Cloud Evolution and the Sea Cloud Evolution and the Sea Breeze FrontBreeze Front
Jennifer Bewley
Dept. of Marine and Environmental Systems
Florida Institute of Technology
Melbourne, FL 32901
OverviewOverview
• What is a sea breeze?• What is a sea breeze front?• Satellite Cloud Edge• Radar Thin Line• Why study sea breezes?• Objectives• Method• Data• Synoptic Setting• Results• Conclusions• Questions
Background InformationBackground Information• What is a sea breeze (SB)?
– Differential heating between land and sea– Formation of a thermal low over the land and a
thermal high over the water– A pressure gradient forms, air flows from high to low
pressure– Creates the sea breeze– Opposite effect happens at night creating the land
breeze
• What is a sea breeze front (SBF)?– The leading edge of the sea breeze– A drop in temperature, a wind shift, and an increase in
relative humidity occurs behind the front
Sea Breeze CirculationSea Breeze Circulation
Source: <http://www.bom.gov.au/weather/nsw/amfs/Sea%20Breeze.shtml>
Background Info. Continued…Background Info. Continued…
• Satellite Cloud Edge– Seen on visible or
infrared satellite images
– A line of cumulus clouds, parallel to the shore, with no more clouds on the seaward side of the line of development
Background Info. Continued…Background Info. Continued…
• Radar Thin Line– A region of enhanced radar reflectivity in the optically clear
boundary layer detected by a sensitive Doppler radar – Intense mixing of land and marine air provides several
interfaces capable of reflecting radio energy
Why Study Sea Breezes?Why Study Sea Breezes?
• Forecasting– Changes temperature, wind speed and direction, and
relative humidity
• Convection, Clouds, Turbulence• Climate Modeling
– Formation of clouds
• Renewable Energy– Wind and solar energy
• Operationally, how can you accurately locate the SBF?
ObjectivesObjectives
• To compare the location of the satellite cloud edge to the surface sea breeze front and the location of the radar thin line
• To analyze the differences in the location of the indicated features and create a possible vertical profile of the sea breeze front
MethodMethod• Team Beach
– Melbourne Beach– Measured air
temperature, RH, and wind speed every 15 mins.
– Sky observations, water temperature, wave height and period, salinity, and dissolved oxygen were taken every 30 mins.
• Team FIT – Collected data
Method Continued…Method Continued…
• Team Mobile Unit– Traveled west on 192, attempting to transect the SBF– The mobile unit was equipped with a wind vane, cup
anemometer, and radiometer.– Wind speeds, RH, air temperature, sky observations,
percent cloud cover and wind direction were recorded.
Method Continued…Method Continued…
DataData
• Team Beach & Team Mobile Unit– Wind speed and direction
• Team FIT– GOES 4 km visible satellite
imagery – Melbourne NWS Doppler
radar base reflectivity images
– Other surface observations
Synoptic SettingSynoptic Setting
Synoptic SettingSynoptic Setting
Synoptic SettingSynoptic Setting
ResultsResults
• Analyzed the progression of the cloud edge, thin line, and the surface fronts
• Developed a model to find the relation of the features for each day
Results Continued…Results Continued…
Location
Time Distance
Date Radar Cloud Edge Radar Cloud EdgeMay 25* N/A 25 mins behind
surface front
N/A 6.9 km behind
surface front
May 26 N/A 75 mins behind
surface front
N/A 8.1 km behind
surface front
May 27 50 mins ahead
surface front
10 mins behind
surface front
1.5 km ahead
surface front
1.7 km behind
surface front
May 25* = Strong easterly flow
May 25May 25
May 26May 26
May 27May 27
ConclusionsConclusions
• The thin line precedes the surface front which precedes the cloud edge
• The actual distances between these features vary and depend on several factors – Operationally, the satellite cloud edge may not always
be a good indication of the location of the surface SBF
• One improvement would be to have higher resolution data, especially satellite and radar imagery and more sampling sites
AcknowledgementsAcknowledgements• A special thanks to…
– Mr. Splitt for advising this project and aiding with the creation of figures
– Mr. Leslie for the mobile renewable energy station
– Andrew Condon for the synoptic maps
– All the MFP students and TA’s for helping with the data collection
Questions?Questions?
Brian ZachryBrian Zachry