The Benguela Current is a current that flows northward along the west coast of southern Africa between about 15 and 35o S. This is the eastern limb of the subtropical gyre circulation system in the South Atlantic Ocean. The Benguela Current originates with the confluence of Indian Ocean and South Atlantic subtropical thermocline water; saline, low-oxygen tropical Atlantic water; and cooler, fresher deep water. The current is noted for its cold temperature, leading to a cold dry wind driven to the coast of the Namib Desert, contributing to the extreme arid conditions of that desert. The Benguela current is 200 to 300 kilometres wide, broadening as it flows northwest along the coast of South Africa and Namibia. Its western, seaward edge is poorly defined, with many time-fluctuating seasonal eddies and meanders; moreover, there is a well defined thermal front between the waters associated with the Benguela Upwelling System and those of the southeast Atlantic Ocean.
Fog formation over the Namib Desert
Frequent fogs occur over the western edge of the Namib Desert due to collision of cold air over the cold Benguela Current with warmer air from the Hadley Cell. These fogs contribute an important moisture component as effective precipitation over the western Namib Desert, since some of the fog results in terrestrial condensation, a very important addition to the otherwise sparse rainfall of the western Namib.
The Angola-Benguela Front (ABF) is a oceanic front caused by the confluence of the southward flowing Angola Current and the northward flowing Benguela Current presently near 16oS off the African coast. This can be identified in the temperature of the upper 50 metres (m) and in the salinity to at least 200 m in depth. The ABF varies somewhat in its exact location depending upon the regional meteorology, but is generally in the vicinity of the border between Angola and Namibia at the mouth of the Kunene River.
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