The atmosphere can be divided into several distinct layers. In the Met Office only the bottom three are currently studied:
Extends from the Earth's surface to the tropopause (about 10-16 km in altitude). It contains about 90% of the mass of the atmosphere and supports weather systems and strong vertical motions.
Is a relatively stable region, characterised by an overall increase of temperature with height and approximately horizontal motion.
Lies above the stratopause, at roughly 50 km in altitude. This is where rapid fluctuations, gravity waves and tides, play a predominant role.
The stratosphere and mesosphere form the middle atmosphere.
Weather forecasting and the stratosphere
Traditionally, meteorologists have focused on the troposphere, as this is where we live and where weather systems occur. Initially interest in the stratosphere arose from concerns over the ozone layer. However, over the last 20 years it has become clear that the middle atmosphere influence tropospheric weather and climate.
Stratospheric research at the Met Office
The Met Office has been involved in stratospheric research since the 1940s. In the early years the focus was on the structure and composition of the stratosphere. Subsequently there has been increasing recognition of the stratosphere's importance.
The discovery of the Antarctic ozone hole drew unprecedented attention to the stratosphere. Met Office researchers are now part of an international group of scientists who prepare the WMO/UNEP four-yearly ozone assessment reports, which have been an important resources for governments and policymakers.
- The Unified Model, which is used for all Met Office forecasts and climate predictions, now includes a stratosphere.
- The Met Office's assimilation system has been extended to allow for the assimilation of stratospheric observations - leading to better weather forecasts in the troposphere and a better description of ozone and other chemical constituents.
Our activities have demonstrated the importance of the stratosphere to weather forecasts and ozone predictions. However, there is a need for improved representations of the stratosphere, and further research into the impacts on surface climate and weather.