CRUISE REPORT
NORTH BRAZIL CURRENT RINGS EXPERIMENT
R/V Seward Johnson Cruise No. 9808
November 7 – December 11, 1998
1. Introduction and Objectives
The North Brazil Current Rings Experiment is a joint effort between the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, NOAA’s Atlantic Oceanographic and Meteorological Laboratory, the Woods Hole Oceanographic Institution, and Columbia University’s Lamont Doherty Earth Observatory. The program is jointly funded by the National Science Foundation (NSF) and the National Oceanic and Atmospheric Administration (NOAA).
The main objectives of the program are:
1. To obtain a thorough description of the temporal evolution of the North Brazil Current retroflection and the shedding of rings from the retroflection.
2. To determine the physical structure of NBC rings after they separate from the retroflection and the volume of South Atlantic water they trap and transport, and
3. To determine the rates of translation, decay, and mixing with resident North Atlantic waters as the rings move northwestward toward the Caribbean Sea.
In order to achieve these objectives, intensive field work will take place during 3 cruises. During the first cruise, two sound sources (S1 and S2), one current meter mooring (CMM1), one CTD mooring (CMM2) and an array of 13 inverted e cho sounders (IES) were deployed. Sixteen surface drifters and fifteen subsurface floats (RAFOS and ALFOS) were launched. CTD casts were obtained at the deployment sites for further calibration. An intensive hydrographic and current survey, guided by sat ellite products, was performed on the rings. During the second cruise, planned for February, 1999, the rings sampled during cruise one will be surveyed again to study the ring evolution. The third cruise (~March, 2000) will be mainly a recovery cruise and additional hydrographic and current data will be collected for further calibration of the moored instrumentation.
2. Cruise Dates and Personnel
CRUISE 1
R/V Seward Johnson 9808
The first cruise was carried out from the R/V Seward Johnson during November 7 - December 11, 1998. The cruise consisted of two consecutive legs.
Leg 1: November 7 to November 25th 1998 - Bridgetown, Barbados to Belem, Brazil
Leg 1 Participants:
1. Silvia L. Garzoli NOAA/AOML Chief Scientist
2. Dave Bitterman NOAA/AOML Engineer, IES
3. Jose Ochoa NOAA/AOML Engineer, IES
4. Robert Roddy NOAA/AOML Technician, IES
5. Christiane Fleurant NOAA/AOML Research Assistant
6. Ryan Smith NOAA/AOML Research Assistant
7. Bill Johns RSMAS/UM Scientist
8. Robert Jones RSMAS/UM Technician, Moorings
9. Mark Graham RSMAS/UM Technician, Moorings
10. David Fratantoni WHOI Scientist
11. Larry Castello WHOI Technician, Moorings
12. Jose E.R. Pereira IOUSP, Brazil Research Assistant
13. Rogerio Silva DHN, Brazil Naval Observer
.
Leg 2: November 27 – December 11 - Belem, Brazil to Bridgetown, Barbados
Leg 2 Participants:
1. Bill Johns RSMAS/UM Chief Scientist
2. Doug Wilson NOAA/AOML Scientist
3. Gustavo Goni NOAA/AOML Scientist
4. Robert Cheney NOAA Scientist
5. Christiane Fleurant NOAA/AOML Research Assistant
6. Ryan Smith NOAA/AOML Research Assistant
7. Phil Richardson WHOI Scientist
8. David Fratantoni WHOI Scientist
9. Jiayan Yang WHOI Scientist
10. Suresh Sookbir IMA/Trinidad Scientist
11. Andrea Xavier IOUSP, Brazil Research Assistant
12. Rogerio Silva DHN, Brazil Naval Observer
3. Cruise Objectives
Leg 1 Objectives:
The objectives of Leg 1 were the following (Figure 1):
1) To deploy four moorings: two sound sources, one current meter mooring, and one CTD mooring.
2) To deploy 17 inverted echo sounders (IES).
3) To perform CTD/LADCP casts at the deployment sites for calibration of the data collected with the moorings.
4) To launch the first array of surface drifters and deploy one ALFOS float to test the sound sources.
Leg 2 Objectives:
Objectives of Leg 2 were:
4. Instrument Deployments:
Sound Sources:
Sound source moorings S1 and S2 were deployed during Leg 1 at the locations shown in Table 1 (see also Figure 1).
Table 1
| Site | Latitude | Longitude | Date of Deployment
| S1 | 13° 00.01' N | 57° 52.96' W | November 9, 1998
| S2 | 12° 59.75' N | 51° 06.40' W | November 11, 1998
| |
Current Meter Moorings
Moorings CMM1 and CMM2 were deployed at the following locations during Leg 1. The characteristics of the moorings are given in Figures 4 and 5.
