An analysis of near-surface atmospheric and oceanographic data over the equatorial Pacific Ocean with a special focus on the daily cycle.

Abstract

This thesis work analyses near-surface atmospheric and oceanographic parameters measured in the Tropical Pacific Ocean by the TAO array. The TAO array comprises almost 70 moored buoys retrieving high-frequency data (10-minutes). This work aims to assess the daily cycles of different physical parameters over the Easter, Central and Western Equatorial Pacific. To this purpose, data from three buoys located at 0°N 95°W, 0°N 140°W, 0°N 165° are examined. The first objective of this work is the characterisation of the diurnal behaviour of the near-surface air temperature, sea surface temperature, relative and specific humidity, sea level pressure, wind direction and velocity, solar radiation and precipitation. Then, this analysis examines the variations of the daily cycles under different background local meteorological conditions, i.e. during sunny, cloudy, windy and calm days, and under different “background” large-scale climatic conditions, i.e. during "warm" and "cold" phase of ENSO. The evolution of the different diurnal cycles over a multi-yearly scale is assessed, highlighting the variation of the cycles under different parameters regimes. Finally, the relations existing between the different physical parameters on a daily time scale are evaluated. The findings of this thesis work are compared with the existing results concerning the variation of the parameters over the day.