GOAL OF THIS WORK ■ To investigate larval transport in “idealized” simulations ● To describe...
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Transcript of GOAL OF THIS WORK ■ To investigate larval transport in “idealized” simulations ● To describe...
GOAL OF THIS WORK
■ To investigate larval transport in “idealized” simulations
● To describe long term & short term dispersal kernels
● Four scenarios considered
▷ Strong or weak upwelling
▷ Northern or southern California
■ To develop modeling to establish short time kernels
from available data sets
IDEALIZED SIMULATIONS
■ Idealized is state that shows
1) statistical stationarity
2) statistical homogeneity in alongshore
3) physically reasonable coastal current
■ Make particle tracking easier
■ No such simulation in literature
● Need to construct our own
OBJECTIVE OF THIS TALK
■ To show progress in simulation construction
● Focus on summer northern California
● Hard to satisfy three “idealized” conditions
● Still some problems in simulations
ROADMAP
■ Four things to be modeled
1) Numerical domain
2) Boundary conditions
3) Initial conditions
4) Forcings
■ Show obtained simulation fields & trajectories
■ Research plan to obtain kernel
1) NUMERICAL DOMAIN
■ 64 x 64 x 32 grid points
512 km x 512 km Depth: 20 m -- 500 m
2) BOUNDARY CONDITIONS
Periodic
Periodic
Free-slip wall
Nudging &sponge layer
Wind stressOpen B.C.'s
2) BOUNDARY CONDITIONS
■ Open B.C.'s
● Outflow: radiation
▷ Extrapolates boundary values from interior values
● Inflow: nudging
▷ Forces boundary values to reference values
● Sponge & nudging layer
▷ Remove numerical difficulty
3) INITIAL CONDITIONS
■ Determined using CALCOFI Atlas
● Velocity: geostrophic velocity
▷ No motion at 500db (500m)
● Temperature
▷ Consistent with given density field
● Sea level
▷ Dynamic height with zero mean
4) FORCINGS
■ Two external forces:
wind stress & pressure gradient
■ Wind stress:
Modeled with Gaussian random process
whose statistics taken from NBDC archive
○ Cross-shore: 0-m/s mean, 1.2-m/s std, 1-hour corr.
○ Alongshore: -5.6-m/s mean, 4.6-m/s std, 2-hour corr.
4) FORCINGS
■ Pressure gradient: imposed as external force
● Periodic domain cannot develop pressure difference
at north/south boundaries
● Computed from dynamic height difference
between Pt. Arena & Pt. Conception
COMPUTATION
■ Two year simulation with 30-minute time stepping
● Using ICESS cluster
▷ Took 6 hours using 2 CPU's
▷ Eventually using 12 CPU's
■ Lagrangian particles:
● Released after fields are fully developed
● Released every day at fixed location
RESULTS: TEMPERATURE
RESULTS: TEMPERATURE
RESULTS: ALONGSHORE VELOCITY
RESULTS: SEA LEVEL
RESULTS: KINETIC ENERGY
RESULTS: PARTICLE TRAJECTORIES
PLAN TO OBTAIN KERNEL
■ Describe kernel in idealized simulations
● Track “settlers” & sort them by PLD
▷ Issue: what is “settlement”?
● Question: how do they look?
▷ Long term? Short term?
■ Model short term kernel
● From available data set
PLAN TO OBTAIN KERNEL
■ Detect particle correlation time & length
● Say, particles released within 20 hours at same source
go to same destination
● Say, particles released at sources separated 2 km or less
at same time go to same destination
■ Release many particles separated by 2 km every 20 hours
■ Observe when kernel becomes Gaussian
● Possibly a month, or possibly over years
SUMMARY
■ “Idealized” simulations are under development
● Little too excited
● But, shows reasonable turbulence structures
● Will be done shortly
■ Dispersal kernel will be provided soon (hopefully)
■ Adding complexity
● Inhomegeneity, behavior, etc