ABSTRACT
Introduction The atmosphere and the ocean are held on the Earth by gravity and irradiated by the Sun. Both are shallow relative to the radius of the Earth and the motions within them are slow relative to that due to the Earth’s rotation: they have similar dynamics. As they share a common boundary it is attractive to treat them as a single, coupled, system, but the physical and chemical properties of air and water are so very different that meteorology and oceanography have developed separately and at different rates. Electromagnetic radiation (light, microwaves, radar, radio …) travels easily through the atmosphere and this, together with the commercial and economic benefit of weather-forecasting, has led to the existence of a global network of meteorological observing stations, making and transmitting regular routine surface and upper-air observations, as well as increasing information from sensors on satellites.
