Fine-scale thermohaline structure revealed by seismic reflection profiling in the Gulf of California.

We present cross-sectional acoustic images of the ocean revealed by standard seismic-reflection profiling acquired in the Gulf of California. The data were acquired with a 6 km streamer, 480 channels and 20 gun array with a frequency content of 10-120 Hz. Seismic lines acquired in several different locations throughout the Gulf of California show similar characteristics. The images reveal acoustic reflections caused by fine-scale thermohaline structure. These reflections are prominent in the uppermost 500 m of the water column and become weaker with depth until they reach 1000 m, where they disappear as the abyssal waters become acoustically transparent. Time-lapse cross-sectional images show no overall change in reflectance characteristics in the uppermost 500m and in deeper waters, but the location of the reflections varies slightly between the images. We believe that these changes in location are consistent with the dynamics of internal waves.