北白令海夏季冷水团的分布及其年际变化研究

利用1982-2008年间的高分辨率CTD数据,对夏季位于北白令海陆架底层的冷水团性质及其多年变化进行了研究.结果表明,依据该区域水体在温盐性质上的差异可以分为4类:陆架冷水团(BSW_C),白令海陆坡流水(BSCW),混合变性水(MW),陆架表层暖水(BSW_S).以-1℃,2℃和4℃温度等值线指示水团边界,清楚地将...     

Population dynamics of four dominant copepods in Prydz Bay, Antarctica, during austral summer from 1999 to 2006

Population dynamics of four dominant Antarctic copepods, Calanoides acutus, Calanus propinquus, Metridia gerlachei and Rhincalanus gigas were studied based on zooplankton samples collected in the Prydz Bay during austral summer from 1999 to 2006. We found that C. acutus was the most abundant species among these four copepods, followed by C. propinquus, M. gerlachei and R. gigas. R. gigas occurred mainly in the warmer oceanic regions and showed distribution patterns discrete from the other three species, whose distribution in the whole survey area overlapped. By December 15th (about one month before our sampling) of the years 1999, 2003 and 2006, sea ice retreated earlier and polynyas existed in the neritic region one month before sampling. These periods were characterized by numerical dominance of C. acutus, C. propinquus and M. gerlachei, elevated proportions of Copepodite I and Copepodite II stages especially in the neritic region. While for the years 2000, 2002, and 2005, the ice edge located more northerly and polynyas did not exist in the neritic region, the copepods abundance was lower, indicating poor recruitment. Population structure of R. gigas was mainly composed of advanced stages Copepodite V and female during all cruises. Log10 (x+1) transformed densities of C. acutus, C. propinquus and M. gerlachei showed positive correlation with temperature and chlorophyll a concentration, while mean population stages of these copopods were negatively correlated with these environmental variables. Younger copepodite stages of C. acutus, C. propinquus and M. gerlachei appeared more often in neritic regions. We confirmed that the polynyas had a great contribution to phytoplankton blooms, which promote copepods reproduction and recruitment success. The study suggested that population dynamics of the four copepods have good correspondence with sea ice and polynya variations during all cruises of the Prydz Bay.     

Variations in some physico-chemical parameters in a hypersaline coastal lagoon of Baja California,Mexico

San Jose lagoon is a hypersaline body of water located in Mexico in the Baja California Peninsula. The lagoon belongs to a system that lies between the fault ridge known as San Jose Creek. Because of its marine origin, it can be considered as thalassohaline, but its isolation from the ocean has brought about changes in its salt composition. It has an area of 13,500 m², a mean depth of 80 cm and a total volume of 10,000 m³. It does not desiccate and can be considered as a permanent lagoon. Seasonal variations are small. TheArtemia population in San Jose produces cysts all year. To determine the physico-chemical conditions inducing permanent production of cysts, temperature, salinity, dissolved oxygen, and pH of the lagoon were monitored, as well as relative humidity and wind conditions in the region in different seasons of the year. From spring to summer, differences of 1 mg L^–1 of O₂, 1°C in water temperature, and 8 g L^–1 in salinity were observed, and from summer to winter differences of 3.3 mg L^–1, 6.5°C, and 14 g L^–1, respectively. Despite small seasonal variations, the lagoon exhibits strong spatial and daily changes that are important for cyst production.     

上海市地面沉降动态分析与灰色预测

本文应用灰色系统理论的关联度分析法,分析了上海市地面沉降在时间、空间上的变化特征,进而以市区和近郊区典型地段的地面沉降监测资料为基础,建立了灰色预测模型,并在某些假定前提下预测了上海市地面最终沉降量及“沉降寿命”。     

Satellite data analysis of ozone differences in the Northern and Southern Hemispheres

Four years of SBUV ozone data and NOAA/NMC temperature data are analyzed for the relations between the annual total ozone behaviour in the Northern and Southern Hemispheres and the transport of ozone by planetary waves. It is found that the interhemispheric differences in the annual variation of total ozone are well explained by the interhemispheric differences in the planetary waves and the resulting ozone transports. The annual variation of the ozone transports by the stationary waves is found to control the ozone behavior in both hemispheres. Both the day-to-day and the interannual variation in total ozone are found to be strongly related to the corresponding variability of the planetary waves.Contribution Number 46 of the Stratospheric General Circulation with Chemistry Project at NASA/GSFC.     

Lunar magnetic variations

Displayed daygraphs of magnetic observatory hourly mean values and of lunar magnetic variations reconstructed from spherical harmonic coefficients are used to illustrate the difficulties that arise in separating lunar magnetic effects from those associated with the 27 day recurrence tendency in magnetic activity.     

Seasonal changes of microbial populations in the sediments of the basins of Lugano and Agno

This research was carried out with the aim to explore the heterotrophic microbial population of two sediments in different oxic conditions of the Lake of Lugano (Lago di Lugano). The values of the viable bacterial counts found in our sediment samples were typical for an eutrophic lake.The increase in the proportion of anaerobic to aerobic bacteria at 30 °C observed in the sediment samples of Agno may reflect the depletion of oxygen concentrations in the water column.The generaAeromonas, Pseudomonas, Bacillus andClostridium, as well as strains belonging to the Coryneform-group, represented the major taxonomic groups of heterotrophic bacterial communities in the water-sediment interface.     

近50年福建气温、降水变化的统计特征

近５０年福建气温呈下降趋势，全省年平均气温变化率为－０．０１１４℃。年＾－＾１，即大约１０年下降０．１１℃，气温下降趋势势沿海大于内陆，冬春季大于夏季，８０年代秋季则呈上升趋势。降水量丰水期方要在５０年代，枯水期在６０年代，８０年代以来春雨（２－４月）显著增多，雨季（５－６月）降水量显著减少。     

Geomagnetically induced currents in the Finnish high-voltage power system

We consider geomagnetically induced currents (GICs) in power systems from the viewpoint of a geophysicist. Special attention is paid to the Finnish high-voltage power system, in which exact theoretical model calculations together with recordings have been performed for several years. We present several examples of theoretically computed GICs using different geophysical models for estimating the geoelectric field driving GICs. Statistical prediction of GICs is outlined referring to studies made in Finland. We show that a combination of GIC recordings at few sites with theoretical modelling of ionospheric currents and the earth's conductivity, and data of geomagnetic activity makes it possible to derive GIC statistics of the entire power system. Finally, we discuss requirements for a long-range prediction of GICs, which will obviously be a widely-studied topic in future.