                  SEAS 2000 - XBT File Data Format

The Shipboard Environmental (data) Acquisition System (SEAS) is a program
developed by National Oceanic and Atmospheric Administration (NOAA) to provide
accurate meteorological and oceanographic data in real time from ships at sea
through the use of satellite data transmission techniques. The system transmits
data through either the GOES or INMARSAT C satellites to NOAA for use in
weather, climatological and ocean models.

NOAA is actively participating in an international effort to increase the
number of subsurface temperature observations in support of global
oceanographic and climate studies. NOAA's XBT program (SEAS) currently supports
about eighty voluntary observing ships (VOS).

For additional information, http://www.aoml.noaa.gov/phod/goos/seas/
(last accessed February 9, 2017)

The Cyclical Redundancy Check (CRC) is incorporated into the SEAS System.
For additional information regarding the CRC, and the data flow, please refer
to document seas2_add_info.


 Field Name             Field Description

 SEAS Version:          SEAS Shipboard software version number

 Ship Name:             Ship's Name

 Call Sign:             Ship's Radio Callsign

 Lloyds Number:         Lloyd's Register of Shipping (LR number)
                        A unique seven digit identification number,
                        it remains unchanged for the life of the ship.

 Date/Time(dd/mm/yyyy): Date of XBT drop (GMT)

 Latitude(ddd.ddd):     Decimal degrees, hemisphere N=north, S=south

 Longitude(ddd.ddd):    Decimal degrees, hemisphere E=east, W=west

 Ship's Speed:          The ship's speed at drop time

 Probe Type:            Type of XBT probe used (4-7,10,11)
                        blank if entry not used.

 Probe Code:            Instrument type for temperature, with fall rate
                        equation coefficients for XBT (WMO Code Table 1770)

 Probe Serial No:       Probe serial number for failure tracking

 Recorder Type:         Type of Recorder used for collecting temperature data

 Recorder Code:         Recorder Code (WMO Code 4770)

 Bottom Depth:          Bottom Depth (meters)

 GTS CRC:               Cyclical Redundancy Check (CRC), Unique Identification
                        of GTS Records. A number derived from, and stored or
                        transmitted with a block of data in order to detect
                        corruption.  By recalculating the CRC and comparing it
                        to the value originally transmitted, the receiver can
                        detect some types of transmission errors.

 SEAS ID:               SEAS Identification #. A 32 bit CRC computed on the raw
                        binary SEAS bathy message.

 INFPTS:                Total number of Inflection Points, followed by
                        the data record. (depth,temp)
                        temperature values (to hundredths of a degree celsius)
                        depths (meters to tenths)

 TWOMETER:              Total number of Two Meter Data Points, followed by
                        the data record. (depth,temp)
                        temperature values (to hundredths of a degree celsius)
                        depths (meters to tenths)

 XBT:                   Total number of Temperatures Points, followed by the
                        data record. Depths of each sample are not saved
                        because they can be computed by knowing the sample
                        number and probe type.


Either Method below can be used to Calculate depths.

Method 1:
  H=A*T-B*T**2 (meters)

  T = Time step; 0.1,0.2 ....time  : time=0.1(# of data points)
  A and B are the constants determined from the following table:

   Probe   XBT
   Code    Probe
   WMO1770 Type       B         A

   061     T-10    .00216    6.301
   071     T-11    .0002557  1.7779
   001     T-4     .00216    6.472
   002     T-4     .00225    6.691
   011     T-5     .00182    6.828
   031     T-6     .00216    6.472
   032     T-6     .00225    6.691
   041     T-7     .00216    6.472
   042     T-7     .00225    6.691
   021     T-FD    .00182    6.346
   051     T-DB    .00216    6.472
   052     T-DB    .00225    6.691

