可容纳空间转换系统的定量模拟

为探讨盆地两侧可容纳空间和层序叠加模式的非一致性变化,利用SEDPAK二维层序模拟软件,通过考虑控制层序沉积过程的不同参数,对可容纳空间转换系统进行定量模拟并提出新的认识.模拟结果表明,盆地两侧同期层序叠加模式可以分为"同步"和"非同步"两种,同步叠加模式多出现在层序的低位体系域及高位体系域后期,非同步叠加模式多出现在层序的水进体系域及高位体系域初期.多种地质参数的合理组合,盆地两侧同期层序均可形成非同步叠加模式.非同步叠加模式对体系域界面的识别、层序对比具有一定的参考价值.     

Anthropogenic Sulfate and Nitrate Signals in Snow from Bogda Glacier, Eastern Tianshan

A 1.2 m snow pit was recovered on July 29th, 2009 from the Bogda Glacier, eastern Tianshan (天山). The sample site temperature of -9.6 ℃ indicates that the unique glaciochemical re-cord was well preserved and suitable for the reconstruction of air pollution levels in this previously un-explored region. Samples were analyzed for major ions (Na+, K+, Ca2+, Mg2+, NH4+, Cl-, SO42-, NO3-, HCOO-, and CH3COO-). NO3- and SO42- were characterized by significant high levels of pollution con-centration. Most air masses ...     

The Falkland Islands’ palaeoecological response to millennial‐scale climate perturbations during the Pleistocene–Holocene transition: Implications for future vegetation stability in the southern ocean islands

Oceanic island flora is vulnerable to future climate warming, which is likely to promote changes in vegetation composition, and invasion of non‐native species. Sub‐Antarctic islands are predicted to experience rapid warming during the next century; therefore, establishing trajectories of change in vegetation communities is essential for developing conservation strategies to preserve biological diversity. We present a Late‐glacial‐early Holocene (16 500–6450 cal a bp ) palaeoecological record from Hooker's Point, Falkland Islands (Islas Malvinas), South Atlantic. This period spans the Pleistocene‐Holocene transition, providing insight into biological responses to abrupt climate change. Pollen and plant macrofossil records appear insensitive to climatic cooling during the Late‐glacial, but undergo rapid turnover in response to regional warming. The absence of trees throughout the Late‐glacial‐early Holocene enables the recognition of far‐travelled pollen from southern South America. The first occurrence of Nothofagus (southern beech) may reflect changes in the strength and/or position of the Southern Westerly Wind Belt during the Late‐glacial period. Peat inception and accumulation at Hooker's Point is likely to be promoted by the recalcitrant litter of wind‐adapted flora. This recalcitrant litter helps to explain widespread peatland development in a comparatively dry environment, and suggests that wind‐adapted peatlands can remain carbon sinks even under low precipitation regimes. © 2019 The Authors. Journal of Quaternary Science Published by John Wiley & Sons Ltd.     

Modeling India’s Coal Production with a Negatively Skewed Curve-Fitting Model

India’s coal demand is forecast to increase at a rapid pace in the future due to the country’s economic and population growth. Analyzing the scope for future production of India’s domestic coal resources, therefore, plays a vital role in the country’s development of sound energy policies. This paper presents a quantitative scenario analysis of India’s potential future coal production by using a negatively skewed curve-fitting model and a range of estimates of the country’s ultimately recoverable resources (URR) of coal. The results show that the resource base is sufficient for India’s coal production to keep increasing over the next few decades, to reach between 2400 and 3200 Mt/y at 2050, depending on the assumed value of URR. A further analysis shows that the high end of this range, which corresponds to our ‘GSI’ scenario, can be considered as the probable upper-bound to India’s domestic coal production. Comparison of production based on the ‘GSI’ scenario with India’s predicted demand shows that the domestic production of coal will be insufficient to meet the country’s rising coal demand, with the gap between demand and production increasing from its current value of about 268 Mt/y to reach 300 Mt/y in 2035, and 700 Mt/y by 2050. This increasing gap will be challenging for the energy security of India.     

