VOCALS is an international program that is part of the CLIVAR VAMOS (Variability of the American MOnsoonS) program. The scientific issues underlying VOCALS can be broken into four interconnected categories:

• atmospheric, oceanic and coupled model biases and model improvement in the Southeast Pacific (SEP) and other subtropical cool-ocean regimes;
• SEP aerosol-cloud interaction and implications for aerosol indirect effect and regional climate;
• SST distribution and the ocean heat budget in the SEP; and
• the role of South America and remote forcing from tropics and midlatitudes, on diurnal to interannual (ENSO) timescales.

The overall goal of VOCALS is to develop and promote scientific activities leading to improved understanding, model simulations, and predictions of the southeastern Pacific (SEP) coupled ocean-atmosphere-land system, on diurnal to interannual timescales. Our two leading concerns are (1) the physical processes affecting the radiative and microphysical characteristics of the persistent stratocumulus clouds of this region, and (2) the ocean budgets of heat and other constituents, and how they determine the sea-surface temperature (SST) throughout this region.