Table 2
| CMM | Latitude | Longitude | Date of Deployment
| 1 | 08° 59.50' N | 52° 44.00' W | November 13, 1998
| 2 | 09° 00.80' N | 52° 45.36' W | November 15, 1998
| |
Inverted Echo Sounders
The original plan called for the deployment of 17 inverted echo sounders (IES) during Leg 1. Several different types of IESs were to be deployed in the experiment (Table 3). Some of the TRIES presented problems with the echo det ector. As a result only 13 deployments took place. Two of the IESs (sites 10 and 12) were equipped with a pressure sensor (PIES). It is planned to repair and deploy the rem aining four instruments during the second project cruise in February 1999. The locations of the IESs deployed during Leg 1 are given in Table 3 and shown in Figure 1.
Table 3
|
IES site |
Latitude |
Longitude |
Depth |
Date |
Make |
S/N |
|
(m) |
(GMT) |
|||||
|
1 |
10° 54.61'N |
52° 04.80' W |
4137 |
12-Nov-98 |
URI |
33 |
|
2 |
09° 44.57' N |
53° 46.80' W |
4580 |
13-Nov-98 |
SeaData |
56 |
|
3 |
08° 09.07' N |
54° 02.45' W |
1115 |
Nov-14-98 |
TRIES |
8 |
|
4 |
07° 30.20' N |
52° 44.06' W |
1140 |
Nov-15-98 |
TRIES |
7 |
|
5 |
09° 45.76' N |
51° 29.08 W |
4843 |
Nov-16-98 |
URI |
37 |
|
8 |
09° 09.01' N |
49° 48.53' W |
4653 |
Nov-17-98 |
URI |
47 |
|
6 |
07° 47.94' N |
51° 09.23' W |
4395 |
N0v-17-98 |
SeaData |
59 |
|
9 |
07° 35.58' N |
49° 10.83' W |
4288 |
Nov-18-98 |
URI |
50 |
|
10 |
06° 27.70' N |
49° 42.52' W |
3858 |
Nov-18-98 |
SeaData/PIES |
58 |
|
12 |
05° 29.90’ N |
48° 19.21 W |
3442 |
Nov-21-98 |
SeaData/PIES |
62 |
|
14 |
06° 46.01’ N |
45° 44.60’W |
4200 |
Nov-22-98 |
URI |
41 |
|
16 |
04° 24.89’ N |
46° 39.18’W |
3273 |
Nov-23-98 |
SeaData/PIES |
50 |
|
17 |
03° 04.70’ N |
47° 09.05’ W |
1802 |
Nov-23-98 |
ELCH |
1 |
Surface Drifters
Satellite tracked surface were launched at the following locations (Table 5):
Table 5. Drifter Launches
|
Name |
Date |
Time (Z) |
Argos ID |
Longitude |
Latitude |
Status |
|
GDC 01 |
11-Nov-98 |
2122 |
16616 |
51 07.35 |
12 59.41 |
OK |
|
GDC 02 |
12-Nov-98 |
1355 |
06207 |
52 05.44 |
10 54.92 |
No Data |
|
GDC 03 |
16-Nov-98 |
1447 |
02861 |
51 29.36 |
09 46.57 |
OK |
|
GDC 04 |
17-Nov-98 |
0443 |
02860 |
49 48.53 |
09 09.07 |
OK |
|
GDC 05 |
21-Nov-98 |
1758 |
03667 |
47 39.68 |
07 18.34 |
OK |
|
GDC 06 |
22-Nov-98 |
1155 |
03666 |
45 45.39 |
06 45.63 |
OK |
|
GDC 07 |
22-Nov-98 |
2303 |
04889 |
46 18.65 |
05 14.38 |
OK |
|
GDC 08 |
23-Nov-98 |
0635 |
03669 |
46 38.08 |
04 23.54 |
OK |
|
GDC 09 |
23-Nov-98 |
2131 |
03668 |
47 10.90 |
03 06.02 |
No Data |
|
GDC 10 |
28-Nov-98 |
0955 |
04888 |
47 34.50 |
02 05.35 |
OK |
|
GDC 11 |
29-Nov-98 |
1651 |
05133 |
49 23.18 |
06 22.51 |
OK |
|
WHOI 01 |
05-Dec-98 |
2142 |
09638 |
49 30.52 |
06 13.85 |
OK |
|
WHOI 02 |
06-Dec-98 |
0151 |
09639 |
50 01.03 |
06 17.07 |
OK |
|
WHOI 03 |
06-Dec-98 |
0608 |
09636 |
50 31.25 |
06 24.31 |
OK |
|
WHOI 04 |
09-Dec-98 |
1716 |
09637 |
56 10.64 |
08 54.06 |
OK |
|
GDC 12 |
09-Dec-98 |
2050 |
06208 |
56 22.36 |
09 13.09 |
OK |
Floats
Acoustically tracked subsurface floats (RAFOS and ALFOS) were deployed at the following locations (Table 6).
