133:"… In any kind of rough weather, this BT position was frequently subject to waves making a clean sweep of the deck. In spite of breaking waves over the side, the operator had to hold his station, because the equipment was already over the side. One couldn't run for shelter as the brake and hoisting power were combined in a single hand lever. To let go of this lever would cause all the wire on the winch to unwind, sending the recording device and all its cable to the ocean bottom forever. It was not at all uncommon, from the protective position of the laboratory door, to look back and see your watchmate at the BT winch completely disappear from sight as a wave would come crashing over the side. … We also took turns taking BT readings. It wasn't fair for only one person to get wet consistently."
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vessel. The wire would be paid out from the surface ship and not from the surface float unit. The surface float would require a minimum of flotation and a small, very simple sea anchor. From this simple platform the expendable BT unit would sink as outlined for the acoustic unit. However, it would unwind as it goes a very fine thread of probably neutrally buoyant conductor terminating at the float unit, thence connected to the wire leading to the ship.
22:
1085:
where, z(t) is the depth of the XBT in meters; t is time; and a & b are coefficients determined using theoretical and empirical methods. The coefficient b can be thought of as the initial speed as the probe hits the water. The coefficient a can be thought of as the reduction in mass with time as
189:
which pay out from both a spool retained on the ship and one dropped with the instrument, provide a data transfer line to the ship for shipboard recording. Eventually, the wire runs out and breaks, and the XBT sinks to the ocean floor. Since the deployment of an XBT does not require the ship to slow
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temperature measurements. They also showed that this varies over time and could be due to both errors in the calculation of depth and in measurement of the temperature. From that the 2008 NOAA XBT Fall Rate
Workshop began to address the problem, with no viable conclusion as to how to proceed with
153:
Briefly, the unit would break down in two components, as follows: the ship to surface unit, and surface to expendable unit. I have in mind a package which could be jettisoned, either by the "Armstrong" method, or some simple mechanical device, which would at all times be connected to the surface
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floats has provided a much more reliable source of temperature profiles than XBTs, however the XBT record remains important for estimating decadal trends and variability and hence much effort has been put into resolving these systematic biases. XBT correction needs to include both a drop-rate
56:
to detect changes in water temperature versus depth down to a depth of approximately 285 meters (935 feet). Lowered by a small winch on the ship into the water, the BT records pressure and temperature changes on a coated glass slide as it is dropped nearly freely through the water. While the
97:. Originally the slides were prepared "by rubbing a bit of skunk oil on with a finger and then wiping off with the soft side of one's hand," followed by smoking the slide over the flame of a Bunsen burner. Later on the skunk oil was replaced with an evaporated metal film.
126:, which are colder layers of water, that would distort the pinging from the surface vessel's sonar, allowing the submarine under attack to "disguise" its actual position and to escape depth charge damage and eventually to escape from the surface vessel.
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A major implication of this is that a depth-temperature profile can be integrated to estimate upper ocean heat content; the bias in these equations lead to a warm bias in the heat content estimations. The introduction of
129:
Throughout the use of the bathythermograph various technicians, watchstanders, and oceanographers noted how dangerous the deployment and retrieval of the BT was. According to watchstander Edward S. Barr:
185:
which is connected electronically to a chart recorder. The probe falls freely at 20 feet per second and that determines its depth and provides a temperature-depth trace on the recorder. A pair of fine
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cast would require stopping the ship for several hours. Airborne versions (AXBT) are also used; these use radio frequencies to transmit the data to the aircraft during deployment. Today
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Since XBTs do not measure depth (e.g. via pressure), fall-rate equations are used to derive depth profiles from what is essentially a time series. The fall rate equation takes the form:
57:
instrument is being dropped, the wire is payed out until it reaches a predetermined depth, then a brake is applied and the BT is drawn back to the surface. Because the pressure is a
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After witnessing firsthand the dangers of deploying and retrieving BTs, James M. Snodgrass began developing the expendable bathythermograph (XBT). Snodgrass' description of the XBT:
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1317:
1080:
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For a considerable time, these equations were relatively well-established, however in 2007 Gouretski and
Koltermann showed a bias between XBT temperature measurements and
122:
More importantly, when the submarine was under attack by a surface vessel using sonar, the information from the bathothermograph allowed the submarine commander to seek
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adjusting the measurements. In 2010 the second XBT Fall Rate
Workshop was held in Hamburg, Germany to continue discussing the problem and forge a way forward.
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by producing inaccurate location results, bathothermographs (U.S. World War II spelling) were installed on the outer hulls of U.S. submarines during
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1306:"New Techniques in Undersea Technology," IEEE Transactions on Aerospace and Electronic Systems, Vol. AES-2, No. 6 (November 1966), 626.
