Hypothesized Hypothesized Thermal Thermal

Circulation Cell Circulation Cell Associated with the Associated with the

Gulf StreamGulf StreamAndrew CondonAndrew CondonDepartment of Marine and Department of Marine and

Environmental SystemsEnvironmental SystemsFlorida Institute of TechnologyFlorida Institute of Technology

Melbourne, FL 32901Melbourne, FL 32901July 15, 2004July 15, 2004

OverviewOverview ObjectivesObjectives What is a Thermal Circulation Cell?What is a Thermal Circulation Cell? Ingredients of Cloud FormationIngredients of Cloud Formation Possible Gulf Stream Circulation CellPossible Gulf Stream Circulation Cell Data Collection MethodsData Collection Methods How do we know if it is there? / How do we know if it is there? /

ResultsResults What influences its formation?What influences its formation? SummarySummary

Objectives Objectives Why Why To determine whether To determine whether

or not a secondary or not a secondary thermal circulation cell thermal circulation cell due to the offshore sea due to the offshore sea surface temperature surface temperature gradient associated gradient associated with the Gulf Stream with the Gulf Stream existsexists

If it does exist how can If it does exist how can it be identified and it be identified and what strengthens and what strengthens and hinders its formationhinders its formation

Not well documented, Not well documented, very little research very little research conducted in this areaconducted in this area

Implications for Implications for Marine Meteorology / Marine Meteorology / air-sea interactionair-sea interaction

Marine Interests Marine Interests (recreational and (recreational and commercial): Clouds commercial): Clouds or thunderstorms or thunderstorms along Gulf Stream along Gulf Stream

Thermally-Forced Thermally-Forced CirculationsCirculations

Mesoscale (10’s-100’s km / hours)Mesoscale (10’s-100’s km / hours) Differential Heating: Temperature Differential Heating: Temperature

ContrastContrast Cooler more dense air causes higher Cooler more dense air causes higher

pressure than warmer less dense airpressure than warmer less dense air Pressure gradient exists and the Pressure gradient exists and the

wind starts to blow from high to low wind starts to blow from high to low pressurepressure

Thermal CirculationThermal Circulation Example: The Sea-BreezeExample: The Sea-Breeze

Ingredients for Cloud Ingredients for Cloud DevelopmentDevelopment

LiftLift Convection (Thermals)Convection (Thermals) OrographicOrographic ConvergenceConvergence FrontalFrontal

TemperatureTemperature MoistureMoisture

Possible Gulf Stream Possible Gulf Stream Circulation Cell?Circulation Cell?

Data Collection MethodsData Collection Methods Data Collected May 25, 26, and 27 2004Data Collected May 25, 26, and 27 2004 Visible Satellite Images from Global Visible Satellite Images from Global

Hydrology and Climate CenterHydrology and Climate Center Omega Cross Sections using GARPOmega Cross Sections using GARP MODIS Satellite Images for the Gulf MODIS Satellite Images for the Gulf

Stream LocationStream Location RUC 850 mb Height and Wind AnalysisRUC 850 mb Height and Wind Analysis Surface and buoy temperature Surface and buoy temperature

observationsobservations

Gulf Stream LocationGulf Stream Location

ResultsResultsDay One Visible Satellite Day One Visible Satellite

ImageImage

Day Two Visible Satellite Day Two Visible Satellite ImageImage

Day Three Visible Satellite Day Three Visible Satellite ImageImage

Omega Cross SectionsOmega Cross Sections

The time rate of change of pressure The time rate of change of pressure following an individual air parcelfollowing an individual air parcel

Since pressure decreases with height, Since pressure decreases with height, negative omega indicates rising motion negative omega indicates rising motion positive omega indicates sinking motionpositive omega indicates sinking motion

dpdt

Day One Omega (Vertical Day One Omega (Vertical Velocity)Velocity)

Pres

sure

(m

b)3.5 km

Location

Day Two Omega (Vertical Day Two Omega (Vertical Velocity)Velocity)

Pres

sure

(m

b)3.5 km

Location

Day Three Omega (Vertical Day Three Omega (Vertical Velocity)Velocity)

Pres

sure

(m

b)3.5 km

Location

Why does it form?Why does it form?Convective Inhibition (J/kg)Convective Inhibition (J/kg)

Time Time (UTC)(UTC)

May 25May 25 May 26May 26 May 27May 27

09000900 00 -303-303 -248-24815001500 NANA -606-606 -179-17921002100 NANA -407-407 -108-108 CINH - A measure of the amount of energy needed in order to CINH - A measure of the amount of energy needed in order to

initiate convection or how unlikely thunderstorm development initiate convection or how unlikely thunderstorm development may be may be

The more negative the CINH in the sounding, the greater the The more negative the CINH in the sounding, the greater the atmospheric stability and lesser the chance of vigorous convectionatmospheric stability and lesser the chance of vigorous convection

Synoptic FlowSynoptic Flow Day One: High pressure ridge to Day One: High pressure ridge to

north, easterly flownorth, easterly flow Day Two: Ridge slides south, more Day Two: Ridge slides south, more

westerly flowwesterly flow Day Three: Ridge to the south, Day Three: Ridge to the south,

westerly flowwesterly flow

Why Does the Sea Breeze Why Does the Sea Breeze Cell DominateCell Dominate

Magnitude of temperature difference between the land and cold Magnitude of temperature difference between the land and cold pool is much greater than the difference between the Gulf Stream pool is much greater than the difference between the Gulf Stream and the cold pooland the cold pool

Day one saw largest difference between Gulf Stream and cold pool, Day one saw largest difference between Gulf Stream and cold pool, land and cold pool temperature difference remains fairly constantland and cold pool temperature difference remains fairly constant

-4

-2

0

2

4

6

8

10

2 12 16 23 4 11 19 3 11 16 22

Time (UTC) Starting 0200 UTC May 25, 2004

Tem

pera

ture

Diff

eren

ces

(C)

TemperatureDifference betweenLand and Cold Pool

TemperatureDifference betweenGulf Stream and ColdPool

Peak on Day one

Day One: Possible Day One: Possible ScenarioScenario

SummarySummary Gulf Stream circulation cell was present on Gulf Stream circulation cell was present on

day one, but was not present on days two day one, but was not present on days two and threeand three

Easterly flow is helpful for Gulf Stream Easterly flow is helpful for Gulf Stream circulation cell formationcirculation cell formation

Westerly winds cause the sea breeze cell to Westerly winds cause the sea breeze cell to dominate over the smaller Gulf Stream celldominate over the smaller Gulf Stream cell

Low and mid-level moisture and temperature Low and mid-level moisture and temperature profiles are important for cloud developmentprofiles are important for cloud development

AcknowledgementsAcknowledgements Professor Michael Splitt for all his Professor Michael Splitt for all his

knowledge and inputknowledge and input Nicole Botto for the land – water Nicole Botto for the land – water

temperature differences datatemperature differences data Fellow MFP students for help with Fellow MFP students for help with

data collectiondata collection

Questions?Questions?