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

2. 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.

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

4. ADCP Measured Currents
30o u v

5. Comparison of ADCP Measured Velocity and Geostrophic Velocity

6. Comparison of ADCP Measured Currents and Geostrophic Currents
VAdj = VObs – VGeo
180 dbar
202 dbar
VObs = 1.75
VGeo = 3.10
VAdj = -1.35

7. Comparison of Geostrophic Velocity and Adjusted Geostrophic Velocity

8. Comparison of Geostrophic Transport and Adjusted Geostrophic Transport

9. Horizontally Summed Transport and Averaged Velocity

10. Comparison of ADCP Calculated Transport and Adjusted Geostrophic Transport

11. Comparison of ADCP Calculated Transport and Adjusted Geostrophic Transport

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

13. Questions?