Study and observation of the great solar event in July 2000 at cusp latitude

A series of solar flare and coronal mass ejection (CME) event occurred in July 2000, particularly the largest flare (X5.7/3B) with CME on 14th of July since 1989, which stimulated a great geomagnetic storm with Dst index reaching -300 nT. A number of data have been obtained from the Chinese Antarctic Zhongshan Station (ZHS, INT Lat. 74.5°, L≈14）, which is located at cusp latitude, and from the ACE satellite. After analyzing these data we have got the results as follows: a lot of solar high energy particles penetrated into the polar ionosphere and ionized it, which significantly increased the cosmic noise absorption (CNA) and blanked the DPS-4 data for more than two days. The magnetic pulsation in Pc 3/5 frequency band on the ground has a high relation with the fluctuation of interplanetary magnetic field (IMF) Bz, which shows the contribution of interplanetary magnetohydrodynamical (MHD) waves to the Pc 3/5 pulsation on the ground. The Pc 3/5 pulsation was intensified much during the great magnetic storm. The H component of the magnetic field at ZHS varied with the southern value of IMF Bz but lagged behind for about 8 10 h. While Dst index responded to the variation of the IMF Bz very quickly, which suggested that the magnetic storm occurred at low latitude firstly and then effected the ionospheric current at high latitude.     

An isopycnic-coordinate internal tide model and its application to the South China Sea

A three-dimensional isopycnic-coordinate ocean model for the study of internal tides is presented. In this model, the ocean interior is viewed as a stack of isopycnic layers, each characterized by a constant density. The isopycnic coordinate performs well at tracking the depth variance of the thermocline, and is suitable for simulation of internal tides. This model consists of external and internal modes, and barotropic and baroclinic motions are calculated in the two modes, respectively. The capability of simulating internal tides was verified by comparing model results with an analytical solution. The model was then applied to the simulation of internal tides in the South China Sea (SCS) with the forcing of M2 and K1 tidal constituents. The results show that internal tides in the SCS are mainly generated in the Luzon Strait. The generated M2 internal tides propagate away in three different directions (branches). The branch with the widest tidal beam propagates eastward into the Pacific Ocean, the most energetic branch propagates westward toward Dongsha Island, and the least energetic branch propagates southwestward into the basin of the SCS. The generated K1 internal tides propagate in two different directions (branches). One branch propagates eastward into the Pacific Ocean, and the other branch propagates southwestward into the SCS basin. The steepening process of internal tides due to shoaling effects is described briefly. Meridionally integrated westward energy fluxes into the SCS are comparable to the meridionally integrated eastward energy fluxes into the Pacific Ocean.     

Optimal estimation of zonal velocity and transport through Luzon Strait using variational data assimilation technique

A P-vector method was optimized using variational data assimilation technique, with which the vertical structures and seasonal variations of zonal velocities and transports were investigated. The results showed that westward and eastward flowes occur in the Luzon Strait in the same period in a year. How ever thenet volume transport is westward. In the upper level (0m -- -500m), the westward flow exits in the middle and south of the Luzon Strait, and the eastward flow exits in the north. There are two centers of westward flow and one center of eastward flow. In the middle of the Luzon Strait, westward and eastward flowes appear alternately in vertical direction. The westward flow strengthens in winter and weakens in summer. The net volume transport is strong in winter (5.53 Sv) but weak in summer (0.29 Sv). Except in summer, the volume transport in the upper level accounts for more than half of the total volume transport (0m -- bottom). In summer, the net volum etransport in the upper level is eastward (1.01 Sv), but westward underneath.     

Inter-hemispheric comparisons of geospace environment in the polar regions—A proposed cooperative research program between China and Norway

1　ＩｎｔｒｏｄｕｃｔｉｏｎＧｅｏｓｐａｃｅｄｅａｌｓｗｉｔｈｔｈｅＥａｒｔｈ’ｓｍｉｄｄｌｅａｎｄｕｐｐｅｒａｔｍｏｓｐｈｅｒｅ ,ｔｈｅｒｍｏｓｐｈｅｒｅ/ｉｏｎｏ ｓｐｈｅｒｅａｎｄｍａｇｎｅｔｏｓｐｈｅｒｅ .Ｔｈｉｓ“ｇｅｏｓｐａｃｅｅｎｖｉｒｏｎｍｅｎｔ”ｉｓｏｆｇｒｅａｔｓｃｉｅｎｔｉｆｉｃａｎｄｐｒａｃｔｉ ｃａｌｉｎｔｅｒｅｓｔ,ｐａｒｔｉｃｕｌａｒｌｙａｓｉｔｉｓｏｆｔｅｎｓｕｂｊｅｃｔｔｏｄｉｓｔｕｒｂａｎｃｅｓ.Ａｂｌａｓｔｗａｖｅｆｒｏｍｔｈｅｓｕｎｃａｎｃｏｍｐｒｅｓｓｔｈｅｍ…     

