R/V ENDEAVOR Cruise EN256
Woods Hole to Georges Bank to Woods Hole
US State Department Cruise No. 94-16
26 October - 31 October, 1994
This report was prepared by Jim Irish and Ann Martin from cruise notes and logs as a first draft document of the activities, positions, data collected, etc. We gratefully acknowledge the excellent support provided by the Captain and crew of the R/V ENDEAVOR. Their hard work at getting the moorings deployed properly and taking the supporting CTD profiles helped us accomplish our primary scientific goals. We thank Jim Bisagni of the NOAA Remote Sensing Laboratory of Narragansett, RI for the satellite sea surface temperature image.
The GLOBEC research effort is sponsored by the National Science Foundation and the National Oceanic and Atmospheric Administration. Support for the Long-Term Moored Program as part of the U.S. GLOBEC Northwest Atlantic/Georges Bank Study was provided by NSF research grant OCE-9313670. All data in this report are to be considered preliminary.
List of Figures:
Figure 1: Ship's track of R/V ENDEAVOR Cruise EN256 from Woods Hole to Georges Bank and back from the ship's GPS log. The 100 meter contour is plotted to outline Georges Bank. The Crest and Southern Flank mooring sites are identified. The main Long-Term Moored Section (through the Crest and Southern Flank sites) and Stratification Section (to the west) lines are also evident.
Figure 2. Design of the two guard moorings deployed at Southern Flank site to help guard the bottom-mounted ADCP and pressure instrumentation. The mooring uses traditional chain hardware.
Figure 3. Southern Flank mooring positions. The bottom contours run from the northeast to the Southwest at about 60ø. The main scientific mooring (to the west) and the ADCP are aligned along this contour. The two guard buoys are located to the east on either side of the contour.
Figure 4. Schematic plan of the Southern Flank scientific mooring and ADCP instruments as deployed. The sensor spacing is at 5 m nominal depth increments; the sensor depths as measured by the array under tension are given in Table II.
Figure 5. Attenuation of surface wave amplitude and pressure with depth at the Southern Flank mooring site.
Figure 6. Schematic plan of the Crest mooring. The elastic tethers should improve mooring life, and buoy dynamic response to the waves. The tension in the mooring line at the buoy is measured by a load cell, and statistics of the tension averaged over one hour.
Figure 7. PDR plot of Stratification Section transition from smoothly decreasing bottom depth to ridge topography.
Figure 8. First Long-Term CTD Section. Temperature (top) and salinity (bottom) summary of the 12 profiles taken (each numbered for identity) are shown.
Figure 9. First Long-Term CTD Section. T-S summary plot of the data shown in Figure 7 with the stations identified.
Figure 10. Sea surface temperature from 20 October 1994 from the NOAA Remote Sensing Laboratory at Narragansett, RI. The warm Gulf Stream water seen just off the bank is very evident, as is the cooler water coming out of the Gulf of Maine and moving down the shelf between the Crest and Atlantic waters.
Figure 11. First Long-Term CTD Section. Transmissometer (top) and fluorometer (bottom) summary of the 12 profiles taken. The profiles are numbered to assist identification.
Figure 12. Second Long-Term CTD Section. Temperature (top) and salinity (bottom) summary of the 12 profiles taken (each numbered for identity) are shown.
Figure 13. Second Long-Term CTD Section. Transmissometer (top) and fluorometer (bottom) summary of the 12 profiles taken. The profiles are numbered to assist identification.
Figure 14. Stratification CTD Section. Temperature (top) and salinity (bottom) summary of the 8 profiles taken (each numbered for identity) are shown.
Figure 15. Stratification CTD Section. Transmissometer (top) and fluorometer (bottom) summary of the 8 profiles taken. The profiles are numbered to assist identification.
