A fairly common word, especially when talking about weather, it seems. It's not one that I remember running across, but I may have just skimmed past it and thought of its near cousin "convection". And it's our first word from meteorology and oceanography!
a. Meteorol. The transfer of heat by the horizontal movement of the air. Similarly, heat transfer by the vertical motion of the air, esp. in a large-scale or steady atmospheric current. Also attrib., as advection fog. Hence advective a., of, or caused by, advection. Cf. CONVECTION.
b. Oceanogr. The horizontal or vertical transfer of material, heat, etc., brought about by the mass movement of the oceans, e.g. in currents.