A continuously stratified nonlinear model for internal solitary waves in the northern South China Sea

A continuously stratified nonlinear model is set up to study the impact of topographical character on the generation of internal solitary waves over a sill by tidal flow. One of the reasons why almost all of the generated internal solitary waves propagate westward in the northern South China Sea is explained. The model simulations describe the generation and propagation of internal waves well. When the strength of imposed barotropic tides and the water stratification stay unchanged, the steepness of the sill slope can control both (a) whether or not the waves induced over a sill by tidal flow are linear internal waves or nonlinear internal solitary waves, and (b) the amplitude of the internal solitary waves generated. If the steepness of the sill is asymmetric, the nonlinear internal solitary waves may be induced on the steeper side of the sill. These conclusions are supported by a numerical experiment with a monthly-mean stratification and an actual seafloor topography from the Luzon Strait.     

Effects of a sloping thermocline and Rayleigh friction on equatorially trapped Kelvin waves

INTRODUCTIONEquatorialKelvinwavesareofspecialsignificanceinthedynamicsoftheequatorialocean ,duetotheirhighpropagationspeedandequatoriallytrappednature.NumericalandobservationalstudiesstronglysuggestedthatKelvinwavesplayamajorroleinElNi no SouthernOscillationandotheroceanphenomena.Themainthermoclinevariabilityinthetropicaloceanswasstudiedextensivelybyvariousre searchers (LongandChang ,1 990 ;YangandYu ,1 992 ) .Animportantfeatureoftheequatorialoceanthermalstructureistheeastwardshoaling…     

Characteristics of metals in the aerosols of Zhongshan Station, Antarctica

Instrumental neutron activation analysis (INAA) was applied to analyze the bulk, high-volume aerosol samples, collected at Zhongshan Station in the Eastern Antarctica, during 1998-2001, to study the chemical species. .A graphical technique was applied to the INAA data. Results showed that Na, Cl, Mg, Ca, Sr, Br, I, Sr and Rb were marine elements while Al, Sc, Fe and Mn were crustal elements. Compared to marine and crustal elements, five elements (Se、Co、Sb、Zn、Cr) were highly abundant in the aerosols collected at Zhongshan station, which indicated that they might come from the petroleum burning, heating and equipment operation. The presence of pollutant elements suggested that human activities have affected the local environments in Antarctica.     

Intensity variations of the postnoon auroral bright spots observed at Zhongshan Station, Antarctica on August 8, 1999

1　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅａｆｔｅｒｎｏｏｎｒｅｇｉｏｎ (ａｐｐｒｏｘｉｍａｔｅｌｙ 1 4 0 0ｔｏ 1 60 0ＭＬＴ)ｈａｓａｓｐｅｃｉａｌｓｉｇｎｉｆｉｃａｎｃｅｆｏｒａｖａｒｉｅｔｙｏｆｍａｇｎｅｔｏｓｐｈｅｒｉｃｐｈｅｎｏｍｅｎａ.Ｉｔｓｐｒｏｘｉｍｉｔｙｔｏｍａｇｎｅｔｉｃｎｏｏｎｓｕｇｇｅｓｔｓｔｈａｔｔｈｅａｕｒｏｒａｌｐｈｅｎｏｍｅｎａｏｂｓｅｒｖｅｄｍａｙｂｅｒｅｌａｔｅｄｔｏｄａｙｓｉｄｅｍａｇｎｅｔｏｓｐｈｅｒｉｃｐｒｏｃｅｓｓｅｓ ,ａｎｄｉｎｄｅｅｄａｖａｒｉｅｔｙｏｆｓｔｕ…     

The extremely intense CNA events observed at Zhongshan Station in July, 2000

1　ＩｎｔｒｏｄｕｃｔｉｏｎＡｌｏｎｇｗｉｔｈｔｈｅａｒｒｉｖａｌｏｆ2 3ｒｄｓｏｌａｒａｃｔｉｖｅｐｅａｋａｎｄｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｔｈｅｓｐａｃｅｓｃｉ ｅｎｃｅ ,ｔｈｅｓｃｉｅｎｔｉｓｔｓａｒｅｍｏｒｅａｎｄｍｏｒｅｉｎｔｅｒｅｓｔｅｄｉｎｔｏｐｉｃｓｏｆｇｅｏｓｐａｃｅｅｆｆｅｃｔｓｃａｕｓｅｄｂｙｔｈｅｉｎｔｅｎｓｅｓｏｌａｒａｃｔｉｖｉｔｉｅｓ.Ｔｈｅｇｅｏｓｐａｃｅｅｆｆｅｃｔｓｏｆｓｅｖｅｒａｌｅｘｔｒｅｍｅｓｏｌａｒａｃｔｉｖｅｅｖｅｎｔｓ,ｓｕｃｈａｓｔｈｅ 1 993Ｎｏ…     

