Giovanni Jimenez--PhD Thesis Defense

(Penn State, Department of Meteorology and Atmospheric Science)

"The Orinoco low-level jet"

What GR Homepage PhD Defense
When Sep 21, 2018
from 08:30 am to 11:00 am
Where 529 Walker Building
Contact Name Giovanni Jimenez
Contact email
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"Advisor: Paul Markowski"

The low-level jet over the Orinoco River basin is characterized using finer horizontal, vertical, and temporal resolution than possible in previous studies via dynamical downscaling. The investigation relies on a 5-month-long simulation (November 2013- March 2014) performed with the Weather Research and Forecasting model, with initial and boundary conditions provided by the Global Forecast System analysis. The Orinoco low- level jet (OLLJ) is found to be a single stream tube over Colombia and Venezuela with wind speeds greater than 8 m s-1, and four distinctive cores varying in height under the influence of sloping terrain. The momentum balance analysis performed in a streamwise- and crosswise-rotated coordinate system showed that the OLLJ is the result of four phenomena acting together to accelerate the wind, i.e., a sea-breeze penetration over the Orinoco River delta and Unare River depression, katabatic flow down the Coastal Cordillera, three expansion fans from point wakes in topography, and diurnal variation of turbulent diffusivity. The latter, opposite to what happens in higher latitudes, plays a secondary role in the OLLJ formation. These results suggest that LLJs near the equator may be originated from different phenomena besides the classical inertial oscillation and topographic thermal forcing mechanisms.