Tropical upper-tropospheric trough
From Glossary of Meteorology
tropical upper-tropospheric trough
A semipermanent trough extending east-northeast to west- southwest from about 35°N in the eastern Pacific to about 15°–20°N in the central west Pacific.
A similar structure exists over the Atlantic Ocean, where the mean trough extends from Cuba toward Spain.
Sadler, J. C. 1963. Rocket and Satellite Meteorology. Wesler, H., and J. E. Caskey Jr., Eds., North–Holland Publ., Amsterdam, . 333–356.