===========================================
Method 2:
 The depth is calculated from coefficients a and b and the
 time, t, as follows:

     z = at + 10-3bt2   or z = a*t + 0.001*b*t*t

      Probe  Probe               Coefficient a    Coefficient b
      Code   Type
       001  Sippican T-4            6.472         -2.16
       002  Sippican T-4            6.691         -2.25
       011  Sippican T-5            6.828         -1.82
       021  Sippican Fast Deep      6.346         -1.82
       031  Sippican T-6            6.472         -2.16
       032  Sippican T-6            6.691         -2.25
       041  Sippican T-7            6.472         -2.16
       042  Sippican T-7            6.691         -2.25
       051  Sippican Deep Blue      6.472         -2.16
       052  Sippican Deep Blue      6.691         -2.25
       061  Sippican T-10           6.301         -2.16
       071  Sippican T-11           1.7779        -0.2557
       201  TSK T-4                 6.472         -2.16
       202  TSK T-4                 6.691         -2.25
       211  TSK T-6                 6.472         -2.16
       212  TSK T-6                 6.691         -2.25
       221  TSK T-7                 6.472         -2.16
       222  TSK T-7                 6.691         -2.25



THE ACTUAL DATA LOOKS AS FOLLOWS:

                   (1 DROP, PER FILE)

 SEAS Version:  6.12
 Ship Name: Columbus Florida
 Call Sign: ELZT3
 Lloyds Number:  9141132
 Date/Time(dd/mm/yyyy): 05/09/2004 23:58 GMT
 Latitude(ddd.ddd): 025.959 S
 Longitude(ddd.ddd): 0173.335 W
 Probe Type: Sippican Deep Blue
 Probe Code:  52
 Probe Serial No: 0000000
 Recorder Type: Sippican MK-21
 Recorder Code:  6
 Bottom Depth: 9999 M
 GTS CRC: 9079AA94
 SEAS ID: 3A842C87

