青藏高原局地因素对近地表层地温的影响

青藏高原近地表层地温既受区域性因素（高度、经度、纬度）控制，同时又受局地因素的影响。观测结果表明，高原稀疏植被地段比裸地地温高，短时期薄层雪盖起降低地温的作用，南坡比北坡地温高2－7℃，黑色沥青路面年平均温度比碎石土天然的年平均地表温度高4．5℃，亦高于其它材料的路面地温。     

A possible cause of the AO polarity reversal from winter to summer in 2010 and its relation to hemispheric extreme summer weather

In 2010, the Northern Hemisphere, in particular Russia and Japan, experienced an abnormally hot summer characterized by record-breaking warm temperatures and associated with a strongly positive Arctic Oscillation (AO), that is, low pressure in the Arctic and high pressure in the midlatitudes. In contrast, the AO index the previous winter and spring (2009/2010) was record-breaking negative. The AO polarity reversal that began in summer 2010 can explain the abnormally hot summer. The winter sea surface temperatures (SST) in the North Atlantic Ocean showed a tripolar anomaly pattern—warm SST anomalies over the tropics and high latitudes and cold SST anomalies over the midlatitudes—under the influence of the negative AO. The warm SST anomalies continued into summer 2010 because of the large oceanic heat capacity. A model simulation strongly suggested that the AO-related summertime North Atlantic oceanic warm temperature anomalies remotely caused blocking highs to form over Europe, which amplified the positive summertime AO. Thus, a possible cause of the AO polarity reversal might be the “memory” of the negative winter AO in the North Atlantic Ocean, suggesting an interseasonal linkage of the AO in which the oceanic memory of a wintertime negative AO induces a positive AO in the following summer. Understanding of this interseasonal linkage may aid in the long-term prediction of such abnormal summer events.     

TRMM/PR资料在中尺度模式MM5中的应用

将中尺度非静力模式MM5中的积云参数化Grell方案作了改进，使它含有降水云的云水，即雨水含量，并用该模式对1998年6月29日08时-30日08时(北京时)和1998年7月1日08时-2日08时(北京时)发生在淮河流域的两次特大暴雨进行数值模拟研究，同时通过采用R-qr关系将TRMM／PR(Tropical Rainfall Measuring Mission/Precipitation Radar)得到的降水强度资料月计算出比含水量qr，然后用qv′＝qv qr取代原模式中的比湿qv。结果表明将TRMM／PR资料加入模式后，由于PR雷达具有较高的空间分辨率，能够很好地反映中小尺度系统的空间结构，能够使湿度值接近实际，缩短了中尺度系统的发展时间，使得模拟出来的降雨强度、雨量中心位置以及雨带形状更接近实况。     

El Niño Modoki connection to extremely-low streamflow of the Paranaíba River in Brazil

Extremely-low discharge events of the Paranaíba River basin during the austral summer season (December–February, DJF), are found to be associated with the Pacific sea surface temperature anomalies resembling the recently identified El Niño Modoki phenomenon. Extreme discharge events are identified based on their persistent flow for 7 days and more after taking retention time into consideration. Ninety percent of the extremely low discharge events during peak streamflow seasons of DJF, are found to occur during the El Niño Modoki years. A diagnostics study of atmospheric anomalies has shown a clear connection between the modified Walker circulation, associated with the El Niño Modoki, and the precipitation anomalies over the Paranaíba River basin. The climate variations have direct relationship with the rainfall. Streamflow variations are considered as the surrogates to rainfalls. Thus, El Niño Modoki phase is important component to understand and predict the streamflow variations in the Paranaíba River basin.     

Oblique and near collision subduction, Sagami and Suruga Troughs —preliminary results of the French-Japanese 1984 Kaiko cruise, Leg 2

Leg 2 of the French-Japanese 1984 Kaiko cruise has surveyed the Suruga and the Sagami Troughs, which lie on both sides of the northwestward moving and colliding Izu-Bonin Ridge, the northernmost part of the Philippine Sea plate. The transition from the Nankai Trough to the Suruga Trough is characterized by northward decrease in width of the accretionary prism, in good agreement with the increasing obliquity between the through axis and the direction of the convergence, as the strike of the convergent boundary changes from ENE-NNE to south-north. South of the area, the southern margin of the Zenisu Ridge shows contractional deformations. This supports the interpretation made by the team of Leg 1 who studied the western extension of the area we studied, that it is an intra-oceanic thrusting of the ridge over the Shikoku Basin. In the Sagami Trough, where the relative motion is highly oblique to the plate boundary, active subduction is mostly confined in the east-west trending portions of the trough located south of the Boso Peninsula and along the lower Boso Canyon, near the TTT triple junction. In between, the present motion is mainly right-lateral along the northwest trending Boso escarpment. However, an inactive but recent (Pliocene to lower Pleistocene) accretionary prism exists south of the Boso escarpment, which suggests that the relative motion was more northerly than at present before about 1 Ma ago.     