Table 6. Float Launches
|
Name |
Date |
Time (Z) |
Argos ID |
Longitude |
Latitude |
Depth |
|
ALFOS 17 |
12-Nov-98 |
1457 |
09628 |
52 13.95 |
10 48.10 |
1000 |
|
RAFOS 431 |
05-Dec-98 |
2142 |
09625 |
49 30.52 |
06 13.85 |
200A |
|
RAFOS 33 |
06-Dec-98 |
0608 |
05014 |
50 31.25 |
06 24.31 |
200 |
|
RAFOS 30 |
06-Dec-98 |
0608 |
05011 |
50 31.25 |
06 24.31 |
450 |
|
RAFOS 42 |
06-Dec-98 |
0608 |
05023 |
50 31.25 |
06 24.31 |
800 |
|
RAFOS 38 |
06-Dec-98 |
1237 |
05019 |
50 46.28 |
07 06.72 |
200 |
|
RAFOS 35 |
06-Dec-98 |
1237 |
05016 |
50 46.28 |
07 06.72 |
450 |
|
RAFOS 41 |
06-Dec-98 |
1237 |
05022 |
50 46.28 |
07 06.72 |
800 |
|
RAFOS 432 |
06-Dec-98 |
1237 |
09626 |
50 46.28 |
07 06.72 |
1000A |
|
RAFOS 29 |
08-Dec-98 |
0314 |
05010 |
56 14.54 |
08 50.48 |
200 |
|
RAFOS 34 |
08-Dec-98 |
0314 |
05015 |
56 14.54 |
08 50.48 |
450 |
|
RAFOS 40 |
08-Dec-98 |
0314 |
05021 |
56 14.54 |
08 50.48 |
800 |
|
RAFOS 430 |
09-Dec-98 |
1716 |
09624 |
56 10.64 |
08 54.06 |
200A |
|
RAFOS 32 |
09-Dec-98 |
2050 |
05013 |
56 22.36 |
09 13.09 |
450 |
|
RAFOS 433 |
09-Dec-98 |
2050 |
09627 |
56 22.36 |
09 13.09 |
200A |
5. CTDO/LADCP Stations
A total of 68 hydrographic stations were occupied on Legs 1 and 2 (Table 7). At each station, profiles of temperature, salinity (conductivity), and dissolved oxygen concentration (CTDO) were collected to a depth of 2000 m or to within approximately 20 m of the bottom at shallower depths, using a Sea-Bird SBE-9plus CTD system, and water samples for calibration of the salinity and dissolved oxygen profiles were collected. Current profiles were also measured using a lowered 300 kHz R.D. Instruments Acous tic Doppler Current Profiler (LADCP).
