Why Do Trade Winds Weaken Or Cease: Unraveling Natures Wind Mysteries

The strength of trade winds is influenced by the phase of the Arctic Oscillation (AO), a climate pattern that affects weather conditions in various regions. When the AO is in its warm phase, trade winds tend to be stronger in tropical areas. Conversely, during the cold phase of the AO, trade winds become weaker. When trade winds are weaker, they bring increased rainfall to landmasses within the tropics, such as Central America. This relationship between the Arctic Oscillation and trade wind strength plays a significant role in shaping weather patterns in tropical regions, impacting precipitation and climate conditions.

During an El Niño or ENSO (El Niño-Southern Oscillation) event, a notable phenomenon occurs where the trade winds, prevailing easterly winds in the tropics, experience a significant weakening and sometimes even reverse their direction. In the case of a robust El Niño event, this alteration in wind patterns can lead to a complete reversal of the trade winds. Consequently, this shift in the wind pattern has a profound impact on oceanic processes. It markedly diminishes or halts the usual westward movement of surface water, thereby reducing the intensity of cold water upwelling along the eastern Pacific coast (as illustrated in Figure 2).

In the field of climate research, a growing body of evidence suggests that when trade winds strengthen, a particular climate phenomenon occurs. This phenomenon involves the intensification of trade winds causing a greater amount of heat to be pushed downward into the ocean. As a result of this process, there is a temporary deceleration in the upward trend of surface temperatures. This finding is significant for understanding how trade wind patterns can influence short-term variations in global climate. (Publication date: February 10, 2014)