中国科学院遥感与数字地球研究所-高光谱遥感应用技术研究室

【作者】              兰穹穹                                                                                                                                           

【导师】              童庆禧；张霞

【 学位年度 】    2012

【论文级别】      硕士    

【关键词】          卫星测高，交叉点平差，共线法，潮汐模型 海面变化 

【Key words】   Satellite Altimetry; Crossover adjustment; Collinear method; Tide model; Sea level change 

【中文摘要】

海平面变化已经成为人类日益关注的重大政治性和经济性的问题，目前较多的观点认为全球海平面变化呈现上升的趋势，然而局部区域的海平面变化却是相当复杂的，不能一概而论。长江口区域海平面变化的研究历来是学者们研究的热点，原因在于海平面变化给我国沿海地区乃至全国范围的经济带来的挑战首先在长江口区域体现出来。

     卫星测高技术能够提供全天候、全天时、高时空分辨率、精密重复覆盖的海面高度信息，是海平面变化研究中的一种重要手段。卫星测高的精度直接决定了海平面变化信息提取的精度。

     本文以长江口区域为研究区域，联合利用T/P卫星和Jason-1卫星的测高数据来开展海平面变化的研究。主要工作为研究利用有效的卫星测高数据处理方法，来计算出精确的海面高，从而提取出长江口区域海面高的时间序列和海平面变化特征。

     本文在测高数据的编辑过程中选择了一种适合于长江口浅水区域的测高数据编辑方法，基于此编辑方法，有80%的数据被认为是有效数据而保留下来。本文对测高数据进行了交叉点平差，并介绍了一种条件平差的方法，虽然没有传统的方法严密，但是利用了一种更合理的误差模型，且计算简单，计算过程稳定，不存在秩亏问题，结果证明是一种行之有效的方法。经过新的交叉点平差方法的处理后，交叉点处海面高不符值由原来的2.35米降低到0.76厘米；利用共线处理的方法将各周期的测高数据校正到统一的参考轨道上，并认为斜率梯度方法是一种比较有效的方法；对同步运行期间两颗卫星的地球物理数据进行了一致性分析，结果表明Jason-1卫星能够在精度上很好地延续T/P卫星的使命；基于18年的测高卫星序列，利用调和分析方法建立了区域潮汐模型，并对测高数据进行了潮汐校正，校正后结果与验潮站的潮位变化较一致，同时对长江口区域平均海面高进行了EOF分析和EMD分析；最后，本文在测高数据精确处理的基础上，提取了长江口海平面变化的时间序列，计算出的海平面变化速率为1.65mm/yr，年内变化规律表现为9,10,11月份海面高较高，4月份海面高有一个极大值点，其他月份海面高度值相对较低。

【Abstract】

The sea surface change has been a major issue with some political and economic significance. So far, many people think that the sea has a trend of continues rise. However, it is difficult to decide the change of a regional sea using the same trend for they each has a complicated change. In history, many researchers focus on the Changjiang Estuary., because the consequence of the sea change firstly take on in this area.

      With an all-weather, all-time, high space resolution and precise repeat coverage, the satellite altimetry is an effective means to obtain the information of the sea surface height. The precisionof the altimetry data decides that of the information extracted from the sea surface.

      In this paper, the T/P and Jason-1 satellite altimeter were combined to detect the sea change of the Changjiang Estuary. The altimetry data has some error such as the radial orbit error and the environment error. This paper studied the sea level change in the Changjiang Estuary.

      An effective method was used to perform the data editing, after which 80% of the data was thought to be good data. A new method was proposed for crossover adjustment. It is easier to perform, steady and without rank defect. After processing with this method, the altimetry data had lower radial orbit error. Meanwhile, in this paper, the altimetry data of different cycles were corrected to a reference orbit using the slop gradient method. Because the T/P and Jason-1 satellite ran the same orbit for nearly 6 months, the analysis of the coherency of the two kinds of altimetry data was performed. The result was that the altimetry data of Jason-1 satellite were consistentwith that of T/P. In addition, a regional tide model was calculated because the tide model of the altimetry data was for the global area and was not fit for a regional area. The regional tide model was calculated using a 18-year time series of altimetry data and conversely was for the correction of the altimetry data. After that, a more precise time series of the altimetry data was calculated, from which the sea rise rate was calculated to be 1.65mm/yr, Moreover, the inter-annual change rule was found:  the mean value of the sea height in September, October and November were higher than other months and in April there was a peak extreme value.