Code 7250

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The REMOTE SENSING HYDRODYNAMICS BRANCH of the Remote Sensing Division at The Naval Research Laboratory NRL) conducts basic and applied research into remotely sensed ocean surface and subsurface phenomena. Detailed information is given by the Mission Statement and Branch Organization. A few examples of our work are shown below.

PROJECTION OF SURFACE CURRENTS TO SUBSURFACE Velocity projection is a practical method of obtaining profiles of subsurface currents from surface current and wind data derivable from radar remote sensing, drifters, or ocean feature tracking. This poster was presented at the Operational Oceanography Symposium, Oceanology International in London on March 5, 2002. Application of velocity projection to three coastal sites is shown, where the surface current data were obtained with shore based HF radars.

[RAR] CONVERGENT FRONT ON THE CONTINENTAL SHELF DETECTED BY AIRBORNE RADAR This X-band radar image (~2.25x1.25km) was one of several collected by Farid Askari near Cape Hatteras, NC. during the first High Resolution Remote Sensing Experiment. (A much larger version of the image is available.) This image shows a converging front (rip) at the shoreward boundary of a Gulf Stream meander and the continental shelf waters (red line indicating highbackscatter). It also shows an accumulation of surfactants on the north side of the rip (dark blue line indicating low backscatter). The collection of images, together with other airborne, satellite, and in-situ measurements taken during the experiment provide a unique study of the temporal evolution of a converging front. The experiment also contributed to the merging of experimental data from multiple sources and the theoretical modeling needed to better understand the underlying dynamics as well as posing questions for future research.

[Duck,NC] PASSAGE OF A SALINITY FRONT DETECTED BY MARINE RADAR This sequence of radar images show the shoreward propagation of a salinity front and were collected by Dennis Trizna during an experiment at the the US Army Coastal Engineering Research Center's facility at Duck, NC. The semicircular images (centered on the land end of the pier) have a 1040 m radius, a six-meter pixel size, and were collected at five minute intervals. The location of the front is characterized by small scale breaking and is marked by a high radar cross section. After the passage of this front, local currents increased from small, wave-induced fluctuations to 60 cm/s to the right (northward). Evidence of the current can be seen in the movement of the buoys northward as the front passes each of them in the movie sequence. Local surface roughness also increased behind the front, which increased the ambient radar echo. These data are currently being studied in conjunction with other surface truth data collected at the pier site to improve our understanding of the air-sea interaction processes associated with such strong frontal features. Both an mpeg movie and a self-animated gif are available.

[Model] SIMULATION OF GULF STREAM MEANDER ONTO THE CONTINENTAL SHELF Many numerical simulations have been performed to better understand the causes and dynamics of ocean phenomena such as the rip shown above. An mpeg movie of one such simulation is available. This shows the evolution of the density field as Gulf Stream water subducts under continental shelf water forming a rip or hydraulic jump. In this experiment a rotor is formed behind the jump and then moves to the left as the jump moves to the right.

ADDITIONAL EXAMPLES OF OUR WORK ARE:

Coastal Ocean Physics

Simulations of Radar Imagery of the Ocean

Small Scale Air-Sea Interfacial Physics Surface

This page has been certified by Dr. Philip R. Schwartz Superintendent, Remote Sensing Division

This page is maintained by: Gloria Lindemann
It was last modified on March 28, 2002.