Table 7. CTDO/LADCP Station Locations
|
Station |
Date |
Time(z) |
Latitude |
Longitude |
Bot. Depth |
Max Pres. |
|
001 |
11/9/98 |
2244 |
13.000 |
-57.900 |
3530 |
2000.9 |
|
002 |
11/11/98 |
2003 |
12.996 |
-51.116 |
5000 |
2003.3 |
|
003 |
11/12/98 |
1230 |
10.911 |
-52.078 |
4914 |
2000.7 |
|
004 |
11/13/98 |
0400 |
9.744 |
-53.783 |
4580 |
1999.7 |
|
005 |
11/14/98 |
1620 |
8.103 |
-54.041 |
1111 |
1121.1 |
|
006 |
11/15/98 |
0257 |
7.503 |
-52.733 |
1150 |
1140.9 |
|
007 |
11/15/98 |
2210 |
8.986 |
-52.769 |
4600 |
2000.0 |
|
008 |
11/16/98 |
1323 |
9.755 |
-51.483 |
4650 |
2001.1 |
|
009 |
11/17/98 |
0319 |
9.148 |
-49.808 |
4600 |
2003.0 |
|
010 |
11/17/98 |
1735 |
7.801 |
-51.151 |
4600 |
2003.5 |
|
011 |
11/17/98 |
2316 |
7.337 |
-50.549 |
4223 |
2001.9 |
|
012 |
11/18/98 |
1027 |
7.769 |
-49.175 |
4000 |
1998.8 |
|
013 |
11/18/98 |
2129 |
6.463 |
-49.709 |
4000 |
2003.0 |
|
014 |
11/19/98 |
2017 |
5.772 |
-51.246 |
1000 |
771.5 |
|
015 |
11/19/98 |
2243 |
5.747 |
-51.269 |
409 |
457.0 |
|
016 |
11/19/98 |
2344 |
5.728 |
-51.325 |
120 |
118.6 |
|
017 |
11/20/98 |
1433 |
4.520 |
-49.688 |
1682 |
1666.4 |
|
018 |
11/21/98 |
0331 |
5.500 |
-48.319 |
3441 |
2000.7 |
|
019 |
11/21/98 |
1611 |
7.350 |
-47.660 |
4236 |
2013.3 |
|
020 |
11/22/98 |
0443 |
7.205 |
-45.754 |
4312 |
2011.9 |
|
021 |
11/22/98 |
1030 |
6.766 |
-45.743 |
4400 |
2001.8 |
|
022 |
11/22/98 |
1617 |
6.001 |
-46.000 |
3969 |
2000.6 |
|
023 |
11/22/98 |
2139 |
5.261 |
-46.310 |
3686 |
2002.5 |
|
024 |
11/23/98 |
0508 |
4.413 |
-46.652 |
3273 |
2002.3 |
|
025 |
11/23/98 |
1111 |
3.751 |
-46.915 |
2606 |
2000.5 |
|
026 |
11/23/98 |
1954 |
3.078 |
-47.150 |
1805 |
1793.0 |
|
027 |
11/24/98 |
0033 |
2.801 |
-47.283 |
1513 |
1544.7 |
|
028 |
11/24/98 |
0330 |
2.567 |
-47.383 |
1293 |
1256.7 |
|
029 |
11/24/98 |
0365 |
2.275 |
-47.479 |
540 |
515.5 |
|
030 |
12/1/98 |
0319 |
8.050 |
-47.600 |
4406 |
2002.0 |
|
031 |
12/1/98 |
1308 |
7.751 |
-47.949 |
4328 |
2001.0 |
|
032 |
12/1/98 |
1707 |
7.399 |
-48.307 |
4300 |
2008.0 |
|
033 |
12/1/98 |
2140 |
7.046 |
-48.665 |
4200 |
1999.0 |
|
034 |
12/2/98 |
0153 |
6.726 |
-49.013 |
4100 |
1997.0 |
|
035 |
12/2/98 |
0601 |
6.387 |
-49.379 |
3800 |
1997.0 |
|
036 |
12/2/98 |
1011 |
6.049 |
-49.734 |
3750 |
2010.0 |
|
037 |
12/2/98 |
1418 |
5.731 |
-50.083 |
3400 |
2023.0 |
|
038 |
12/2/98 |
1734 |
5.520 |
-50.309 |
2950 |
1997.0 |
|
039 |
12/2/98 |
2038 |
5.366 |
-50.468 |
2008 |
1947.0 |
|
040 |
12/2/98 |
2330 |
5.279 |
-50.571 |
406 |
409.0 |
|
041 |
12/4/98 |
0059 |
3.395 |
48.437 |
515 |
519.0 |
|
042 |
12/4/98 |
0317 |
3.566 |
48.252 |
956 |
742.0 |
|
043 |
12/4/98 |
0750 |
3.783 |
48.033 |
1400 |
1289.0 |
|
044 |
12/4/98 |
1049 |
4.015 |
47.772 |
1241 |
2082.0 |
|
045 |
12/4/98 |
1423 |
4.277 |
47.486 |
2400 |
2006.0 |
|
046 |
12/5/98 |
0221 |
6.000 |
47.500 |
3812 |
2002.0 |
|
047 |
12/5/98 |
0638 |
6.049 |
47.995 |
3795 |
2002.0 |
|
048 |
12/5/98 |
1116 |
6.100 |
48.500 |
3786 |
1996.0 |
|
049 |
12/5/98 |
