Analysis Of The Sea-Level Anomaly Character Index In The Seas Near China

With the data observed by TOPEX/POSEIDON altimeter during the period from October 1992 through February 2000, five representative areas along the coast in China were chosen. In this study, the sea-level height anomaly character indexes are computed, its variety regulation and its relationships with El Nino are analyzed. Passing the calculation analysis of the characteristic index number, we discover that there is obvious annual variety regulation of it on the all sea region. Between these nine years, sea-level and excrescent characteristic in Bohai Sea gulf in first half year index number are all negative, while the second half year positive, and July is the converted period. There is obvious related relationship between the El Nino phenomenon and the gulf of Bohai Sea. Yellow sea, the north of South China sea Bashi and Balintang straits.For example, from the beginning October of year to March of the second year, going to Southern Hemisphere with the sun, the north Pacific Ocean circulation (include the Japan current with the warm current of Yellow sea) dies down, when the warm current of Yellow sea dies down, the sea water of Bohai Sea flows to the versa direction of Yellow sea to become the main sea water loses to carry direction, so Bohai Sea is sea-level here at that time period descent. With the moving Northern Hemisphere of the sun from April to September, the north Pacific Ocean circulation (include the Japan current with the warm current of Yellow sea) enhances, when the warm current of Yellow sea enhances, the sea water of Bohai Sea flows to the versa direction of Yellow sea to become the next in importance sea water loses to carry direction, and the Bohai Sea sea-level rise. So, under the general circumstance, from October, sea-level descent in Bohai Sea, reach in 2-4 months (spring) a little bit lowest; From April, the sea-level of Bohai Sea rise, reaching the highest in 9-11 months (autumn). The variety range of excrescent sea-level on the Bohai Sea from the lowest to the highest is generally from -10cm to 10cm, and the tallest can reach the range that is from -15cm to 15cm. From descending to rising, there is a fluctuation which makes one year for center period. However, the value of the sea-level height anomaly character indexes keep negative and it didn't turn positive until October. It explained that in 93 year El Nino died down the north Pacific Ocean circulation (include the Japan current with the warm current ofYellow sea) obviously, and the warm current of Yellow sea died down to cause the sea-level instauration in Bohai Sea postpones. In 97 year, the sea-level height anomaly character indexes in the bohai sea is not affected by the El Nino. During the period from May in 98 to December in 99 ( La Nina) the positive value of the sea-level height anomaly character increase obviously ,and the swing is sometimes over 15cm. It explained that the La Nina increased the north Pacific Ocean circulation( include the Japan current with the warm current of Yellow sea), and the increment of the warm current of Yellow sea causes sea-level of Bohai Sea to jack up. The period motion of the high frequency is caused by the unbalance of the exit and entrance sea water exchange in Bohai Sea, and by the factor of the wind caused by the native weather, and also by the fluctuation of the north Pacific Ocean circulation (include the Japan current with the warm current of Yellow sea).At the same time, making use of the data of the fortnight average wind field and the data of the sea level temperature field, doing a related analysis for the sea-level height anomaly character in our near sea, and making a comparison between the wind velocity at the related maximum center and the variance time sequence of the sea-level temperature SST and the variance time sequence of the sea-level height anomaly character, we discover both contain fixed phase shift. The correlation coefficient of the sea-level high degree in the gulf of Bohai Sea( the area of A) abnormality and the world-wide locations breeze field attains the bigge...