Aspects of the physical and physical-biogeochemical dynamics of Massachusetts Bay and Stellwagen Bank

Pierre F.J. LermusiauxDivision of Engineering and Applied Sciences

Harvard University

Sand Lance Workshop, November 24, 2003http://www.deas.harvard.edu/~pierrel

1. The Harvard Ocean Prediction System- Predictions, data collection and data assimilation- Recent applications relevant to fisheries and society (*)

2. Massachusetts Bay and Stellwagen Bank processes3. Some Directions for Sand Lance Research (physics-biology)

• HOPS – Harvard Ocean Prediction System (A. R. Robinson et al.)

• Internal Weather of the Sea (most energetic motions)• Applications: e.g. AFMIS (G. Bank), EgyptAir Flight 990, Prestige Oil Spill

Multi-Variate Coupled Physical-Acoustical-Biological System

DATA ASSIMILATION: Combines model and data for best ocean estimate

Error Subspace Statistical Estimation – ESSE

R/V Alliance (NATO) inMassachusetts Bay (June 2001)

Dr. Pat Haleyand

Wayne Leslie

Physical ObservationsAUV

WHOI GlidersSIO GlidersDoradoNPS REMUSCal Poly REMUS

Moored/Fixed

CODAR M1/M2NPS ADCPMBARI Profiler

Aircraft

Twin OtterP3 / AXBT/ SST

Ships

Pt. SurJohn Martin

Drifting

Surface DriftersProfilers

Satellite

SSTSeaWiFS

FOOD WEB: Multiple trophic relations, e.g. leading to adult herring (arrows show energy flow). Notice the Sand Lance!

Cartoon of horizontal circulation patterns for stratified conditions in Massachusetts Bay, overlying topography in meters (thin lines).

• Patterns are not present at all times • Most common patterns (solid), less

common (dashed)• Patterns drawn correspond to main

currents in the upper layers of the pycnocline where the buoyancy driven component of the horizontal flow is often the largest

HORIZONTAL CIRCULATION PATTERNS IN MASSACHUSETTS BAY

ASCOT-01 (6-26 June 2001) : Positions of data collected and fed into models

ASCOT-01: Sample Real-Time Forecast Products

Massachusetts Bay Gulf of Maine

2m Temp. 10m Temp. 3m Temp.

25m Temp.5m Chlorophyll 15m Nitrate

Coupled bio-physical sub-regions of Massachusetts Bay

in late summer:Dominant dynamics for trophic enrichment and

accumulation

Chlorophyll at 5m, from June 14 to June 28, 2001

Chlorophyll cross-section, from June 14 to June 28, 2001

Scituate

StellwagenBank

Sub-surface wind-forced upwelling/downwelling at Stellwagen Bank: sustained impacts on Sand Lance?

Internal tides, waves and bores and their effects on plankton distribution: impacts on Sand Lance?

Left: Interpolated backscatter (top panel) and velocity magnitude (bottom panel) with depth (m) and time (s) obtained from the shipboard Doppler current meter. Bin size is 1 m. Boat steaming towards Stellwagen bank (Massachusetts) at about 3-4 knots. Patterns in backscatter and velocity magnitude reveal an internal bore followed by internal solitary waves.11552 s is about 9:11 EDT, 18 Sep 2001.

http://science.whoi.edu/labs/pinedalab/Subpages/PLanktonDistributionInISW.html

Jesus Pineda and Scott Gallager Woods Hole Oceanographic Institution;

Alberto Scotti, University of North Carolina

Right: a surface slick associated to the leading edge of the bore (see left panels) observed from the bow of the RV Connecticut. The photo was taken 91 minutes after 09:11 EDT, 18 Sep 2001. The boat was steaming onshore, in the direction of propagation of the wave.

Ship Radar screen

The three parallel clouds of green points are the surface manifestation of a train of internal waves.

Jesus Pineda and Scott Gallager Woods Hole Oceanographic Institution;

Alberto Scotti, University of North Carolina

Directions for Sand Lance Research (physics-biology)

• What are the impacts of physical forcing on the Sand Lance? (either directly due to temperature and currents, or indirectly through plankton)

– Meanders of the Gulf of Maine coastal current

– Mesoscale gyres and eddies

– Sub-surface wind-induced upwelling/downwelling

– Tides (barotropic and internal)

– Internal waves, bores and solitons (mainly summer/fall)

• Is the Sand Lance behavior modified by these physical forcings? If yes, how? What about predators behavior?

• What is the seasonal and inter-annual variability of the Sand Lance population?

• Are the Sand Lance larvae and juvenile locally maintained or advected from elsewhere (Jeffreys Ledge, GOM, etc)

• Is the Sand-Lance population predictable?

– Weather of the Sea: 2-3 days because of winds (internal ecosystem: at least 2 weeks)

– Seasonal predictions

• How can we best help fishermen and local Mass. Bay communities/management?

EXTRA VUGRAFS

Integrated Ocean Observing and Prediction Systems

Platforms, sensors and integrative models

Surface standard deviations error forecasts for Oct. 1 overlaid with the sampling tracks carried out on Sep. 30 and Oct. 1, 1998

Objective Adaptive Sampling