Ln-Lz

LODYC

Abbreviation for Laboratoire de Physique de Océans.

LOICZ

Abbreviation for Land Ocean Interactions in the Coastal Zone, an IGBP project directed at an assessment of:

• fluxes of matter between land, sea and atmosphere through the coastal zone;
• the responses of the land-sea interface to global change, particularl sea level rise;
• the biogeochemical responses of coastal systems to global change, with emphasis on the carbon cycle and exchanges of certain atmospheric trace gases; and
• socio-economic implications of the degradation of the coastal zone and the need for development of new policies for the integrated management of coastal environments.

The project began in 1993 with the establishment of the International Project Office (IPO) at the Netherlands Institute for Sea Research (NIOZ). The IPO is supported by the Dutch government and scheduled to run for ten years.

[http://www.nioz.nl/loicz/info.htm]

LOIS

Acronym for Land-Ocean Interaction Study, the U.K. contribution to LOICZ. The project aims to quantify and simulate the fluxes and transformations of materials, e.g. sediments, nutrients, contaminants, into and out of the coastal zone, extending from the catchment to the edge of the continental shelf. The main study area is the U.K. East Coast from Berwick upon Tweed to Great Yarmouth, concentrating on the Humber River and its catchment. See the LOIS Web site.

Lombok Strait

A strait located at 155$^\circ$37'E-116$^\circ$02'E and 8$^\circ$20'S-8$^\circ$50'S between the islands of Lombok and Bali in the Australasian Mediterranean Sea. This is one of many possible and the second largest of the passages for throughflow from the Pacific to the Indian Ocean, and connects the western Flores Sea to the Indian Ocean. The strait spans a length of about 60 km with a north-south orientation. It is about 40 km wide and 1000 m deep at its northern opening, but only 18 km wide and 300 m deep at the sill in the southern opening.

Despite its small size, the Lombok Strait is considered critical for the Indonesian Throughflow. This is because of a 600 m deep trough along the edge of the Sunda Shelf extending from south of Makassar Strait to north of Lombok Strait that effectively funnels a maximum salinity water mass from Makassar Strait directly to Lombok Strait. Its position at the edge of the Sunda Shelf also allows it to transport both Java Sea and Flores Sea surface waters to the Indian Ocean.

It is one of the few passages where measurements have been made. The transport has been found to vary semiannually between about 1 Sv in March to 4 Sv in September, comprising about 20-50% of the total Indonesian Throughflow. Currents in the Strait are bidirectional in the northeast-southwest direction, with large spatial and temporal variability. In the upper 100 m the currents are 150 m s$^{-1}$ in the midstrait region and increase to 350 m s$^{-1}$ toward the sill. The currents decrease with depth, although tidal currents of 80 cm s$^{-1}$ are observed at 800 m. See Arief (1998).

Lombok Strait Experiment

See Murray and Arief (1988).

longshore bar

A ridge of sand running roughly parallel to the shoreline which may become exposed at low tide. There can be a series of these running parallel to one another at different water depths. See Komar (1976).

longshore current

See Komar (1976).

longshore trough

An elongated depression extending parallel to the shoreline and any longshore bars that are present and, like the longshore bars, there may be more than one present. See Komar (1976).

Loop Current

The continuation of the Mediterranean Current through the Yucatan Strait and on into the Gulf of Mexico. It is dynamically a western boundary current that separates from the shelf north of the Yucatan Strait, becomes unstable, and intermittently sheds anticyclonic eddies or rings into the Gulf of Mexico. The speed of the current has been estimated to be 1.0 m/s in Yucatan Strait, falling off to 0.4 m/s at 1000 m depth. A highly irregular southward flowing undercurrent has also been found in the 200 m above the sill depth. See Maul and Vukovich (1993).

LOPACC

Acronym for Late Quaternary Ocean Paleocirculation and Climate Change.

LOREX

Acronym for Lomonosov Ridge Experiment, a 1979 Canadian Department of Energy, Mines and Resources multi-discliplinary project to study the nature and origins of the Lomonosov Ridge, an underwater 3000 m high mountain range running from the continental shelf off Greeland and Ellesmere Island to the Siberian continental shelf.

LOS

Abbreviation for Law of the Sea.

LOSS

Acronym for LAPS Observing System Simulation.

