The horizontal transfer of any atmospheric property by the wind.
WRCC Climate and Weather Terms Glossary

A horizontal movement of a mass of fluid, such as ocean or air currents. Can also refer to the horizontal transport of something (e.g., pollution, phytoplankton, ice, or even heat) by such movement.
nbsp;NASA Earth Observatory

Advection - To transport or carry. In air quality, the rate at which particulate matter is transported. [Journal of the Atmospheric Sciences; v51n21; pages 3109-3121; 1994.] [Deep-Sea Research ; v41n2A; pages 243-261; 1994.]
Atmospheric Chemistry Glossary