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

1997 Events in BIO Moorings (NECE, NECW, SEF)

The last deployment of the BIO moorings under Phase II was placed in September, 1996, and recovered at the end of June, 1997 (Parizeau 97-025, Fig. 1). The near-surface (24m) instrument on the east side of Northeast Channel (NECE, 200m isobath) showed fresh SSW (S<32) through most of Jan-June, 1997, period, punctuated by a few short-term (~10d) events (32<33) in April-June. At depths >150m, slope water (S>35) was present for most of the Jan.-June period, while the 100m salinity oscillated erratically between 33 and 35. On the west side of the Channel (NECW), near-surface salinity generally exceeded 32, except for brief periods in early Jan., early March and May, which may represent SSW cross-overs. At depth (>150m), the salinity ranged between 33 and 35 (slope water) during Jan.-June, while at 100m slope water was rarely seen. At the southeast flank mooring (SEF, 95m), two prominent expressions of SSW (S<32) occurred in early Jan. and early March (Fig.2d), consistent with the NECW observations. A weak slope water intrusion (33<34) was evident throughout the water column during April (Fig.2c,d).

1999 Events in BIO Moorings (NECE, NECW, BBO, BBI)

The BIO Phase III moorings were placed in late November, 1998, and recovered in September, 1999. CTD data from the deployment cruise indicated that a major SSW cross-over was occurring at that time, which was later confirmed by the near-surface (23m) salinity record at NECW (Fig.3d). In fact, SSW (S<32) persisted at NECW (23m) for most of December, 1998, and was present at NECW(33m) for a good part of that period as well. SSW appeared sporatically in the NECW surface layer in January and, in late February, a slope water intrusion at all depths immediately preceeded a prolonged (~10d) cross-over event. In early March, SSW appeared again in the NECW surface layer, and also briefly in early April. For the last part of April and most of May, SSW was again evident in the NECW surface layers to depths of at least 33m. Some of these cross-over events (e.g. in early April) have been confirmed by surface drifter tracks. In late June, a major slope water intrusion occurred throughout the water column on the eastern side of Northeast Channel (NECE) and on Browns Bank (BBO, BBI). Slope water was also present for much of February at NECE and BBO.