Prof. Ruby Krishnamurti
Time: Monday, April 13, 2015 at 2:30 PM
Place: Melvin Stern Seminar Room, 018 Keen Bldg.
Refreshments will be served at 2:00 PM
ABSTRACT: This report is an update on two laboratory experiments: 1. Estuary salt flux model and 2. Source-sink flow on a rotating beta plane.
Cool fresh water from rivers and/or rainfall can lie over warm saline seawater in the Bay of Bengal (B.B.). This arrangement is shown to be susceptible to diffusive convection. Laboratory models show that the resulting flow is in the form of predominantly horizontal motion with narrow regions of sinking (and rising) and with very little vertical mixing outside of these regions. The importance of this non-mixing is noted in the layered salinity profiles in the northern BB, intact after wintertime cooling. This is an important characteristic for determining the strength of thermal forcing of the atmosphere by the upper ocean.
In the second experiment, with source in the north, sink in the south, a two-gyre flow results with anticyclinic circulation in the north, cyclonic in the south. At the confluence of these two gyres, a bottom boundary current is found that is an order of magnitude deeper than an Ekman layer. This result is found both for homogeneous fluid and for diffusive convecting two-layer fluid. A nonlinear (Oseen approximate) bottom boundary layer analysis shows a depth E1/4 layer (where E is the Ekman number) which is, for our experiment parameters, an order of magnitude greater than the classical E1/2 Ekman layer, and is in agreement with observations.
GFDI Associate Dr. Ming Ye appeared in a recent episode of NOVA, Sinkholes—Buried Alive, which aired January 28, 2015 on PBS. Dr. Ye demonstrated a laboratory model of sinkhole formation designed by Dr. Daniel Kuncicky and run by graduate students Xia Tao and Roger Pacheco. The segment starts at 14:32