Santala Markku J.

No Thumbnail Available
Last Name
Santala
First Name
Markku J.
ORCID

Filters

2 1
1989 - 1989 1 1990 - 1991 1
1 1
2
Reset filters

Settings

Search Results

Now showing 1 - 2 of 2
  • Technical Report
    The surface acoustic shear sensor (SASS) as used during the Shelf Mixed Layer Experiment (SMILE) November 1988-March 1989
    (Woods Hole Oceanographic Institution, 1989-07) Montgomery, Ellyn T. ; Santala, Markku J.
    The SMILE (Shelf Mixed Layer Experiment) field program took place during the winter of 1988-1989. The SMILE program itself was large and involved many investigators and instruments. This report documents the use of the Surface Acoustic Shear Sensor (SASS) as part of the suite of measurements taken during SMILE. The SMILE mooring array was deployed from early November 1988 until June, 1989. SASS, being a newly developed instrument, was deployed for two shorter periods; a test deployment between November 26 and December 8, 1988, and a longer second deployment, February 23 through March 14, 1989. SASS is based on BASS (Benthic Acoustic Stress Sensor) components (Williams et al., 1987), mounted on a structure that allowed continuous sampling of velocity, temperature and conductivity in the top five meters of the ocean. BASS was modified for this surface application to acquire data from a gyro, and conductivity sensors. The attitude data from the gyro allows the velocities of the current meter to be referenced to an inertial frame of reference. The other data obtained from SASS will be used to calculate shear current gradients, and other descriptors of turbulence and mixing.
  • Thesis
    Surface-referenced current meter measurements
    (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1991-09) Santala, Markku J.
    A general discussion of possible techniques for observation of near-surface currents indicates that the surface-following frame of reference will provide several advantages over the Eulerian or Lagrangian frames. One problem with surface-following measurements is the biasing effects of the waves. A technique for making unbiased measurements is developed. This technique requires that both the sensor velocity and the fluid velocity be measured. A sensor platform, the Surface Acoustic Shear Sensor (SASS), which makes the required measurements is described. The processing scheme for interpreting the measurements from the SASS is described at length. The data that SASS has obtained from two deployments in the Shelf Mixed Layer Experiment (SMILE) is presented. This data shows clearly that the biasing effects of waves can not, in general, be ignored. In the summary of the data we find surprisingly little shear in the downwind direction in the top 4m of the water column. In the crosswind direction observed, observed shear seems to be indicative of an across shelf pressure gradient and intense near-surface mixing.