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

Florida

By: Takashi KidaMeteorology

Department of Marine and Environmental SystemsCollege of Engineering

Florida Institute of Technology

Objective

• Purpose of this study

To validate two theories on the development of convergence zones in areas of irregular coast lines.

1. Coast line curvature effects.

2. 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 & Convergence

Simpson 1994Sills1998

Impact of Coriolis Force• McPherson (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 simulation 6 hours into simulation

Curvature Only

Major convergent zone migrates with time.

Two convergent zones at convex coastline regions.

1

D

Curvature + Coriolis

Later

Sea BreezeMaximum

Convergence Zone Divergence Zone

D

Migration

2

Methods (Data Analysis)

• Sea Breeze Identification Radar imagery, surface winds, and temperature Sharp wind shifts from westerly to easterly Timing of the sea breeze passage

• Maximum Convergence Identification FIT Meteorology high resolution surface objective analysis (4km)

Kennedy Space Center Network APRS Weather Network WXFL Network NWS/FAA stations FIT Davis Weather Stations

Values not sustaining at least -80 * 10-5 s-1 for a minimum of two hours were filtered out

Methods: FIT Surface Stations

FIT#1 (28°45’05.3” N 080°46’04.4”W)FIT#2 (28°40’24.9” N 080°42’54.3”W)FIT#3 (28°39’02.8” N 080°37’45.3”W)FIT#4 (28°42’11.3” N 080°40’05.2”W)FIT1

FIT3

FIT2

FIT4

June 23, 2008 22Z

Case Study: June 23, 2008

Sea breeze identification using surface observations and NWS MLB NEXRAD.

19Z (3PM)

Convergence Values from the FIT High Resolution Surface Analysis

19Z (3PM)

Sea breeze identification using surface observations and NWS MLB NEXRAD.

20Z (4PM)

Convergence Values from the FIT High Resolution Surface Analysis

20Z (4PM)

Sea breeze identification using surface observations and NWS MLB NEXRAD.

21Z (5PM)

Convergence Values from the FIT High Resolution Surface Analysis

21Z (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.

17Z

18Z

19Z

20Z

21Z

22Z

Time

Maximum Convergence Zones for 10 Sea Breeze Cases

Conclusion

• The 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.

Reference

Sills, 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, 193–211.

McPherson, R.D., 1970: A Numerical Study of the Effect of a Coastal Irregularity on the Sea Breeze. J. Appl. Meteor., 9, 767–777.

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