1. Clearing of 19 July (0800Z to 1000Z) and Catalina Eddy Development
Jodi Beattie

2. Coast and ship track
Time period of clearing

3. Motivation
Image seen
An eddy does appear with-in 6hrs of us leaving the area.

4. Requirements for Eddy Formation
Offshore Northerlies
Along shore Southerlies
Amplifying subtropical ridge moving closer toward coast
500mb trough
Though not crucial for formation
Coastal Mountains appear to be the initiating mechanism
They create a lee trough
forms a low that helps reverse the along coast pressure gradient, forcing the southerly flow.
This area is slightly warmer and drier due to subsidence.

5. Results from SAIL data as we sailed from marine stratus to clear skies
Wind speed drops 7m/s
Pressure drops ~1.5mb
Supports idea of lee troughing
T and Td increase (RH decreases)
Also supports lee troughing
Long wave Radiation decreases
Proving it is becoming clear
Paper has these figures attached, not here for brevity.

6. Goleta, CA Profiler
Shows the vertical profile of winds and temperature (note time from right to left)
Concentrate on 700m+ winds
want them from the north in order to establish the lee trough

7. profiler
Here we see the MBL is diurnal and quite high in the am local time
See northerlies establish, m layer…looking at weak low winds…ideal

8. profiler
See Northerlies continure into the 19th until about ( local)
Still thru the m layer
Again can see diurnal fluctuations of the MBL

9. Development of the Eddy
Satellite images used
See clear skies we experienced turn into region of eddy development (arrow is where we were at the time)
Observe offshore winds from NNW to WNW and along coast winds from SSE
Notice the cyclonic rotation of the eddy

11. Surface Wind Analysis
See the winds, NW offshore and S alongshore, with vectors
Look near Goleta/Santa Barbara see cyclonic circulation
Note: doesn’t move SW like eddy
Winds near Goleta agree with profiler

13. Conclusions The clearing we experienced was the pre-cursor to the eddy
It was a typical Catalina Eddy
If our transit had been a few hours later we could have gone right into the eddy

14. Questions