Hawaii Air-sea Logging Experiment


The inaugural deployment of the HALE ALOHA physical-biogeochemical mooring at Station ALOHA (hereafter called HALE ALOHA - I) was successfully completed on Sunday, 12 January 1997 by a team of scientists aboard the R/V Moana Wave (D. Karl, chief scientist).

I. Mooring Configuration

HALE ALOHA - I is configured as a semi-taut mooring consisting of a 3-m diameter Guardian style buoy with running lights, radar reflector, solar panel and Argos satellite position-only transmitter (and scientific instrumentation detailed below), 3/8" plastic jacketed torque balanced, wire rope and 3/4" chain (0-125 m), 5/16" plastic jacketed torque balanced wire rope (125-2000 m), 3/4" nylon line (2000-3500 m) -- short spliced to 3/4" polypropylene line (3500 - 5000 m), 36 - 17" glass floatation spheres on 34 m 3/8" chain (5000-5034 m), dual Benthos model 865A deep-sea acoustic releases on a stainless steel mount (5034-5035 m), 5 m of 1/2" chain (5035-5040 m), 10 m of 1" nylon line (5040-5050 m), 5 m of 1/2" chain (5050- 5055 m), 3600# (wet weight) anchor; total water depth (4830 m).

II. Scientific Instrumentation
    1. Meteorological instruments on the HALE ALOHA buoy (scientist in charge: Pierre Flament, UH)

      Qty Description Model Manufacturer
      2 marine anemometer 5106 R.M. Young
      2 meteorological probe w/multi-plate radiation shield MP101A Rotronic
      1 rain gauge 50203 R.M. Young
      1 Precision Spectral Pyranometer w/aluminum base PSP Eppley Labs
      1 air/water temp difference thermocouple (experimental) N/A N/A
      Data Logging System:
      1 data logger 21X Campbell Sci.
      1 4-channel relay driver A21REL-12 Campbell Sci.
      1 card storage module (w/2Mb memory card) CSM1 Campbell Sci.

    2. Sampled parameters

      # Measurements Description Rate
      2 wind speed (m/s) 2 min average every 10 min
      2 wind direction (deg az) "
      2 relative humidity (%) 1 sample every 10 min
      2 air temperature (Deg C) "
      1 rain accumulation (mm) "
      1 solar radiation (W/m2) "
      1 air/water temp diff (Deg C) "
      1 buoy azimuth (Deg) "
      1 equipment box temp (Deg C) "
      1 battery voltage (V) "
      Note: Some parameters are logged as voltages and converted to SI units during post processing.

    This present effort is being funded through a NSF Academic Research Infrastructure (ARI) grant #OCE96-01850, awarded to D. Karl, R. Lukas and P. Flament.

  1. Temperature (scientists in charge: Dave Karl and Terry Houlihan, UH)

    Ocean temperature data loggers are deployed at depths of 2 m (2 instruments attached to the subsurface portion of the buoy) and at 40, 50, 60, 80, 90, 100, 110, 120, 130 and 150 m (1 instrument per depth).

    Description: The Richard Brancker Research (Rbr) XX-105 is a single channel data logger with a built-in, high stability YSI46033 thermistor. It has an operating range of +5 Deg C to +30 Deg C and resolution of 0.002 Deg C to 0.005 Deg C with the variation in resolution due to the non-linear response of the thermistor used. The loggers were programmed to sample every 30 min from 1/12/97 until 5/10/97. This should fall within the power potential recommended by the battery manufacturer for the AA alkaline batteries. This present effort is being funded through a NSF Academic Research Infrastructure (ARI) grant #OCE96-01850, awarded to D. Karl, R. Lukas and P. Flament.

  2. Optical sensor (scientists in charge: Ricardo Letelier and Mark Abbott, OSU)

    Description: A Downwelling Irradiance sensor (OCI-200, Satlantics Inc., Canada) and an Alpha-Omega datalogger (Alpha-Omega, USA) are the principal components of the Downwelling Irradiance Monitoring system deployed at 25 m. Seven discrete channels with 10 nm bandwidth centered at 412, 443, 490, 510, 555, 670 and 680 nm measure the downwelling irradiance which is recorded every 20 min in the datalogger. Initially, the data collected will be used to estimate the temporal variability of dissolved organic matter, chlorophyll and chlorophyll natural fluorescence in the upper layer of the euphotic zone at Station ALOHA. This present effort is being funded through the NASA grant NAS5-31360 awarded to M. R. Abbott.

