CHARACTERISTICS AND CAUSE ANALYSIS OF WESTERN PACIFIC SUBTROPICAL HIGH DURING THE HUAIHE RIVER FLOODS IN 2003

1 INTRODUCTION In summer, different assembly of the intensity, location and vertical structure of the subtropical high and the earlier/later time of its seasonal northwards jump bring about different precipitation patterns over China. Therefore, subtropical high activity and its cause during the occurrence of extreme climatic event over China and the cause of China drought/flood are studied to improve weather forecasting.

Experimental investigation of loss and gain characteristics of an abnormal In_xGa_(1-x)As/GaAs quantum well structure

In this Letter, the loss and gain characteristics of an unconventional InxGa1-xAs∕Ga As asymmetrical step well structure consisting of variable indium contents of InxGa1-xAs materials are measured and analyzed for the first time, to the best of our knowledge. This special well structure is formed based on the indium-rich effect from the material growth process. The loss and gain are obtained by optical pumping and photoluminescence（PL）spectrum measurement at dual facets of an edge-emitting device. Unlike conventional quasi-rectangle wells, the asymmetrical step well may lead to a hybrid strain configuration containing both compressive and tensile strains and, thus, special loss and gain characteristics. The results will be very helpful in the development of multiple wavelength In Ga As-based semiconductor lasers.

Electromagnetic Abnormity Observed at Sujiatun Seismic Station and Its Relation toEarthquake

The Sujiatun seismic station is a local professional seismic observation station in the city of Shenyang, Liaoning province. Electromagnetic radiations observation apparatus, of the type EMAOS-L, are used there. In this paper, four years observation data and observed earthquakes with M_S≥4.0 were collected in the Sujiatun observation station. The characteristics of electromagnetic radiation abnormities and earthquakes are analyzed from such aspects as capabilities of the apparatus used, tectonic structure, origins of electromagnetic radiations and so on. By analysis, precursor abnormities observed at this observation station are remarkable. The electric and magnetic abnormities are with good synchronism and the abnormities can respond better to the earthquakes with the epicenter distance being less than 20km and taking place in the upper crust. At the same time, for earthquakes with large magnitudes, the variation of precursor abnormities shows a periodic diurnal variation.

Dynamics of saltwater intrusion in the Modaomen Waterway of the Pearl River Estuary

Observations indicate an abnormal characteristic of saltwater intrusion in the upper Modaomen Waterway of the Pearl River Estuary,i.e.,the maximum salinity occurs during the neap tide or the coming moderate tide instead of during the spring tide.To explore the associated dynamic mechanisms,a high resolution three-dimensional numerical model was set up based on the Finite Volume Coastal Ocean Model(FVCOM),which covered the entire river network,the Pearl River Estuary,and the adjacent sea.Numerical experiments illustrated that the upper Modaomen Waterway is significantly influenced by the saltwater intrusion from the Hongwan Waterway,a narrow and shallow channel connecting the Modaomen Waterway to the sea.Specific topography,spring-neap tidal variation,local wind stress,and their interaction drive an up-estuary residual current in the Hongwan Waterway,which is much stronger during the neap tide than during the spring tide.As a result,more saltwater in the Hongwan Waterway is spilled over into the Modaomen Waterway during the neap tide or the coming moderate tide.This is the inherent dynamic mechanism why the saltwater intrusion in the upper Modaomen Waterway reaches its maximum during the neap tide or the coming moderate tide.Besides,we also found that the winter prevailing wind can pronouncedly enhance the saltwater intrusion in the Modaomen Waterway.