East Asia and Western Pacific METEOROLOGY AND CLIMATE

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I. Introduction
Climate is one of the basic factors in human life that
strongly affects the social and economic fabric of societies.
Recent changes in climate, especially the severe droughts over
most of the world in the last few years, have made us pay
specific attention to the earth environment and made us want
to increase our understanding of the causes of climate change.
Accurate predictions on climatic conditions are most valuable
for making intelligent decisions about how to overcome the
caused hardship and to make the best mitigatory adjustments.
Several international organizations such as the World
Meteorological Organization (WMO), the International Council
of Scientific Union (ICSU) and the Intergovernmental
Oceanographic Commission (IOC) are jointly encouraging the
industrialized nations to monitor, measure, and study the
earth environment as a single interactive system. Many
ongoing and planned programs such as the scientific research
program under the International Geosphere-Biosphere program
(IGBP), notably the Climate and Global Change Program (C&GC),
and the World Climate Research Program (WCRP), notably the
Tropic Ocean and Global Atmosphere Program (TOGA) and the
World Ocean Circulation Experiment (WOCE), are designed to
better understand and predict for the natural earth
environment on climate time scales.
The earth receives its energy from the sun. However, the
most obvious and dominating factor affecting climate changes
is the energy exchange between the oceans and the atmosphere.
Energy fluxes of momentum, heat, radiation, and water at the
air-sea interface drive the ocean circulation and ice
formation, and determine the coupling between the atmosphere
and the oceans. The ocean, mostly due to its large heat
capacity and slow motions, redistributes the energy, hence
plays a very important role in climatic changes. On climatic
time scales, i.e., greater than the weather prediction skill
of about two weeks, slowly varying conditions at the earth's
surface, especially the sea surface temperature, force the
climate system to respond accordingly and yield predictive
skill of a different type. Instead of being able to predict
the temperature and precipitation for a given day, we might be
able to predict the warmth or dryness of a given month, a
season to a few years in advance. At time scales from weeks
to years, only the upper layers of the tropic ocean need be
included because the atmosphere and the tropic oceans are
almost directly coupled. At a time scale of one hundred
years, the intermediate layers of the global ocean become
important. Similarly, deep water processes and ice processes
together with land processes become important as we move to
still longer time scales. As the time scale of interest