INFPTS: 23
   20 2087  750 2040 1090 1993 1870 1883 2530 1718 2850 1630 2990 1596 3250 1530

 3720 1365 4090 1272 4300 1197 4590 1120 4820 1061 5170  965 5460  938 5690  848

 6100  768 6180  776 7440  658 7870  647 8470  591 8640  578 8840  586

TWOMETER:  442
   20 2087   40 2086   60 2084   80 2082  100 2082  120 2079  140 2077  160 2077

  180 2075  200 2075  220 2075  240 2075  260 2075  280 2076  300 2076  320 2075

  340 2075  360 2076  380 2076  400 2073  420 2073  440 2073  460 2072  480 2071

  500 2063  520 2062  540 2062  560 2061  580 2060  600 2060  620 2060  640 2060

  660 2060  680 2060  700 2059  720 2054  740 2048  760 2032  780 2026  800 2021

  820 2020  840 2020  860 2021  880 2021  900 2021  920 2021  940 2021  960 2020

  980 2019 1000 2019 1020 2018 1040 2014 1060 2011 1080 2001 1100 1989 1120 1987

 1140 1987 1160 1982 1180 1971 1200 1969 1220 1969 1240 1969 1260 1969 1280 1968

 1300 1968 1320 1968 1340 1965 1360 1962 1380 1955 1400 1952 1420 1951 1440 1945

 1460 1944 1480 1943 1500 1943 1520 1942 1540 1940 1560 1935 1580 1929 1600 1926

 1620 1922 1640 1922 1660 1922 1680 1922 1700 1921 1720 1920 1740 1914 1760 1907

 1780 1905 1800 1901 1820 1895 1840 1893 1860 1887 1880 1879 1900 1876 1920 1875

 1940 1869 1960 1864 1980 1862 2000 1860 2020 1857 2040 1854 2060 1846 2080 1837

 2100 1832 2120 1826 2140 1822 2160 1814 2180 1809 2200 1803 2220 1798 2240 1796

 2260 1793 2280 1782 2300 1781 2320 1779 2340 1779 2360 1778 2380 1776 2400 1763

 2420 1760 2440 1755 2460 1747 2480 1737 2500 1735 2520 1729 2540 1711 2560 1704

 2580 1696 2600 1688 2620 1679 2640 1673 2660 1670 2680 1668 2700 1665 2720 1656

 2740 1648 2760 1644 2780 1637 2800 1635 2820 1632 2840 1630 2860 1630 2880 1630

 2900 1630 2920 1629 2940 1625 2960 1620 2980 1604 3000 1592 3020 1585 3040 1582

 3060 1581 3080 1577 3100 1577 3120 1577 3140 1572 3160 1563 3180 1560 3200 1547

 3220 1540 3240 1534 3260 1527 3280 1522 3300 1514 3320 1501 3340 1490 3360 1486

 3380 1478 3400 1475 3420 1472 3440 1464 3460 1460 3480 1452 3500 1443 3520 1436

 3540 1435 3560 1431 3580 1418 3600 1410 3620 1406 3640 1406 3660 1402 3680 1382

 3700 1375 3720 1364 3740 1359 3760 1355 3780 1352 3800 1343 3820 1332 3840 1325

 3860 1317 3880 1310 3900 1305 3920 1300 3940 1297 3960 1297 3980 1293 4000 1289

 4020 1280 4040 1276 4060 1273 4080 1273 4100 1269 4120 1264 4140 1260 4160 1253

 4180 1251 4200 1247 4220 1242 4240 1231 4260 1228 4280 1219 4300 1197 4320 1188

 4340 1182 4360 1172 4380 1168 4400 1164 4420 1159 4440 1148 4460 1140 4480 1136

 4500 1132 4520 1123 4540 1123 4560 1122 4580 1122 4600 1114 4620 1102 4640 1093

 4660 1090 4680 1089 4700 1085 4720 1077 4740 1067 4760 1067 4780 1067 4800 1065

 4820 1061 4840 1056 4860 1052 4880 1050 4900 1050 4920 1044 4940 1038 4960 1027

 4980 1025 5000 1022 5020 1018 5040 1010 5060 1005 5080 1002 5100 1002 5120 1000

 5140  990 5160  976 5180  961 5200  956 5220  952 5240  947 5260  946 5280  939

 5300  939 5320  940 5340  940 5360  935 5380  932 5400  932 5420  935 5440  938

 5460  938 5480  935 5500  926 5520  911 5540  900 5560  885 5580  877 5600  868

 5620  864 5640  861 5660  856 5680  852 5700  846 5720  842 5740  839 5760  832

 5780  831 5800  830 5820  827 5840  825 5860  822 5880  818 5900  815 5920  814

 5940  811 5960  810 5980  805 6000  802 6020  801 6040  800 6060  790 6080  778

 6100  767 6120  782 6140  790 6160  782 6180  776 6200  775 6220  773 6240  771

 6260  773 6280  776 6300  773 6320  771 6340  765 6360  765 6380  767 6400  767

 6420  765 6440  765 6460  759 6480  757 6500  755 6520  755 6540  753 6560  751

 6580  746 6600  742 6620  742 6640  742 6660  742 6680  740 6700  736 6720  730

 6740  726 6760  723 6780  721 6800  721 6820  719 6840  715 6860  713 6880  713

 6900  711 6920  711 6940  711 6960  709 6980  705 7000  701 7020  698 7040  698

 7060  698 7080  703 7100  705 7120  701 7140  698 7160  696 7180  692 7200  690

 7220  690 7240  682 7260  676 7280  673 7300  673 7320  673 7340  675 7360  675

 7380  671 7400  665 7420  661 7440  657 7460  657 7480  661 7500  663 7520  657

 7540  653 7560  653 7580  655 7600  655 7620  657 7640  655 7660  650 7680  646

 7700  644 7720  644 7740  648 7760  644 7780  638 7800  632 7820  634 7840  640

