TAILIEUCHUNG - Satellite Altimetry and Earth Sciences_2

Satellite altimetry was developed in the 1960s soon after the flight of artificial satellites became a reality. From the vantage point in space, a radar altimeter is able to measure the shape of the sea surface globally and frequently. Such measurements have a wide range of applications to oceanography, geodesy, and geophysics. The results are often revolutionary. For example, in oceanography; it takes a ship weeks or months to cross the ocean making measurements while the ocean is constantly changing its circulation, temperature, and salinity. Therefore, it is unfeasible to make synoptic observations of the global ocean using in situ instrumentation. The advent of satellite altimetry has given oceanographers a unique tool. | CHAPTER 5 Data Assimilation by Models ICHIRO FUKUMORI Jet Propulsion Laboratory California Institute of Technology Pasadena CA 91109 1. INTRODUCTION Data assimilation is a procedure that combines observations with models. The combination aims to better estimate and describe the state of a dynamic system the ocean in the context of this book. The present article provides an overview of data assimilation with an emphasis on applications to analyzing satellite altimeter data. Various issues are discussed and examples are described but presentation of results from the non-altimetric literature will be limited for reasons of space and scope of this book. The problem of data assimilation belongs to the wider field of estimation and control theories. Estimates of the dynamic system are improved by correcting model errors with the observations on the one hand and synthesizing observations by the models on the other. Much of the original mathematical theory of data assimilation was developed in the context of ballistics applications. In earth science data assimilation was first applied in numerical weather forecasting. Data assimilation is an emerging area in oceanography stimulated by recent improvements in computational and modeling capabilities and the increase in the amount of available oceanographic observations. The continuing increase in computational capabilities have made numerical ocean modeling a commonplace. A number of new ocean general circulation models have been constructed with different grid structures and numerical algorithms and incorporating various innovations in modeling ocean physics . Gent and McWilliams 1990 Holloway 1992 Large et al. 1994 . The fidelity of ocean modeling has advanced to a stage where models are utilized beyond idealized process studies and are now employed to simulate and study the actual circulation of the ocean. For instance model results are operationally produced to analyze the state of the ocean . Leetmaa and Ji 1989 .

• Năng lượng
• Ocean Circulation
• General Circulation
• Temporal Variability
• Pressure Forcing
• Equatorial Waves
• Changes of Mass
• InterannualVariability
• oceanography
• geophysics
• wave prediction
• tides
• ocean acoustic
• Surface Circulation
• North Atlantic Deep Water
• Antarctic Bottom Water
• Deep Water Masses
• Mediterranean Water
• Nuclear energy
• Persian gulf
• Baroclinic circulation
• Lagrangian rapid response model
• HYCOM operational ocean model