List of Tables:
Table 1. GLOBEC Long-Term Mooring Positions
Table 2.Sensor IDs and Location
Table 3. ADCP Initialization Parameters
Table 4. CTD Station Sheets I
Table 5. CTD Station Sheets II
Table 6. CTD Station Sheets III
Two supportive CTD sections were made from the Crest of the bank into the North Atlantic one day apart passing through the two mooring sites. Then a PDR and CTD section was run through the proposed Stratification Experiment mooring sites to the west of the main mooring section to aid in final mooring design and construction for that experiment.
After the scientific mooring was in place, the second guard buoy was deployed to make a triangle along the 76 m isobath (see Figure 3 and Table 1). The bottom in this region is quite flat and so there is no noticeable orientation. The bottom mounted ADCP was deployed in the middle of the three surface buoys, close to the main scientific mooring since the watch circle of this is less, due to the elastic tethers. In a 1.5 kt current (twice what is expected at this site), the guard buoy watch circles are about 37 meters radius and the main scientific mooring 19 m radius. The guard moorings also have chain at the bottom with a watch circle of 12 to 15 meters which the scientific mooring does not have. The final configuration of sensors is shown in Figure 3 and listed in Table 1. The sensor type, serial numbers and depths on the main scientific mooring are listed in Table 2.
To measure the tidal elevation and wave climate at the site, a Sea Data Model 635-11 Wave and Tide Recorder was deployed on the same bottom instrument frame as the ADCP. Previous narrow band ADCPs had provision for recording external temperature, conductivity and pressure sensors, but the present narrow band ADCP used here did not have this feature. Therefore, an existing Sea Data pressure recorder was modified by the addition of two counter cards to record the temperature of the Paroscientific pressure sensor as well as a Sea Bird Conductivity sensor. The basic sampling program records 15 minute averages of temperature, pressure and conductivity in solid state memory. The instrument also burst-samples the pressure sensor for 128 2 second samples every 6 hours to get a measure of the surface waves. Surface wave amplitude is attenuated with depth as shown in Figure 5, so a 3 second sample interval would not alias any surface waves at the bottom, and waves with periods greater than 6 seconds can be measured by dividing the obtained frequency spectrum by the frequency dependent attenuation shown in Figure 5. Unfortunately for this deployment, the conductivity counter card failed during final testing the day the ship was being loaded, and the conductivity measurement had to be abandoned for the first 6-month deployment. However, the temperature and pressure components as deployed appeared to be working properly.
In order to find a satisfactory location for the Crest mooring, surveys were conducted on EN246 in June 1994. Based on these surveys a region was selected, and more detailed surveys were done on the deployment heading to select the exact location. After this was done, the buoy successfully deployed in 43 meters of water. The location of this mooring is listed in Table 1 and shown on the ship's track in Figure 1.
While we were doing CTD sections near the buoys, we were able to use our Telonics uplink receiver to check the operation of the buoys, and determine the battery voltages and status. Before this cruise we did not have time to program the receiving PC to normalize the data from the bits transmitted to geophysical and engineering units; this will be available for later cruises. Then this real-time readout of the data in geophysical units will to allow us to make an optimal check of the buoy system operation before the ship leaves the area. It can also be placed on other GLOBEC cruises to check out suspected mooring problems. Below is a representative ARGOS data set, gathered during the CTD section, for each buoy.
