The effect of magnetic substorms on near-ground atmospheric current

Ionosphere-magnetosphere disturbances at high latitudes, e.g. magnetic substorms, are accompanied by energetic particle precipitation and strong variations of the ionospheric electric fields and currents. These might reasonably be expected to modify the local atmospheric electric circuit. We have analysed air-earth vertical currents (AECs) measured by a long wire antenna at Esrange, northern Sweden during 35 geomagnetic substorms. Using superposed epoch analysis we compare the air-earth current variations during the 3 h before and after the time of the magnetic X-component minimum with those for corresponding local times on 35 days without substorms. After elimination of the average daily variation we can conclude that the effect of substorms on AEC is small but distinguishable. It is speculated that the AEC increases observed during about 2 h prior to the geomagnetic X-component minimum, are due to enhancement of the ionospheric electric field. During the subsequent 2 h of the substorm recovery phase, the difference between substorm and quiet atmospheric currents decreases. The amplitude of this substorm variation of AEC is estimated to be less than 50% of the amplitude of the diurnal variation in AEC during the same time interval. The statistical significance of this result was confirmed using the Van der Waerden X-test. This method was further used to show that the average air-earth current and its fluctuations increase during late expansion and early recovery phases of substorms.     

Hydrodynamical Modeling Of Oceanic Vortices

Mesoscale coherent vortices are numerous in the ocean.Though they possess various structures in temperature and salinity,they are all long-lived, fairly intense and mostly circular. Thephysical variable which best describes the rotation and the density anomaly associated with coherent vortices is potential vorticity. It is diagnostically related to velocity and pressure, when the vortex is stationary. Stationary vortices can be monopolar (circular or elliptical) or multipolar; their stability analysis shows thattransitions between the various stationary shapes are possible when they become unstable. But stable vortices can also undergo unsteady evolutions when perturbed by environmental effects, likelarge-scale shear or strain fields, -effect or topography. Changes in vortex shapes can also result from vortex interactions. such as the pairing, merger or vertical alignment of two vortices, which depend on their relative polarities and depths. Such interactions transfer energy and enstrophy between scales, and are essential in two-dimensional and in geostrophic turbulence. Finally, in relation with the observations, we describe a few mechanisms of vortex generation.     

High-Resolution Seismic Reflection Evidence for Middle Holocene Environmental Change, Owasco Lake, New York

Approximately 70 km of new decimeter-resolution seismic reflection profile data from Owasco Lake, New York define a middle Holocene (4600 ¹⁴C yr B.P.) erosion surface in the north end of the lake at water depths as great as 26 m. Beneath the lake, post-glacial sediments are up to 9 m thick and represent about 10% of the total sediment fill. Early to middle Holocene sediments, 6 m thick, contain biogenic gas at the south end of the basin and a large (4 km×300 m×15 m) subaqueous slide deposit along the east-central portion of the lake. Late Holocene sediments are thinner or absent, particularly at the north end of the lake. The middle Holocene erosion surface may have been produced by a drop in lake level. Alternatively, it may represent a change in climate during the transition between the relatively warm Holocene hypsithermal and cool neoglacial. At this time (4600 ¹⁴C yr B.P.) circulation in Owasco Lake appears to have evolved from sluggish to active. The increased circulation, which persists today, probably resulted from atmospheric cold fronts with strong southwesterly winds that piled up water at the north end of the lake. The increased water circulation may have been ultimately driven by decreasing insolation, which produced an increased pole-to-equator thermal gradient and, thus, stronger global winds that began at the transition between the hypsithermal and neoglacial.     

Influence of Temporal Variations in River Discharge, pH, Alkalinity and Ca on the Speciation and Concentration of Heavy Metals in Some Mining Polluted Rivers

Dissolved (dialysis in situ) and total concentrations ofCu, Zn, Cd and Al in eight mining polluted rivers in the Røros area, central Norway, were determinedby atomic absorption spectrometry (flame and graphite furnace) and compared to pH, Caconcentration and alkalinity through seasonal variations in river discharge. Totalconcentrations of the metals were highest during early spring flood and during summer andautumn rain episodes. Dissolved concentrations also increased as the spring floodproceeded, but small discharge peaks within this 2 month period as well as a considerableautumn flood episode appeared to lower rather than to raise the dissolved metal concentrations.Consequently the dissolved fractions of Zn, Cd and Al showed a significant negative correlationwith river discharge, and were low at the discharge peaks. Possibly high sediment concentrationsoccurring at high flood conditions more than counteracted desorption induced by pHdecrease, and led to decreased dissolved fractions through adsorption. Cu speciationon the other hand seemed to be more closely linked to pH. Alkalinity and Ca concentration,both assumed to protect aquatic life from metal pollution, were significantly lowerduring episodes with high Cu and Al total concentrations.     

