SEAS IV - XBT File Data Format The Shipboard Environmental (data) Aquisition 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. This SEAS IV XBT file is the Delayed-mode version of the copy transmitted through the satellite and placed onto the GTS as a BATHY message. 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://seas.amverseas.noaa.gov/seas/ Field Name Field Description SEAS Version: SEAS Shipboard software version number Drop: Sequential Number assinged for the Probe dropped during data collection Probe Type: Type of XBT probe used (4-7,10,11) blank if entry not used. Code: XBT Instrument Code (WMO Code 1770) for temperature Equation: Fall Rate Equation Coefficients for XBT (WMO Code Table 1770) Recorder: Type of Recorder used for collecting temperature data Code: Recorder Code (WMO Code 4770) Launcher height: Height of the XBT launcher above the water (meters) Date/Time: Date (dd/mm/yyyy) 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: Ship's Name Cruise: Cruise ID, example: AX70903, (TWI line AX7, year 2009, month 03) Call sign: Ship's Radio Callsign. Used to identify the ship from which the data is transmitted Bottom Depth: Bottom Depth (meters) Transmitter: Satellite Transmitter and Data Collector Mode: Data is saved for Transmission as Binary or Ascii Code: Tranmitter Code (N/A) Sea Surface Temp Type: Type of sensor used to acquire sea surface temperature. Code: Codes for "Method of sea-surface measurement", see Codes below 00 Ship intake 01 Bucket 02 Hull contact sensor 03 Reversing thermometer 04 STD/CTD sensor 05 Mechanical BT 06 Expendable BT 07 Digital BT 08 Thermister chain 09 Infrared scanner 10 Microwave scanner 11-14 Reserved 15 Missing Value: Sea Surface Temperature (deg. C) Depth: Average depth of temperature sensor below sea surface (meters) 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) 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: SEAS Version 4.54 Drop 016 Probe Type Sippican Deep Blue Code 05 Equation 2 Recorder SIPPICAN MK-12 Code 05 Launcher height 35.0 M Date/Time 18/09/2003 07:46 GMT Latitude 20 32.8 N Longitude 131 59.0 W Ship TAUSALA SAMOA Cruise Call sign V2FA2 Bottom depth 1543476 M Transmitter UNKNOWN Mode UNKNOW Code 00 Sea Surface Temp Type Ship Intake Code 00 Value 99.9 C Depth 1.0 M INFPTS 4 20 2487 490 2471 540 2322 700 2167 XBT 119 24812485248724872487248624862486248624862485248624852486248524862485248524862486 24852486248524862485248524852486248524852486248524852483248324822482248224822482 24802479247724772477247624762478247724752474247424712470247024702469246924702471 24712472247224712472247224712471247124722471247124712470244624112384236623502337 23212313230622982291228222762272227022612254224922452238223322282220221122022194 2198218821772173216721612156218022782325218123042388268425282179212221183126