The CTD methodology applies to all data associated with Lake Superior and August Lake Erie. All of the other Lake Erie data is covered by the Sonde methodology.

SeaBird Model 911 plus CTD profiler

At each site, the SeaBird Model 911 plus CTD profiler was moved over the site using the A-frame at the rear of the R/V Blue Heron. The profiler was then lowered into the water and allowed to collect the data on the way down to the bottom of the water column. This is based on the water depth at each site, which ranged from about 7m to over 160m. Once at the bottom of the water column, the profiler was then raised back through the water column. During this process, the profiler was stopped at select water depths based on the site. This was done so the onboard 8L Niskin bottles could be used to collect the water at the selected sites. For each site, several casts of the profiler were necessary to collect the desired amount of water. Despite this, representative casts from each site during each cruise were selected to avoid unnecessary confusion and cluttering of the files with redundant data. The profiler produced two different data sets, marked as ASC1 and ASC2, both of which are included as supplemental files. The ASC1 files are continuous readings from the CTD as it moved through the water column. The ASC2 files is the same data set, but has been binned into 1m increments. Data from the ASC2 files were converted to Excel format and included in the main dataset, as that matches the data collected with the Sonde.

Eureka Manta 2 Sonde

At each site, the Eureka Manta 2 Sonde was placed into the water off the side of the R/V Gibraltar III. The Sonde was slowly lowered through the water column and was stopped every meter. At each meter increment the data readout from the Sonde was recorded into a notebook. The Sonde was lowered through the entire water column, but was only used to record water conditions on the way down through the water column. There are no associated raw files for this data, as the data was recorded directly from a real-time readout.

2021 Cruises

May 12-13: Superior cruise R/V Blue Heron (BH21-02)
July 12-14: Erie cruise R/V Gibraltar III
Aug 8-15: Superior cruise R/V Blue Heron (BH21-09)
Aug 24-28: Erie cruise R/V Blue Heron (BH21-10)
Oct 11-13: Erie cruise R/V Gibraltar III
Oct 18-20: Superior cruise R/V Blue Heron (BH21-20)

2022 Cruises

May 25-27: Superior cruise R/V Blue Heron (BH22-05)
May 31-June 2: Erie cruise R/V Gibraltar III
July 5-7: Erie cruise R/V Gibraltar III
July 12-14: Superior cruise R/V Blue Heron (BH22-11)
Aug 14-16: Lake Superior cruise R/V Blue Heron (BH22-15)
Aug 20-24: Lake Erie cruise R/V Blue Heron (BH22-15)
Oct 3-5: Erie cruise R/V Gibraltar III
Oct 10-12: Superior cruise R/V Blue Heron (BH22-26)

2023 Cruises

May 23-25: Superior cruise R/V Blue Heron (BH23-04)
May 31-June1: Erie cruise R/V Gibraltar III
July 6-9: Superior cruise R/V Blue Heron (BH23-07)
July 12-13: Erie cruise R/V Gibraltar III
Aug 15-17: Superior cruise R/V Blue Heron (BH23-10)
Aug 21-25: Erie cruise R/V Blue Heron (BH23-10)
Oct 10-13: Superior cruise R/V Blue Heron (BH23-21)

2024 Cruises

May 1-16: Erie cruise R/V Gibraltar III