Role of precursory less-viscous mixed magma in the eruption of phenocryst-rich magma: evidence from the Hokkaido-Komagatake 1929 eruption

During the 1929 activity of Hokkaido-Komagatake volcano, the Plinian eruption of a phenocryst-rich andesite was preceded by a small eruption of more mafic magma formed by magma mixing. A similar eruption sequence has been reported for some other eruptions (Pallister et al. 1996; Venezky and Rutherford 1997), suggesting that eruption of a mixed magma is a precursor of phenocryst-rich magmas. For the purpose of understanding the tapping processes of the phenocryst-rich magma chamber, we investigated the temporal variation in the erupted magma and estimated the viscosity and density of the end-member and mixed magmas with constraints drawn from petrography. For the precursory mixed magma we estimate 33dž vol.% phenocrysts, andesitic-dacitic melt composition, 3 wt.% H₂O content, and temperature of 1040°C. In comparison, for the climactic, silicic end-member magma we estimate 48Dž vol.% phenocryst, high-silica rhyolitic melt, 3 wt.% H₂O, and temperature of 950°C, respectively. The mafic end-member magma, which was not erupted, is thought to be an almost aphyric basaltic-andesitic magma, based on mass balance calculation of the phenocryst content. The proportion of the mafic end-member magma component in the mixed magma was calculated to be 20-40 wt.%. On the basis of these data, we estimate magma viscosities of 10^3.9, 10^6.9, and 10^2.0 Pa s for the mixed, silicic end-member, and mafic end-member magmas, respectively. The calculated density differences among these magmas are inconsequential when possible errors are considered. We calculate the minimum excess pressure required for dike propagation to be 31 MPa for the silicic end-member magma and 8 MPa for the mixed magma, using the estimated viscosity and dike propagation model of Rubin (1995). If we assume that excess pressure is limited by the wall rock strength of the magma chamber, excess pressure retainable in the magma chamber is less than ca. 20 MPa. This suggests that the mixed magma was able to ascend to the surface without freezing, whereas the viscous silicic end-member magma could not. The formation and precursory eruption of the mixed magma are, therefore, effective and necessary initiation processes for the phenocryst-rich, viscous magma eruption.     

Effect of grain growth on cation exchange between dunite and fluid: implications for chemical homogenization in the upper mantle

The effect of grain growth on the cation exchange between synthesized forsterite aggregates (i.e., dunite) and nickel-rich aqueous fluid was evaluated experimentally at 1.2 GPa and 1,200°C. The grain boundary (GB) migration caused nickel enrichment in the area swept by the GBs in a fashion similar to that reported for stable isotope exchange in the quartz aggregates. The progress of the grain growth resulted in an increase in the average nickel concentration in the dunites of up to ~80 times that was calculated for a system having stationary GBs. The overall diffusivity of the nickel along the wet GBs and interconnected fluid networks was found to be 6.5 × 10⁻¹⁹–6.7 × 10⁻¹⁸ m³/s, which is 4–5 orders of magnitude higher than the grain boundary diffusivity in the dry dunite. These results show that the grain growth rate is a fundamental factor in the evaluation of the time scale of chemical homogenization in the upper mantle.     

Identification of stable remanence carriers through a magneto-impedance scanning magnetic microscope

To identify the stable remanence carrier in rock samples, we conducted magnetic microscopic observations combined with conventional stepwise demagnetization experiments. The instrument, which employs an amorphous wire-based magneto-impedance sensor (30 μm diameter, 5 mm length), can document magnetic anomalies (vertical component) of the millimeter to sub-millimeter-thick rock samples with a resolution of 500 μm. Our new technique allows identification of the sources of both stable and unstable remanence components in meteorite and shocked granite samples. However, stray magnetic fields from the sensor magnetize the magnetic minerals in the sample and makes serious artifacts on the magnetic images. Although the artifacts of the induced magnetization should be solved, this new corroborative technique leads to a microscopic discrimination of stable paleomagnetic records from terrestrial and extraterrestrial materials.     

Stiffness‐damping simultaneous identification using limited earthquake records

A new method of stiffness‐damping simultaneous identification of building structures is proposed using limited earthquake records. It is shown that when horizontal accelerations are recorded at the floors just above and below a specific storey in a shear building model, the storey stiffness and the damping ratio can be identified uniquely. The viscous damping coefficient and the linear hysteretic damping ratio can also be identified simultaneously in a numerical model structure. The accuracy of the present identification method is investigated through the actual limited earthquake records in a base‐isolated building. It is further shown that an advanced identification technique for mechanical properties of a Maxwell‐type model can be developed by combining the present method with a perturbation technique. Copyright © 2000 John Wiley & Sons, Ltd.     

Determination of Fluorine and Chlorine by Pyrohydrolysis and Ion Chromatography: Comparison with Alkaline Fusion Digestion and Ion Chromatography

A method to determine F and Cl in silicate materials by employing pyrohydrolysis and ion chromatography (IC) is described. Pyrohydrolysis involved mixing a pulverised sample (∼ 40 mg) with V₂O₅ (∼ 160 mg) and heating to 1100 °C under a wet oxygen flow in a quartz tube. Recovery yields of F and Cl were ∼ 97% using a NaF + NaCl standard solution. Detection limits of the pyrohydrolysis-IC method for silicate samples were 0.36 and 0.69 μg g^-1 for F and Cl, respectively. Fluorine and Cl concentrations were determined in the reference materials JB-2, JB-3 and JA-1 from the GSJ; BCR-2, BHVO-1, BHVO-2, AGV-1 and AGV-2 from the USGS; and NIST SRM 610, 612 and 614 glasses. Precisions (RSD) for determinations of F were 1–13% (except NIST SRM 614) and 2–19% for Cl, and were dependent on the concentration and blank correction. Most results obtained in this study were in good agreement with those of previous studies. In comparison, the Na₂CO₃ + ZnO fusion method at 900 °C showed that the yields of F and Cl by alkaline fusion systematically decreased with fusion duration time. The yields were 84% and 83% for JB-3, inferring that F and Cl were lost in this alkaline fusion.