Crest Buoy: Raw ARGOS Received: 10-29-94 12:52:21 ID 11709 NA 000 012 000 016 010 000 000 015 005 084 154 207 000 129 001 026 000 202 000 025 054 042 054 096 005 228 004 220 007 244 005 076 Format: 1. Day after system start 2. GMT hour in day (time of data) Hourly Averages of: 3. Air Temperature 4. PAR 5. Sea Surface Temperature 6. Sea Surface Conductivity 7. Minimum Tension 8. Maximum Tension 9. Mean Tension 10. Standard Deviation of Tension 11. Battery One on half hour 12. Battery Two on half hour 13. Status after last GOES Transmission 14. Battery After last GOES Transmission 15. System Temperature on half hour 16. System Bus voltage on half hour South Flank Buoy: Raw ARGOS Received: 10-28-94 17:29:54 ID 12778 NA 000 003 000 020 010 060 001 087 001 158 254 128 005 097 010 072 003 131 006 047 250 237 006 077 255 096 051 126 054 177 004 212 10-28-94 17:31:44 ID 12778 NA 000 003 000 021 010 082 001 050 001 159 254 160 005 137 010 125 004 063 006 006 251 222 008 024 001 067 051 078 053 232 004 212
Note how time (fourth set of numbers in data) changed from 20 to 21 on the half hour as the ARGOS data is updated. Data for hour 21 is the average of data from 20:30 to 21:30 and is written to ARGOS and recorder on the half hour.
Format: 1. Day after system start 2. GMT hour in day (time of data) Hourly Averages of: 3. Air Temperature 4 PAR 5. Sea Surface Temperature 6. Temperature at 5 meters 7. Temperature at 15 meters 8. Temperature at 20 meters 9. Temperature at 25 meters 10. Temperature at 30 meters 11. Temperature at 35 meters 12. Temperature at 45 meters 13. Temperature at 50 meters 14. Battery One 15. Battery Two 16. System Status after last GOES Transmission
Figure 8 shows a summary of the first Long-Term Section of temperature (top) and salinity (bottom). The 12 CTD stations in the section are marked to aid interpretation. The salinity record is the simplest, showing lower Crest salinities (represented by profiles 1, 2, 3, 4 and possibly 5), and the higher North Atlantic salinities (represented by profiles 11 and 12). Between, there is a simple mixture of the two. This result is pretty much repeated in the second section 22 hours later (Figure 12), except that profile 5 and possibly 6 is now in the Crest water. The temperature profiles in Figure 8 and Figure12, show a similar picture, except that the coolest water is located in the stratified region of profiles 6 and 7. The Crest is a little warmer, and the North Atlantic is very much warmer due to a streamer from the Gulf Stream residing offshore (Figure 10). The region of the Southern Flank mooring is in the region of highest gradients, but possibly in the shelf slope front pushed up on the shelf further by the warm Gulf Stream water. The T-S plot (Figure 9) shows this same result, with profiles 1 through 5 at nearly the same salinity and cooling down as you go off the bank. Then there appears to be a linear mixture of water of this cool fresh type with the warmer saltier water seen in profiles 11 and 12.
The fluorometer and transmissometer records from the two long-term section (Figure 11 and Figure 13) are nearly the same. The fluorometer records give an indication of the primary productivity since they are tuned to the chlorophyll a emission frequency. Therefore, we expect to see a high correlation of primary productivity with high fluorometer readings. Since we are not calibrating the sensors with known biological signal, we will report the results in volts as a qualitative measure of relative chlorophyll signal. The transmissometer is calibrated in % transmission,with 100% being full transmission of light with no attenuation or absorption, and 0% being all light emitted from the sensor is scattered or absorbed before it hits the receiver 25 cm away.
The fluorometer and transmissometer readings at the Crest profiles 1 and 2 show uniform top to bottom signal with relatively high chlorophyll a and relatively low transmission. The offshore stations (11 and 12) have the lowest chlorophyll a readings and the highest transmission, with relatively little vertical structure -- slightly higher chlorophyll a and lower transmission above 40 meters depth. The highest chlorophyll a peak (and lowest transmissometer) is at station 7, with 8 and 9 both being high chlorophyll a stations (and lower transmission) in the upper 20 meters. The highest chlorophyll a peaks are seen at 10 meters, the depth of the moored bio-optical package at the Southern Flank site (CTD station 8). The second section (Figure 13) shows similar results.
