stars. In this talk,
we list and describe the measurements obtained for 14 Mira stars, many of them representing first-time determinations of the
visibility. In particular, we devote special attention to a study of Mira itself, for which very accurate determinations of
the visibility at several baseline lenghts and orientations could be obtained. We find that a two-component model is more
consistent with the data than a single stellar disc. Further observations are needed for a better understanding of this source.
The VLTI will constitute an ideal instrument for such studies in the future. In particular it will permit detailed investigations
of southern AGB stars, such as accurate measurements of surface structureparameters (diameters, diameter variations, asymmetries,
center-to-limbvariations, special features like hot spots) and of circumstellar envelopes.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献