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Expendable
Bathythermograph Expendable Sound Velocimeter (XBT/XSV) Expendable Profiling Systems from Lockheed Martin Sippican
82:
86:
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93:. The device was modified during World War II to gather information on the varying temperature of the ocean for the
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By monitoring variances, or lack of variances, in underwater temperature or pressure layers, while submerged, the
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196:, such as cargo ships or ferries, and also by dedicated research ships conducting underway operations when a
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Scripps
Institution of Oceanography: Probing the Oceans 1936 to 1976. San Diego, Calif: Tofua Press, 1978.
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contracted
Sippican Corporation of Marion, Massachusetts to develop the XBT, who became the sole supplier.
119:
accuracy. This was especially important when firing torpedoes at a target based strictly on a sonar fix.
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Helicopter-Based Ocean
Observations Capture Broad Ocean Heat Intrusions Toward the Totten Ice Shelf
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1348:
1318:"Expendable Bathythermograph Expendable Sound Velocimeter (XBT/XSV) Expendable Profiling Systems"
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The unit is composed of a probe; a wire link; and a shipboard canister. Inside of the probe is a
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showed that water at depth above freezing temperature was melting the under-side of the glacier.
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Antarctic helicopter mission helps confirm Totten
Glacier melting from below due to warm water
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1377:
Gouretski, Viktor; Koltermann, Klaus Peter (2007). "How much is the ocean really warming?".
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High resolution for U.S. Navy mine counter-measures and physical oceanographic applications.
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started experimenting. He then forwarded the development of the BT to his graduate student
8:
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65:), temperature measurements can be correlated with the depth at which they are recorded.
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Increased depth for improved sonar prediction in ASW and other military applications
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down or otherwise interfere with normal operations, XBT's are often deployed from
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Provides maximum depth capabilities at the highest possible ship speed of any XBT
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1442:. XBT Bias and Fall Rate workshop. Hamburg, Germany. p. 14. Archived from
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commander could adjust and compensate for temperature layers that could affect
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1243:"Bathythermograph, Athelstan Spilhaus, 1936 | the MIT 150 Exhibition"
1528:"Climate and Atmospheric Science at Scripps: The Legacy of Jerome Namias"
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81:, who then fully developed the BT in 1938 as a collaboration between
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Scripps
Institution of Oceanography: Probing the Oceans 1936 to 1976
1119:: to obtain information on the temperature structure of the ocean.
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Participation by Month of
Country and Institutions deploying XBTs
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Increased launch speed for oceanographic and naval applications
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Atlantic Oceanographic & Meteorological Laboratory of NOAA
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Letter from Allyn Vine to Richard H. Fleming, 20 August 1941.
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1499:. Annapolis, Maryland: Naval Institute Press. p. 458.
1277:. Annapolis, Maryland: Naval Institute Press. p. 458.
1297:"MIDPAC — The First Big Step," manuscript, 17 August 1975.
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Since water temperature may vary by layer and may affect
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A study in 2019 (published 2023) at the outfall of the
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Silent Victory, the U.S. Submarine war against Japan
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Silent Victory, the U.S. Submarine war against Japan
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142:"XBT" redirects here. For the cryptocurrency, see
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1432:
1169: – Platform for measurements on the seabed
1163: – Measuring the depths of a body of water
397:Below is the list of XBT deployments for 2013:
261:Deep ocean scientific and military applications
16:Device to detect water temperature and pressure
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1461:
1436:XBT Bias and Fall Rate Workshop Summary Report
169:An XBT being launched via a handheld launcher.
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73:The true origins of the BT began in 1935 when
1223:. College Station: Texas A&M University.
1175: – Device to measure seawater properties
1470:, Yoshihiro Nakayama et al, AGU, 2023-09-11
1316:Lockheed Martin Sippican (September 2005).
1203:http://ark.cdlib.org/ark:/13030/kt109nc2cj/
87:Woods Hole Oceanographic Institution (WHOI)
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1103:correction and a temperature correction.
238:Standard probe used by the U.S. Navy for
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204:has manufactured over 5 million XBTs.
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1433:Viktor Gouretsk (25–27 August 2010).
1349:"SOOP Operations Report: XBT Program"
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1217:Introduction to Physical Oceanography
1146:) used by submarines to avoid active
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356:Commercial fisheries applications
1526:Richard C.J. Somerville (2003).
1142:: to determine the layer depth (
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1075:{\displaystyle z(t)=at^{2}+bt}
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1:
1575:Oceanographic instrumentation
1413:"NOAA XBT Fall Rate Workshop"
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1379:Geophysical Research Letters
1358:. 31 October 2014. p. 2
177:A rendering of an XBT probe.
7:
1323:. p. 3. Archived from
1214:Stewart, Robert H. (2007).
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138:Expendable bathythermograph
45:; is a device that holds a
39:Mechanical Bathythermograph
10:
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299:Oceanographic applications
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68:
1556:with a bathythermograph)
1495:Blair, Clay Jr. (2001).
