Determining coastal water sampling frequencies using a profiling mooring

Abstract

As part of the Northwest Association of Networked Ocean Observing Systems (NANOOS), a mooring is maintained in Pu-get Sound, WA that makes water-column profiles for temperature, salinity, oxygen, fluorescence, turbidity, nitrate and currents as well as surface pCO2 and air pCO2 every two hours. Additionally, 10-minute averages of the meteorological data (atmospheric temperature, wind velocity, wind direction, relative humidity, solar radiation) are also taken. All data is telemetered back to a laboratory computer in near-real time, where it is automatically processed and posted to the Internet. Analysis of data obtained from the mooring for the summer 150 day growing season are used to determine the frequency of sampling at this site necessary to characterize various parameters. High frequency variability is characteristic of the study site and the variability is caused by a combination of tidal advection of horizontal patchiness as well wind induced destabilization of the mixed layer. The analysis suggest that sampling frequencies on the order of hours to weekly are required to resolve the seasonal cycles and true values of various parameters and variables.