The soft X-ray polychromator for the Solar Maximum Mission

The 1.4–22.4 Å range of the soft X-ray spectrum includes a multitude of emission lines which are important for the diagnosis of plasmas in the 1.5–50 million degree temperature range. In particular, the hydrogen and helium-like ions of all abundant solar elements with Z > 7 have their primary transitions in this region and these are especially useful for solar flare and active region studies. The soft X-ray polychromator (XRP) is a high resolution experiment working in this spectral region. The XRP consists of two instruments with a common control, data handling and power system. The bent crystal spectrometer is designed for high time resolution studies in lines of Fe i-Fe xxvi and Ca xix. The flat crystal scanning spectrometer provides for 7 channel polychromatic mapping of flares and active regions in the resonance lines of O viii, Ne ix, Mg xi, Si xiii, S xv, Ca xix, and Fe xxv with 14 spatial resolution. In its spectral scanning mode it covers essentially the entire 1.4–22.5 Å region.This paper summarizes the scientific objectives of the XRP experiment and describes the characteristics and capabilities of the two instruments. Sufficient technical information for experiment feasibility studies is included and the resources and procedures planned for the use of the XRP within the context of the Solar Maximum Mission is briefly discussed.     

Evidence for rapid ice flow and proglacial lake evolution around the central Strait of Magellan region,southernmost Patagonia

This paper presents a detailed palaeoglaciological reconstruction of ice sheet dynamics in the Seno Skyring, Seno Otway and Strait of Magellan region of the former Patagonian Ice Sheet, with a particular focus on previously hypothesised zones of rapid ice flow and the evolution of proglacial lakes. Geomorphological mapping from a combination of satellite imagery and oblique and vertical aerial photographs reveals a variety of glacial landforms that are grouped into several discrete flow‐sets and associated ice margin positions. The most distinct features are represented by flow‐sets of highly elongate streamlined glacial lineations on both sides of the Strait of Magellan. Based on the shape and dimensions of the flow‐sets and their abrupt lateral margins, a transverse and longitudinal variation in glacial lineation length and elongation ratio, and the reported presence of a potentially deformable bed and thrust moraines, the flow‐sets are interpreted as zones of rapid ice flow within the Otway and Magellan lobes. We hypothesise that this provides evidence for contemporaneous surge‐like advances within the lobes, which may explain the asymmetry in the lobate margin positions on either side of the strait. The mechanisms that initiated rapid flow are unclear, but are likely to have been influenced by internal factors such as a change in thermal/hydrological conditions at the bed. The topography of the region suggests ice‐dammed lakes would have formed as the ice lobes retreated. The westernmost of the former lakes, Lake Skyring, is delimited by a series of palaeo‐shorelines surrounding the present‐day lake Laguna Blanca and we reconstruct lake evolution based on manipulation of a digital elevation model. The size and orientation of meltwater channels and a large outwash plain indicate that Lake Skyring drained eastwards towards the Strait of Magellan, probably quite rapidly. We conclude that the potential for quasi‐independent surge‐like behaviour within adjacent lobes raises the possibility that, during climate‐driven ice expansion, some advances in this region may have been partly controlled by secondary internal feedback mechanisms. Copyright © 2012 John Wiley & Sons, Ltd.     

Building a Virtual Observatory for Heliophysics

Heliophysics is a new discipline that studies of the effect of the Sun on the Solar System and spans a number of existing scientific domains—solar physics, heliospheric physics, and magnetospheric and ionospheric physics. In order to build a virtual observatory for heliophysics we have to find ways to conduct searches that span the domains and track the evolution of phenomena in 4 dimensions as they propagate through interplanetary space. To facilitate this it will be necessary to improve the quality of the metadata that are used in the search and to describe the observations. We describe some of the issues and how these can be addressed.     

Reconstructing the Last Glacial Maximum ice sheet in the Weddell Sea embayment,Antarctica, using numerical modelling constrained by field evidence

The Weddell Sea Embayment (WSE) sector of the Antarctic ice sheet has been suggested as a potential source for a period of rapid sea-level rise – Meltwater Pulse 1a, a 20 m rise in ～500 years. Previous modelling attempts have predicted an extensive grounding line advance in the WSE, to the continental shelf break, leading to a large equivalent sea-level contribution for the sector. A range of recent field evidence suggests that the ice sheet elevation change in the WSE at the Last Glacial Maximum (LGM) is less than previously thought. This paper describes and discusses an ice flow modelling derived reconstruction of the LGM ice sheet in the WSE, constrained by the recent field evidence. The ice flow model reconstructions suggest that an ice sheet consistent with the field evidence does not support grounding line advance to the continental shelf break. A range of modelled ice sheet surfaces are instead produced, with different grounding line locations derived from a novel grounding line advance scheme. The ice sheet reconstructions which best fit the field constraints lead to a range of equivalent eustatic sea-level estimates between approximately 1.4 and 3 m for this sector. This paper describes the modelling procedure in detail, considers the assumptions and limitations associated with the modelling approach, and how the uncertainty may impact on the eustatic sea-level equivalent results for the WSE.