For three consecutive periods during the summer of 1974, ships of many nations made observations along the Atlantic equator as part of the GATE program [GARP (Global Atmospheric Research Program) Atlantic Tropical Experiment]. Combining these observations, it is found that the zonal pressure gradient over the central Atlantic at the surface and at 50 dbar, relative to 500 dbar, increased from 3.2 to 7.3 and 2.2 to 5.3 × 10-5 dynes/g respectively between June/July and August and then held close to the high values in September....
Katz, Eli J., R. Belevitsch, J. Bruce, V. Bubnov, J. Cochrane, W. Düing, P. Hisard, H.-U. Lass, J. Meincke, A. deMesquita, L. Miller, and A. Rybnikov. 1977. "Zonal pressure gradient along the equatorial Atlantic." Journal of Marine Research 35, (2). https://elischolar.library.yale.edu/journal_of_marine_research/1394