Daily changes of spatial patterns of meteorological elements over Pearl River Delta based on GIS and MM5

The spatial distribution of meteorological elements is important for understanding the regional meteorology and climate changes. However, previous studies rarely focused on the daily changes of the spatial patterns of meteorological elements due to the limitation of remote sensing (RS) techniques and traditional meteorological methods. In this paper, the regional meteorological elements were simulated by the fifth-generation non-hydrostatic Mesoscale Model (MM5), and the spatial patterns of meteorological elements and their diurnal variations were analyzed in landscape level over the Pearl (Zhujiang) River Delta (PRD), China. The results showed that there were several centers of urban heat islands, cold islands, dry islands, wet islands, high wind over the PRD at noon. The diurnal changes of Moran I of meteorological elements were obvious and they reached the extremum at noon and 2-3 hours after the sunrise. The landscape indices of meteorological elements, such as area-weighted mean Fractal Dimension Index (FRAC_AM), Landscape Shape Index (LSI), Shannon's Diversity Index (SHDI) and Contagion Index (CONTAG), were more variable at about the sunrise, noon and sunset. The occurrence of wave crests and vales of landscape indices was affected by the surface net radiation, turbulence and local circumfluence. The spatial patterns of meteorological elements correlated well with the land surface, thermal exchanges and local circumfluence. A new approach combining GIS, RS and numerical simulatious technologies and the landscape ecology method was presented to analyze spatial patterns of meteorological elements, which may be useful for studying global and regional climate changes.     

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Topographic features around Zhongshan Station,southeast of Prydz Bay

Considering the complex topographic features of the southeast of Prydz Bay where China＇s Zhongshan Station is located, three types of geomorphologic units can be identified, i.e., submarine slopes, canyons, and terrains. The major topographic features in the study area are the submarine canyon and trough system outside the calving ice front of Dalk Glacier. A 3.8 km × 80 m fissure is found on the submarine terrain at Zhongshan Anchorage, which, once triggered by geological hazards such as earthquakes and ice falls, would be a threat to the usage and maintenance of the anchorage.     

Summer weather characteristics on the Grove Mountain of East Antarctica

The summer weather characteristics of the Grove Mountain, East Antarctica, are presented based on the data obtained by Chinese National Antarctic Expedition (CHINARE) in January 1999. The result shows that the pattern of daily variation of temperature and the prevailing wind direction in Grove is similar to that of Zhongshan Station. However, the daily range of temperature and strong wind frequency are much higher than those of Zhongshan Station. The change of wind direction is close to the weather system that impacted the Grove Mountain. The warm and wet air from northern parts often causes the precipitation. The clear weather appears when controlled by eastern winds in January.     

A study on the multi-component substrom current

A new technique of eigen mode analysis, Method of Natural Orthogonal Components (MNOC) is used to analyze the ionospheric equivalent current systems obtained on the basis of magnetic data at six meridian magnetometer chains in the northern hemisphere during March 17 - 19, 1978. The results show that the whole current pattern for any given instant consists of a few eigen modes with different intensities. The first eigen mode exhibits a two-cell current construction, characterizing the large-scale magnetospheric convection and directly driven process, while the second eigen mode shows a concentrated westward electrojet at midnight sector, characterizing the substorm current wedge and the loading-unloading process. The first mode consistently exists whenever during quiet periods or at substorms, and its intensity increases from the beginning of the growth phase of substorms, then quickly intensifies in the expansion phase, followed by a gradual decrease in the recovery phase. On the other hand, the intensity of the second mode remains to be near zero during both quiet time and the growth phase of substorrns. Its rapid enhancement occurs in the expansion phase. These characteristics in the current patterns and the intensity variations coincide with the defined physical processes of the directly driven and loading-unloading components.     

