极区电离层TEC监测和发布系统

极区是研究各种高空大气物理现象和日地关系的理想场所,通过GPS获取的电离层TEC信息具有高精度、全天候、大范围等优势,所以利用GPS研究极区电离层有重要意义。本文所设计的极区电离层信息监测和发布系统,包含数据回传、数据处理、数据发布三个部分。数据回传包括卫星网络回传和格式转换。数据处理是利用每天回传的GPS双频数据,解算单站VTEC,解决了硬件延迟的求解问题,并用二次建模获得测站上空的VTEC,计算结果表明该方法能较好地给出电离层TEC的大小及变化规律。数据发布是通过中国极地科学考察管理信息系统提供实时的查询服务。     

渤海湾盆地晚古生代煤系烃源岩及其生烃性评价

在对渤海湾盆地晚古生代煤系烃源岩特征进行研究的基础上,分别从烃源岩的主要生烃组分、有机质类型及生烃门限等方面对其生烃性进行了评价,认为太原组烃夺生烃性要好于山西组;渤海地晚古生代煤系烃源岩不但具有良好的生烃物质基础,较高的生烃能力和热成熟条件,而且具有良好的天然气勘探前景。     

乌达矿区主采煤层煤相特征与煤的可选性

对内蒙古乌达矿区主采煤层9煤层的煤岩学特征和煤相进行了分析,用煤样密度组成的煤岩学方法讨论不同煤相煤的可选性。研究表明,相同煤相不同煤的可选性相似,聚煤环境决定了煤中矿物的含量和赋存状态,同时也决定了煤的可选性。高位泥炭沼泽形成的煤可选性好,而低位泥炭沼泽形成的煤可选性差。      

吉林省延边地区二叠纪的三类植物群与古陆缘再造

吉林省延边地区早二叠世晚期－晚二叠世早期存在着开山屯、解放村、青沟子等二处不同类型的植物群、前者属华夏植物群,中间为华夏与安加拉混生植物群,后者则是安 拉植物群,反映出和龙地块北部陆缘活动带、兴凯地块西部陆缘活动带、佳木斯地块东南部陆缘活带达三者鼎足而立的古地理展布格局。阐明这三类不同植物群的古植物地理区的属性,不仅藉以证明上三地块间各自陆缘活动带的存在及其相互关系,且将为解决延边地区争论至今的二     

Different spatial structures between network regions and active regions indicated by TRACE 171 Å observation

By comparing TRACE 171 Å observations with photospheric magnetograms, we find that the root of TRACE 171 Å emission is centered in magnetic elements in simultaneous Huairou photospheric magnetogram and the luminosity of TRACE 171 Å emission is not always in proportion to the strength of the corresponding photospheric magnetic field. While TRACE emission from an active region shows an obvious upward extension as a whole, fibril-like emissions from network elements show little extension along the structure from the root of each emission to 40′′ higher up in the solar atmosphere. Together with previous studies by Zhang and Zhang (1999, 2000), it is suggested that the magnetic fields in active regions and quiet-Sun regions present different spatial structures from the solar photosphere to the chromosphere and maybe even in the corona.     

Evaluation of vertical crustal movements and sea level changes around Greenland from GPS and tide gauge observations

To better monitor the vertical crustal movements and sea level changes around Greenland, multiple data sources were used in this paper, including global positioning system(GPS), tide gauge, satellite gravimetry, satellite altimetry, glacial isostatic adjustment(GIA). First, the observations of more than 50 GPS stations from the international GNSS service(IGS) and Greenland network(GNET) in 2007–2018 were processed and the common mode error(CME) was eliminated with using the principal component analysis(PCA). The results show that all GPS stations show an uplift trend and the stations in southern Greenland have a higher vertical speed. Second, by deducting the influence of GIA, the impact of current Gr IS mass changes on GPS stations was analysed, and the GIA-corrected vertical velocity of the GPS is in good agreement with the vertical velocity obtained by gravity recovery and climate experiment(GRACE). Third, the absolute sea level change around Greenland at 4 gauge stations was obtained by combining relative sea level derived from tide gauge observations and crustal uplift rates derived from GPS observations, and was validated by sea level products of satellite altimetry. The results show that although the mass loss of Gr IS can cause considerable global sea level rise, eustatic movements along the coasts of Greenland are quite complex under different mechanisms of sea level changes.     

Quantitative analysis of Arctic ice flow acceleration with increasing temperature

This study explores the ice flow acceleration(21.1%) of Pedersenbreen during 2016–2017 after the extremely warm winter throughout the whole Arctic in 2015/2016 using in situ data and quantitatively analyses the factors contributing to this acceleration. Several data sets, including 2008–2018 air temperature data from Ny-?lesund,ten-year in situ GPS measurements and Elmer/Ice ice flow modelling under different ice temperature scenarios,suggest that the following factors contributed to the ice flow acceleration: the softened glacier ice caused by an increase in the air temperature(1.5℃) contributed 2.7%–30.5%, while basal lubrication contributed 69.5%–97.3%.The enhanced basal sliding was mostly due to the increased surface meltwater penetrating to the bedrock under the rising air temperature conditions; consequently, the glacier ice flow acceleration was caused mainly by an increase in subglacial water. For Pedersenbreen, there was an approximately one-year time lag between the change in air temperature and the change in glacier ice flow velocity.     