1536 |
6.168 |
49.003 |
3750 |
2003.0 |
|
050 |
12/5/98 |
2025 |
6.233 |
49.500 |
3683 |
1999.0 |
|
051 |
12/6/98 |
0021 |
6.283 |
50.000 |
3813 |
2002.0 |
|
052 |
12/6/98 |
0439 |
6.397 |
50.506 |
3694 |
2009.0 |
|
053 |
12/6/98 |
1101 |
7.084 |
50.777 |
4088 |
2001.0 |
|
054 |
12/6/98 |
1500 |
7.272 |
51.202 |
4083 |
2000.0 |
|
055 |
12/6/98 |
1905 |
7.500 |
51.649 |
4144 |
2000.0 |
|
056 |
12/6/98 |
2302 |
7.751 |
73.067 |
3317 |
1999.0 |
|
057 |
12/7/98 |
0250 |
7.884 |
52.527 |
2319 |
1999.0 |
|
058 |
12/9/98 |
0029 |
7.387 |
55.408 |
540 |
535.0 |
|
059 |
12/9/98 |
0228 |
7.634 |
55.514 |
1556 |
1550.0 |
|
060 |
12/9/98 |
0532 |
7.950 |
55.664 |
2169 |
2001.0 |
|
061 |
12/9/98 |
0908 |
8.267 |
55.851 |
2631 |
2002.0 |
|
062 |
12/9/98 |
1232 |
8.586 |
56.015 |
2932 |
2002.0 |
|
063 |
12/9/98 |
1552 |
8.901 |
56.182 |
3252 |
2006.0 |
|
064 |
12/9/98 |
1924 |
9.213 |
56.369 |
3360 |
2001.0 |
|
065 |
12/9/98 |
2258 |
9.535 |
56.549 |
3518 |
2008.0 |
|
066 |
12/10/98 |
0233 |
9.833 |
56.716 |
3600 |
2000.0 |
|
067 |
12/10/98 |
0619 |
10.166 |
56.899 |
3685 |
2000.0 |
|
068 |
12/10/98 |
0955 |
10.467 |
57.050 |
3813 |
2006.0 |
Temperature profiles were measured at a total of 176 stations using type T-7 expendable bathythermograph (XBT) probes launched from the stern of the vessel while underway. The locations of the XBT stations are given in Table 8. The launches are liste d in sequential order; probes that failed are not listed.
|
XBT |
Date |
Time |
Latitude |
Longitude |
|
003 |
11/14/98 |
0429 |
08.535 |
-53.395 |
|
004 |
11/14/98 |
1647 |
07.823 |
-53.512 |
|
005 |
11/15/98 |
0845 |
08.250 |
-52.745 |
|
006 |
11/15/98 |
0848 |
08.250 |
-52.745 |
|
007 |
11/16/98 |
0429 |
09.395 |
-52.127 |
|
008 |
11/16/98 |
2020 |
09.438 |
-50.615 |
|
010 |
11/18/98 |
1608 |
06.987 |
-49.468 |
|
011 |
11/19/98 |
0247 |
06.235 |
-50.323 |
|
012 |
11/19/98 |
1806 |
05.895 |
-51.065 |
|
013 |
11/19/98 |
1840 |
05.830 |
-51.152 |
|
014 |
11/19/98 |
1859 |
05.792 |
-51.200 |
|
016 |
11/20/98 |
1902 |
04.877 |
-49.260 |
|
020 |
11/20/98 |
1921 |
04.910 |
-49.208 |
|
021 |
11/20/98 |
2139 |
05.152 |
-48.850 |
|
024 |
11/21/98 |
1244 |
06.813 |
-47.850 |
|
025 |
11/21/98 |
2205 |
07.203 |
-46.927 |
|
026 |
11/22/98 |
0123 |
07.205 |
-46.318 |
|
027 |
11/22/98 |
1427 |
06.335 |
-45.887 |
|
028 |
11/23/98 |
1428 |
03.445 |
-47.022 |
|
029 |
11/24/98 |
0604 |
02.332 |
-47.468 |
|
030 |
11/28/98 |
1414 |
02.302 |
-47.488 |
|
032 |
11/28/98 |
1512 |
02.472 |
-47.420 |
|
033 |
11/28/98 |
1659 |
02.797 |
-47.293 |
|
034 |
11/28/98 |
1900 |
03.177 |
-47.143 |
|
035 |
11/28/98 |
1954 |
03.342 |
-47.077 |
|
036 |
11/28/98 |
2056 |
03.528 |
-47.005 |
|
037 |
11/28/98 |
2149 |
03.683 |
-46.955 |
|
038 |
11/28/98 |
2259 |
03.867 |
-47.092 |
|
039 |
11/29/98 |
0000 |
04.018 |
-47.207 |
|
040 |
11/29/98 |
0100 |
04.153 |
-47.333 |
|
042 |
11/29/98 |
0204 |
04.288 |
-47.485 |
|
043 |
11/29/98 |
0300 |
04.418 |
-47.592 |
|
044 |
11/29/98 |
0401 |
04.557 |
