SCUD
This presentation is the property of its rightful owner.
Sponsored Links
1 / 21

SCUD PowerPoint PPT Presentation


  • 100 Views
  • Uploaded on
  • Presentation posted in: General

SCUD. Diagnostic Surface Currents SCUD and application to marine debris. Jan Hafner and Nikolai Maximenko [email protected], [email protected] IPRC/SOEST University of Hawaii. Hydrodynamics of Marine Debris workshop 5IMDC – 20 March 2011 Honolulu, Hawaii. Outline. Motivation

Download Presentation

SCUD

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Scud

SCUD

Diagnostic Surface Currents SCUD

and application to marine debris

Jan Hafner and Nikolai Maximenko

[email protected], [email protected]

IPRC/SOEST University of Hawaii

Hydrodynamics of Marine Debris

workshop

5IMDC – 20 March 2011 Honolulu, Hawaii


Scud

Outline

  • Motivation

  • Methodology

  • Data

  • Model formulation

  • Application to Marine Debris

  • Future


Scud

Motivation

  • Ocean Surface Currents – important factor in marine debris problem

  • Direct measurements difficult – few in situ observations

  • Utilize satellite data to arrive with surface ocean currents

  • supported by the following agencies:

  • NASA Physical Oceanography Program (Ocean Surface Topography Science Team)

  • US National Fish and Wildlife Foundation

  • JAMSTEC

  • NOAA sponsoring IPRC

  • Our direct motivation is from applications on marine debris


Scud

Methodology

  • Task: to develop a simple diagnostic model of surface ocean currents to fit drifters' trajectories

  • Input parameters: AVISO sea level anomaly (geostrophic current component)‏

  • Ocean surface wind data: daily QSCAT – wind driven current component ( Ekman)‏


Scud

DATA

  • Drifter data: AOML - Atlantic Oceanographic and Meteorological Laboratory www.aoml.noaa.gov

  • 8058 drifters, drogued at 15m

  • from 1979 till 2008, interpolated on 6 hourly intervals


Scud

DATA

  • AVISO mean sea level anomaly maps: 1/3 degree maps, merged product (up 4 satellites), weekly time frequency, starting Oct. 1992 (www.aviso.oceanobs.com)‏

  • MDOT - Mean Dynamic Ocean Topography, developed by Maximenko et al. (2009), ½ degree map produced using combined drifters, sea altimetry, GRACE and surface wind data, 1992-2002.

  • QSCAT 3-day moving averages of surface winds (10 m), ¼ degree daily maps July 1999 – November 2009, (www.ssmi.com)


Scud

Formulation of the diagnostic model

USCUD(x,y,t) =

U0 + uhx⋅∇xh(x,y,t) + uhy⋅ ∇yh(x,y,t) + uwx⋅wx(x,y,t) + uwy⋅wy(x,y,t)‏

And similarly

VSCUD(x,y,t) =

V0 + vhx⋅∇xh(x,y,t) + vhy⋅ ∇yh(x,y,t) + vwx⋅wx(x,y,t) + vwy⋅wy(x,y,t)‏

Where: USCUD , VSCUD- modeled ocean current components

U0 , V0 - constant coefficient (mean)‏

h - sea level anomaly

wx, wy U and V component of surface wind (QSCAT)

uhx, uhy , uwx , uwy - U component coefficients corresponding to sea level gradient and surface wind (function of x and y only)‏

vhx, vhy , vwx , vwy- similarly corresponding V component coefficients


Scud

Formulation of the diagnostic model

The coefficients are solved by minimizing the cost function:

Fcost=Σ[(Udrifter ‐ USCUD)2 + (Vdrifter ‐ VSCUD)2]

where the summation is over all drifters' data in a given lat/lon box (total 5,700,000 6-hourly data points).


Scud

RESULTS


Scud

RESULTS

Local Scale


Scud

SCUD application on marine debris

transport and convergence

Where the marine debris goes?

How it gets there ?

Numerical Experiment: SCUD currents

applied on ocean tracers released daily

from coast and weighted by coastal population

count


Scud

Animation of tracer transport by

SCUD currents


Scud

Structure of SCUD tracers “patches”


Scud

SCUD model application on marine debris

What model can do:

zones of convergence

structure of the patches

trajectories = pathways

What model cannot do:

prediction

vertical structure of marine debris

coastal processes – emission and deposition of marine debris


Scud

Future – what is needed

1. operational SCUD product requires QSCAT to be replaced

with ASCAT winds

2. global inventory of marine debris sources and sinks

in the ocean and onshore is needed

3. effect of vertical mixing on floating debris needs to be

included in the model

4. coastal dynamical processes, esp. high frequency and debris

deposition processes, need to be considered in the model

5. validation of SCUD model results by in situ data needed

Thank you


Scud

Data preprocessing

  • AVISO, MDOT and QSCAT wind data were interpolated on times and locations of 6-hourly drifters' data

  • Filtering out high frequency signal by Hanning cosine filter with halfwidth = inertial frequency, minimum frq. ~ 3 days (9°37' lat.)‏


Scud

Fit to the data

Absolute misfit to drifters' data

R.M.S. of cost function (m/s)‏

Global average misfit : 0.162 m/s

(0.118 m/s for USCUD

and 0.107 m/s for VSCUD)‏

Relative misfit to the drifters' data

Ratio of cost function and drifters'

R.M.Ss.

Global average : 0.566

(0.541 and 0.653, for U and V components respectively)‏


Scud

Data and Access

  • ¼ degree surface currents maps: daily from 01Aug1999 till 19Nov2009 (span of QSCAT data)‏

  • SCUD dataset is open for free unrestricted use and distribution

  • Disseminated by APDRC servers :

  • http://apdrc.soest.hawaii.edu/projects/SCUD/

  • LAS, LAS7, OpeNDAP, DChart

  • SCUD manual : http://apdrc.soest.hawaii.edu/projects/SCUD/SCUD_manual_02_17.pdf

  • SCUD users listserver:http://apdrc.soest.hawaii.edu/projects/SCUD/registration.html


Scud

From S.Pacific ST gyre

To S.Pacific ST gyre

From N.Pacific ST gyre

To N.Pacific ST gyre

From Hawaii

To Hawaii

Trajectories of real drifter starting from (left column) and ending in (right column) the South Pacific (top row), North Pacific (middle row), and Hawaii (bottom row).


Scud

Statistics

R.M.S. of modeled velocities related to

sea level (m/s)

R.M.S. of modeled velocities related to surface winds (m/s)


  • Login