大洋钻探与地层学——高分辨率磁性生物年代地层格架

深海钻探计划（ＤＳＤＰ）和大洋钻探计划（ＯＤＰ）实施以来促进了地层学的发展。通过对大洋沉积物的研究，利用生物属，种的始，末现面事件建立起了晚中生代－新生代高精度的钙质超微化石，有孔虫，放射虫以及沟鞭藻的化石带，综合利用这些基准面事件，可使地层划分精度达１０万年以内。使用液压活塞取心技术，建立起了完整，连续的中，新生代磁性地层剖面，加之放射性年龄的测定，确定了数百个生物属，种始，末现面的绝对年龄值，     

Parameterisation of the Planetary Boundary Layer for Diagnostic Wind Models

The planetary boundary-layer (PBL) parameterization is a key issue for the definition of initial wind flow fields in diagnostic models. However, PBL theories usually treat separately stable, neutral, and convective stability conditions, so that their implementation in diagnostic wind models is not straightforward. In the present paper, an attempt is made to adopt a comprehensive PBL parameterisation, covering stable/neutral and unstable atmospheric conditions, which appears suitable to diagnostic models. This parameterisation is implemented into our diagnostic mass-consistent code. A validation of the consistency between the implemented PBL parameterisations has been checked through an analysis of the sensitivity of the vertical wind profiles to atmospheric stability.     

Climatic impacts of historical wetland drainage in Switzerland

The effects of historical land-use and land-cover changes on the climate of the Swiss Plateau in the different seasons were investigated. In the 19th century, a civil engineering project was initiated to reshape the lake and river system on the Swiss Plateau in order to ban the frequent flooding during extreme weather events. The landscape modifications consisted primarily of a conversion of wetlands with extended peat soils into a highly productive agricultural landscape. Historical maps (1800–1850) served as a basis for the reconstruction of the past land use. The “Lokal-Modell” of the Consortium for Small-Scale Modelling was used to conduct eight one-month long high-resolution simulations (1.5 × 1.5 km²) with present and past landscape conditions. The modified soil and surface properties led to distinctly altered energy and moisture exchanges at the surface and as a consequence affected the local and regional climate. The climatic changes show different characteristics and magnitudes in the cold (October – March) as compared to the warm season (April – September). The landscape modifications led to an average daytime cooling between −0.12 °C (January) and −0.61 °C (April) and a night-time warming of 0.19 °C−0.34 °C. The differences in the mean monthly temperatures show a warming of 0.1 °C−0.2 °C in the cold season and a cooling of similar magnitude in most of the study area in the warm season. The modification of the radiation budget and the surface energy balance distinctly affected the convective activity in the study area in the warm season, but had only a weak effect on convectivity in the cold season. The cloud coverage in the warm season is therefore distinctly reduced compared to the past.     

Internal architecture of the soft sediment cover of the South-Aquitaine shelf (Bay of Biscay): A record of high frequency sea level variations?

Very high-resolution seismic profiles highlighted three main depositional sequences of several hundred meters thick on the South-Aquitaine shelf. The youngest one, the soft sedimentary cover (U1), is presented in this article. It is composed of six seismic units deposited during the Late Quaternary and corresponds to a repetition of a sequence type. The sequence type is formed in four phases: an erosional unconformity (S), a sub-unit “a”, an internal erosional unconformity (St) and a sub-unit “b”. The first phase begins with the erosional unconformity (S), which could be formed during the sea level fall. The second phase is the deposition of the sub-unit “a”, likely during the sea level lowstand and the early sea level rise. Its acoustic facies is generally chaotic with small channels and could be filled by coarse or heterogeneous sediments. The third phase is the formation of a plane and high amplitude unconformity (St) which could be correlated with a transgressive or a wave ravinement surface. The fourth phase corresponds to the deposition, probably during the sea level rise, of the sub-unit “b” which is characterized by subparallel reflections.     

两步保形平流方案在高分辨率球面经纬网格下的跳点差分试验

尝试用一个基于有限差分的两步保形平流方案（TSPAS）替代美国国家大气研究中心第5版公用大气模式（NCAR-CAM5）欧拉-谱动力框架中的半拉格朗日传输（SLT）平流方案,并针对不同分辨率版本,计算水汽等物质的传输过程。通过设计保证守恒性的跳点差分法,解决了基于经纬网格的模式在高分辨率下由于极区纬向格距过小而造成的差分方案积分时间步长过短的问题,使得TSPAS在高分辨率下仍然可以使用较大的时间步长。理想试验表明：（1）跳点TSPAS在守恒性、数值精度（量级上）、保形性等方面均较好地保持了原TSPAS的特点,而积分步长可增大到与CAM5-SLT相同,比原TSPAS提高超过一个数量级;（2）较半拉格朗日传输方案,尽管TSPAS的耗散更大,但是在相同时间步长下更省时,且改进了半拉格朗日传输求解平流方程造成的不守恒问题。CAM5的比较试验表明：（1）采用跳点TSPAS的模式结果与非跳点计算结果相当,在高纬度跳点区域也并未出现模拟异常;（2）在高分辨率下,采用跳点TSPAS方案的CAM5模拟结果与原模式结果相近,并初步显示对东亚青藏高原南侧的虚假降水有所抑制。该工作确保了基于欧拉通量差分型的TSPAS在高分辨率模式下的大时间步长稳定积分,为解决有限差分方法在高分辨率模式发展中的相关计算问题提供了启示,为后续针对东亚地区的模式性能改进奠定了基础。     

