Samples of water column chemical analyses were collected mostly in the upper 1000m using Niskin bottles mounted on a rosette. The strategy was to sample at density horizons within the main thermocline at pressure horizons above and below this region (i.e., <150 dbar and >2000 dbar). Care was applied to ensure the highest possible accuracy and precision.
Lukas, Dr. Roger , Unknown, Niskin Bottle Data of the Hawaii Ocean Time-series (HOT) program in the North Pacific 100 Miles North of Oahu, Hawaii for Cruises HOT122-154 during 2001-2003. (NODC Accession 0001707): None None, Unpublished material, Unpublished Material.
/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
/bot Bottle data. Filenaming convention:
hotccc.sea where ccc is cruise number
BOTTLE FORMAT: Format for *.sea files: -----------------------
Welcome to the HOT Water Sample Data Base
Water sample data from HOT are written according to the *.sea files specified by the WOCE Hydrographic Programme Office, for submission of these data to the WHP. One file is written for each HOT cruise (e.g., hot1.sea contains the data from HOT-1). Files from the ALOHA-Climax (AC) cruises have the prefix ac (e.g., ac1.sea contains the data from AC-1).
Formats for these files are detailed in the WHP Office Report WHPO 90-1, available from Steve Diggs, WHPO Data Manager, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093-0214.
The files are self-explanatory, one column is written for each measured parameter. Missing data are filled with -9. A 5-line heading labels each column.
The first year's temperatures are reported in IPTS-68. Subsequent temperature are reported in ITS-90 units. Since temperature sensor calibrations were done in IPTS-68 units, and the UNESCO routines require IPTS-68 temperature, all intermediate processing was done in IPTS-68. As a final step, temperature and potential temperature were converted to ITS-90 using t_90 = 0.99976 t_68.
Variables having 7 asterisks on the 4th heading line have a quality flag associated with them. These 1-digit quality flags are concate- nated to form quality word which is listed as the last variable in each row. The values each digit can assume and their meanings are listed below:
Bottle quality flag definitions:
Byte Value Definition 1 Not assigned. 2 No problems noted. 3 Leaking. 4 Did not trip correctly. 5-8 Not assigned. 9 Samples not drawn from this bottle.
Water sample quality flag definitions:
Byte Value Definition 1 Sample for this measurement was drawn from water bottle but analysis not received. 2 Acceptable measurement. 3 Questionable measurement. 4 Bad measurement. 5 Not reported. 6 Mean of replicate measurements. 7 Manual chromatographic peak integration. 8 Irregular digital chromatographic peak integration. 9 Sample not drawn for this measurement from this bottle.
1) Hawaii Ocean Time-series (HOT) (Lukas and Karl) 2) World Ocean Circulation Experiment (WOCE) (officially ended in 1998) 3) Joint Global Ocean Flux Study (JGOFS) HOT was initiated and funded through grants from the National Science Foundation under the auspices of the Joint Global Ocean Flux Study (JGOFS) and the World Ocean Circulation Experiment (WOCE). The field phase of these programs has ended, but support from the Ocean Sciences Division of NSF has enabled continuation of our basic HOT measurement program until mid-2001. The PO component contributes to the objectives of the World Climate Research Programme (WCRP) Climate Variability and Predictability (CLIVAR) Programme by providing information on interannual to decadal variability of the North Pacific Ocean.
Data transfer to NOAA via the NODC/NCDDC Hawaii Liaison, Mr.Patrick C. Caldwell.
The objective of the physical component of HOT is to describe and understand the ocean climate and variability at a deep-water site in the North Pacific subtropical gyre near Hawaii. This requires a long time series of physical oceanographic variables, including water mass properties and currents, supporting and complementing the objectives of the biogeochemical component of HOT.
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.
Water samples are collected during HOT cruises using a 24 place rosette. Samples of salinity, oxygen, phosphate, nitrate and silicate are regularly taken from both shallow and deep water casts. Salinity samples are taken back to the University of Hawaii where they are measured using an Autosal salinometer . Phosphate, nitrate and silicate samples are also measured at the University of Hawaii while oxygen measurements are conducted aboard ship during the cruises.
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).
Person who carried out this activity:
quality control completed
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints: Dataset credit required
NOAA makes no warranty regarding these data,expressed or implied, nor does the fact of distribution constitute such a warranty. NOAA, NESDIS, NODC and NCDDC cannot assume liability for any damages caused by any errors or omissions in these data, nor as a result of the failure of these data to function on a particular system.
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