The Effect of Coastline Curvature and Sea Breeze Development on the Maximum Convergence Zone at Cape Canaveral, Florida

By: Takashi KidaMeteorologyDepartment of Marine and Environmental SystemsCollege of EngineeringFlorida Institute of Technology

Objective

Purpose of this studyTo validate two theories on the development of convergence zones in areas of irregular coast lines.

Coast line curvature effects.Coast line curvature with modification by the Coriolis force.

Why should this subject be investigated? Coast line curvature is an important factor in determining the location of the maximum convergence zone. The heaviest precipitation occurs near convex coastlines (Baker et al. 2001)

Coast Line Curvature & ConvergenceSimpson 1994Sills1998

Impact of Coriolis ForceMcPherson (1970) showed modification of coastline convergent zones due to the Coriolis effect in model simulations, causing asymmetries in convergence zones.

However, Banta et al. (1993) did not find evidence of Coriolis impact on the sea breeze in an observational study over Monterey Bay, California.2 hours into simulation6 hours into simulation

Curvature OnlyMajor convergent zone migrates with time.Two convergent zones at convex coastline regions.1DCurvature + CoriolisLaterSea BreezeMaximum Convergence ZoneDivergence ZoneDMigration2

Methods (Data Analysis)

Sea Breeze IdentificationRadar imagery, surface winds, and temperature Sharp wind shifts from westerly to easterlyTiming of the sea breeze passage

Maximum Convergence IdentificationFIT Meteorology high resolution surface objective analysis (4km)Kennedy Space Center NetworkAPRS Weather NetworkWXFL NetworkNWS/FAA stationsFIT Davis Weather StationsValues not sustaining at least -80 * 10-5 s-1 for a minimum of two hours were filtered out

Methods: FIT Surface Stations

FIT#1 (284505.3 N 0804604.4W)FIT#2(284024.9 N 0804254.3W)FIT#3 (283902.8 N 0803745.3W)FIT#4 (284211.3 N 0804005.2W)

FIT1FIT3FIT2FIT4

June 23, 2008 22ZCase Study: June 23, 2008

Sea breeze identification using surface observations and NWS MLB NEXRAD.19Z (3PM)

Convergence Values from the FIT High Resolution Surface Analysis19Z (3PM)

Sea breeze identification using surface observations and NWS MLB NEXRAD.20Z (4PM)

Convergence Values from the FIT High Resolution Surface Analysis20Z (4PM)

Sea breeze identification using surface observations and NWS MLB NEXRAD.21Z (5PM)

Convergence Values from the FIT High Resolution Surface Analysis21Z (5PM)

Zone 1 not predicted by coastline curvature.

Inclusion of Coriolis predicts a 2nd maximum, but one that migrates. The timing does not validate this theory. 17Z18Z19Z20Z21Z22ZTimeMaximum Convergence Zones for 10 Sea Breeze Cases

ConclusionThe maximum convergence zone located in the center of Cape Canaveral was consistent with the coastline curvature theory.

The secondary maximum convergence zone at north of Cape Canaveral was not predicted either by the coastline curvature or the Coriolis effect theories.

ReferenceSills, D.M.L., 1998: Lake and land breezes in southwestern Ontario: observations, analyses and numerical modeling. PhD dissertation. York University, 338 pp. [Available from the Centre for Research in Earth and Space Science, York University, 4700 Keele St., Toronto, Ontario, Canada, M3J 1P3]

Baker, R.D., B.H. Lynn, A. Boone, W.K. Tao, and J. Simpson, 2001: The Influence of Soil Moisture, Coastline Curvature, and Land-Breeze Circulations on Sea-Breeze-Initiated Precipitation. J. Hydrometeor., 2, 193211.

McPherson, R.D., 1970: A Numerical Study of the Effect of a Coastal Irregularity on the Sea Breeze. J. Appl. Meteor., 9, 767777.

Miller S.T.K., B. D.Keim, R. W. Talbot, and H. Mao, 2003: Sea Breeze: Structure, Forecasting, and Imapacts. Climate Change Reserch Center, Institute for the Study of Earth, Ocean and Space, University of New Hampshire, Durham, New Hampshire, USA

Questions?Stephanie James