Aero-Terms are designed to be a daily reminder of the terms, names, acronyms and explanations of the unique language that populates the aviation world. Aerospace, sport aviation, fixed wing, helo, you name it... it's all fair game.
Aero-Terms should serve as a quick but intriguing reminder of the terms you may use every day, or an introduction to an aspects of the Aero-World you may not yet be familiar with. ANN also encourages readers to go beyond the FMI link, and further research any intriguing terms.
A shift in position of various high and low pressure systems that in climate terms is usually defined as an index ... a single numerically-derived number that represents the distribution of temperature and pressure over a wide ocean area. (i.e. El Niño-Southern Oscillation, North Atlantic Oscillation, and Pacific Decadal Oscillation).