| Introduction |
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| Figure 1 |
Locations of long-term sites LT-A and LT-B in western Massachusetts Bay. |
| Figure 2 |
Winter mean flow in Massachusetts Bay. |
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| Field Program |
| Figure 3 |
A subsurface mooring being deployed at site LT-B from the U.S. Coast Guard Cutter Marcus Hanna. |
| Figure 4 |
(A) Large tripod frame used to deploy instrumentation at site LT-A being deployed from the U.S. Coast Guard Cutter Marcus Hanna, and (B) small tripod frame used to deploy instrumentation at site LT-B being deployed from the U.S. Coast Guard Cutter White Heath. |
| Figure 5 |
(A) Two views of U.S. Coast Guard Cutter White Heath, (B) U.S. Coast Guard Cutter Marcus Hanna, and (C) fishing vessel Christopher Andrew. |
| Figure 6 |
Map showing the location of moorings deployed at site LT-A, the location of the U.S. Coast Guard Boston Approach Buoy, and the location of sea-floor photographs. |
| Figure 7 |
(A) The sea floor on the crest of a ridge about 0.6 kilometers north of site LT-A, and (B) the sea floor in a topographic low about 0.7 kilometers south of site LT-A. |
| Figure 8 |
(A) Schematic diagram showing instruments deployed at site LT-A in western Massachusetts Bay from 1989 to 1994, (B) schematic diagram of the subsurface mooring deployed at site LT-A in western Massachusetts Bay from 1989 to 1994, and (C) the near-surface Vector-Measuring Current Meter with transmissomter attached being hung from the side of the Large Navigational Buoy in March 1990. |
| Figure 9 |
(A) Schematic diagram of moored instruments deployed at site LT-A in western Massachusetts Bay from 1995 through 1996, and (B) schematic diagram of one of the surface-mooring configurations deployed at site LT-A in western Massachusetts Bay from 1994 to 1996. |
| Figure 10 |
(A) Schematic diagram of moored instruments deployed at site LT-A in western Massachusetts Bay from 1998 through 2002, and (B) schematic diagram of the subsurface mooring deployed at site LT-A in western Massachusetts Bay from 1998 through 2002. |
| Figure 11 |
(A) Schematic diagram of moored instruments deployed at site LT-A in western Massachusetts Bay from 2003 to 2006, and (B) schematic diagram of the subsurface mooring deployed at site LT-A in western Massachusetts Bay from 2003 to 2006. |
| Figure 12 |
(A) Map of western Massachusetts Bay showing the location of long-term mooring site LT-B, and (B) map of the sea floor of western Massachusetts Bay showing the location of the long-term subsurface and tripod moorings at site LT-B. |
| Figure 13 |
The sea floor about 0.3 kilometers to the north of site LT-B. |
| Figure 14 |
(A) Schematic diagram of moored instruments deployed at site LT-B in western Massachusetts Bay from 1997 to 2004, and (B) schematic diagram of the subsurface mooring deployed at site LT-B in western Massachusetts Bay from 1997 to 2004. |
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| Supporting Observations |
| Figure 15 |
River basins in the western Gulf of Maine and location of U.S. Geological Survey streamflow-gaging stations on the Saint John, Penobscot, Androscogin, Merrimack, Ipswich, and Charles Rivers. |
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| Instrumentation |
| Figure 16 |
(A) Benthic Acoustic Stress Sensor (BASS) attached to a large tripod being recovered at site LT-A, and (B) BASS current sensor. |
| Figure 17 |
Sea-Bird oxygen, conductivity, and temperature sensors and pump mounted on tripod fame. |
| Figure 18 |
Benthos 35-millimeter underwater camera mounted on tripod frame. |
| Figure 19 |
Acoustic Doppler current profiler (ADCP) mounted on small tripod frame being recovered at site LT-B. |
| Figure 20 |
Vector Measuring Current Meter (VMCM) being deployed at site LT-A. |
| Figure 21 |
SEACAT data logger. |
| Figure 22 |
A MicroCAT mounted on the top of a 41-inch steel float. |
| Figure 23 |
(A) A Sea-Tech 25-centimeter folded-path transmissometer mounted horizontally on the large tripod frame, and (B) a Delrin(TM) anti-fouling ring mounted around the transmissometer window. |
| Figure 24 |
Time-series sediment trap deployed at sites LT-A and LT-B. |
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| Data Processing |
| Figure 25 |
Filter weights applied to the time-series data in the low-pass filter PL33. |
| Figure 26 |
Amplitude transfer function for the low-pass filter PL33, showing the amplitude response
as a function of frequency. |
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| Biological Fouling |
| Figure 27 |
(A) Surface of a 41-inch subsurface float that was deployed at about 10 meters, and (B) tripod recovery floats that were deployed about 3 meters above the bottom from September 1998 to February 1999. |
| Figure 28 |
(A) A Vector-Measuring Current Meter deployed on mooring 348 at about 22 meters from July to October 1990, (B) a portion of the Vector-Measuring Current Meter and the transmissometer deployed at 5 meters from July to October 1990 on mooring 348, and (C) a heavily fouled subsurface float and Vector-Measuring Current Meter deployed at about 5 and 8 meters below the surface, respectively, at site LT-A from March to September 2003 on mooring 707. |
| Figure 29 |
The lens of the bottom camera and battery case deployed from May to September 1999 on mooring 569 at site LT-A. |
| Figure 30 |
A tripod tangled with lobster gear recovered from site LT-A in February 1993. |
| Figure 31 |
The top of a time-series sediment trap with exceptional bio-fouling after a summer deployment at site LT-B. |
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