Coastal Connectivity in the Southern California Bight

Dave Siegel, James Watson, Satoshi Mitarai,(UCSB)

Charles Dong & Jim McWilliams(UCLA)

Coastal Environmental Quality Initiative 2007-2008

Goal of This Study

• Assess coastal connectivity via advection of water parcels in SoCal Bight

•Help MPA design (e.g., Chris’s work)

• Approach: implement offline particle tracking in Charles’ flow simulations

Charles’ ROMS Simulations

Simulated flow fields (surface vorticity normailized by f)

Forced by “realistic” wind

Dong and McWilliams (2007)

Conil & Hall (2006)

Simulated wind field

Wind forcing

Flow Circulation in SoCal Bight

A Big Upllwelling shadow

6 synoptic views of circulation in SBC

Offline Particle Tracking

• Nearshore habitat = 100 m or shallower

• Lagrangian particles are released & settle within habitats

• Settlement = particles within nearshore habitat during competency time window

Nearshore habitat range

100-m isobath

Where do they go?(From North Shore of SBC Islands)

Day 0 = 7/1/02 Day 0 =1/1/02

• Natal areas (self settlement)• Nowhere (few settlements)

Red dots = settling particles (competency = 20 - 40 d)

Single day release in Summer Single day release in Winter

Where do they go?(From Palos Verdes Peninsula)

• “Everywhere” • North of PV / SBC

Red dots = settling particles (competency = 20 - 40 d)

Summer Winter

Day 0 = 7/1/02 Day 0 =1/1/02

Where do they go?(From San Niclolas Islands)

• Few settlements • Mainland / SBC Islands

Red dots = settling particles (competency = 20 - 40 d)

Summer Winter

Day 0 = 7/1/02 Day 0 =1/1/02

Where do they come from?(To North Shore of SBC Islands)

• Mostly from Ventura / LA • From “everywhere”

Red dots = settling particles (competency = 20 - 40 d)

Summer Winter

Day 0 = 7/1/02 Day 0 =1/1/02

Where do they come from?(To Palos Verdes Peninsula)

• From natal areas • South of PV / San Nicholas

Red dots = settling particles (competency = 20 - 40 d)

Summer Winter

Day 0 = 7/1/02 Day 0 =1/1/02

Where do they come from?(To San Nicholas Islands)

• PV / natal areas (few) • PV / SBC (few)

Red dots = settling particles (competency = 20 - 40 d)

Summer Winter

Day 0 = 7/1/02 Day 0 =1/1/02

Schematic Diagram

Role of Chaotic Eddying Motions(From San Nicholas Island)

Day 0 = Jan. 1, 2002 Day 0 = Jan. 15, 2002

• From “everywhere” • Palos Verdes / Natal

Red dots = settling particles (competency = 20 - 40 d)

Summer Winter

Rolf of Vertical Positioning(From Palos Verdes)

Day 0 = July 1, 2002 Day 0 = Jan. 1, 2002

• More spread • More clustering

Red dots = settling particles (competency = 20 - 40 d)

Passive vertical transport DVM (20 m)

And more...

•Inter-annual variability

•Climate variability (e.g., ENSO)

•Eileen brought 1997 & 1998 flow simulations

Short-term Goal

•Write up a physical oceanographic two papers describing dispersal patterns in SCB

•By January

•James talk more about connectivity