山东五莲七宝山金铜矿控矿因素及找矿方向

五莲七宝山金铜矿床赋存于隐爆角砾岩筒中 ,与次火山岩关系密切。火山机构受NE ,NW向断裂联合控制。根据隐爆角砾岩筒的地质标志 ,结合对物、化、遥等资料的综合分析认为七宝山地区还有较好的找矿前景     

包气带土体生物地球化学特征与氮转化研究—以河北平原正定试验场剖面为例

为研究氮素的生物地球化学循环问题,通过对河北平原典型试验场贯穿包气带18．5m钻孔剖面土样的物理性质,地球化学指标,有机质含量的测试和微生物的培养鉴定,发现土体的氮素,可溶盐含量（TDS）,Cl^-含量以及微生物细菌的变化随深度不呈简单的线性分布。经分析认为,剖面中的粘性土层是生物的活性层,在氮素转化过程中起主导作用;剖面中多种指标的变化与地质结构呈良好 对应关系,反映环境演化的过程,同时表明,包气带存在着更多尚待提取的全球变化对比研究信息。     

大气传播延迟改正在GAMIT软件中的应用

卫星信号从GPS卫星发射到地面的过程中经过了以充满大气为介质的空间,电磁波在这种变化的介质中传播,其传播的方向、速度、强度都可能随时改变,本文简略地介绍了大气传播延迟的产生及其对GPS测量的影响,并就GAMIT软件对大气传播延迟的控制方法和所采用的改正模型做一简单介绍,并对减弱和消除大气传播延迟的方法和手段进行了讨论。     

大气环流的季节突变与季风的建立II·个别年份南海夏季风的情况

将流的标准化变差度概念应用到各年南海夏季风建立研究中去,并用其作为大气环流调整的客观定量指标。用该指标定义的南海夏季风建立的预兆日期与用传统天气气候学方法确定的南海夏季风的来临日期,在绝大多数具体年份两者均很接近,故可作南海夏季风建立的先兆指标。但有一些年份,南海季风的建立不伴随着低空环流的突变过程,两种方法都可能不准确,可靠的方法也许是用场相似度作指标。此外,南海夏季风建立前,对流层顶和平流层下层就出现了环流调整,该调整为南海夏季风建立打下基础,而南海夏季风爆发则表现为低空环流的大调整。南海夏季风的爆发是高、低空全球大气环流发生显著调整的结果,并非限于南海范围局部,南海夏季风建立不能看作是发生在南海的局部现象。     

On the nonlinear dynamics of the boundary layer of intense atmospheric vortex

The paper describes a stationary model of the boundary layer of a large-scale vortex. The model takes into account two types of nonlinearities: (1) advection of the momentum and centrifugal accelerations, that is related to large values of the Rossby number; (2) a nonlinear turbulent friction on the lower boundary (generally speaking, not only quadratic, but also more complicated). Nevertheless, the model may be studied analytically. This approach allows discovery and analysis of several universal regularities, which are not revealed by numerical modeling. The model provides the actual values for the speed of the surface wind and the angle of cross-isobar surface flow in the tropical cyclones.     

ANALYSIS ON WAVELET POWER SPECTRUM OF WARM AND COLD EVENTS IN THE NI?O REGIONS

We statistically analyze the tropical typhoon forming in the South China Sea and use TC (Tropical Cyclone) for short in the following) by typhoon yearbook. The typhoon quantity is very different in different months and years. TC appears in all months except March, and the most TC quantity in a year is 11, the least is 1 and 6.2 on average. The most TC quantity in a month is 5 and the least is 0. TC lands most in August and no TC lands on Chinese continent from December to the following April. The primary landing area is between Shantou and Hainan Island. The sustaining period of TC is usually between 4 days to 7days, and the longest is 19 days. Only 15% of the TC forming in the South China Sea can intensify to typhoon, and they all form in the ocean area deeper than 150m. The South China Sea is the ocean area over which the TC occurs frequently.