  3. Gas tension device / Seacat (scientist in charge: Steve Emerson and Chuck Stump, UW)

    Description: This instrument, deployed at 50 m, provides a novel method of inferring dissolved N2 and O2 gas concentrations in seawater based on a local measurement of gas tension, water temperature and salinity. The gas tension device (Gtd) is identical in design to that described by McNeil et al. (Deep-Sea Research 42: 819, 1995) and has been previously field tested at Sta. ALOHA prior to the mooring deployment. An integrated Seacat provides the necessary C/T and O2 measurements.

  4. Nitrate osmoanalyzers (scientist in charge: Hans Jannasch, MBARI)

    Description: In situ osmotically pumped nitrate analyzers (OsmoAnalyzers) are deployed at 120 and 180 m to monitor nitrate intrusions into the mixed layer. These long-term submersible chemical analyzers use zero-power osmotic pumps to propel sample and reagents through a miniature reaction manifold. A simple LED/photodiode detector measures the concentration of the azo-dye produced by the standard sulfanilamide/NED colorimetric reaction for determining nitrate concentrations in seawater. OsmoAnalyzers automatically inject standard and blank solutions every 3 days for in situ calibration. Added sensors integral to the analyzer provide measurements of water temperature and salinity, the latter by use of an inductive coil. This effort is funded by MBARI.

  5. Intermediate Water Seacats (scientists in charge: Roger Lukas and Craig Nosse, UH)

    Description: SeaBird Electronics Seacat (SBE-16) conductivity and temperature recorders are deployed at 410, 475, 540, 560, 650 and 785 m (1 instrument per depth). Seacats have a measurement range of -5 to 35 deg C and 0 to 7 S/m (0 to 70 mmho/cm) with a resolution of 0.001 deg C and 0.0001 S/m. The Seacats were programmed to sample every 10 minutes. This present effort is being funded through NSF grant OCE-9303094 (The Hawaii Ocean Time-series Program: WOCE Component).

  6. MER2020A (scientists in charge: Dave Karl and Terry Houlihan, UH)

    Description: The moored spectroradiometer is a battery powered self-contained optical instrument that measures eight downwelling irradiance wavelengths, eight upwelling radiance wavelengths, dual axis angle sensors, pressure transducer and a log of battery voltage, internal temperature, time and date. The irradiance detector array views a single cosine-corrected optical collector optimized for use in water. The radiance array uses individual Gershun tube radiance collectors where the collection angle is constrained inside the housing to remain within the SeaWiFS specifications.

III. Service Schedule

Monthly visits will be made to the HALE ALOHA mooring location during regularly scheduled HOT cruises. Each month, a Ctd cast will be taken at a safe distance from the mooring for the collection of water samples for dissolved O2, nitrate and chl a determinations. If possible, a mid-day light cast will also be taken. HALE ALOHA - I will be recovered in May 1997 and redeployed within a week of recovery. After a thorough evaluation of biofouling and other considerations, we will determine an optimal duty cycle for the mooring (4-6 months). During the May turnaround we plan to install a direct cellular phone link for the meteorological data. Additional instruments may also be added to HALE ALOHA in the future and we invite all potential users to contact Dave Karl (email: dkarl@soest.hawaii.edu; phone: (808) 956-8964; fax: (808) 956-5059) if you have any questions.

IV. Data Availability and Distribution

As with all other HOT program data sets, HALE ALOHA mooring data, including those obtained by ancillary investigators, will be available to the community as soon after processing as possible. These data will reside in a workstation at the University of Hawaii and may be accessed using anonymous ftp on Internet or the World Wide Web. More details will be posted after the mooring and its suite of scientific instruments and data are successfully recovered. Stay tuned!