Date of Completion

5-3-2016

Embargo Period

5-3-2016

Advisors

James Edson, Michael Whitney

Field of Study

Oceanography

Degree

Master of Science

Open Access

Open Access

Abstract

Sea breezes are mesoscale atmospheric coastal circulations that develop in response to diurnal variations in the land-sea thermal gradient resulting in cooler air temperatures in coastal regions. Accurate numerical model hindcasts and forecasts of sea breezes, used to study and predict these circulations, are important for a variety of communities beyond the atmospheric sciences. For example, sea breezes can influence marine processes such as oceanic upwelling, estuarine circulation, and air-sea fluxes, as well as impact the energy, aviation, and air quality industries. Representations of the coastline and sea surface temperature (SST) in the numerical model can influence simulated sea breezes. In this study, a series of sensitivity experiments are performed to highlight the impact of the horizontal resolution of the numerical coastline and SST on simulated sea breeze dynamics.

The 21 August 2013 and 08 July 2013 coastal CT sea breeze events are simulated using the Weather and Research Forecasting (WRF) model, initialized with the 32 km North American Regional Reanalysis (NARR) for atmospheric conditions. Coastline sensitivity experiments compare simulated sea breeze circulations using a coastline resolved at 32 km (O(NARR)) and 1 km (O(WRF)). Sea surface temperature sensitivity experiments compare a spatially uniform SST (22˚C), NARR (32 km) spatially varying SST, and the G1SST (1km) spatially varying SST.

Coastline sensitivity experiments illustrate the use of a relatively coarse representation of the coastal geography results in the mischaracterization of western Long Island Sound as land, resulting in an inaccurate land-sea temperature gradient and thus an inaccurate sea breeze circulation. Sea breeze circulations are less sensitive to the resolution of the offshore SST, though the inland propagation distance of the sea breeze front varies among the sensitivity experiments. While the surface fluxes respond to the varying SST products, the impact on the overlying air temperature is confined to the lowest 100 m of the marine atmospheric boundary layer due to the relatively high stability limiting vertical mixing.

Major Advisor

Kelly Lombardo

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