The measured data is essentially a mixture of various signals. Statistical data analysis plays an important role in extracting the important signals. With the progress in techniques, huge amount of measured data are available to scientists in Geosciences. I believe that scientific discoveries depend on the power to extract the interesting signals. This monograph gives a few examples of it. The signal of basin mode oscillation in the Japan/East Sea had not been discovered for a long time because it is much weaker than other background signals. You would have the opportunity to see in this monograph how statistical methods can extract a signal by using its distinct features . The study of the oceanic vertical coupling gives an additional example of it. The first part of the monograph illustrates you how to improve sea-level estimates from satellite altimetry using field measurements in the Japan/East Sea. It suggests that fundamental problems of one type observation can be resolved from another type of observation under certain circumstance. It provides an innovative way to improve the satellite observations.