FIELD OBSERVATIONS AND MODEL SIMULATIONS OF LOW-LEVEL FLOWS OVER THE MID-ATLANTIC DURING AUGUST 1-5, 2006

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dc.contributor.advisorZhang, Da-Linen_US
dc.contributor.authorRabenhorst, Scott Danielen_US
dc.contributor.departmentAtmospheric and Oceanic Sciencesen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2013-04-04T05:39:55Z
dc.date.available2013-04-04T05:39:55Z
dc.date.issued2012en_US
dc.description.abstractFor years, basic mountain, sea breeze, and low-level jet (LLJ) circulations have been studied, usually in locations with a high frequency of occurrence, sharp gradients, or significant geographic prominence. However, there is evidence that similar circulations exist in non-classic locations with more mild topography and atmospheric gradients. One such understudied area is the U.S. Mid-Atlantic region. The Water Vapor Variability - Satellite/Sondes (WAVES) 2006 field campaign provided a contiguous 5-day period of concentrated high resolution observations to examine fine-scale details of a weather pattern typical of the Mid-Atlantic summertime. These measurements presented an opportunity for an intensive modeling study to further investigate peculiar phenomena with verification against research-grade observations. The observations captured two significant events: an official LLJ and a cold front with a prefrontal trough. A pronounced diurnal cycle was revealed which can be categorized into three stages: (1) daytime growth of the planetary boundary layer (PBL), (2) flow intensification into a LLJ regime after dusk, and (3) interruption by downslope winds (DW) after midnight. The third stage is most interesting owing to the lack of literature documenting similar occurrences in the Mid-Atlantic, which can impact air quality forecasting. Prior to high resolution modeling of the case study, sensitivity studies were conducted examining four areas to which the model was believed most sensitive: (1) initial condition data, (2) cumulus schemes, (3) PBL parameterizations, and (4) initialization times. Results also revealed shortcomings in model precipitation and PBL profiles, model biases, urban anomalies, and tendencies for forecast convergence. High resolution regional modeling showed the evolution of these nocturnal events and were verified against WAVES observations. A hybrid solenoidal influenced afternoon and early evening circulation east of the mountains. Afternoon deepening of a lee trough by an oscillating warm air band influenced low-level wind fields. Wind flow was further influenced by the thermal wind that originated over sloping terrain. Airflow traversed the Appalachian barrier and moved down the east flank of the Appalachians with katabatic and hydraulic contributions. This DW swept the LLJ regime off to the southeast. The prefrontal LLJ outflow in the Midwest strengthened DW events as the cold front approached.en_US
dc.identifier.urihttp://hdl.handle.net/1903/13824
dc.subject.pqcontrolledAtmospheric sciencesen_US
dc.subject.pquncontrolleddownslope windsen_US
dc.subject.pquncontrolledlow level flowsen_US
dc.subject.pquncontrolledlow level jeten_US
dc.subject.pquncontrolledmidatlanticen_US
dc.subject.pquncontrollednocturnal flowsen_US
dc.subject.pquncontrolledwaves 2006en_US
dc.titleFIELD OBSERVATIONS AND MODEL SIMULATIONS OF LOW-LEVEL FLOWS OVER THE MID-ATLANTIC DURING AUGUST 1-5, 2006en_US
dc.typeDissertationen_US

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