GPS-derived horizontal ice flow velocities along the traverse route from Zhongshan Station to Dome-A, East Antarctica

1　IntroductionFromitsoriginalformulationin 1 990 ,theInternationalTrans AntarcticScientificExpedition (ITASE)hashadasitsprimaryaimthecollectionandinterpretationofacon tinental widearrayofenvironmentalparametersassembledthroughthecoordinatedeffortsofscientistsfromseveralnations(Mayewskietal.1 996) .AsaconsequenceITASEhasbeenfocusedtoaddresstwokeyscientificobjectives:1 )Todeterminethespatialvariabil ityofAntarcticclimate (eg.accumulation,airtemperature,atmosphericcirculation)overthelast2…     

The study of magnetic anomalies over Davis Strait

Magnetic data collected during several cruises in Davis Strait show north-south lineations over most of the area. The central positive magnetic zone coincides well with a major gravity low. These results suggest that the magnetic anomalies were produced by seafloor spreading and that the gravity low marks an extinct spreading center in Davis Strait. Comparison between the geomagnetic polarity time-scale and dated anomalies in Labrador Sea suggests identification of anomalies 13–27 (37 to 62 MY). In southern Davis Strait (63°N), the spreading rates are 8.4 mm/y. east of the spreading center, and 2.7 mm/y to the west. In northern Davis Strait (66°N), the spreading rates are 4.5 mm/y east of the spreading center, and 2.1 mm/y to the west. Seafloor spreading in Davis Strait was there-fore very asymmetrical, with decreasing rates from south to north. Spreading is interpreted as having begun at 61–63 M and ending at 37 MY. Three fracture zones have been delineated, suggesting oblique spreading about the ridge axis in the Davis Strait. A distinct northeast-southwest anomaly zone is interpreted as the, expression of faults caused by volcanically-induced vertical crustal movements, and not by spreading-related horizontal crustal movement. Faulting along this northeast-southwest anomaly zone is inferred to have occurred after the spreading and before 30 MY. The magnetic anomalies off Cape Dyer are proposed to be different from the anomalies striking in northeast-southwest direction. The Cape Dyer anomaly is interpreted as being formed at 58 MY while the northeast-southwest anomaly zone formed more recently. This work was carried out at Department of Geology and Centre for Marine Geology, Dalhousie University, Halifax, N. S. Canada.     

Distribution of the tropical Pacific surface zonal wind anomaly and its relation with two types of El Niño

El Nio events with an eastern Pacific pattern(EP) and central Pacific pattern(CP) were first separated using rotated empirical orthogonal functions(REOF).Lead/lag regression and rotated singular value decomposition(RSVD) analyses were then carried out to study the relation between the surface zonal wind(SZW) anomalies and sea surface temperature(SST) anomalies in the tropical Pacific.A possible physical process for the CP El Ni o was proposed.For the EP El Ni o,strong westerly anomalies that spread eastward continuously produce an anomalous ocean zonal convergence zone(ZCZ) centered on about 165°W.This SZW anomaly pattern favors poleward and eastward Sverdrup transport at the equator.For the CP El Nio,westerly anomalies and the ZCZ are mainly confined to the western Pacific,and easterly anomalies blow in the eastern Pacific.This SZW anomaly pattern restrains poleward and eastward Sverdrup transport at the equator;however,there is an eastward Sverdrup transport at about 5°N,which favors the warming of the north-eastern tropical Pacific.It is found that the slowness of eastward propagation of subsurface warm water(partly from the downwelling caused by Ekman convergence and the ZCZ) is due to the slowdown of the undercurrent in the central basin,and vertical advection in the central Pacific may be important in the formation and disappearance of the CP El Nio.     

Temperature variations at the Great Wall and Zhongshan stations

Surface meteorological observations have been carried out at the Great Wall station (GW) and Zhongshan station (ZS) from 1984 to 2008 and from 1989 to 2008 respectively. The variation in mean air temperature and its trends are derived from the meteorological observation data recorded at both stations. The warming rate of the annual mean temperature at GW is similar to that at Bellingshausen station, which is about 3 km distant. Thus, the warming trend is representative of the King George Island region. The warming rate of ZS is less different from that at Davis station,which is about 100 km from ZS. It can be said that the meteorological data recorded at both stations are representative of the regions of the King George Island and east coast of the Antarctic.     

The Features of Dasyclad Algae and the Dasycladaceae Fossils in Jiaonan Region

The features of all fossil assemblage from Jiaonan region are equal to those of the plant in the forth stage or the fifth stage. The time of samples association of Dasycladaceae algae in Jiaonan area should be in early Cretaceous period. The group of Dasycladaceae algae in Jiaonan region is marine plant, and belongs to the Tethys paleobotanic province. They began to distribute westward and eastward from Triassic period in a radiating way. And the geographical position was in tropical or subtropical zoneat that time.