Evaluation of Simulated CO_2 Concentrations from the CarbonTracker-Asia Model Using In-situ Observations over East Asia for 2009–2013

The CarbonTracker(CT) model has been used in previous studies for understanding and predicting the sources, sinks, and dynamics that govern the distribution of atmospheric CO_2 at varying ranges of spatial and temporal scales. However, there are still challenges for reproducing accurate model-simulated CO_2 concentrations close to the surface, typically associated with high spatial heterogeneity and land cover. In the present study, we evaluated the performance of nested-grid CT model simulations of CO_2 based on the CT2016 version through comparison with in-situ observations over East Asia covering the period 2009–13. We selected sites located in coastal, remote, inland, and mountain areas. The results are presented at diurnal and seasonal time periods. At target stations, model agreement with in-situ observations was varied in capturing the diurnal cycle. Overall, biases were less than 6.3 ppm on an all-hourly mean basis, and this was further reduced to a maximum of 4.6 ppm when considering only the daytime. For instance, at Anmyeondo, a small bias was obtained in winter, on the order of 0.2 ppm. The model revealed a diurnal amplitude of CO_2 that was nearly flat in winter at Gosan and Anmyeondo stations, while slightly overestimated in the summertime. The model's performance in reproducing the diurnal cycle remains a challenge and requires improvement. The model showed better agreement with the observations in capturing the seasonal variations of CO_2 during daytime at most sites, with a correlation coefficient ranging from 0.70 to 0.99. Also, model biases were within-0.3 and 1.3 ppm, except for inland stations(7.7 ppm).     

Mineralogic and Oxygen Isotopic Studies of Open System Magmatie Processes in the South Kawishiwi Intrusion, Spruce Road Area, Duluth Complex, Minnesota

The South Kawishiwi intrusion, located along the western marginof the Duluth Complex, Minnesota, is one of several compositeintrusions that are found in the Complex. The Duluth Complexis the principal exposed plutonic portion of the 1.1 Ga MidcontineniRift system. In the Spruce Road area the South Kawishiwi intrusionis divided into seven distinct units that are part of the broaderSouth Kawishiwi Troctolite Series defined by Severson (Tech.Rep. NRRI/TR-91/13a, Natural Resources Research Institute, Universityof Minnesota, Duluth, 1994). Units may be characterized as follows:Unit I—basal accumulation of heterogeneous gabbro, troctolite,and norite; Unit II—norite with abundant inverted pigeonite;Unit III—troctolite and olivine gabbro with local oxide-richlayers; Unit IV—mlatroctolite, troctolite, olivine gabbro;Unit VI—increased plagioclase abundance in troctolitesand leucocratic troctolites; Unit VI—strongly alteredtroctolite; Unit VII—similar to Unit V, troctolite andleucocratic troctolite. Country rocks in the Spruce Road areaare granodiorite to quartz monzonite of the Archean Giants RangeBatholith. Sutfide mineralization, consisting of 1–5 vol.% of disseminated pyrrhotitt, cubanite, chalcopyrite and pentlandite,occurs in Units I, II, III, and VI. Oxygen isotopic analysesindicate that Unit II has experienced extensive crustal contamination.¹⁸O values of Unit II range from 6.9 to 7.1% and are ¹⁸O enrichedcompared with values of 5.1–6.8% found in other units.Silica contamination is indicated based not only on ¹⁸O values,but also by the predominance of orthopyroxene in the unit. Possiblehigh-¹⁸O contaminant rocks include the Giants Range Batholithand pelitic rocks of the Lower Proterozoic Virginia Formationor Biwabik Iron Formation. Mass balance computations suggestthat units in the Spruce Road area may be related through varyingdegrees of fractionation of a high-Al, olivine tholeiite magma.Modeling of trace element concentrations and variations in mineralchemistry suggest that discontinuities within the major unitsdeveloped by in situ boundary-layer equilibrium crystallizationof solidification zones 20–50 m in thickness, followedby recharge of fresh magma. Upward enrichment of incompatibleelements, olivine Fa content, and plagioclase Ab content maybe effectively explained by this process. ¹⁸O values of uncontaminatedrock types are strongly correlative with modal mineralogy, andcan also be modeled by boundary-layer fractionation, A parentalmagma ¹⁸ O value of 6.3% is calculated for Unit VII based onolivine and plagioclase values, and is similar to that of severalother large, layered mafic intrusives. KEY WORDS: Duluth Complex; South Kawishiwi Intrusion; high-Al olivine tholeiite; open system crystallization; oxygen isotopes ^* Present address: Korea Basic Science Center, Isotope Research Group, Yeocun Dong 224–1, Yusung Ku, Yusung P.O. Box 41, Taejean 305–333, Korea     