First observations of the Na exosphere of Mercury with the high-resolution spectrograph of the 3.5M Telescopio Nazionale Galileo

Analysis of three spectra of the exosphere of Mercury in the Na-D lines are presented. Spectra were secured with the high-resolution spectrograph (SARG) of the 3.5 M Telescopio Nazionale Galileo (TNG, located on the Roque de los Muchachos, Canaries) on the evenings of August 23 and 24, 2002. Spectra have resolution ; the slit length was 26.7”. The Na column abundances range from 4.3 to with the highest abundances being close to the illuminated limb. Our observations at true anomaly angles (TAA) from 171°to 174°show the traces of the emission lines to be strongly peaked at the illuminated limb, supportive of recent modeling that shows thermal desorption to be a strong factor in determining the distribution of Na about the planet.     

CBERS-02B卫星遥感影像的区域网平差

针对中巴资源一号卫星(CBERS-02B)卫星遥感影像姿态角误差较大的特点,提出了利用区域网平差方法提高其对地目标定位精度的策略和具体计算过程。首先对参与平差的每景影像选取4个地面控制点进行影像姿态角常差检校,然后采用与地形无关方案解求各自的RPC参数,最后选取带仿射变换项的有理函数模型(RFM)进行多重覆盖影像的区域网平差。对两个地区的0级CBERS-02B单条CCD立体影像对的区域网平差试验表明,对地目标定位的平面和高程精度均达到了±3个像元的水平,且高程精度明显优于平面精度。相对于常规的卫星遥感影像区域网平差方法,平面和高程精度均有明显提升,几乎达到国外同等高分辨率卫星遥感影像的几何定位精度。这说明中国卫星遥感影像亦具有较好的几何定位潜力,在区域网平差之前进行系统误差预改正是必要和可行的。     

Luciola hypertelescope space observatory: versatile, upgradable high-resolution imaging, from stars to deep-field cosmology

Luciola is a large (1 km) “multi-aperture densified-pupil imaging interferometer”, or “hypertelescope” employing many small apertures, rather than a few large ones, for obtaining direct snapshot images with a high information content. A diluted collector mirror, deployed in space as a flotilla of small mirrors, focuses a sky image which is exploited by several beam-combiner spaceships. Each contains a “pupil densifier” micro-lens array to avoid the diffractive spread and image attenuation caused by the small sub-apertures. The elucidation of hypertelescope imaging properties during the last decade has shown that many small apertures tend to be far more efficient, regarding the science yield, than a few large ones providing a comparable collecting area. For similar underlying physical reasons, radio-astronomy has also evolved in the direction of many-antenna systems such as the proposed Low Frequency Array having “hundreds of thousands of individual receivers”. With its high limiting magnitude, reaching the m _v?=?30 limit of HST when 100 collectors of 25 cm will match its collecting area, high-resolution direct imaging in multiple channels, broad spectral coverage from the 1,200 Å ultra-violet to the 20 μm infra-red, apodization, coronagraphic and spectroscopic capabilities, the proposed hypertelescope observatory addresses very broad and innovative science covering different areas of ESA’s Cosmic Vision program. In the initial phase, a focal spacecraft covering the UV to near IR spectral range of EMCCD photon-counting cameras (currently 200 to 1,000 nm), will image details on the surface of many stars, as well as their environment, including multiple stars and clusters. Spectra will be obtained for each resel. It will also image neutron star, black-hole and micro-quasar candidates, as well as active galactic nuclei, quasars, gravitational lenses, and other Cosmic Vision targets observable with the initial modest crowding limit. With subsequent upgrade missions, the spectral coverage can be extended from 120 nm to 20 μm, using four detectors carried by two to four focal spacecraft. The number of collector mirrors in the flotilla can also be increased from 12 to 100 and possibly 1,000. The imaging and spectroscopy of habitable exoplanets in the mid infra-red then becomes feasible once the collecting area reaches 6 m², using a specialized mid infra-red focal spacecraft. Calculations (Boccaletti et al., Icarus 145, 628–636, 2000) have shown that hypertelescope coronagraphy has unequalled sensitivity for detecting, at mid infra-red wavelengths, faint exoplanets within the exo-zodiacal glare. Later upgrades will enable the more difficult imaging and spectroscopy of these faint objects at visible wavelengths, using refined techniques of adaptive coronagraphy (Labeyrie and Le Coroller 2004). Together, the infra-red and visible spectral data carry rich information on the possible presence of life. The close environment of the central black-hole in the Milky Way will be imageable with unprecedented detail in the near infra-red. Cosmological imaging of remote galaxies at the limit of the known universe is also expected, from the ultra-violet to the near infra-red, following the first upgrade, and with greatly increasing sensitivity through successive upgrades. These areas will indeed greatly benefit from the upgrades, in terms of dynamic range, limiting complexity of the objects to be imaged, size of the elementary “Direct Imaging Field”, and limiting magnitude, approaching that of an 8-m space telescope when 1,000 apertures of 25 cm are installed. Similar gains will occur for addressing fundamental problems in physics and cosmology, particularly when observing neutron stars and black holes, single or binary, including the giant black holes, with accretion disks and jets, in active galactic nuclei beyond the Milky Way. Gravitational lensing and micro-lensing patterns, including time-variable patterns and perhaps millisecond lensing flashes which may be beamed by diffraction from sub-stellar masses at sub-parsec distances (Labeyrie, Astron Astrophys 284, 689, 1994), will also be observable initially in the favourable cases, and upgrades will greatly improve the number of observable objects. The observability of gravitational waves emitted by binary lensing masses, in the form of modulated lensing patterns, is a debated issue (Ragazzoni et al., MNRAS 345, 100–110, 2003) but will also become addressable observationally. The technology readiness of Luciola approaches levels where low-orbit testing and stepwise implementation will become feasible in the 2015–2025 time frame. For the following decades beyond 2020, once accurate formation flying techniques will be mastered, much larger hypertelescopes such as the proposed 100 km Exo-Earth Imager and the 100,000 km Neutron Star Imager should also become feasible. Luciola is therefore also seen as a precursor toward such very powerful instruments.     

