Abstract
Eddy viscosity parameterizations that depend on a gradient Richardson number R (sub i) have been most pertinent to the open ocean. Parameterizations applicable to stratified coastal regions typically require implementation of a numerical model. Two novel parameterizations of the vertical eddy viscosity, based on R (sub i) , are proposed here for coastal waters. One turbulence closure considers temporal changes in stratification and bottom stress and is coined the "regular fit." The alternative approach, named the "lateral fit," incorporates variability of lateral flows that are prevalent in estuaries. The two turbulence parameterization schemes are tested using data from a Self-Contained Autonomous Microstructure Profiler (SCAMP) and an Acoustic Doppler Current Profiler (ADCP) collected in the James River Estuary. The "regular fit" compares favorably to SCAMP-derived vertical eddy viscosity values but only at relatively small values of gradient R (sub i) . On the other hand, the "lateral fit" succeeds at describing the lateral variability of eddy viscosity over a wide range of R (sub i) . The modifications proposed to R (sub i) -dependent eddy viscosity parameterizations allow applicability to stratified coastal regions, particularly in wide estuaries, without requiring implementation of a numerical model. Abstract Copyright (2017). American Geophysical Union. All Rights Reserved.