ADCP Referenced Geostrophic Velocities and Transport Part II

ADCP Referenced Geostrophic Velocities and Transport Part II: Along-Shore LT Eric Macdonald Line 85

Goals • Calculate transport across a CTD transect – Calculate geostrophic current from CTD temperature and salinity profiles between stations. – Compare that geostrophic velocity to ADCP measured currents at a specified level. – Use the difference between these two velocity measurements as an adjustment to the geostrophic velocity. – Apply that adjustment to the entire geostrophic velocity field. – Use the adjusted geostrophic velocity field to calculate transport across the CTD transect.

Geostrophic Velocity Calculated using a geopotential anomoly from CTD salinity, temperature, and pressure measurements 202 dbar

ADCP Measured Currents n s v u 30 o

Comparison of ADCP Measured Velocity and Geostrophic Velocity

Comparison of ADCP Measured Currents and Geostrophic Currents 180 dbar 202 dbar Measured Currents VAdj = VObs – VGeo VObs = 1. 75 VGeo = 3. 10 VAdj = -1. 35

Comparison of Geostrophic Velocity and Adjusted Geostrophic Velocity

Comparison of Geostrophic Transport and Adjusted Geostrophic Transport

Horizontally Summed Transport and Averaged Velocity

Comparison of ADCP Calculated Transport and Adjusted Geostrophic Transport

Comparison of ADCP Calculated Transport and Adjusted Geostrophic Transport

Things to think about (possible sources for error): Due to horizontal variability the Should theof. ADCP velocity, would this data be interpolated What might be the result be more onto sameby the error the caused accurate if alongitude different latitude differentand units in z? adjustment were of the CTD casts? made between each of the CTD casts?

Questions?