Slope Water Interaction Workshop

23-24 August, 2000

Clark Laboratory, Woods Hole Oceanographic Institution

Abstract

• Introduction
• Basic Phenmenon
  • May 1999 Slope Water Intrusion (AVHRR)
  • June 1997 Gulf Stream Intrusion (AVHRR)
  • May 1997 Detrainemnt Event (AVHRR)
  • Eddy-Continental Shelf Interaction (Model Results)
  • April 1999 Scotian Shelf Crossover Event (AVHRR)

Overviews

• 1995 Events
• 1997 Events
• 1997 Cruises
• 1999 Events
• 1999 Cruises

Observations and Models

• BIO Moorings
  • June 1997 R/V Parizeau Cruise Track
  • 1997 Southeast Flank Mooring
  • 1999 Northeast Channel Mooring
• Great South Channel Mooring Deployment Cruises
  • Mooring Positions
  • Jan 1997 (OC 296) CTD Stations
  • Aug 1997 (OC 311) CTD Stations
• Eddy Interactions with the Continental Shelf- Model Results
  • No Background Flow
  • Background Shear Flow
• May-June 1997 Detrainment
  • EN301 Cruise Track with AVHRR
• March 1997 SeaSoar- Storm Induced Exchange and Scotian Shelf Crossover
  • Pre-Storm AVHRR
  • Post-Storm AVHRR
  • Survey Chart
• June-July 1997 SeaSoar- Gulf Stream Plume Interactions
  • Survey Chart
  • Early AVHRR (streamer)
  • Mid AVHRR (streamer)
  • Late AVHRR (tendril)
• 1995-1999 Remote Sensing

1999 Slope Water/Gulf Stream Intrusion Study

EVENTS

AVHRR and the South Flank mooring time series show two intrusion events in May and June 1999.

SWI99-1: Begins May 24 at SF with a sudden jump in bottom S to ~32.5 to ~33.5. Maximum subtidal S occurs near bottom, and bottom salinity remains elevated through ~ June 10. SF velocity data suggests stronger flow near surface, with cyclonic motion (perhaps an eddy) moving southwestward through SF between May 24 and June 4.

SWI99-2: Begins June 18 at SF with sudden jump in near surface S from ~ 32.6 to over 34. Bottom S increases by less than ~ 0.1.

OBJECTIVES

• Describe intrusions of warm,salty water onto the southern flank - spatial/temporal evolution of intrusions, associated flows, nutrients, biology,...
• Determine if intrusions have any lasting biological (and physical) effects on the southern flank environment.
  

METHODS

• April, May, and June BS surveys give before, during SW1, and after SWI99-1 during SWI99-2 T,S, species snapshots. Warm water tracer species can be identified in the May survey and then looked for in the June survey to see if any remained after SWI99-1 left. (Durbin et al).
• The SF, Tidal Mixing Front (TMF), and NDBC mooring data can be used to establish time/space description of T,S, bio-optical, currents, plus surface forcing during period.
• CTD/MOCNESS sampling was done on the southern flank during a) Lough April and May process cruises, b) Schlitz TMF March deployment, June turnaround, and August recovery cruises, c) Wishner June process cruise (in tandem with Barth SeaSoar cruise). This sequence of MOCNESS data spanning SWI99-1 and 2 may provide evidence of any lasting biological influence of SWI's.
• CTD/VPR/drifter/tracer data collected on Ledwell and Houghton May southern flank tracer cruises provide additional information on evolution of water structure and currents during SWI99-1.
• Modelers conducted real-time data assimulation studies in the May period. Hind-cast studies with full supporting data may give much better model fields which could help with the description of the SWI events.