中国极地考察40年进展与展望

极地考察在提升极地认知、保护极地生态环境、合理利用极地资源、促进极地产业发展等各方面发挥着重要作用。从1984年我国首次南极考察和南大洋调查以来,我国极地考察从无到有、由弱变强,取得了突破性进展,1999年,实施了中国首次北极科学考察,实现了两极考察发展战略,正从极地科考大国向科考强国迈进:建成“两船七站”的极地科考支撑平台,构建了“天-空-地-海”极地立体观测网,研发了极地深冰芯钻具等多套极端环境采样装备,组织实施了“‘九五’国家攻关南极计划”“南北极环境综合调查与评估”等极地专项,在极地冰盖不稳定性、南大洋和北冰洋生物地球化学循环及其对全球变化的响应与反馈作用等多个领域取得有国际影响力的研究成果,成功实施了“南极普里兹湾—埃默里冰架—冰穹A的综合断面科学考察与研究”(PANDA)等国际合作计划,为我国极地事业发展做出了重大贡献。未来应进一步完善极地船站科考平台,增强南大洋和北冰洋长期观监测能力,牵头重大国际合作项目,推进我国极地考察站的国际化应用,为“认识极地、保护极地、利用极地”作出更大贡献。

Monitoring Efficiency Evaluation of the Well-water-level Observation Network in China

In order to understand the monitoring efficiency status of the well-water-level observation network in China after the completion of the 10 th "Five-year Plan " digital network project,and to provide a basis for the future network optimization and equipment updating, the monitoring efficiency of the well-water-level observation network was evaluated. On the whole,61. 8% observing stations have good monitoring effectiveness,the observation environment of 73. 5% of observing stations meets the monitoring requirements of well-water-level. The operation status of the network is as a whole getting better,operation rates of 75% observing instruments are above 95%. Most well water levels can monitor crustal stress changes and seismic activities. However,some observation stations,due to inherent deficiency in wells,environmental disturbance,instrument aging,and low-level operation and maintenance,need to improve the monitoring efficiency level by taking measures such as observation environment improvement,equipment updating,and management training. About 6. 5% of the stations need to stop observation due to the unqualified observational environment.

The Jinsha River Groundwater Observation Network and Discussion about Its Earthquake Precursor Monitoring Capability

A groundwater observational network for monitoring seismic precursors has been established at the reservoirs on the lower reaches of the Jinsha River in southwestern China, where a series of hydropower stations are under construction. It is the second network in China that is operated by enterprises with the purpose to observe and study earthquake precursors in reservoir areas. This paper presents the layout and technical constitution of the network, features of its observational wells and aquifers and the preliminary result of its experimental operation. Its capability to monitor seismic precursor is evaluated based on an analysis of the well-aquifer system as well as the multiple-monthly, monthly, daily and hourly variations of water levels and water temperatures observed by this network.

Numerical Simulation of the Response Features of Apparent Seismic Wave Velocity Ratio in a Horizontal Layered Medium

This paper deals with the response features of AR(apparent ratio of seismic wave velocities to the changes of TR(true ratio of wave velocities)in the horizontal layered model by mathematical modeling.The results show that:(1)the response features of AR are associated with the parameters of the structure and its dynamic changes,and the relative position between the hypocenters and the monitoring networks,showing complicated patterns strongly related to the concrete paths of propagation of seismic waves from the source to the receiver in the observatories of the network;(2)the depth of the seismic source would have important influence on the response features of AR,especially the capacity to carry the anomalous information in the condition of the earth media,being in the anomalous state would be greater for those earthquakes which occur inside the anomalous layers than those underneath the anomalous layers;(3)the response features of AR are clearly related to the changes of TR(true ratio of wave velocities)instead of changes of wave velocities themselves,i.e.the response could be small as the changes in TR is small even in the case of large changes in the wave velocities.It is suggested that more attention must be paid to all these features in combination with detailed investigation of the velocity structure of the earth media in the study region and best fitting of precise hypocenter locations when one wants to obtain the reliable precursors from the changes in AR.

Comparison of Aerosol Single Scattering Albedo Derived from the Ozone Monitoring Instrument with Aerosol Robotic Network Observations

The single-scattering albedo （SSA）, which quantifies radiative absorption capability, is an important optical property of aerosols. Ground-based methods have been extensively exploited to determine aerosol SSA but there were no satellite-based SSA measurements available until the advent of advanced remote sensing techniques, such as the Ozone Monitoring Instrument （OMI）. Although the overall accuracy of OMI SSA is estimated to approach 0.1, its regional availability is unclear. Four-year SSA daily measurements from three Aerosol Robotic Network （AERONET） sites in China （Xianghe, Taihu, and Hong Kong） are chosen to determine the accuracy of OMI SSA in specific locations. The results show that on a global scale, the OMI SSA is systematically higher （with a mean relative bias of 3.5% and a RMS difference of ~0.06） and has poor correlation with the AERONET observations. In the Xianghe, Taihu, and Hong Kong sites, the correlation coefficients are 0.16, 0.47, and 0.44, respectively, suggesting that the distinct qualities of OMI SSA depend on geographic locations and/or dominant aerosol environments. The two types of SSA data yield the best agreement in Taihu and the worst in Hong Kong; the differing behavior is likely caused by varying levels of cloud contamination. The good consistency of the aerosol variation between the two SSA datasets on a seasonal scale is promising. These findings suggest that the current-version OMI SSA product can be applied to qualitatively characterize climatological variations of aerosol properties despite its limited accuracy as an instantaneous measurement.