Palaeoclimatology: Archaean atmosphere and climate

Ohmoto et al. argue that carbon dioxide was abundant in the late Archaean and early Proterozoic atmosphere and that methane was probably scarce, based on a reanalysis of the occurrence of siderite, FeCO3, in ancient rocks. Here I consider several factors that may undermine their conclusions.     

Palaeoclimatology: the record for marine isotopic stage 11

The marine isotopic stage 11 (MIS 11) is an extraordinarily long interglacial period in the Earth's history that occurred some 400,000 years ago and lasted for about 30,000 years. During this period there were weak, astronomically induced changes in the distribution of solar energy reaching the Earth. The conditions of this orbital climate forcing are similar to those of today's interglacial period, and they rendered the climate susceptible to other forcing--for example, to changes in the level of atmospheric carbon dioxide. Here we use ice-core data from the Antarctic Vostok core to reconstruct a complete atmospheric carbon dioxide record for MIS 11. The record indicates that values for carbon dioxide throughout the interglacial period were close to the Earth's pre-industrial levels and that both solar energy and carbon dioxide may have helped to make MIS 11 exceptionally long. Anomalies in the oceanic carbonate system recorded in marine sediments at the time, for example while coral reefs were forming, apparently left no signature on atmospheric carbon dioxide concentrations.     

Palaeoclimatology: Archaean palaeosols and Archaean air

Ferrous carbonate, as the mineral siderite, occurs in Archaean palaeosols (ancient soils). Ohmoto et al. contend that siderite was not in equilibrium with the oxygen in Archaean air and that its presence in palaeosols provides little constraint on the partial pressure of carbon dioxide in Archaean air. But their argument is invalid because it fails to distinguish the different behaviours of the trivial component oxygen and the significant component carbon dioxide in the partly closed system of soil waters. The presence or absence of siderite in ancient soils is a valid constraint on the carbon dioxide partial pressure (pCO2) in ancient atmospheres.     

基于极坐标等角度分布的钢轨廓形测量误差校准

针对钢轨廓形(轨廓)动态测量系统现场长期应用精度下降问题,提出采用接触式轨廓测量仪对动态测量系统进行校准.首先根据极坐标系等角度分布原则,分别对接触式测量轨廓和非接触式测量轨廓进行数字化建模和重采样处理.然后选取接触式测量轨廓作为基准,建立非接触式测量轨廓与基准轨廓之间的映射关系.最后通过对比二者偏差,实现轨廓动态测量系统误差现场校准.实际应用表明,经校准后的轨廓动态测量系统,静态测量误差由0.96mm降低到0.14mm,动态重复性误差最大值、平均值和均方根值分别为0.29mm、0.13mm和0.18mm,验证了校准方法的可行性.     

A novel Chinese polar knowledge repository based on polar data-sharing ontology

In order to archive and utilize the information from Chinese polar expeditions to the greatest extent, we design a novel knowledge repository, in which an automatic query model based on neural networks is proposed and a data call trigger is established to keep data consistent between polar data-sharing platforms. And in this repository, anybody can make contributions to the repository by creating or updating entries with version control and an authority control mechanism. In this paper, the data sources, data processes and network structure of this repository are described, and the keywords extraction and decision support operation are detailed. The analysis of this design’s feasibility and applicability indicates that this knowledge repository is open, sole and authoritative for Chinese polar expeditions.     

Ecology: widespread colonization by polar hypoliths

High-latitude polar deserts are among the most extreme environments on Earth. Here we describe a large and previously unappreciated habitat for photosynthetic life under opaque rocks in the Arctic and Antarctic polar deserts. This habitat is created by the periglacial movement of the rocks, which allows some light to reach their underside. The productivity of this ecosystem is at least as great as that of above-ground biomass and potentially doubles previous productivity estimates for the polar desert ecozone.