Southern Ocean Drifters
location | information | SST | optics | derived | processing | data | SOFeX log

The data and figures presented here are preliminary and subject to change. 

Click on any figure for an enlarged view.

Location

Drifter tracks overlaid on the bathymetry (m).  The legend and circles indicate the most recent known positions.

Information

Four optical drifters from Oregon State University were deployed in the Southern Ocean as part of the Southern Ocean Iron Experiment (SOFeX).  In this study, two patches of iron were created, one to the north of the Antarctic Polar Front Zone (which is near 61^oS), and one to the south of the front.  To help track the movement and properties of the patches, drifters were deployed within and outside of each of the patches.  

One of the drifters (27385) failed immediately after deployment.  

Because drifter data tend to be noisy, part of the data processing involves the subjective removal of outliers.  In the figures shown below, the blue dots represent all of the data, and the red dots show those that have passed the subjective criteria.  The derived products (chlorophyll, FLH/Ed(490), CFE) were calculated using only the data that passed the criteria.

Sea Surface Temperature (SST)

27383 (I-N)

failed

 Sea surface temperature (^oC) as a function of decimal day (GMT).

Optics
Downwelling irradiance, upwelling radiances

27383 (I-N)

27384 (O-N)

27385 (I-S)

failed

27386 (O-S)

Downwelling irradiance at 490 nm and upwelling radiances at 412, 443, 490, 510, 555, 670, and 683 nm as a function of decimal day (GMT).

Derived Products
Chlorophyll (Abbott, Gordon), FLH/Ed(490), CFE

27383 (I-N)

27384 (O-N)

27385 (I-S)

failed

27386 (O-S)

Chlorophyll (mg/m³) calculated using two different algorithms (by Abbott and Gordon), fluorescence line height (FLH) normalized to the downwelling irradiance at 490 nm (Ed(490)), and a proxy for the chlorophyll fluorescence efficiency (CFE) as a function of time.  The two chlorophyll algorithms used are:

Abbott:  C=0.56353*(Lu443/Lu555)^(-0.595)

Gordon: C=1.13*(Lu443/Lu555)^(-1.71) for C<1.5
              C=3.33*(Lu510/Lu555)^(-2.44) for C>1.5

FLH and the CFE proxy were calculated as follows:

              FLH = Lu683-baseline, 
              where baseline=(1-(683-670)/(712-670))*Lu670,
              which assumes a linear baseline between 670 and 712 nm with Lu712=0.

              CFE proxy = (FLH/Ed490)/C, where C is the Gordon chlorophyll.

These products were calculated using only the data that passed the subjective criteria.

Processing Data
Ratios of Lu to Ed(490) - used to help clean the data

27383 (I-N)

27384 (O-N)

27385 (I-S)

failed

27386 (O-S)

Ratios of upwelling radiances at 412, 443, 490, 510, 555, 670, and 683 nm to the downwelling irradiance at 490 nm as a function of decimal day (GMT).  These ratios are used to help subjectively clean the data.

Data Files
Calibrated and cleaned data (subjective) 

The data files are ASCII with the following format:

location | information | SST | optics | derived | processing | data | SOFeX log