Upper-ocean Responses to Rainfall: Observations from Profiling Floats

The input of freshwater to the ocean through precipitation is an important component of the global hydrologic cycle. Using salinity as a proxy, satellites and the Argo array have provided new insights into the larger-scale, integrated responses of the ocean to rainfall. Due to the often-small footprint and short lifespan of precipitation events however, the effect of individual precipitation events on upper ocean temperature and salinity has been difficult to observe. High vertical resolution (<10 cm) measurements of temperature and salinity in the near surface layer have been obtained from ~80 profiling floats enhanced with an auxiliary Surface Temperature and Salinity (STS) CTD. While observations from these floats show the upper ocean is well mixed the majority of the time, significant (> 0.1 PSU) salinity drop events have also been observed. The vertical structure, stability, and time evolution of these salinity drop events are examined under a variety of background conditions.