HYCOM/Quoddy Nested
Baroclinic Nowcast/Forecast
System for the South Atlantic Bight
(and other things)
Thomas Shay, Francisco Werner, Alfredo
Aretxabaleta, Brian Blanton
Department of Marine Sciences
The University of North Carolina at Chapel Hill
SAB NC/FC System
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SAB regional baroclinic model is Quoddy
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4-day diagnostic run (spin up tides + mixing),
up to 21-day prognostic run
HYCOM provides IC and open BC
Tidal open BC from ADCIRC TDB
NCEP ETA (now WRF/NMM) for surface
forcing (AWIP12)
HYCOM/Quoddy NC/FC System
Quoddy SAB Domain
36
Cape Hatteras
35
Latitude
34
33
32
31
30
29
Cape Canaveral
28
−82
−80
−78
−76
Longitude
−74
−72
Temperature
Salinity
Quoddy output surface
temperature, salinity,
elevation, and velocity.
Interpolated onto regular grid.
Elevation
Temperature Sections
1
2
4
2
3
1
3
4
Shelf Temperature Sections
1
2
4
2
3
1
3
4
NC/FC System Timing
(constant
fluxes)
Ideal t1 is <1 day
Typical t1 is 8-12 days owing to
HYCOM posting delay
Effect of HYCOM Posting Delay
Typical
Ideal
t1 = 8 days
t1< 1day
20 Sep HYCOM nowcast
27 Sep HYCOM nowcast
72 hour Quoddy forecast
72 hour Quoddy forecast
NCCOOS Model Output Web Page
http://nccoos.org/models
HYCOM and Quoddy SST
2 Nov 2006 1100UTC
My Rookie Mistake
(NCEP Changed Sign of Heat Fluxes)
Using old sign convention after
“stealth” change by NCEP
Using new sign convention
Summer 2003 Cold Event in SAB
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Observations: Fixed moorings, ship transects
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ADCIRC TDB tidal elevation
Quoddy with climatological IC and BC or
nested HYCOM/Quoddy
NCEP EDAS (AWIP12) surface forcing
USGS river input at 5 nodes (20psu)
Summer 2003 Cold Event
∆T = Near-surface T minus long-terms means
∆T > -1°C
-2°C < ∆T < -1°C
∆T < -2°C
Cold Event Study Domain
Cape Fear
34
Pee Dee
SC
33
20
40
200
60
600
Edisto
Charleston
GA
32
Fort Pulaski
Latitude
Altamaha
31
1000
Savannah
GR
Satilla
R2
Fernandina
St. Johns
30
FL
29
28
−82
−81
−80
−79
Longitude
−78
−77
Quoddy Cases
Mid-shelf T Comparison
NDBC 41008 (GRAY’S REEF) Near−surface Temperature
32
Bottom R2 Temperature
30
28
28
26
26
24
o
C
o
C 22
22
20
Obs.Clim.
Obs. 2003
HYCOM
CASE1
CASE2
CASE5
18
16
14
04/01
24
05/01
06/01
07/01
2003
08/01
Bottom R2
09/01
20
Obs.Clim.
Obs. 2003
HYCOM
CASE1
CASE2
CASE5
18
16
04/01 04/15 05/01 05/15 06/01 06/15 07/01 07/15 08/01 08/15 09/01 09/15
2003
Surface Gray’s Reef
Shelf Temperature
Shelf Salinity
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Aretxabaleta, et al. (2006) Cold event in the
South Atlantic Bight during summer of 2003:
Anomalous hydrographic and atmospheric
conditions, JGR, 111, C06007.
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Aretxabaleta, et al., Cold event in the South
Atlantic Bight during summer of 2003: Model
simulations and implications, JGR (undergoing
revisions after positive reviews)
Future Steps
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Make NC/FC system more automatic and
robust
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Access to more timely HYCOM results
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Explore transition to baroclinic version of
ADCIRC (MPI = significant speed increase
over Quoddy)
Documentation
Evaluate performance of system w.r.t.
available data