Grace C. Chang - Research

Current Research

Since joining the Ocean Physics Laboratory (OPL) as a graduate student and now as a researcher, I have been studying various oceanographic topics such as: theoretical optics and bio-optics, temporal and spatial variability, bottom boundary layers and sediment resuspension, internal solitary waves, frontal processes, thermodynamics, biogeochemical cycling, and ecosystem dynamics and harmful algal blooms. I have also been active in the area of ocean technologies, i.e., sensor development and testing, observatory system design, and anti-biofouling methods. I am especially interested in interdisciplinary coastal ocean experiments because they enable the study of physical processes (e.g., air-sea interaction, wind mixing, surface and internal gravity waves, tides, sediment resuspension, mesoscale advection and mixing) coupled with bio-optical responses, which are important for establishing an understanding of particulate (including organisms, sediment, and contaminants) movement and distribution in the water column and along the ocean bottom. The results have value for assessing various aspects of the global carbon budget, environmental impacts, and ultimately the role of the coastal ocean in global climate change, as particulate motion influences organic matter and primary production.

Currently, I am working on the HyCODE and MOSEAN experiments. HyCODE is an ONR sponsored project; it is a five-year ONR initiative, which began in January 1999. HyCODE is designed to utilize hyperspectral imagery to improve understanding of the diverse processes controlling inherent optical properties (IOPs) in the coastal ocean. The program will also develop operational ocean color algorithms in both the optically-shallow ocean (i.e., where the signal detected by the satellite sensor is affected by the seafloor) and the optically-deep ocean (i.e., where the signal detected by the satellite sensor is not directly affected by the seafloor).
MOSEAN is a NOPP-funded experiment designed to develop and test relatively small, lightweight optical and chemical sensors for autonomous deployment. We have deployed these new instruments on a shallow-water mooring in the Santa Barbara Channel. Data are real-time telemetered to my house. My main interest is using these new technologies for scientific purposes: phytoplankton identification (including harmful algal blooms) and determining factors contributing to variability in remote sensing reflectance.

Previous Research

As a graduate student, I worked at the UCSB OPL on the ONR-sponsored Coastal Mixing and Optics Project (CMO). The goal of my study was to determine how particle and optical properties respond to physical forcing under various oceanic conditions. The approach to the research is to collect time-series of physical and optical data at several depths with moorings placed at a mid-shelf location on a broad continental shelf just south of Martha's Vineyard near Cape Cod, Massachusetts. The first deployment was from July 8 - September 25, 1996, and the second deploymentfrom September 25, 1996 - January 3, 1997. The third deployment was from January 6 through April 6, 1997, and the fourth deployment was from April 16 through June 11, 1997.

The time-series from the first deployment provides a new data set showing the effect of Hurricane Edouard and Hurricane Hortense on physical, optical, and particle properties in the coastal ocean. This study contributed to investigations of the predictions of tropical storms, and thus, the prevention of extensive storm damage in coastal areas.

I had also been working on the Bermuda Testbed Mooring project. My work has mostly involved the a single instrument that takes concurrent measurements of attenuation and absorption characteristics at nine wavelengths (WET Labs, Inc. ac-9) in the water column.

As an undergraduate at the University of Minnesota, I worked as a Junior Research Scientist at the St. Anthony Falls Laboratory for Professor Gary Parker, where I gained valuable research experience in particle transport. I conducted experiments studying downstream fining and other scale-related problems, viscous layers affecting downstream coarsening, debris flows in turbidity currents, and the relationship between Reynolds numbers and the formation of alluvial fans.