Lost Instrument Network

A clearinghouse created at WHOI to collect and broadcast information about lost and found oceanographic research equipment. It is implemented as a moderated mailing list to which interested parties can subscribe.

[http://woodshole.er.usgs.gov/mmartini/lostlist/]

LOTUS

Acronym for Long Term Upper Ocean Study, a two year Woods Hole study beginning in 1983 designed to acquire and analyze a continuous set of measurements of currents and temperatures throughout the water column in the open ocean. A total of ten moorings were deployed in about 5365 meters of water near 33$\deg$ N, 70$\deg$ W.

[http://uop.whoi.edu/data/lotus/lotus.html]

low

Abbreviated form of low pressure center.

Low Density XBT Network

A GOOS project to determine the monthly to interannual variability in the large-scale upper ocean heat constant via the operational deployment of XBT instruments from volunteer merchant ships.

[http://ioc.unesco.org/igossweb/xbt.htm]

low pass filter

In data or signal analysis, a filter that passes frequencies below some cutoff frequency while attenuating higher frequencies.

low pressure center

In meteorology, a region of relatively low barometric pressure. These are characterized by upward moving air at altitude and convergence near the ground. These predominate in midlatitudes, i.e. around 40-50$^\circ$. These are also known as cyclones and as such rotate clockwise/counterclockwise in the southern/northern hemisphere. Low pressure systems are generally characterized by clouds, precipitation, and occasionally thunderstorms, all of which are facilitated by the upward movement of moist air from near the ground.

lower high water (LHW)

The higher of two high waters on a day when the tide is neither The lower of two low waters on a day when the tide is neither predominantly diurnal nor predominantly semidiurnal but rather intermediate to either (a situation sometimes called a mixed tide).

lower high water interval (LHWI)

The time interval between the transit of the moon over either the local or Greenwich meridian and the next lower high water (LHW). This is generally used when the diurnal inequality is large.

lower low water (LLW)

The lower of two low waters on a day when the tide is neither predominantly diurnal nor predominantly semidiurnal but rather intermediate to either (a situation sometimes called a mixed tide).

lower low water interval (LLWI)

The time interval between the transit of the moon over either the local or Greenwich meridian and the next lower low water (LLW). This is generally used when the diurnal inequality is large.

LPO

Abbreviation for Laboratoire de Physique des Océans.

LROD

Abbreviation for Long-Range Overwater Diffusion, an experiment that took place in the Pacific Ocean northwest of Kauai, Hawaii in July 1993. The objective was to improve transport and diffusion models by improving the understanding of alongwind diffusion. The experiment involved a series of airborne SF$_6$ releases from an Air Force C-130 transport aircraft, which flew perpendicular to the prevailing wind direction and released lines of SF$_6$ in the marine boundary layer. A second aircraft with a continuous SF$_6$ analyzer sampled the plume at distances up to 100 km downwind, with six small boats also tracking the plume to similar distances. Analyses indicated that both vertical and downwind diffusion components are needed for highly accurate model simulations.

[http://www.noaa.inel.gov/frd/Projects/lrod.html]

LSG

Abbreviation for Large Scale Geostrophic model, an ocean general circulation model (OGCM) developed at the Max-Planck-Institut für Meteorologie in Hamburg, Germany. See Maier-Reimer et al. (1993).

LSS

Abbreviation for Light Scattering Sensor, an instrument built by SeaTech and used to obtain in-situ measurements of light scattering in sea water. This measurement also provides a crude measure of the particle abundance in the water. The instrument works by projecting a beam of light into the water and measuring the amount of light scattered back to a detector place next to the source. The OBS is a similar instrument.

LSW

Abbreviation for Labrador Sea Water.

LTE

See Laplace's tidal equations.

Luzon Undercurrent

A subsurface countercurrent located on the shoreward side of the Kuroshio Current with an upper boundary at about 500 m. The current is about 50 km wide and, despite considerable variability in both velocity profile and intensity, is apparently a permanent feature. The maximum speed relative to 2500 db is calculated to be 7 cm s$^{-1}$ at about 700 m and the mean geostrophic volume transport 3.6 Sv. The latter was composed of about 28% NPIW. See Tangdong et al. (1997).

lysocline

The upper portion of the transition zone in sediments between supersaturated (shallow) and undersaturated (deep) sediments in the ocean. The transition is between the burial and dissolution of CaCO3 sediments. See Najjar (1991).