- Abbreviation for harmful algal blooms, also known as marine
phytoplankton blooms or red tides. In this naturally occurring
phenomenon for which instances are reported for around 300
species blooms with cell concentrations of several million
per liter occur. About a fourth of the species produce toxins
which cause damage or kill other flora and fauna in the area of
- HAB Program
- An IOC program originating with the formation
of an Ad hoc Intergovernmental Panel on Harmful Algal Blooms (IPHAB)
in 1991. The panel was requested to identify adequate resources
for a sufficiently broad program to solve some of the problems caused
by algal blooms.
The first session of IPHAB was held in 1992 and the HAB Program
plan was adopted in 1993.
See the HAB Program Web site.
- More later.
- Hadley Cell
- A part of the atmospheric
circulation system extending from the Equator to 30 latitude
on both sides of the Equator. It is a thermally-driven system
in which heated air rises at the Equator, flows poleward, cools
and descends at subtropical latitudes, and then flows back towards the Equator.
This description was suggested by Hadley in the 18th century.
- hadopelagic zone
- One of five vertical ecological zones into which the
deep sea is sometimes divided.
The is the lowest of the levels and is separated from
at about 6000 meters.
See Bruun (1957).
- Haida Current
- A narrow, poleward flowing surface current over the continental
slope of northwestern British Columbia and southwestern
Alaska. It is seasonal, occuring predominantly between
October and April with maximal flow taking place in midwinter
from November through February. Its characteristics include
a minimal length of 200-300 km, a width of 20-30 km, a depth
scale of 500 m, a near-surface speed typically around 0.1 m s,
and a near-surface temperature signature
about 1 C greater than ambient.
The temporal variability is not well known, although it evinces
spatial variability in the form of large-amplitude (around 10 km)
mesoscale waves and eddies. The primary driving mechanisms are
wind stress and alongshore sea surface slope.
See Thomson and Emery (1986).
- Related to salinity.
- Halmahera Sea
- A regional sea located in the central eastern part of the
Australasian Mediterranean Sea. It is centered at about
1 S and 129 E and is bordered by the
Pacific Ocean to the north, Halmahera to the west, Waigeo
and Irian Jaya to the east, and the
Seram Sea to the south.
It covers about 95,000 km and the topography comprises
a number of separate basins and ridges, the chief of which
is the Halmahera Basin reaching a depth of 2039 m.
Other prominent geographic features include
Kau Bay (between the two northward pointing lobes of Halmahera), Buli
Bay (between the two eastward pointing lobes), Weda Bay (between the
two southward point lobes), the Jailolo, Bougainville and
Dampier Straits connecting it to the Pacific, and the Obi Strait
connecting it to the
The surface salinities range from 34 (March through May)
to 34.6 (September through November) and the temperatures
from 25.7 C in August to 28.6 in May.
The surface currents are variable with the seasonal
monsoon winds. The deep water in the Halmahera Basin is
renewed by water from the Pacific which passes from north
to south over sills 700 m and 940 m deep. The surface
waters are a mixture of oxygen rich Pacific water and
oxygen poor water from the
See Fairbridge (1966) and
Cresswell and Luick (2001a).
- In oceanography, a relatively sharp change in salinity with depth.
- halocline catastrophe
- A process wherein deep convection and the formation of bottom waters
ceases if the ocean surface salinity decreases sufficiently via enhanced
freshwater input. This process is thought to have shut down the
thermohaline overturning cell in the Atlantic in the past.
See Bryan (1986).
- Acronym for Hamburg Model of the Ocean Carbon Cycle.
- Happel, Eberhard (1647-1690)
- A German writer of epics, romance and adventure who published a
book entitled Groste Denkwurdigkeiten der Welt oder
Sogenannte Relationes Curiosae in 1985 which contained the
second chart ever to depict the global ocean circulation.
His chart and explanations were very similar to those
of Kircher's previous
and first-published chart. He also favored the explanation
for the tides that had water being withdrawn from the oceans
through the north pole and expelled from the south pole, although
differing slightly from Kircher on the matter of timing. Happel
had the water being withdrawn and discharged at special hours
rather than just being rhythmically passed through the earth.
See Peterson et al. (1996).
- harbor wave
- A type of seiche found in harbors.
The Japanese word ``tsunami''
means ``harbor wave'' but
is a misnomer for what is really a
seismic sea wave, more popularly
(and even more incorrectly) known as a
- A frequency that is a simple multiple of a fundamental frequency.
A second harmonic, for example, would have twice the frequency of
- Haro Strait Experiment
- See the
Haro Strait Experiment Web site.
- Harrison, John (1693-1776)
- See Peterson et al. (1996), p. 53.
- Bernard Haurwitz (1905-1986)
- An atmospheric scientists who published many basic contributions to
the study of short-period atmospheric wave motions, planetary waves
(including atmospheric tides), and vortex motions in tropical cyclones.
He also published on atmospheric radiation, the wave structure of
noctilucent clouds, and internal tides in the oceans.
- Hawaii-Tahiti Shuttle Experiment
- See Wyrtki et al. (1981).