The Stratification CTD section was made during a PDR survey up the line through the proposed Stratification mooring locations. Station 1 is offshore and station 9 onshore -- the opposite of the Long-Term moored section. Again the temperature and salinity (Figure 14) show the cooler fresher water on the bank, and the warmer saltier water offshore with strong vertical gradients and mixing between. The transmissometer and fluorometer profile summary are shown in Figure 15. Again the results are very similar to the Long-Term section profiles, with the high biological activity concentrated in the top 20 meters in the highly stratified region, and in the full water column in the Crest water, and lowest in the offshore water.
25 October 1994 1729 - Crest Buoy Data System Started "CREST.FIN" listing of sampling program 1731 - Triangle Data System Recorder Display has 115 records in it 008 021 last record written "ZERO" works ok "WORK" is OK 3 seconds between terminal skip observed Bottom Pressure/Temperature Recorder hooked up to Notebook with log file 18:07:31 EDT Instrument wrote Sample # 100 (hex) Only End Cap Temperature data in this record Paroscientific Pressure Sensor Plugged in System is working OK 26 October 1994 1130 - Crest Scientific Buoy "B" T & C plugged in Load Cell plugged in Solar Panel #1 - 19.57 v no load Solar Panel #2 - 20.4 v no load Solar Panel #3 - 16.9 v no load Solar Panel #4 - 17.6 v no load 1145 Guard Buoy "A" (Guard Buoy #1) Solar Panel #1 - 19.57 v no load Solar Panel #2 - 19.96 v no load Battery - no load, no solar panels - 12.57 v - no load, solar panels just plugged in - 12.71 v 1150 Guard Buoy "C" (Guard Buoy #2) Solar Panel #1 - 20.5 v no load Solar Panel #2 - 19.6 v no load Battery - no load, no solar panels - 12.81 v - no load, solar panels just plugged in - 13.08 v
Acoustic Release - BACS S/N 15050 BB - ADCP S/N 1272 Paroscientific Pressure Sensor S/N 53084 - 130 m range 1430 - ADCP Started Time set rel WWV for No bottom track; BP set to 000 300 pings @ 2s per 30 minute ensemble Erase Recorder Save Parameters as defaults Check Crest transmitter after 1506 transmission - Crest buoy not reaching GOES or ARGOS is it because antenna is on side and shielded by ship? or other problem? 1545 - Underway to South Flank Site Use Rossby ADCP set up for shipboard unit as no GLOBEC setup on ship 1608 - Talking with CREST data system A39 = Forward GOES power = 47.6 db A38 = Battery after GOES transmission = 12.00 v A37 = STATUS = 1260 = 010011101100 => F/R power error flag! Reattached Type N connector at antenna end shield had become frayed and looked like shorting to center pin 1630 - new ARGOS data updated on half hour Status = 3*256+228 = 996 and shows no F/R power error! Attached third Bio-Optical Package to CTD for test in AM Seas 1-3', Wind 10 kts 2200 - ETA at site 0530 EDT Notes of things to check before launch: Poison tubes on all Conductivity sensors Check TDS recorders in buoys Check ARGOS telemetry on each buoy Start ADCP pinging 27 October 1994 0550 - On station - 40ø 57.93' N x 67ø 18.83' W Wind 12 kts, ADCP water velocity 25 cm/sec, Water Depth 75 m System Status - 12778 (South Flank) - 2*256+212 = 724 - OK 11709 (Crest) - 3*256+228 = 996 - OK Rigging for CTD/Bio-Optical test 0638 - CTD Package in Water 0638 - System at ~ 10 