202:Lockheed Martin Sippican
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158:In the early 1960s the
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1140:Anti-submarine warfare
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193:vessels of opportunity
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24:
1550:on 24 February 2019.
1399:10.1029/2006GL027834
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230:Vertical Resolution
37:, also known as the
1543:(3). Archived from
1391:2007GeoRL..34.1610G
1330:on 3 February 2013
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1021:XBT Fall Rate Bias
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79:Athelstan Spilhaus
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25:A bathythermograph
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99:
72:
63:Pascal's law
42:
38:
34:
30:
28:
18:
1144:thermocline
1117:hydrography
403:Cntry/Month
386:18 cm
367:65 cm
361:600 ft
348:65 cm
329:65 cm
310:65 cm
291:65 cm
272:65 cm
253:65 cm
47:temperature
1569:Categories
1418:3 December
1334:2015-07-20
1180:References
931:USA/Others
242:operations
183:thermistor
89:, and the
54:transducer
1229:169907785
1136:Submarine
334:Deep Blue
277:Fast Deep
160:U.S. Navy
113:submarine
95:U.S. Navy
91:U.S. Navy
1273:(2001).
1155:See also
799:USA/AOML
364:10 knots
345:20 knots
326:15 knots
307:15 knots
288:20 knots
250:30 knots
212:Source:
59:function
1387:Bibcode
1362:20 July
1150:search.
843:USA/SIO
491:AUS/SIO
383:6 knots
269:6 knots
264:1830 m
144:Bitcoin
69:History
1503:
1281:
1227:
1014:17992
442:Total
283:1000 m
245:460 m
52:and a
50:sensor
1585:Sonar
1548:(PDF)
1531:(PDF)
1453:8 May
1447:(PDF)
1440:(PDF)
1385:(1).
1352:(PDF)
1328:(PDF)
1321:(PDF)
1221:(PDF)
1148:sonar
975:Total
882:4623
838:5598
662:1140
486:3360
378:460 m
359:200 m
340:760 m
321:760 m
302:460 m
218:Model
117:sonar
102:sonar
41:, or
33:, or
1501:ISBN
1455:2014
1420:2013
1364:2015
1279:ISBN
1225:OCLC
1138:and
1115:and
1107:Uses
1100:Argo
1011:1753
1005:1477
1002:1310
999:1611
996:1542
993:1802
990:1756
984:2006
981:1246
978:1822
926:338
794:782
750:289
618:769
574:268
530:705
372:T-11
353:T-10
29:The
1395:doi
1173:CTD
1126:in
1091:CTD
1008:887
987:780
970:61
893:144
879:477
876:104
873:525
870:382
867:300
864:172
861:591
858:350
855:240
852:607
846:788
835:396
832:235
829:436
826:456
823:634
820:559
817:341
814:812
808:773
805:477
802:477
779:115
755:JPN
711:ITA
706:59
667:GER
659:206
644:301
632:258
623:FRA
603:105
600:146
597:130
579:CAN
535:BRA
527:182
521:105
509:100
483:262
480:232
477:208
474:316
471:313
468:278
465:397
462:311
459:277
456:241
453:292
450:233
447:AUS
439:DEC
436:NOV
433:OCT
430:SEP
427:AUG
424:JUL
421:JUN
418:MAY
415:APR
412:MAR
409:FEB
406:JAN
315:T-7
296:T-6
258:T-5
240:ASW
235:T-4
198:CTD
83:MIT
43:MBT
1571::
1541:16
1539:.
1533:.
1393:.
1383:34
1381:.
1354:.
1260:^
1188:^
958:10
955:39
952:12
923:84
920:26
890:84
887:ZA
849:87
791:37
788:99
785:67
782:34
776:74
773:94
770:81
767:57
764:41
761:25
758:58
747:29
744:26
741:16
738:40
729:30
726:27
723:38
720:54
714:29
673:21
670:38
656:51
650:62
641:71
638:47
635:93
629:42
615:40
612:54
609:72
606:10
594:73
591:38
588:32
585:53
582:16
571:40
565:48
559:46
553:48
547:35
541:46
524:55
515:52
506:55
497:59
494:97
108:.
85:,
35:BT
1509:.
1457:.
1422:.
1401:.
1397::
1389::
1366:.
1337:.
1287:.
1245:.
1231:.
1070:t
1067:b
1064:+
1059:2
1055:t
1051:a
1048:=
1045:)
1042:t
1039:(
1036:z
967:0
964:0
961:0
949:0
946:0
943:0
940:0
937:0
934:0
917:0
914:0
911:0
908:0
905:0
902:0
899:0
896:0
811:2
735:0
732:0
717:0
703:0
700:0
697:0
694:0
691:0
688:0
685:0
682:0
679:0
676:0
653:0
647:7
626:2
568:5
562:0
556:0
550:0
544:0
538:0
518:0
512:0
503:0
500:0
146:.
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