OBSERVATION, ANALYSIS AND MODELING OF THE SEA BREEZE CIRCULATION DURING THE NOAA/ARL-JSU METEOROLOGICAL FIELD EXPERIMENT SUMMER 2009

摘要

In this study an attempt is made to simulate thediurnal variations of the coastal land and sea breezeatmospheric circulations over the Mississippi GulfCoast region. It is known that the characteristics ofthe coastal circulations are dependent on the localtopography and land use patterns and theMississippi Gulf Coast region assumes importancedue to its complex terrain features and land use andhouses number of industries.Observations collected at the locations ofHarrison County School and Wiggins Airport,situated normal to the Mississippi Gulf Coast region,during June-2009 as a joint NOAA-ARL and JSUTLGVRCfield experiment, were analyzed tounderstand the characteristics of the sea breezecirculation. These comprise radio-sondeobservations collected at 5 times of 0900, 1100,1300, 1500 and 1700 CST (local US time) for fourconsecutive days of 16 to 19 June, 2009. The mainobjective of this field experiment was to study thecoastal boundary layer structure associated with thedevelopment of sea breeze circulation. During thisperiod, radio-sonde observations were collected atthe two locations, normal to the Mississippi GulfCoast, of Harrison County School (30.5N,89.1W)and Wiggins Airport (30.8N,89.13W) at five times(i.e.) 1400, 1600, 1800, 2000 and 2200 UTC daily.For the modeling part, a high resolutionmesoscale model, ARW (Advanced Research WRF),was used to simulate the boundary layercharacteristics associated with the sea breezecirculation over the Gulf Coast Region correspondingto this 4-day period. The model was designed tohave nested two-way interactive three domains with36, 12 and 4 km resolutions, with the inner mostdomain covering the entire Gulf Coast region, and 41vertical levels of which 30 levels were chosen to bebelow 500 hPa level so as to fine resolve theboundary layer features. The initial and boundaryconditions were provided from NCEP FNL dataavailable at 1 degree interval and the boundaryconditions were updated at every 6 hours. Themodel was integrated for 48 hours starting from 00and 12 UTC of each day starting from 15 June up to00 UTC of 18 June 2009.The model simulated atmospheric fields were usedto derive the wind, temperature and humidityparameters corresponding to the two locations andthe available observation times. The model resultswere compared with corresponding observations forvalidation. The model could simulate the gradualdevelopment and strengthening of the sea breezewith the progress of daytime. The model could alsosimulate the variations in the sea breeze at the twolocations which are separated by about 25 miles.From the model output, the horizontal and verticalextent of the sea breeze circulation at different timeduring the daytime period could be identified. Thetemperature and humidity variations associated withthe sea breeze circulation over the Gulf Coast regionwere also analyzed. These features were comparedwith the observations collected at the two locationsof Harrison County School and Wiggins Airport.These features are noted to have goodcorrespondence with the observations. This studydemonstrates the use of WRF ARW high resolutionmodel in the mesoscale atmospheric predictionapplications.