- Heard Island Feasibility Test (HIFT)
- An ocean acoustical tomography experiment in which computed
geodesics (minimum paths) for acoustics transmissions were
compared with observations. The acoustic source was suspended
from the R/V Cory Chouest 50 km southeast of Heard
Island located about halfway between Africa and Australia at
about 50 S in the South Indian Ocean.
Receiver arrays were located on various research vessels
throught the oceans as well as at South Africa, Bermuda,
India, Christmas Island, Samoa, Hobart (Tasmania) and
See Baggeroer and Munk (1992) and Munk et al. (1995).
- heat capacity
- The heat capacity of a body is the product of its mass and its
- heat equator
- See thermal equator.
- Acronym for High Energy Benthic Boundary Layer Experiment.
See Nowell et al. (1982) and
Nowell and Hollister (1985).
- An isotope of helium that is useful in ocean tracer studies.
There are two sources for Helium-3 in the ocean: volcanic
sources at mid-ocean ridge crests and the decay of man-made
tritium. The former source makes helium-3 a unique tracer
due to its being injected into the middle of the water column.
This leads, for example, to a stark contrast in helium-3 content
between incoming and outgoing deep waters in the Pacific.
It also provides a dramatic picture of the relative movement
of helium poor NADW and helium rich
(due to sources in the Pacific) ACC
water. The helium-3 tritium decay (sometimes
called trituigenic) source is much larger than the deep sea
sources, with the global average of the latter being
about 4 at/cm2/s as opposed to a northern hemisphere average
of about 32 at/cm2/s for the former.
Helium-3 is used in combination with tritium to date water
on timescales of 0-10 years with a resolution of around 0.1 years
(in North Atlantic surface waters).
It is better to treat them as separate but related
tracers on longer timescales or in the presence of extensive
mixing. Their relationship is a diagnostic of vertical versus
horizontal mixing, and has been used to assess an upper limit
to vertical mixing that is consistent with physical estimates.
This has also been used to show that horizontal mixing is the
dominant mechanism of thermocline ventilation in subtropical
See Sarmiento (1988) and
Broecker and Peng (1982).
- Helland-Hansen, Bjorn
- More later.
- Or or pertaining to continental margins and the adjacent abyssal plains.
- To be completed.
- Acronym for Humidity Exchange Over the Sea, a 1986 program to measure
water vapor and droplet fluxes from sea to air at moderate to
high wind speeds. HEXOS was the first comprehensive open ocean air-sea
flux field project to emphasize surface exchange processes.
It was conducted on the Dutch Noordwijk platform, and featured the
largest range of windspeeds over which momentum, sensible heat, and latent
heat fluxes had been measured.
It provided the physical basis for linking aerosol, sea spray, and
sensible and latent heat fluxes under a common framework.
See Katsaros et al. (1987),
Smith et al. (1992) and
DeCosmo et al. (1996).
- Acronym for High Intake, Defined Excitation Bathyphotometer, a vertical
profiler for measuring stimulated bioluminescence.
The features include statistically rigorous sampling (faciliatated by
high pumping rates), hydrodynamically calibrated excitation at the
entrance to the large volume detection chamber, and the capability
of rapid vertical deployment to depths of 500 m at descent velocities
up to 50 m min.
See Widder et al. (1993).
- Acronym for
Heard Island Feasibility Test.
- Abbreviated form for
high pressure center.
- high pressure center
- In meteorology, a region of relatively high barometric pressure.
These are characterized by subsidence
at altitude and by divergence near
the surface. They predominate at 30 and 90 latitude
where the global generation circulation patterns exhibit
downward motion. This type of circulation feature is also
known as an anticyclone and
as such rotates clockwise/counterclockwise in the
norther/southern hemisphere. High pressure systems are
generally characterized by clear skies and fair weather since
cloud development is impeded therein, and winds are also
- High Resolution Profiler (HRP)
- An oceanographic instrument designed to collect fine- and microstructure
data during vertical profiles. As the HRP is lowered
has two profiling modes, with the transition between the fine and
micro modes triggered by the onboard CTD pressure sensor
reaching a user-defined
The fine structure sensors are sampled at 10 Hz and the microstructure
sensors at 200 Hz, with the fine sampling continuing simultaneously
with the micro sampling.
The HRP is designed to minimize ship-induced noise in the measurements,
and as such profiles while falling freely from the ship until it releases
a set of weights and ascends to the surface to be recovered.
The nominal descent rate is 0.6 ms with a 1000 meter dive
typically taking thirty minutes during which half a megabyte of fine
data and two megabytes of micro data will be acquired and stored.
The data is downloaded from instrument memory to a shipboard computer
once it has been loaded on deck.
See Schmitt et al. (1988).
- HiHo HiHo Experiment
- Acronym for Harmonious Ice and Hydrographic Observations - Heat In,
Halide Out Experiment, a
Antarctic CRC experiment to study the
Antarctic pack ice during winter. The project aims include: (1)
providing a quantitative assessment of the mass budget and
Antarctic winter sea ice and to relate this to the rate of water
mass modification; (2) providing a quantitative estimate of the
surface energy exchanges in the winter Antarctic sea ice zone and,
in conjunction with FORMEX, to relate
surface vertical energy exchange to the ocean heat budget and
advection; and (3) describing the processes by which new ice
deforms and thickens and the atmospheric and ocean forcing which
determine these processes.
HiHo Web site.