Maria Josefina Olascoaga
Research Projects
If you are interested in pursuing graduate studies
at RSMAS in any of these areas,
there are opportunities within the group.
If you are interested in pursuing graduate studies
at RSMAS in any of these areas,
there are opportunities within the group.
We have developed a methodology to predict major short-term changes in environmental contamination patterns, such as oil spills in the ocean. Our approach is based on the identification of key material curves, widely known as Lagrangian Coherent Structures (LCSs), that drive tracer mixing in unsteady two-dimensional flows. More specifically, some of these LCSs admit highly attracting cores that lead to inevitable material instabilities. As such, these LCS cores have the potential to forecast imminent shape changes in the contamination pattern, even before the instability builds up and brings large masses of water or air into motion. Exploiting this potential, our methodology, which we have called LCS-core analysis, provides a model-independent forecasting scheme that relies only on already observed or validated flow velocities at the time the prediction is made. The L C S-core analysis was applied to the Deepwater Horizon oil spill in the Gulf of Mexico to predict major instabilities in the shape of the oil slick.
The methodology we have developed and applied to the Deepwater Horizon Oil Spill can be used to predict the short-term changes of any tracer in a flow. We are testing the LCS-core analysis using reanalyzed wind data in an attempt to forecast changes in the ash cloud produced by the Eyjafjallajškull volcano eruption in Iceland in 2010.
Analysis of drifter trajectories in the Gulf of Mexico (GoM) has revealed the existence of a region on the West Florida Shelf (WFS) that is not visited by drifters that are released outside of the region. This so-called “forbidden zone” (FZ) suggests the existence of a persistent cross-shelf transport barrier on the southern portion of the WFS. Seven-year-long records of surface currents produced by a Hybrid- Coordinate Ocean Model simulation of the GoM are used to compute Lagrangian coherent structures (LCSs), which reveal the presence of a persistent cross-shelf transport barrier in approximately the same location as the boundary of the FZ. The analysis also suggests the existence of other two regions with similar isolation characteristics on the Texas-Louisiana Shelf and the Yucatan Shelf.
Olascoaga etal. (GRL, 2006)
Beron-Vera and Olascoaga (JPO, 2009)
Olascoaga (NPG, 2010)
Several theories have been proposed to explain the development of harmful algal blooms (HABs) produced by the toxic dinoflagellate Karenia brevis on the West Florida Shelf. We are evaluating causative factors of HABs using novel and dynamic modeling techniques that focus on simulating early developmental stages of K. brevis. These aims are critical for prediction and prevention efforts aimed at minimizing human health exposures.
Olascoaga etal.(GRL,2006)
Olascoaga etal.(JGR,2008)
Olascoaga (NPG, 2010)
Maze et al. (in preparation, 2012)
Liang et al. (in preparation, 2012)
The accumulation of pollutants near the shoreline can result in low quality coastal water with negative effects on human health. To understand the role of mixing by tidal flows in coastal water quality we study the nearshore Lagrangian circulation. Particular focus is placed on Hobie Beach, a recreational subtropical marine beach located in Virginia Key, Miami, Florida. According to studies of water quality, Hobie Beach is characterized by high microbial levels. Possible sources of pollution in Hobie Beach include human bather shedding, dog fecal matter, runoff , and sand eflux at high tides. Consistent with the patterns formed by satellite-tracked drifter trajectories, the LCSs extracted from simulated currents reveal a Lagrangian circulation which favors the retention near the shoreline of pollutants released along the shoreline, which can help explain the low quality water registered at Hobie Beach.
Fiorentino et al. (submitted, 2012)
We are currently applying dynamical systems techniques to objectively identify and track oceanic mesoscale eddies in altimetry sea-surface height (SSH) datasets.
Photo credit: http://thecelestialconvergence.blogspot.com/2012/02/monumental-earth-changes-underwater.html
