Daily surface wind variations over the equatorial Pacific Ocean

Daily surface wind variations over the equatorial eastern Pacific Ocean during summer 1992 are documented, using hourly observations from the tropical atmosphere ocean moored buoy array. The phase of the semidiurnal cycle in zonal wind is approximately uniform across the equatorial eastern Pacific Ocean, with westerly wind maxima at ~0300 and 1500 LT. The diurnal cycle dominates the daily march of meridional wind. The low-level flow is southward across the equator at night (relative to the daily mean), regardless of whether the mean winds are southerly or northerly. In particular, surface wind divergence along the equator (which is dominated by the meridional component) exhibits a pronounced diurnal cycle, with the strongest divergence in the early morning when deep convection in the ITCZ is at a maximum. The average daily range of the equatorial surface wind divergence is 1.5 × 10^-6 s^-1, or ~30% of the daily mean. -from Author