From AMS Glossary
A zone of enhanced meridional gradients of sea surface temperature and salinity in the poleward part of the subtropical convergence.
In the Southern Hemisphere, the subtropical front can be traced from 40°S at the east coast of South America across the Atlantic into the Indian Ocean and across the Great Australian Bight, where it shifts to 45°S to pass south of Tasmania and reach the southern tip of New Zealand's South Island. It continues in the Pacific Ocean from the Chatham Rise east of New Zealand near 40°S and reaches the west coast of South America near 30°S. In the Northern Hemisphere a well- developed subtropical front exists in the Pacific Ocean between 25°N, 135°E and 30°N, 140°W.