-47.718 |
|
045 |
11/29/98 |
0501 |
04.682 |
-47.858 |
|
046 |
11/29/98 |
0559 |
04.818 |
-47.982 |
|
047 |
11/29/98 |
0700 |
04.965 |
-48.113 |
|
048 |
11/29/98 |
0758 |
05.103 |
-48.240 |
|
049 |
11/29/98 |
0858 |
05.247 |
-48.367 |
|
050 |
11/29/98 |
1000 |
05.393 |
-48.500 |
|
052 |
11/29/98 |
1200 |
05.677 |
-48.755 |
|
054 |
11/29/98 |
1302 |
05.823 |
-48.890 |
|
055 |
11/29/98 |
1400 |
05.963 |
-49.013 |
|
056 |
11/29/98 |
1502 |
06.115 |
-49.152 |
|
057 |
11/29/98 |
1558 |
06.253 |
-49.275 |
|
058 |
11/29/98 |
1701 |
06.387 |
-49.400 |
|
060 |
11/29/98 |
1803 |
06.537 |
-49.537 |
|
061 |
11/29/98 |
1859 |
06.675 |
-49.665 |
|
063 |
11/29/98 |
2003 |
06.832 |
-49.805 |
|
064 |
11/29/98 |
2059 |
06.970 |
-49.925 |
|
066 |
11/29/98 |
2259 |
07.253 |
-50.197 |
|
XBT |
Date |
Time |
Latitude |
Longitude |
|
067 |
11/30/98 |
0000 |
07.392 |
-50.335 |
|
070 |
11/30/98 |
0104 |
07.543 |
-50.478 |
|
071 |
11/30/98 |
0200 |
07.677 |
-50.603 |
|
072 |
11/30/98 |
0258 |
07.813 |
-50.732 |
|
073 |
11/30/98 |
0356 |
07.948 |
-50.858 |
|
074 |
11/30/98 |
0456 |
08.088 |
-50.992 |
|
075 |
11/30/98 |
0556 |
08.233 |
-51.128 |
|
076 |
11/30/98 |
0656 |
08.380 |
-51.263 |
|
077 |
11/30/98 |
0755 |
08.527 |
-51.397 |
|
078 |
11/30/98 |
0855 |
08.670 |
-51.528 |
|
079 |
11/30/98 |
0956 |
08.812 |
-51.657 |
|
080 |
11/30/98 |
1200 |
08.797 |
-51.368 |
|
081 |
11/30/98 |
1358 |
08.722 |
-51.015 |
|
082 |
11/30/98 |
1603 |
08.640 |
-50.630 |
|
083 |
11/30/98 |
1803 |
08.565 |
-50.258 |
|
084 |
11/30/98 |
1958 |
08.487 |
-49.897 |
|
085 |
11/30/98 |
2200 |
08.400 |
-49.522 |
|
086 |
12/01/98 |
0000 |
08.340 |
-49.153 |
|
087 |
12/01/98 |
0200 |
08.263 |
-48.787 |
|
088 |
12/01/98 |
0400 |
08.193 |
-48.438 |
|
089 |
12/01/98 |
0601 |
08.120 |
-48.092 |
|
090 |
12/01/98 |
0758 |
08.055 |
-47.770 |
|
091 |
12/01/98 |
1158 |
07.895 |
-47.787 |
|
092 |
12/01/98 |
1601 |
07.528 |
-48.170 |
|
093 |
12/01/98 |
1858 |
07.353 |
-48.308 |
|
094 |
12/01/98 |
2002 |
07.220 |
-48.438 |
|
095 |
12/01/98 |
2005 |
07.213 |
-48.447 |
|
096 |
12/02/98 |
0039 |
06.867 |
-48.843 |
|
097 |
12/02/98 |
0448 |
06.520 |
-49.217 |
|
098 |
12/02/98 |
0843 |
06.227 |
-49.548 |
|
099 |
12/02/98 |
1310 |
05.862 |
-49.945 |
|
100 |
12/02/98 |
1639 |
05.628 |
-50.207 |
|
101 |
12/02/98 |
1956 |
05.445 |
-50.418 |
|
102 |
12/02/98 |
2000 |
05.437 |
-50.425 |
|
103 |
12/02/98 |
2305 |
05.320 |
-50.545 |
|
104 |
12/04/98 |
0232 |
03.490 |
-48.342 |
|
105 |
12/04/98 |
0552 |
03.680 |
-48.152 |
|
106 |
12/04/98 |
0941 |
03.890 |
-47.915 |
|
107 |
12/04/98 |
1313 |
04.148 |
-47.633 |
|
108 |
12/04/98 |
1728 |
04.602 |
-47.432 |
|
109 |
12/04/98 |
1928 |
04.967 |
-47.382 |
|
110 |
12/04/98 |
2130 |
05.332 |
-47.333 |
|
111 |
12/04/98 |
2329 |
05.693 |
-47.285 |
|
112 |
12/05/98 |
0053 |
05.950 |
-47.255 |
|
113 |
12/05/98 |
0510 |
06.020 |
-47.755 |
|
114 |
12/05/98 |
0942 |
06.075 |
-48.247 |
|
115 |
12/05/98 |
1413 |
06.135 |
-48.770 |
|
116 |
12/05/98 |
1902 |
06.173 |
