Transcript A preview: modeling Puget Sound with ROMS

Connecting the sound to the shelf:
a numerical modeling study
of estuarine exchange flow
in the Salish Sea
Dave Sutherland1
Parker MacCready1, Neil Banas2
1
School of Oceanography, UW
2 Applied Physics Laboratory, UW
CERF, Portland, OR, November 2009
Connecting the sound to the shelf:
a numerical modeling study
of estuarine exchange flow
in the Salish Sea
Acknowledgments:
PRISM (Jeff Richey)
Barb Hickey, Amy MacFadyen, David Darr (UW)
WA DOE
All data sources
PRISM
Puget Sound Regional Synthesis Model
The Salish Sea
Strait of Georgia
Strait of
Juan de Fuca
400 m
Puget
Sound
Columbia
River
The Straits
Salinity, July
Salinity, July
(Collias et al., 1974)
(Masson and Cummins, 2000)
Strait of Juan de Fuca
Strait of Georgia
• 100 km long, 20 km wide, 200 m deep
• ~0.2 Sv exchange flow
• significant spring/neap variability,
seasonal variability, and tidal rectification
• Fraser River: mean ~7500 m3/s, large
seasonal variability
• intense mixing in SJI’s and sill regions,
more stratified in basins
• significant spring/neap variability
(see Martin and MacCready, 2009)
Puget Sound
Deception
Pass
Whidbey
Basin
Admiralty Inlet
Hood
Canal
South
Sound
Skagit
Snohomish
2 largest rivers
(~75% of Puget Sound
mean ~1000 m3/s)
Main
Basin
5 km
Tacoma Narrows
Puget Sound
exchange flow
150 m
(cm/s)
Main
Basin
Salinity, July
Puget Sound
Hood
Canal
• series of reaches (basins) connected by shallow sills
• 0.04 Sv exchange flow
• ~1000 m3/s river input
• large seasonal and spring/neap variability
• residence times: range from 5-70 days
river
river
sill
(Ebbesmeyer and Barnes, 1980; Cokelet and Stewart, 1985)
Hypothesis: Puget Sound, SJdF, and the SoG are characterized
by quiescent reaches (e.g. Main Basin) and turbulent sill regions (e.g. AInlet)
Tool: realistic ROMS numerical model setup of the Salish Sea to
investigate patterns of exchange flow on varied time and space scales
• Construct realistic hindcast simulations for 1998-2008 in Puget Sound
and greater Salish Sea region
• Puget Sound resolution ~200 m
• coastal resolution ~2 km
• use best available forcing (rivers, meteorological, boundary)
Model Set-up
Parameters
- stretched, spherical grid with 25 vertical
levels, qb = 0.6 and qs = 5
- k-e version of GLS turbulence closure
- horizontal diffusivity = 0.5 m2 s-1
- quadratic bottom friction, Cd = 0.003
- hmin = 4 m, rmax ~ 0.7, no wet/dry
Forcing
Boundaries
- Radiation and nudging at southern
and western boundaries (NCOM-CCS)
Atmosphere
- Bulk fluxes from hourly fields from the
MM5 regional forecast model
Rivers
- 19 rivers, daily time series (USGS)
Tides
- 8 constituents calculated from TPXO7.1
global tide model
Model validation
CTD profiles
ROMS
OBS
Whidbey Basin
JEMS
SJDF
mid Strait
of Georgia
Mooring time-series outside Columbia
Patterns of
exchange flow
SoG-N
AI-N
“out-estuary”
SoG-mid
JdF-W
SoG-S
WB
JdF-mid
JdF-E
AI-N,S
MB
HC
SS
“in-estuary”
(May-July mean)
|Ue| ~ 20,000 m3/s
net Ue ~ 500 m3/s
Patterns of
exchange flow
SoG-N
SoG-mid
AI-N
AI-S
“out-estuary”
JdF-W
SoG-S
WB
JdF-mid
JdF-E
AI-N,S
MB
HC
SS
“in-estuary”
(May-July mean)
Patterns of
exchange flow
SoG-N
SoG-mid
MB-N
MB-mid
MB-S
“out-estuary”
JdF-W
SoG-S
WB
JdF-mid
JdF-E
AI-N,S
MB
HC
SS
“in-estuary”
(May-July mean)
SoG
JdF
AI
Strait of Juan de Fuca
JdF-E
JdF-mid
JdF-W
“out
estuary”
“in-estuary”
|Ue| ~ 130,000 m3/s
net Ue ~ 6000 m3/s
Patterns of
exchange flow
Strait of Georgia
SOG-N
SOG-mid
SOG-S
Admiralty Inlet
“out
estuary”
“in-estuary”
|Ue| ~ 80,000 m3/s
net Ue ~ 5000 m3/s
AI-N
AI-S
“in-estuary”
|Ue| ~ 20,000 m3/s
net Ue ~ 500 m3/s
“out
estuary”
Variability of exchange flow at Adm. Inlet
Skagit
river
discharge
(m3/s)
Snohomish
N/S winds
(m/s)
depth mean
current (m/s)
exchange flow
(1000 m3/s)
“in-estuary”
“out-estuary”
Conclusions
• Development underway of
realistic, high resolution
simulations of Puget Sound
and the surrounding coastal
ocean
• Patterns of exchange flow
are useful in characterizing
estuarine regions in the
Salish Sea and will lead to
quantitative comparisons in
the future
(http://faculty.washington.edu/dsuth/MoSSea/)