South Atlantic Offshore Drilling Forum, 2015

1. Cape Hatteras
the Confluence of the
South & Mid Atlantic Bight Provinces
and the Appalachians & the Gulf Stream
On Events and Implications
Part I
Len Pietrafesa, Shaowu Bao,
Tingzhuang Yan, Paul Gayes,
Jim Epps

2. The “confluence”
Is clearly depicted
In this AVHRR SST
Where 6o C waters
Meet 12o to 20o
Waters
And Cold, Dry Air
Masses encounter
Warm, Moist
Gulf Stream
Conditioned
Air Masses

3. Cape Hatteras has many special properties
Like multiple cross shelf fronts
And topographic influences,
Which induces SB and Slope
Upwelling ~ 10-1 cm/sec

4. Thus creating a very complex Air-Sea interaction system

5. And conditions for “explosive cyclogenesis”
=> D(D(T))/DXDZ = maximum baroclinicity =>
an atmospheric “bomb”

8. The spawning or further intensification of ETCs
left: The New England Blizzard of 2004

9. a) Onset of an ETC
b) of ~ 100 cm/sec
and waves of height
(O) 5-10 meters;
effecting huge
Shear Stresses =>
bottom resuspension
and lateral erosion
c) Note MAB waters
breeching Diamond
Shoals down into
Raleigh Bay
d) The system relaxes
After 7- 8 days

10. • So, ETCs carry heat northward… and
• drop heavy precipitation …and
• are characterized by southward to southwestward , i.e. northeasterly winds…hence
the term “Nor’Easters”
• which move blue crab juveniles from Chesapeake Bay to the south and into the
primary nurseries and settlement areas of Pamlico Sound via Oregon Inlet …and also…
• Bottom sediments are picked up by storm induced waves and currents and along with
the Chesapeake Bay Plume also enter the Inlets
• The sediments follow a track similar
to the crabs. The dirt ends up going
through Oregon Inlet and being
deposited on the backsides of the Outer
Bank, barrier island chain.
• This process allows these ephemeral
strips of sand to migrate west toward
the mainland, thus ensuring their
future during this period of sea level
rise
• Estuarine dependent finfish also move
across the shelf at the surface and the
interior into the Pamlico Sound
estuary

11. Numbers of ETCs
13 in 1998 and 24 in 2001

12. During a low ETC year there is less coastal water in the system
than during a high ETC year

13. With NE’ ly winds
Hydraulic Heads get created
Along the axes of the Inlets
And water pours into the system

17. 0
2
4
6
8
10
12
1986 1988 1990 1992 1994 1996 1998 2000 2002
Catchpereffort Cluster 1 Cluster 2
Cluster 3 Cluster 4

18. -2
-1
0
1
2
3
4
5
6
7
8
1988 1990 1992 1994 1996 1998 2000 2002
Year Class
Y-O-YAbundanceIndex
0
1,000,000
2,000,000
3,000,000
4,000,000
5,000,000
6,000,000
7,000,000
AbundanceatAge(#s)
Y-O-Y
Age 1
Age 2
Variability within age classes. . .

19. 2000 4000 6000 8000 10000
March Discharge
-1.0-0.50.00.51.0
Cluster4Abund
400 600 800 1000
Feb-Mar N-NE Winds
-0.50.00.51.0
Cluster4Abund
20 40 60 80 100 120
Feb-Mar E-SE Winds
-0.50.00.51.0
Cluster4Abund Cluster 4 vs. Environmental Factors
Comments:
Steve Ross?