Movie of May 3rd Ebb Tide Drifter Trajectories

The above movie was made by Matthew Spydell. It shows May 3rd ebb tide drifter trajectories from the RIVET experiment at New River Inlet. Bathymetry is shaded. Land regions are in gray. The bar on top indicates elapsed time (in hours) since the start of the release. For more information on this release look at this blog entry.  This movie contains a lot more drifter information though.  In the original blog entry the drifters got out of radio contact so we couldn’t track them in real time.   But they log their GPS positions onboard the drifter memory.    What was interesting (as noted in the original post)  is that there was no indication that the drifters going back  onshore during the flood tide.

FTP data site is now up

RIVET-ers:   our ftp data site is now up.   We are slowly in the process of putting processed and quality controlled data onto it.   To access the ftp site please ftp to

or use the ftp shell program and ftp to  with username “rivet”

If you would like access to the data please email falk feddersen (ffeddersen at and you’ll be sent a password.

DATA POLICY & CAVEATS:   Our data policy is similar to the Raubenheimer/Elgar (WHOI) policy and is repeated here:
1) We are actively analyzing the dye and drifter data sets from New River.    If you want to use the drifter or dye data please let us know so that the same analysis is not performed twice.

2) If you use the data, we would like to be offered the opportunity to consider co-authorships. We try not to be parasites, and if we do not feel we made a contribution, we will decline.

3) If you use the data, please let us know so we can ensure our sponsors are acknowledged.

4) Please do not distribute these data to any third parties. That means if you let your students use the data, please inform them they are not to share with anyone else. Others can contact us and we will give them the data.  This practice will ensure that everyone can be kept up to date with improved quality control, and our sponsors can be acknowledged.

5) The data have undergone a significant quality control.  However, likely some wierdness remains.  If you find anything strange, please let us know and we will update the data files.

6) If you would like to collaborate, let us know. We’d be happy to share science ideas, suggestions, and processing efforts.

FTP site format

The format of the ftp site should be fairly self explanatory.   We are only starting to put data up so the site will chane and expand.   Currently, the top level directory looks like:

Index of

Up to higher level directory

Name Size Last Modified
drifter 8/29/12 8:35:00 PM
fluorometers 9/4/12 6:27:00 PM
wirewalker 9/4/12 8:54:00 PM

The fluorometer directory contains all the data from the deployed fluorometers in two sub directories  fixed_fluorometers (mounted on pipes near current meters) and towed_fluorometers (towed behind a boat).

Index of

Up to higher level directory

Name Size Last Modified
File:SIO_fluorometer_data_report.pdf 746 KB 9/4/12 6:27:00 PM
fixed_fluorometers 8/29/12 8:34:00 PM
towed_fluorometers 9/3/12 11:27:00 PM

Let me know if you have any questions

Results from both WireWalkers : both deployments

All the Wirewalker data has now been processed.   Below are plots for WW1 deployment 2 and WW2 deployments 1 & 2.   Note in the plots below that the dark cross-hatched areas are times when the WW data is bad.   See the previous post for the map of the WW locations.

WW1 Deployment 2

WireWalker 2, deployment 1

WW2 deployment 1 (30 Apr to 10 May). Same format as above figure

WireWalker 2, deployment 2

WireWalker 2 Deployment 2 (10 May -21 May) in the same format as the above figures.



WireWalker #1 Deployment 1 results

We now have our first look at the wirewalker (WW) mooring observations.   The wirewalkers use the up and down motion of the sea-surface to move a CTD+fluorometer profiling package up and down the water column.   As such, good vertical and tempral resolution of the watercolumn can be acheived with a single sensor.    During RIVET-I, we deployed 2 WW in appoximately 8 m depth.  WW1 was deployed just offshore of the “new” channel at approximate locations (x,y) = (1000,0) m.    See the legend of the figure below summarizing instrument locations.

Map of New Rivet Inlet NC bathymetry (from the ASACE FRF) in the RIVET coordinate system with the SIO (Feddersen/Guza) and WHOI (Raubenheimer/Elgar) ADV, ADCP, and wirewalker (WW) instrument locations as noted in the legend. The TopSail side of the inlet is below and the Camp Lejuene side is on top. SIO ADV locations are marked V1-V8. All locations also had a co-located pressure sensor Map of New Rivet Inlet NC bathymetry (from the ASACE FRF) in the RIVET coordinate system and many locations also had a co-located Rhodamine WT dye fluorometer. Dye was released either near x ≈ −600 m and y ≈ −300 m, or about 1.2 km further up the inlet towards the Inter-Coastal Waterway.

Each WW as deployed twice for ~11 days.    Below is the results of the 1st deployment of WW1.    A semi-diurnal temperature signal is evident over the 11 days as inlet water comes out the New River Inlet on ebb tide.   Typically a salinity signal is associated as well.

Wirewalker #1 Deployment #1 data from 0000 1 May and spanning 1-6 m in the watercolumn. Gridded are temperature (top), salinity (middle), and Rhodamine WT dye (log10 – bottom).

Dye was released on May 6, 7, 8th (note this is equivalent to time 5, 6, 7) on the plot above as the xaxis is days from 0000 1 May.   Note also data collection had begun on Apr 30th (day = -1).     For each of the dye releases there is a clear dye signal at WW!.  For the 1st two releases, the dye passes the WW relatively quickly and appears to be well mixed consistent with the temperature and salinity.    However, on the 3rd release, the resulting dye signal is more complex.    The dye first passes at t=7.7, and superficially does not appear to be well mixed.   However, approximately 12 hours later, dye is again present at WW1.   This indicates that dye had been recirculated back into the inlet on the flood tide and ejected again on the subsequent ebb.    There is another weaker dye signal on the next semi-diurnal cycle as well.