HOT thermosalinograph data have been obtained since cruise 63 using a SBE-21 Seacat thermosalinograph system. Data are recorded every 10 seconds from water collected by a continuous seawater system aboard each vessel from a depth of about 3 meters.
Data transfer to NOAA via the NODC/NCDDC Hawaii Liaison, Mr.Patrick C. Caldwell.
Upon arrival at ALOHA (station 2), operations commence with a deep cast (maximum depth approximately 4750 m), 36-hour burst sampling3 of the upper 1000 m at the same location, plus CTD casts to support ancillary JGOFS work of about an extra 12 hours duration. Time permitting, the last CTD cast of the cruise will be a deep cast. On occasion, one cast will be done at station 3 (40 miles north of ALOHA at 23 25' N, 158 W).
The second and following casts at station ALOHA are sampled to at least 1000 m depth. Cast 2 is called a "density cast" because water samples are taken at a number of specified density values ranging from [sigma-theta]= 27.37 to the surface with the intent to resolve the profiles of salinity, dissolved oxygen, and nutrients in potential density coordinates Depths sampled during the following casts within the 36-hour burst sampling period are chosen both by the JGOFS group and the WOCE team, who have to ensure that at least one water sample each is taken within the mixed layer, the shallow salinity maximum, the intermediate salinity minimum and the deepest position of the rosette for calibration of the CTD conductivity sensor. If oxygen bottles will be taken from the cast, then the sampling should include at least the mixed layer, oxygen maximum, oxygen minimum and the deepest rosette position for calibration of the CTD oxygen sensor. The second deep cast of the cruise (if there is one) should include sampling of oxygen bottles in at least seven levels appropriate for calibration of the CTD oxygen sensor, i.e. in the oxycline and two more levels below the oxygen minimum, in addition to the four levels mentioned before.
The primary objective of the HOT program is to assess variability in the central Pacific Ocean on annual and interannual time scales. One of our most important concerns, therefore, is to ensure that the highest possible precision and accuracy is consistently maintained for all water column chemical measurements. In order to achieve the highest possible data quality, we have instituted a quality-assurance/quality-control program, and have attempted to collect all ancillary information necessary to ensure that our data are not biased by sampling artifacts.
Because sampling is over 36 hours, one can average out the effects short-term changes of the depth of density surfaces and the magnitude of hydrographic and nutrient variables (inertial, tidal, and shorter periods).
Thermosalinograph data are recorded every 10 seconds from water collected by a continuous seawater system aboard each vessel from a depth of about 3 meters. These data are processed and quality controlled. Details of the thermosalinograph processing are documented (Tupas et. al., 1996).
Navigation data are also included in the thermosalinograph data file. The navigation data are recorded every minute from the Global Positioning System (GPS) aboard R/V Moana Wave and linearly interpolated at the same times of the thermosalinograph record. These data include latitude and longitude.
Error flags were incorporated in the data.
/woce_sum WOCE-type sum file which gives details on position and parameters taken of each cast and station of each cruise. Filenaming convention:
hotccc.sum where ccc is cruise number
/ths thermosalinograph data. Filenaming convention:
hotcccts.dat where ccc is cruise number ts is constant
Data File Format:
Thermosalinograph data are distributed in a format specified here.
The thermosalinograph data for each cruise are stored together with the navigation data in an ASCII file. The file names are determined by cruise name and number. For example, the thermosalinograph data for HOT-63 can be found in hot63ts.dat.
The thermosalinograph data files do not contain any header information. Only the data for each cruise are presented in the files. The order of variables in a thermosalinograph record are as follows: time (year, decimal year day), longitude, latitude, temperature, salinity and quality. Note, negative longitude corresponds to West longitude.
Data Record Format:
Column Variable ------- ------- 1 Year 2 Decimal Year Day (January 1 = Year Day 0) 3 Longitude (decimal degrees) 4 Latitude (decimal degrees) 5 Temperature (Degrees Celsius, International Temperature Scale of 1990) 6 Salinity (1978 International Practical Salinity Scale) 7 Quality (defined by investigator) **
FORTRAN FORMAT (i4, f10.5, f12.6, f11.6, f7.3, f7.3, i3)
** The quality word is the left-to-right concatenation of required quality bytes for temperature and salinity; the first byte represents temperature, the second represents salinity. Quality information is only available for cruises after HOT-71.
The byte values are defined as follows:
byte value Definition 2 Acceptable measurement. 3 Questionable measurement. 4 Bad measurement.
Sample File: (First few records)
1996 142.40750 -157.994382 22.749950 25.313 34.877 23 1996 142.40762 -157.994536 22.749976 25.310 34.873 23 1996 142.40773 -157.994677 22.750001 25.309 34.876 23 1996 142.40785 -157.994831 22.750029 25.308 34.882 23