Katabatic Winds, or gravity drainage winds, are of larger regional scale and are usually stronger than local winds. These winds are not specifically related to the pressure gradient. What causes Katabatic winds? with references (if you get info from

Katabatic Winds, or gravity drainage winds, are of larger regional scale and are usually stronger than local winds. These winds are not specifically related to the pressure gradient. What causes Katabatic winds?  

with references (if you get info from the web), 1 page at least, font 12 times new roman .