Subaquatic slope instabilities: The aftermath of river correction and artificial dumps in Lake Biel (Switzerland)

River engineering projects are developing rapidly across the globe, drastically modifying water courses and sediment transfer. Investigation of the impact of engineering works focuses usually on short-term impacts, thus a longer-term perspective is still missing on the effects that such projects have. The ‘Jura Water Corrections’ – the largest river engineering project ever undertaken in Switzerland – radically modified the hydrological system of Lake Biel in the 19th and 20th Century. The deviation of the Aare River into Lake Biel more than 140 years ago, in 1878, thus represents an ideal case study to investigate the long-term sedimentological impacts of such large-scale river rerouting. Sediment cores, along with new high-resolution bathymetric and seismic reflection datasets were acquired in Lake Biel to document the consequences of the Jura Water Corrections on the sedimentation history of Lake Biel. Numerous subaquatic mass transport structures were detected on all of the slopes of the lake. Notably, a relatively large mass transport complex (0·86 km²) was observed on the eastern shore, along the path of the Aare River intrusion. The large amount of sediment delivered by the Aare River since its deviation into the lake likely caused sediment overloading resulting in subaquatic mass transport. Alternatively, the dumping since 1963 in a subaquatic landfill of material excavated during the second phase of river engineering, when the channels flowing into and out of Lake Biel were widened and deepened, might have triggered the largest mass transport, dated to 1964 or 1965. Additional potential triggers include two nearby small earthquakes in 1964 and 1965 (M_W 3·9 and 3·2, respectively). The data for this study indicate that relatively large mass transports have become recurrent in Lake Biel following the deviation of the Aare River, thus modifying hazard frequency for the neighbouring communities and infrastructure.     

Coherence algorithm with a high-resolution time–time transform and feature matrix for seismic data

Traditional coherence algorithms are often based on the assumption that seismic traces are stationary and Gaussian. However, seismic traces are actually non-stationary and non-Gaussian. A constant time window and the canonical correlation analysis in traditional coherence algorithms are not optimal for non-stationary seismic traces and cannot describe the similarity between adjacent seismic traces in detail. To overcome this problem, a new coherence algorithm using the high-resolution time–time transform and the feature matrix is designed. The high-resolution time–time transform used to replace the constant time window can produce a frequency-dependent time local series to analyse non-stationary seismic traces. The feature matrix, constructed by the frequency-dependent time local series and the related local gradients, defines a new correlation metric that enhances more details of the geological discontinuities in seismic images than does the canonical correlation analysis. Additionally, the Riemannian metric is introduced for related calculations because the feature matrices are not defined in a Euclidean space but rather in a manifold space. Application to field data illustrates that the proposed method reveals more details of structural and stratigraphic features.