-49.258 |
|
117 |
12/05/98 |
2305 |
06.260 |
-49.762 |
|
118 |
12/06/98 |
0304 |
06.307 |
-50.247 |
|
XBT |
Date |
Time |
Latitude |
Longitude |
|
119 |
12/06/98 |
0741 |
06.585 |
-50.702 |
|
120 |
12/06/98 |
1348 |
07.188 |
-50.982 |
|
121 |
12/06/98 |
1740 |
07.398 |
-51.422 |
|
122 |
12/06/98 |
2141 |
07.660 |
-51.823 |
|
123 |
12/07/98 |
0138 |
07.858 |
-52.308 |
|
124 |
12/07/98 |
0616 |
08.232 |
-52.747 |
|
125 |
12/07/98 |
0807 |
08.553 |
-52.957 |
|
126 |
12/07/98 |
1005 |
08.895 |
-53.177 |
|
127 |
12/07/98 |
1058 |
09.045 |
-53.282 |
|
128 |
12/07/98 |
1158 |
09.222 |
-53.395 |
|
129 |
12/07/98 |
1236 |
09.332 |
-53.468 |
|
130 |
12/07/98 |
1329 |
09.333 |
-53.647 |
|
131 |
12/07/98 |
1440 |
09.332 |
-53.888 |
|
132 |
12/07/98 |
1530 |
09.335 |
-54.053 |
|
133 |
12/07/98 |
1630 |
09.333 |
-54.250 |
|
134 |
12/07/98 |
1730 |
09.332 |
-54.450 |
|
135 |
12/07/98 |
1830 |
09.333 |
-54.648 |
|
136 |
12/07/98 |
1929 |
09.332 |
-54.838 |
|
137 |
12/07/98 |
2029 |
09.315 |
-55.035 |
|
138 |
12/07/98 |
2130 |
09.278 |
-55.227 |
|
139 |
12/07/98 |
2228 |
09.212 |
-55.407 |
|
140 |
12/07/98 |
2234 |
09.203 |
-55.428 |
|
141 |
12/07/98 |
2330 |
09.143 |
-55.598 |
|
142 |
12/08/98 |
0030 |
09.075 |
-55.787 |
|
143 |
12/08/98 |
0131 |
09.008 |
-55.995 |
|
144 |
12/08/98 |
0227 |
08.903 |
-56.150 |
|
145 |
12/08/98 |
0242 |
08.880 |
-56.183 |
|
146 |
12/08/98 |
0402 |
08.755 |
-56.365 |
|
XBT |
Date |
Time |
Latitude |
Longitude |
|
147 |
12/08/98 |
0459 |
08.650 |
-56.518 |
|
148 |
12/08/98 |
0600 |
08.537 |
-56.680 |
|
149 |
12/08/98 |
0700 |
08.428 |
-56.838 |
|
150 |
12/08/98 |
0703 |
08.422 |
-56.847 |
|
151 |
12/08/98 |
0759 |
08.318 |
-56.998 |
|
152 |
12/08/98 |
0900 |
08.203 |
-57.163 |
|
153 |
12/08/98 |
1000 |
08.097 |
-57.332 |
|
154 |
12/08/98 |
1100 |
07.977 |
-57.500 |
|
155 |
12/08/98 |
1103 |
07.970 |
-57.510 |
|
156 |
12/08/98 |
1113 |
07.953 |
-57.535 |
|
157 |
12/08/98 |
1530 |
07.725 |
-56.855 |
|
158 |
12/08/98 |
1628 |
07.677 |
-56.687 |
|
159 |
12/08/98 |
1728 |
07.627 |
-56.515 |
|
160 |
12/08/98 |
1829 |
07.578 |
-56.342 |
|
161 |
12/08/98 |
1937 |
07.522 |
-56.143 |
|
162 |
12/08/98 |
2034 |
07.472 |
-55.975 |
|
163 |
12/08/98 |
2129 |
07.422 |
-55.810 |
|
164 |
12/08/98 |
2132 |
07.418 |
-55.800 |
|
165 |
12/08/98 |
2228 |
07.368 |
-55.627 |
|
166 |
12/09/98 |
0149 |
07.530 |
-55.477 |
|
167 |
12/09/98 |
0432 |
07.790 |
-55.597 |
|
168 |
12/09/98 |
0807 |
08.120 |
-55.767 |
|
169 |
12/09/98 |
1136 |
08.433 |
-55.940 |
|
170 |
12/09/98 |
1459 |
08.760 |
-56.110 |
|
171 |
12/09/98 |
1816 |
09.052 |
-56.272 |
|
172 |
12/09/98 |
2207 |
09.413 |
-56.482 |
|
173 |
12/10/98 |
0131 |
09.703 |
-56.635 |
|
175 |
12/10/98 |
0515 |
10.008 |
-56.813 |
|
176 |
12/10/98 |
0854 |
10.317 |
-56.977 |
Thermosalinograph
Values of surface temperature and salinity were continuously monitored and logged on the ships computer using a Sea-Bird temperature-conductivity recorder installed in the ships seawater intake line.