 7860  644 7880  648 7900  644 7920  632 7940  628 7960  625 7980  626 8000  630

 8020  630 8040  623 8060  615 8080  615 8100  613 8120  617 8140  615 8160  609

 8180  603 8200  605 8220  607 8240  607 8260  603 8280  598 8300  594 8320  594

 8340  598 8360  600 8380  598 8400  596 8420  590 8440  588 8460  590 8480  592

 8500  588 8520  578 8540  571 8560  569 8580  576 8600  573 8620  576 8640  578

 8660  573 8680  571 8700  571 8720  582 8740  584 8760  584 8780  578 8800  576

 8820  582

XBT: 1385
21002093208720872086208620862085208520842084208220822082208220822081208020792079

20782077207720772077207720762075207520752073207320752075207520752075207520752075

20762076207720772076207620752075207520752073207320752076207620762077207720762075

20732073207320732073207320732075207320722072207220712070206520632062206220632063

20622062206220612061206120602060206020602060206020602059205920602059206020602060

20602060206020602060205920572056205420532052204820442037203220292028202620252023

20212020202020202020202020202020202120212021202120212021202220222021202120212022

20212021202020202019201820192019202020192018201920192019201820172015201320122011

20102005200219971993198919881987198719871987198719871987198519791976197219701969

19671967196719671968196919691969196919691969196819681968196819681968196819681968

19681967196419631962196219611957195419531952195219511951195119481947194519451945

19441943194319421940194019421943194419431943194319401938193719351934193019291928

19271926192519231922192219221922192219221922192219231922192219221921192019201920

19201919191519121910190719071906190519041903190119001897189618951895189418921889

18871886188418801878187718781876187518751875187318701868186518651864186318621862

18621861186018601857185718561855185418531851184718431839183718371836183418301829

18271825182518231821181918151812181118091807180618041803180118001797179717971796

17951794179217871785178217821781178117791779177917791779177917781778177817771777

17761773176817631762176117601757175617551755175317481745173917371737173617351734

17321730172817191712171017071705170417031700169516941690168716851681167916781677

16731670167016701669166916681668166716651664166216571654165216501647164516451643

16401638163716371635163516351634163216311629162916291629163016301630163016301630

16311631162916291628162616251622162116201617161116061601159415921590158815851585

15841582158215811581158115781577157715771577157815771577157615771577157215681564

15631563156115601557155315471543154215401539153915351531153015271527152515221522

15211518151415091502150014971493149014891489148614841481147814771477147514751473

14721471146814651463146014601459145614521451144714461443143914381436143514351435

14341434143114261421141814141411141014101409140614061406140614061405140214001393

13851381137813771373136913671364136313601359135613561355135313521352135213481344

13421336133413301327132613231322131813151313131013101309130613051302130113001298

12971297129712971297129712961293129312921290128812851281127712771277127512731273

12751275127312731272127112691268126712641264126312601257125612531252125212511250

12481247124712441243124012361234123112311231122812271225121912141206119811931189

11881186118511851181117711751172116811691168116511641164116011601159115611531148

11461143114211391136113511351136113511311127112511231122112211221122112211231126

11271127112511191115111011061102110010971094109310901090109010891089108910891088

10851084108110771072106810671065106510671067106710671067106710671064106410631060

10591057105610531052105210511050105010481050105010501048104610431040103910361032

10301027102710261025102310221022102210211019101710131010100910061006100310031002

1002100210021002100210011000 997 994 992 985 981 977 971 964 961 960 959 956 956

 955 952 952 951 948 946 946 947 946 943 939 938 934 932 936 939 940 942 942 943

 943 940 939 936 935 931 928 927 928 930 932 935 935 934 934 935 936 938 938 939

 939 939 938 935 931 928 926 922 918 913 907 905 902 897 893 886 884 881 878 877

 873 869 868 867 865 864 864 864 863 860 859 856 855 853 852 851 848 847 846 843

 843 842 840 839 839 839 835 834 831 831 831 831 831 830 830 827 827 827 827 827

 825 823 823 822 822 821 818 817 815 815 815 814 814 814 813 811 811 810 810 810

 809 806 805 803 802 802 803 802 802 801 800 800 801 798 794 790 788 782 778 778