m P=11.0 dbars S=32.766 PSU T=12.75ø C 0707 - wire angle about 30ø Pat & Kent rigging Guard Buoy #1 SST 12.81ø C, SSS 31.92 PSU, FL=0.7 Wind 15 kts 0712 = CTD @ 10 m P=10.2, T=12.60, S=32.7, XM=78% Mooring Program: assume a 1.5 kt current Guard buoy - watch circle radius=37m at top, 15m at bottom Guards > 100 m apart Surlyn buoy - watch circle radius=19m at top 6 bungie tethers gives 850 pounds tension 4 bungie tethers gives 600 pounds tension Tethers something like 50% stretched 0813 Checking South Flank Buoy Reset clock @ 12:24:00 Check at 12:34:30 - OK Recorder stepping - OK 1236 -GMT - A1 & Start system 0855 -Getting ready for Guard Buoy Launch 0908 - Picking up buoy 0909 - Buoy released and behind ship 0915 - Attaching anchor to chain 0933 - 1333GMT anchor away Bridge position - 40ø 58.124' N x 67ø 18.987' W - depth 76 m Lab position - 40ø 58.128' N x 67ø 18.985' W - depth 76 m moved science mooring position to 40ø 58.07 x 67ø 19.10 STATUS 12778 (South Flank) - 3*256 + 212 = 980 - OK 11709 (Crest) - 3*256 + 228 = 996 - OK South Flank Battery #2 = 12.687 v 0954 - 2nd anchor moved into launch position Moving scientific buoy into launch position Batteries 11709 (Crest) - at last half hour B1=12.687 B2=12.714 12778 (South Flank) - average over last hour B1=12.630 B2=12.675 Rigging buoy 1103 - Bio-Optical package #1 @ 10m Cond SN=041340 Temp SN=031622 Fluorometer=296 Transmissometer=621 PAR=1660 Pump=40 Array Sensors: T1=1630 - C1=1379 T3=1628 - C3=1343 T4=1629 - C4=1365 T5=1615 - C5=1366 T6=1632 - C6=1367 T7=1631 - C7=1377 T9=1624 - C9=1342 T10=1613 - C10=1369 Buoy Sensors PAR=4949 Air Temp=?? Acoustic Release 17307 Ch A 11 kHz down, 12 kHz reply Ch B 9 kHz down, 11 kHz reply Enable A/B 56631 Disable A 566377 Disable B 566377 Release 544214 1130 STATUS and Battery voltage reading 12778 (South Flank) - B1=13.350 B2=13.221 STATUS=980 - OK 11709 (Crest) - B1=13.077 B2-13.605 STATUS=996 - OK Wind 16 kts, seas 2-4' Bio-Optic Package #2 @ 40 m Cond=041333 Temp=031623 Par=1659 Trans=620 12?? - start launch of South Flank Science buoy 1239 - all sensors in water 1244 - Acoustic release in water and chain tight to anchor 1306 - Anchor in water 1307 - Anchor released - GPS position: Wheel - 40ø 58.123 x 67 19.183 Trimble - 40ø 58.096 x 67 19.173 1330 - Running by Science buoy to check fix Wheel - 40ø 58.06 x 67 19.21 Trimble - 40ø 58.091 x 67 19.214 Magellan - 40ø 58.093 x 67 19.213 Visual bearing between two buoys shows 81ø True, bathymetry aligned 60ø T 1400 - Rigging for Guard Buoy #2 Changing position on deck 1438 - Start launch by picking up buoy 1442 - Buoy in water 1452 - Anchor released on Guard #2 Wheel - 40ø 58.20 x 67 19.07 Trimble - 40ø 58.186 x 67 19.086 15:00:05 - started ADCP system Log "STARTADCP.LOG" wrote record with time 19:00:07 19:40:07 UTC - Wrote record on time 1552 - ADCP deployed (allowed to free fall to bottom) Trimble Position- 40ø 58.118 x 67 19.129 1699 - Kent ranging on acoustic releases 1820 - starting CTD series at site Winch readout not functioning, holding up CTD series 1926 - CTD02 at South Flank Mooring 2030 - CTD03 at South Flank Mooring 2045 - End of operations at South Flank Mooring site - head for Crest Site repairing winch readout 0630 - Wind 8 kts, Seas 2-3', nice sunrise setting up PDR for Crest final site survey run line @ 320øT (deployment heading) through site 1.5 nm on each side keep speed down to 5 kts 0715 - turning onto survey course 0752 - changing PDR paper 0945 - Crest survey done, site selected north of initial position, good flat area 43 m deep 0946 - Setting up and preparing buoy for launch getting ship 1/2 nm below site 1026 - Pick up buoy 1028 - buoy on tether behind ship 1030 - streamed out and towing behind ship 1048 - anchor aweight Trimble position - 41ø 24.413' N x 67ø 32.485' W 1106 - SST=14.25øC, SSS=31.77 PSU NOTE ARGOS uplink receiver time is off 10/28/94 - 11:12:00 - reads 10/09/94 - 12:09:15 Steaming to first station of Main Line Section CTD survey 1306 - Station 01 - CTD05 - well mixed top to bottom 1417 - Station 02 - CTD06 - Crest Mooring Site - well mixed top to bottom 1527 - Station 03 - CTD07 1612 - Station 04 - CTD08 1659 - Station 05 - CTD09 1740 - Station 06 - CTD10 1818 - Station 07 - CTD11 1902 - Station 08 - CTD12 - Southern Flank Site - one hour yo-yo at site 2038 - Station 09 - CTD13 2119 - Station 10 - CTD14 2204 - Station 11 - CTD15 2309 - Station 12 - CTD16 2330 - Put bio-optical package on CTD for testing and end ops for day 29 October 1994 0500 - Deploy bio-optical package on CTD at 10 meters depth 0900 - Winds 18 kts, seas 3-4' sunny 1000 - Bio-optical package out of water and end comparison test testing on deck, heading for main line CTD station 01 1114 - Station 01 - CTD18 1200 - at Crest buoy - wind 18 kts, seas 4' buoy leaning at slight angle - took pictures 1213 - good ARGOS test of Crest buoy STATUS = 1508 - 10-22øC, no F/R error, 48 db out, 13.0 v after GOES Battery #1 - 13.599 v Battery #2 - 13.839 v Battery after last GOES transmission 12.12 MCM temperature 12.12øC MCM Bus voltage 13.56 v 1247 - Station 02 - CTD19 at Crest Buoy 1302 - reset ARGOS uplink receiver clock to 10/28/94 - 13:02:00 1350 - Station 03 - CTD20 1425 - Station 04 - CTD21 1500 - wind 15-16 kts 1505 - Station 05 - CTD22 1540 - Station 06 - CTD23 1620 - wind down to 10 kts 1623 - Station 07 - CTD24 1705 - Station 08 - CTD25 - yoyo at South Flank Buoy 1840 - Station 09 - CTD26 1918 - Station 10 - CTD27 1950 - Station 11 - CTD28 2000 - Wind and seas back up 2108 - Station 12 - CTD29 2120 - Done with CTD survey mounting bio-optical package on CTD new batteries in CTD for night operations ship to be at stratification section start at 0700 on Sun seas about 5', wind 20 kts. 30 October 1994 0600 - pulling up bio-optical package on CTD break off CTD frame and move in lab Transit to start of PDR section 0656 - start of survey line putting new batteries in CTD 0730 - Steady on PDR line wind 20 kts, seas 4-5' 0934 - Station 01 - CTD31 NOTE Sea Surface Temperature and Conductivity Clock off Reads 30 Oct 1994 - 01:07:00 PM instead of 13:40:47 UTC - not reset 1035 - Station 02 - CTD32 1127 - Station 03 - CTD33 1213 - Station 04 - CTD34 1300 - Station 05 - CTD35 1344 - Station 06 - CTD36 1431 - Station 07 - CTD37 1510 - Station 08 - CTD38 1525 - End of CTD section through Stratification Moorings 1550 - End of PDR section through proposed Stratification Mooring Sites End of operations, securing deck and heading for Woods Hole Dock 31 October 1994 0830 - arrive at WHOI dock in thick fog 0900 - unloading our equipment rigging shop taking off winches, deck boxes, etc.