Petrogenesis and shock metamorphism of the enriched lherzolitic shergottite Northwest Africa 7755

Northwest Africa (NWA) 7755 is a newly found enriched lherzolitic shergottite. Here, we report its detailed petrography and mineralogy. NWA 7755 contains both poikilitic and non‐poikilitic lithologies. Olivine has different compositional ranges in the poikilitic and non‐poikilitic lithologies, Fa_30–39 and Fa_37–40, respectively. Pyroxene in the non‐poikilitic lithology is systematically Fe‐richer than that in the poikilitic lithology. The chromite grains in non‐poikilitic lithology are highly Ti‐richer than those in the poikilitic lithology. The chemical variations of olivine, pyroxene, and chromite between the poikilitic and non‐poikilitic lithologies support a two‐stage formation model of lherzolitic shergottites. Besides planar fractures and strong mosaicism in olivine and pyroxene, shock‐induced melt veins and pockets are observed in NWA 7755. Olivine grains within and adjacent to melt veins and/or pockets have either transformed to ringwoodite, amorphous phase, or dissociated to bridgmanite plus magnesiowüstite. Merrillite in melt veins has completely transformed to tuite; however, apatite only has partially transformed to tuite, indicating a relatively sluggish transformation rate. The partial transformation from apatite to tuite resulted in fractional devolatilization of Cl and F in apatite. The fine‐grained mineral assemblage in melt veins consists mainly of bridgmanite, minor magnesiowüstite, Fe‐sulfide, Fe‐phosphide, and Ca‐phosphate minerals. The coexistence of bridgmanite and magnesiowüstite in these veins indicates a shock pressure of >~24 GPa and a temperature of 1800–2000 °C. Coesite and seifertite are probably present in NWA 7755. The presence of these high‐pressure minerals indicates that NWA 7755 has experienced a more intense shock metamorphism than other enriched lherzolitic shergottites.     

Potential source and diagenetic signatures of oceanic dissolved and particulate organic matter as distinguished by lipid biomarker distributions

Potential biogenic sources of ultrafiltered dissolved and suspended particulate organic matter (UDOM and POM, respectively) from the Sargasso Sea (SS) and North Central Pacific (NCP) Ocean were investigated using lipid biomarker compounds. Organic carbon (OC) concentrations were ~ 20–40 times greater in UDOM than POM and decreased with depth. However, total OC-normalized lipid concentrations were 2–3 orders of magnitude higher in POM than in UDOM. Particulate total lipids decreased 3–10-fold with depth, compared to 10–20% for dissolved total lipids. Total fatty acids (FA), the most abundant lipids, showed similar patterns as total lipids, comprising ~ 62–88% of the total lipids analyzed in UDOM and ~ 57–84% in POM.FA were dominated by straight-chain saturated compounds followed by monounsaturated, polyunsaturated, and branched FA. Polyunsaturated FA were enriched in POM vs. UDOM and in surface vs. deep waters for both UDOM and POM, likely reflecting the algal origins and greater reactivity of surface-derived materials. In both UDOM and POM, sterols of planktonic origin dominated, including cholest-5-en-3β-ol (C₂₇Δ⁵), 24-methylcholesta-5,24(28)E-dien-3β-ol (C₂₈Δ^5,24(28)) and 24-ethylcholest-5-3β-ol (C₂₉Δ⁵), with varying contributions from cholesta-5,22E-3β-ol (C₂₇Δ^5,22), 24-methylcholesta-5,22E-3β-ol (C₂₈Δ^5,22) and 24-ethylcholesta-5,22E-3β-ol (C₂₉Δ^5,22).Factor analysis of lipid biomarkers showed major differences between the UDOM and POM pools and for each pool as a function of depth, but not between the SS and NCP. While UDOM and POM biomarkers were both dominated by autochthonous sources, differences between the two pools suggest potential effects from some combination of source and diagenetic factors. The lipid biomarker data are further evaluated relative to previous studies of radiocarbon (¹⁴C) and elemental (C:N:P) characteristics of UDOM and POM in the SS and NCP.     

NCC_CGCM产品对长江中下游夏季降水预报的释用

通过对1983-2002年国家气候中心NCC_CGCM季节预报模式的2月初始场的5个预测场(500 hPa高度场,200 hPa经向风、纬向风场,850 hPa经向风、纬向风场)与NCEP实况场的相关检验,指出模式预测与实况有一定差距,但也存在预报效果好的区域,其中预报效果最好的是200 hPa和850 hPa纬向风场,正相关达到95%信度的点数最多;500 hPa高度场正相关达到95%信度的点数最少;利用模式预报效果好的区域的预测值,对2003-2007年长江中下游区域夏季降水指数进行释用,预报准确率达到80%;对比模式在该地区的降水预报以及仅用模式高度场的解释预报发现,用挑选有用信息后的预报效果更好.该方法在全国其他14个区夏季降水的释用中,江南区和内蒙古区预报准确率也可达到80%.