Aqueous alteration in the matrix of the Vigarano (CV3) carbonaceous chondrite

Abstract The matrix of Vigarano, a meteorite which belongs to the reduced subgroup of the CV3 chondrites, contains small amounts (<10%) of ferrihydrite and smectite. These hydrous minerals occur together as fine fibrous intergrowths between anhydrous silicate and oxide grains. Coarser crystals of ferrihydrite fill fractures that cut matrix minerals, and smectite also lines narrow channels within olivine grains. These channels may have formed by preferential alteration of olivines along (100)-parallel defects. Formation of ferrihydrite and smectite in the matrix of Vigarano was the result of mild aqueous alteration in a low-temperature (<150 °C), oxidising parent body environment. Partial equilibration of matrix olivines indicates that alteration was followed by thermal metamorphism with a peak temperature of 400–500 °C. Mineralogically similar alteration products, which also were formed by parent body processes, have previously been described from the matrices of four CV meteorites: Bali, Grosnaja, Kaba and Mokoia, all of which belong to the oxidised subgroup. This discovery of the products of oxidative aqueous alteration in Vigarano has important consequences for understanding the chemical and thermal history of the CV class of meteorites.     

THE EFFECT OF SEEING ON SOLAR MAGNETIC FLUX MEASUREMENTS

We investigate the influence of seeing upon measurement of magnetic flux of photospheric fields. For this purpose we quantify seeing variation in one day's observation at Big Bear Solar Observatory in terms of the Fried function, a Modulation Transfer Function for the atmospheric seeing. The temporal variation of seeing quality is compared with that of magnetic flux measured in a quiet region with size 5 \times 4 near the solar disk center. A good correlation is found between the seeing change and apparent evolution of magnetic flux values, implying, as a possibility, that magnetic flux measurement might have been modulated by seeing. Based on a simple model of ensembles of Gaussian magnetic elements we argue that even the net flux as well as the total flux can change due to seeing variation if the magnetograph has a finite detection threshold and if the intrinsic fluxes in one and the other polarities are unbalanced.     

Geochemistry of peridotite xenoliths in alkali basalts from Jeju Island, Korea

Abstract   Ultramafic xenoliths in alkali basalts from Jeju Island, Korea, are mostly spinel lherzolites with subordinate amounts of spinel harzburgites and pyroxenites. The compositions of major oxides and compatible to moderately incompatible elements of the Jeju peridotite xenoliths suggest that they are residues after various extents of melting. The estimated degrees of partial melting from compositionally homogeneous and unfractionated mantle to form the residual xenoliths reach 30%. However, their complex patterns of chondrite-normalized rare earth element, from light rare earth element (LREE)-depleted through spoon-shaped to LREE-enriched, reflect an additional process. Metasomatism by a small amount of melt/fluid enriched in LREE followed the former melt removal, which resulted in the enrichment of the incompatible trace elements. Sr and Nd isotopic ratios of the Jeju xenoliths display a wide scatter from depleted mid-oceanic ridge basalt (MORB)-like to near bulk-earth estimates along the MORB–oceanic island basalt (OIB) mantle array. The varieties in modal proportions of minerals, (La/Yb)_N ratio and Sr-Nd isotopes for the xenoliths demonstrate that the lithospheric mantle beneath Jeju Island is heterogeneous. The heterogeneity is a probable result of its long-term growth and enrichment history.     

