Trough 08 : An undersea depression that is U-shaped rather than V-shaped like a trench or canyon, which it otherwise resembles; also, an atmospheric low about which winds circulate. See canyon, trench
Intergovernmental Oceanographic Commission IOC technical series 37, Tsunami Glossary (A glossary of terms and acronyms used in the tsunami literature - English), , United Nations Educational, Scientific and Cultural Organization UNESCO, Paris, France 1991. http://unesdoc.unesco.org/images/0008/000885/08853 8eb.pdf, (ND/ Tsunami Sci - Brit) {590}