The HOT program makes repeated observations of the physics, biology and
chemistry at a site approximately 100 km north of Oahu, Hawaii. Two stations
are visited about once a month: Kahe Point (Station 1: 21.34N, 158.27W) and
Station ALOHA (Station 2: 22.75N, 158W). Various other stations are made
intermittently in support of similar research objectives or mooring
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.
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
Sensor_Name: Niskin bottles
Source_Name: ship; SeaBird Carousel
Project_Campaign: Hawaii Ocean Time series (HOT)
Originating_Center: University of Hawaii
Online_size: 1.485 Mbytes; 73 files
Dataset credit required
1000 Pope Rd
Marine Science Bldg. Room 418
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
Data transfer to NOAA via the NODC/NCDDC Hawaii Liaison,
Mr.Patrick C. Caldwell.
quality control completed
Each of the (approximately monthly) HOT cruises follows the same basic pattern with some flexibility for ancillary projects to be done after the core sampling has been completed. During transit from Honolulu to the time-series station ALOHA (A Long-term Oligotrophic Habitat Assessment) one weight test is done to between 700 and 1000 m at station 1 off Kahe Point (16 km offshore from the western tip of Oahu, 21 20.6' N, 158 16.4' W, 1500 m water depth). Following the successful winch test, a CTD/rosette cast to 1000 m is conducted. This cast serves as a "shakedown" for the remainder of the cruise, and the functioning of the components of the CTD/rosette system as well as coordination between winch, deck and console operators can be tested. The training of new personnel in activities such as taking meteorological observations, and sampling salinities is also done in this station. The data taken at Kahe Point (station 1) represent an additional time-series of water properties at a near-shore site. 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).
Directories and files: /data root data directory /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.
National Coastal Data Development Center, Building 1100
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.
1000 Pope Road, MSB 316
Dept. of Oceanography
University of Hawaii at Manoa
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