西天山两侧前陆盆地晚新生代沉积特征及构造意义

天山两侧前陆盆地晚新生代地层发育,沉积厚度较大。盆地沉积序列的韵律性反映了天山造山带的构造演化历史。晚新生代沉积特征及孢粉组合表明,中新世一上新世一早更新世碎屑岩不稳定组分明显增加,阔叶植物花粉含量减少、耐干地喜早的蒿、藜等显著增加,反映天山活动性增强,上新世晚期天山强烈隆升,天山两侧前陆盆地上新世晚期开始出现磨拉石建造,由于山体隆升造成的大气环流改变,天山两侧盆地封闭性增强,大陆性气候流改变,天     

1976年唐山大地震的孕震环境:密集地震台阵观测得到的结果

1976-07-28唐山地区发生了震惊中外的7.8级大地震。为什么在华北古老克拉通内部的唐山地区能够发生如此的大地震一直是一个令人费解的问题。是否会在唐山地区再次出现同样的破坏性地震值得认真研究。利用流动地震观测台阵数据和接收函数反演方法,我们研究了唐山地区60 km深度范围内的三维地壳上地幔速度结构。结果表明:(1)由活动断裂切割的唐山断块与周围介质存在明显差异,围限唐山断块的断裂均为超壳的活动断裂;(2)唐山大震区中上地壳具有明显的非均匀壳内低速体;(3)该地区壳幔界面表现为明显的断块式隆升,与两侧相比,唐山菱形地块下方的上地幔顶部异常隆起的高度达到10 km左右,下伏的上地幔具有异常的非均匀结构;(4)唐山大震区可能有幔源物质较大规模的侵入,形成了中、上地壳内的低速体。由于较已往的研究结果有更高的空间分辨率,我们得到了一些以往尚未发现的有关唐山地区深部结构的异常特征;(5)首都圈地区内破坏性地震发生的地点绝非偶然,它们均与其相应的深部构造背景密切有关,这为强震发生地点的预测提供了可能。根据本文结果,我们认为,1976年唐山大地震的主因源于上地幔的垂向运动变形及壳幔之间物质及能量的交换,区域水平向应力场为次要作用。这有助于解释为什么能够在我国华北古老克拉通地区发生7级以上强震,在唐山地区再次发生7级以上大地震的可能性值得给予进一步的研究和关注。     

贵州省遵义市降水中低分子有机酸对自由酸度的贡献

贵州省遵义市是我国酸雨高发地区,研究遵义降水中有机酸对自由酸度的贡献是认识遵义市有机酸地球化学循环和酸雨机制的重要内容。在遵义市中心城区进行了一年的降水采集,并利用离子色谱法和原子吸收光谱法对主要阴离子（包括无机和有机阴离子）和阳离子进行了测定。结果显示,年均pH值为4．11（范围3．12～6．04）,pH〈5．6的样品占93．1％,说明遵义市酸雨污染仍然严重;单因素方差分析显示四季的pH值存在显著差异（P〈0．05）,表明遵义市降水酸化程度具有显著的季节性特征;甲酸和乙酸的雨量加权平均值分别为9．29umol／L和6．47umol／L,检出率分别为98．68％和93．42％,表明有机酸在降水中广泛存在;应用热力学理论计算了有机酸对降水自由酸度的贡献量,发现在pH〈5的遵义降水中甲酸和乙酸对自由酸度的平均贡献量分别为14．79％和3．66％,表明有机酸对降水自由酸度具有重要贡献;对比显示,遵义市的有机酸贡献量低于边远地区,这与遵义市降水的低pH值和高无机酸度有关;四季的有机酸贡献量大小为：春季（31．95％）〉夏季（26．16％）〉冬季（11．17％）〉秋季（8．02％）,可见有机酸对自由酸度的贡献量存在明显的季节性变化。在低酸度和低水温的春季降水中,由于人类活动或有机物质的燃烧所释放的大量有机酸（如汽车尾气的排放、燃煤的燃烧）,促使有机酸对降水自由酸度的贡献量最高;其次是在低酸度和强降雨的夏季;而在低酸度的秋季和冬季,有机酸对酸度的贡献量相对最低。     

四川运动及其在中国之分布

中国中生代末期之造山运动发生于白垩纪之末或白垩纪与第三纪之间,并非如翁文灏氏所说燕山乙墓发生于上下白垩纪之间,此期运动我们称之为四川运动,其时期与北美之拉惹米运动相当。四川运动之强烈程度难各地互有差异,但分布则最广泛,遍及各省。四川运动在四川省表现最为强烈,在云南、西康、贵州、陕西南部,甘肃中部,宁夏、察哈尔、热河等省都县最重要的造山运勤,台湾省之始新统前造山运动尚不能定其确期,可能亦是这一幕,在其他各省,虽有时不是最重要的造山运动,但其影响则都曾见到。