Chirp sub-bottom geophysical data offshore of the Lower Mississippi River Delta, Louisiana, collected from the R/V Acadiana, 2024-06-23 to 2024-07-02

In June-July 2024, 831 line-kilometers of Chirp sub-bottom geophysical data were collected in shallow water offshore of the Lower Mississippi River Delta as part of the Mississippi River Delta Transition Initiative (MissDelta) project. This dataset serves as an archive of raw, high-resolution Chirp sub-bottom files in standard Society of Exploration Geophysicists (SEG) SEG-Y revision 1 format, which produce high-resolution, shallow-penetration images of stratigraphy beneath the seafloor. Data were collected using an Edgetech DS2000 towfish instrument that was towed at a depth of 1-3 meters below the water's surface. This instrument collected both sub-bottom geophysical data and sidescan sonar data concurrently. The Chirp system emitted a high frequency pulse of 2-16 kHz with a 20 to 40 millisecond pulse at a ping rate of 5 Hz. Acoustic energy transmitted from the instrument was reflected off density boundaries in seafloor or sub-seafloor sediment layers, received by the transducer, and recorded by a topside computer. This process generated a two-dimensional profile of the structure of sediment layers beneath the towfish and the seafloor. Positioning data for the Chirp geophysical data was collected by a Hemisphere Global Positioning System antenna.