Progress toward better understanding of ocean variability is closely linked to the development of signal processing tools for multi-scale analysis of ocean flows. This book includes a review of recent progress in physical oceanography, such as results on studying ocean circulation and mesoscale ocean dynamics derived from satellite altimetry. Ocean currents are driven by wind as well as by thermal differences. This book examines the basic functions of the global three dimensional thermohaline circulation and its influence on climate. The impacts of the El Nino/Southern Oscillation(ENSO) on tropical climates are well-established. Research is presented to provide a relationship to the European climates. In the semiarid zones of western South America, for example, implications of increased rainfall during ENSO warm phases are multiple and complex. An investigation of the interannual and intraseasonal variability in the summer wind fields in the Asian monsoon system is presented. The book also includes information from the scientific community on the state-of-art studies related to climate risk in agriculture and helps to identify priorities for ongoing and future research.