The Study On The Characteristic Of The Sea Surface Wind Field Around The Antarctic Area Based On The Scatterometer Data

Sea surface wind field is an important physical parameter in oceanography. One of the boundary condition of planetary boundary layer is the sea surface wind field in meteorology. It also plays an important role in the climate model, In the marine dynamic process, dynamic formation of sea wave is the sea surface wind field. Sea surface wind field is crucial power on global and regional ocean circulation. In the marine-atmospheric dynamical systems, wind field is a very important factor. For example, current, storm surge and wave numerical model need the input factor, generally determine the wind field as an input factor. In addition, sea surface wind speed alse influences sea surface temperature, global biochemical process and the hydrological cycle. In the study of ocean dynamic processes, observation and analysis of the sea surface wind field is the important foundation.Microwave remote sensing has many advantages.It is able to work around the clock,and is not affected by clouds、rain and fog,can work at night.And it can obtain the information following near the ground through the vegetations snow and ice and dry sand,is widely applied to ocean research,land resources survey and mapping. It has become one of the main means of observation and study of the ocean.Microwave Scatterometer is the microwave remote sensing.It is the only remote sensing system that is capable of measurement of wind speed and direction of sea surface simultaneously.It can provide all day,high precision,global,short cycle and high resolution wind data of sea surface field.By means of microwave Scatterometer,not only can realize the real-time monitoring of the global ocean, but also can obtain large range and long time series ocean observation data.Empirical orthogonal function is a kind of dimensionality reduction analysis method that is widely used in the meteorological data and the ocean field,can analyze structural characteristic of matrix data,extract the main data characteristics,is one of the main methods of studying temporal and spatial variation characteristics of the variable ocean elements.This dissertation focuses on the study on the characteristic of the sea surface wind field around the Antarctic area based on the Scatterometer data.The main contents and conclusions of this study are as follows:1.The ASCAT wind data is not grid data,so the ASCAT wind data need to be gridded, first, test the accuracy of the ASCAT wind data before gridded.And ocean buoys are capable of collecting ocean environment data all the day and steadily,Ocean buoy data is the basis of wind field data.Firstly,this paper describes in detail the characteristics of ocean buoy. Then carrying out inspection and correction buoy and ASCAT wind field data, comparing the ASCAT data with wind speed and direction are observed by NDBC, TAO, PIRATA and RAMA buoy, Space-time window of the data comparison is12.5km and5minutes,a total of21426data points are matched, The calculated data error of ASCAT and buoy data:the mean absolute error of wind speed is0.69m/s, the average deviation of wind speed is0.10m/s, the root mean square error of wind speed is0.99m/s; the mean absolute error of wind direction is19.34degree, the average deviation of wind direction is1.52°, the root mean square error of wind direction is45.04°.2.ASCAT wind data set gridded by applying an optimum interpolation method based on the inspection ASCAT wind data, get the grid daily sea surface wind data.3.Based on the QuikSCAT from2000to2009and ASCAT from2010to2011grid wind data,using long time series of grid wind data around Antarctica wind farm, according to the basic statistical analysis method and the empirical orthogonal function statistical analysis method, analyse the regular pattern of spatial distribution and time variation of sea surface wind field. According to the basic statistical analysis method, for the2000to2009Antarctic sea area, the regional average wind speed is7-9m/s, annual number of days throughout the year is more than300days;for the2010Antarctic sea area, the regional average wind speed is9.5-10.5m/s, annual number of days throughout the year is more than250days; for the2011Antarctic sea area, the regional average wind speed is7.7-8.5m/s, annual number of days throughout the year is more than200days. The sea surface wind speed at the south of60(?) region around Antarctica is smaller, the frequency of more than6m/s is lower, the sea surface wind speed at the north of0(?)～120(?),60(?) is relatively larger. The proportion of the frequency of sea surface wind speed greater than6m/s in the spring at the south of60(?) region is less than0.6; in the summer, at the south of65(?) region, the proportion is less than0.6; in the autumn, at the north of the sea ice edge region, the proportion is more than0.6; in the winter, at the north of65(?)、60(?)～120(?) region the proportion is more than0.6, the other regions in the north of60(?) area proportion is greater than0.6, the sea surface wind speed at South Pole60(?)～120(?) region is greater than that of the other neighboring regions.By the empirical orthogonal function analysis method, the cumulative contribution rate of the first two modes is49.04%, which is a good explanation of the main part of the total deviation of wind speed;for the Antarctic sea area,summer sea surface wind speed is significantly greater than in winte;the first two modal mainly to annual change, after the four modes mainly to seasonal change.4.Based on the QuikSCAT grid wind data,using long time series of grid wind data around Antarctica wind farm, combining with the Southern Oscillation Index, carry out the analysis of relationship between surrounding the Antarctic sea surface wind field change and the global change. Variation characteristics between sea surface wind speed and SOI slightly has uniformity,synchronous correlation coefficient between them is about-0.2022, and changes with the time, showing the change characteristics of opposite phase. After through low pass filter,obtain the change relationship of the low frequency component between sea surface wind speed and SOI, synchronous correlation coefficient reaches0.3067. The phase change in the low-frequency fluctuation components between the Antarctica wind speed and the southern oscillation index is almost entirely the same, this means that the Antarctica wind speed is significantly modulated by the southern oscillation. Long periodic oscillation of the southern oscillation will cause quasi synchronous response of the Antarctica wind speed. The correlation coefficient of the first time principal component and the SOI index is0.4668, the first time principal component is the mode about SOI, reacting the SOI whole process from happening to ending. The Antarctica sea surface wind speed and the southern oscillation index has similar change features, then the changes of the Antarctica sea surface wind speed can also describe the southern oscillation events.