(5) Combining the bottom stress estimates from BASS (data of Dr. William and 



Churchill of WHOI), to reach a formulation for the bottom boundary condition for 

 sediments, relating stress and a reference concentration. 



SPATIAL AND TEMPORAL SAMPLING SCALES 



The LIS ST instrument measures the size distribution and concentration of particles at a 

 minimum of 7.7 cm above bed - a distance chosen to ensure that the instrument does not cause 

 local scour. The sample volume dimensions are 5 mm long x 3 mm dia. Samples are possible 

 at 0.1 second intervals, however such sampling requires enormous memory. As a result our 

 present sampling scheme is to obtain 1Hz data for 100 seconds, every 6 hours. An on-board 

 pressure sensor, recording synchronously, permits correlation of particle data with sediments. 



METHODS AND PLATFORMS 



The instrument is mounted on Dr. Williams' tall tripod. 



STRENGTHS AND LIMITATIONS OF PROPOSED RESEARCH 



The measurement is new and sorely needed for boundary layer physics. A limitation is 

 that the measurements do not specifically separate organic mass from total sediment mass. This 

 will be addressed by combining Dr. Lohrenz's fluorometry data. 



STATUS OF RESEARCH 



The LISST-3 instrument was deployed on the mid- Atlantic bight July 23. Recovery 

 cruise is planned for late august. Data analysis and subsequent cruise participation will then 

 follow. 



Keywords: benthic boundary layer, particle size spectra, suspended sediments 