 778 769 761 767 778 784 788 790 790 788 782 782 784 782 776 773 773 773 776 778

 776 773 771 771 771 773 773 771 775 776 776 776 776 773 773 771 771 771 769 767

 765 765 765 765 765 765 767 767 767 767 767 765 767 765 765 765 765 763 763 759

 757 757 757 755 755 755 755 757 757 755 755 755 753 753 751 751 750 748 746 744

 744 742 742 742 742 742 742 742 742 742 742 742 742 742 740 740 738 736 734 734

 732 730 728 726 726 725 723 723 721 721 721 721 721 721 721 721 719 719 717 715

 715 715 713 713 713 713 713 713 711 711 711 711 711 711 711 711 711 711 711 709

 709 707 707 705 703 701 701 700 698 698 698 698 698 696 698 698 698 700 701 703

 705 705 705 705 703 701 698 698 698 698 696 696 696 694 694 692 690 690 690 690

 690 690 688 686 684 682 680 678 676 676 675 673 673 673 673 675 673 675 673 673

 675 675 676 675 675 673 671 671 669 667 665 663 663 661 661 661 659 657 657 657

 657 657 659 659 661 663 663 663 661 661 657 655 653 653 653 653 653 653 653 655

 655 655 655 655 657 657 657 657 657 655 653 651 651 650 650 648 646 646 644 644

 644 644 644 646 648 648 648 646 646 644 642 640 638 636 634 632 632 632 632 634

 634 636 640 642 644 644 646 648 648 648 648 646 644 640 636 632 630 628 628 626

 625 625 626 626 626 626 628 630 630 630 630 630 630 628 626 623 619 617 615 615

 615 615 613 613 613 613 615 617 617 617 617 615 613 611 609 607 605 603 603 603

 603 605 605 605 607 609 609 607 607 605 603 603 601 600 598 596 596 594 594 594

 594 594 596 596 598 598 600 600 600 600 598 598 598 596 596 594 590 590 588 588

 588 588 588 590 590 592 592 592 590 590 588 584 580 578 576 573 571 569 571 569

 567 571 576 578 576 573 573 571 571 575 578 578 578 578 576 575 573 573 573 571

 571 571 571 571 576 580 582 584 582 584 584 584 586 584 584 580 578 576 576 576

 576 578 582 584 584



The Cyclical Redundancy Check (CRC) is incorporated into the SEAS System. The
algorithm used was supplied by MEDS. It is a 32 bit value based on the ASCII
generated BATHY message of those values following the 888 group and terminating
at the equal (=) sign of the message.

Below is a crude description of the SEAS data flow regarding unique record
identification.

When an XBT is taken, SEAS shipboard software creates a binary record of the
entire data stream, metadata, and computed unique SEAS ID for archive aboard
ship. This is referred to as the complete message. The complete message is the
delayed mode record sent to AOML and forwarded to NCEI in the SEAS2K File
Format. SEAS shipboard software also creates a best binary message for
transmission to Silver Spring which also has the SEAS ID of the archived
message on the ship.

The SEAS processing servers in Silver Spring essentially build two real time
messages from the best message. One is the familiar BATHY (JJVV) formatted
record distributed on the GTS to MEDS among other places. (The GTS record
reaches MEDS and is incorporated into their GTSPP operation. MEDS computes a
CRC and attaches it to the record.) The other real time message is a real time
archive message. The real-time archive message contains all metadata and the
highest level of bathy information contained in the message transmitted from
the ship. For example, if full resolution data were transmitted from the ship,
the archive message contains inflection points, two meter data and the full
resolution data in SEAS2K format. If only inflection points were transmitted
from the ship, the real-time archive file contains only the inflection point
data. In either case, the SEAS ID of the original shipboard archive is
included as well as the GTS CRC which is computed on the WMO formatted bathy
message distributed on the GTS. This archive record is sent to NCEI and
becomes part of their GTSPP data management operation.

  Ideally, NCEI receives two SEAS records from NOAA. The real-time archive
message (SEAS ID + GTS CRC ID) and the delayed mode complete message (SEAS ID).
Comparison of the SEAS ID completes the data flow from NOAA. Ideally NCEI also
receives a GTSPP record from MEDS which has the same GTS CRC ID computed.
Comparing GTS CRC IDs of archive message to MEDS GTSPP record completes the
GTSPP data flow. NCEI data management determines which record becomes part of
the permanent archive.