Shipboard Acoustic Doppler Current Profiler
Upper ocean currents were continuously measured with a 150 kHz Narrow-band Acoustic Doppler Current Profiler (ADCP) mounted in the ship’s transducer well. The depth range of good velocity data typically extended to 250 m below the vessel, depe nding on sea state conditions.
The hydrographic and underway measurements collected during the cruise
revealed the presence of a North Brazil Current Ring located near 8.5° N, 53.5° W during Leg 1 and near 9° N, 56° W during Leg 2 (Fig. 3).This ring was carefully surveyed during Leg 2 and showed maximum swirl velocities of more than 1 m/s at 150-200 m depth. An interesting feature of this ring was that its surface signature was much weaker than at the thermocline level, which was an unanticipated finding that had not been previously observed for a North Brazil Current Ring.
The North Brazil Current retroflection was found to be well developed during both legs and its northwestward extent had increased considerably between Legs 1 and 2, from approximately 7.5° N to 9° N. The retroflection was carefully surveyed on Leg 2. A partially closed circulation cell was found within the retroflection which suggested that a second ring was in the process of pinching off, although this was not observed to take place before the ship left the area. These features as well as other general features of the near surface circulation during the time of the cruise are illustrated in Figures 3a and b which show the shipboard Acoustic Doppler Current Profiler measurements at the surface and 200 m for cruise legs 1 and 2, respectively.
9. Release of Project Data
In accordance with the provisions specified in the cruise prospectus and application for foreign clearances, the full data results from this experiment will be provided to all clearance countries according to the following schedule:
Shipboard Measurements
All shipboard measurements, including underway data records, CTDO/LADCP station data, and XBT profile data will be provided within 6 months of the termination of the cruise (June 1, 1999).
Moored Instrumentation and Drifters/Floats
Time series data records from current meters, IESs, surface drifters, and subsurface floats will be provided within 2 years after final recovery of the moored instrumentation (nominally June 1, 2002).
10. Foreign Observers and Participants
Scientific participants from Brazil joined both legs of the cruise (Mr. Jose Perreira on Leg 1 and Ms. Andrea Xavier on Leg 2, both from IOUSP), and a participant from Trinidad and Tobago (Mr. Suresh Sookbir from IMA) joined Leg 2 of the cruise. I n addition, a Brazilian Naval Officer (Lt. Rogerio Silva) was an observer on both cruise legs.
11. Acknowledgements
The support and able assistance provided by the Captain and crew of the R/V Seward Johnson is gratefully acknowledged. The scientific participants from Brazil and Trinidad and Tobago were extremely helpful in all aspects of the cruise operations a nd their interest and assistance is much appreciated. Financial support for this research was provided by the U.S. National Science Foundation and the National Oceanic and Atmospheric Administration.
Figure 1: Subsurface moorings and inverted echo sounders (IES) deployed during the cruise. Positions of sound source moorings (triangles), current and CTD moorings (square), and IES (circles) are shown.
Figure 3. Upper-ocean current measured during Leg 1 at depths of 20m (upper panel) and 200 m (lower panel) with the shipboard ADCP.
Figure 4. Upper-ocean current measured during Leg 2 at depths of 20m (upper panel) and 200 m (lower panel) with the shipboard ADCP
(No figure available)