Na-Nm

 

NADP/NTN

Abbreviation for the National Atmospheric Deposition Program/National Trends Network, a nationwide network of precipitation monitoring sites. The network was started in 1978 and currently consists of around 200 sites. The purpose is to collect data on the chemistry of precipitation for monitoriong of geographical and temporal long-term trends. See the NADP/NTN Web site.

 

NADW

See North Atlantic Deep Water.

 

NAML

Abbreviation for the National Association of Marine Laboratories. See the NAML Web site.

 

nanoplankton

Phytoplankton whose lengths range from 10 to 50 m. Compare to microplankton and ultraplankton.

 

Nansen, Fridtjob

More later.

 

Nansen bottle

A reversing water bottle comprising a water bottle and a pair of thermometers on a reversing frame. This was developed by Nansen around 1910. See Schlee (1973).

 

NAO

Abbreviation for North Atlantic Oscillation, the index of which is defined as the normalized winter pressure differential between the Icelandic Low and the Azores High centers of action. Low (high) NAO index values occur when sea level pressure is above (below) average in the vicinity of the subpolar Icelandic Low and below (above) average near the subtropical Azores High pressure cell. See Van Loon and Rogers (1978) and Rogers (1984).

 

National Oceanic and Atmospheric Administration

A branch of the U.S. Dept. of Commerce whose mission is to promote global environmental stewardship to conserve and wisely manage the nation's marine and coastal resources, and to describe monitor, and predict changes in the Earth's environment to ensure and enhance sustainable economic opportunities. NOAA comprises the following program offices: NESDIS, NMFS, NOS, NWS, OAR, COP, OGP and HPCC. More information can be found at the NOAA Web site.

 

NATRE

Abbreviation for North Atlantic Tracer Release Experiment.

 

natural broadening

In atmospheric radiative transfer, a process by which the broadening of absorption lines is associated with the finite time of photon emission or absorption and with the uncertainty principle. The frequency can only be known to a finite precision if the energy is known exactly. This mechanism is less important in the atmosphere than are pressure broadening and Doppler broadening.

 

natural variability

The range of climate variations that would theoretically exist in the absence of anthropogenic forcing. Information on this hypothesized spectrum of climate variability can be derived from instrumental data, paleoclimatic reconstructions, and numerical model results.

 

NASA

Acronym for National Aeronautics and Space Administration.

 

Navier-Stokes equations

The fundamental equations of the dynamics of an incompressible and Newtonian. When , i.e. for infinite Reynolds numbers, the Navier-Stokes equations reduce to the Euler equations.

 

Nautilus expedition

More later.

 

NBIOME

Abbreviation for the Northern Biosphere Observation and Modelling Experiment, whose objective is to increase our understanding of the role of terrestrial vegetation in the total Earth system and its changes with time. See the NBIOME Web site.

 

NCAR

Acronym for the National Center for Atmospheric Research located in Boulder, Colorado. NCAR comprises five divisions: (1) Atmospheric Chemistry Division (ACD), (2) Atmospheric Technology Division (ATD), (3) Climate and Global Dynamics Division (CGD), (4) Mesoscale and Microscale Meteorology Division (MMM), and (5) Scientific Computing Division (SCD). See the NCAR Web site.

 

NCC

Abbreviation for Norwegian Coastal Current.

 

NCDC

Acronym for National Climate Data Center, a branch of the NESDIS division of the Office of Environmental Information Services of NOAA that is the collection center and custodian for all U.S. weather records. More information can be found at the NCDC Web page.

 

NDBC

Abbreviation for National Data Buoy Center, a NOAA site that is the source of buoy-measured environmental data. See the NDBC Web site.

 

NDVI

Abbreviation for normalized difference vegetation index, a model for converting satellite-based measurements into surface vegetation types. The NDVI uses a complex ratio of reflectance in the red and near-infrared portions of the spectrum to accomplish this. Reflectance in the red region decreases with increasing chlorophyll content of the plant canopy, while reflectance in the infrared increases with increasing wet plant biomass. This technique has been used most successfully with data from the AVHRR, and is actually used operationally to predict the degree of drought adn potential famine in the Sahel region of Africa. It is a quantity that measures greenness and vigor of vegetation. See Tarpley et al. (1984), Tucker et al. (1985) and Tucker et al. (1986).

 

NEADS

Acronym for Northeastern Atlantic Dynamics Study, an array of instrumentation moorings anchored in the northeastern Atlantic basin in the early 1980s. This was a collaboration between West Germany, England and France and complementary to the contemporanous MODE program.

 

neap tide

The tides produced when the gravitational pull of the Sun is in quadrature, i.e. at right angles to, with that of the Moon. These occur twice a month at about the times of the first and last quarters. In these situations the gravitational pull of the Sun/Moon produces high/low water or vice-versa, and as such the differences between high and low tides are unusually small, with both the high tide lower and the low tide higher than usual. The tidal height is about .375 that of maximum during neap tides. See also spring tide.

 

Nebraskan

The American name for the glacial period starting about 750,000 to 800,000 years ago and lasting about 50,000 years. North America and the Alps were ice-covered with Northern Europe and the Arctic Ocean relatively ice-free. Two stadials are recognized in this period, and it is called the Gunz period in the Alpine classification system. The was followed by the Kansan period.

 

NECC

Abbreviation for the North Equatorial Countercurrent.

 

NECOP

Acronym for Nutrient Enhanced Coastal Ocean Productivity, a NOAA research program to study the dynamics of physical, geological, chemical and biological processes as they are influenced by the runoff from the Mississippi River and Atchafalaya Bay. The main objectives of the study include describing a clear anthropogenic signal and any resultant nutrient-enhanced productivity of significant magnitude and demonstrating the impact of enhanced production on coastal environmental quality. See the NECOP Web site.

 

negative feedback

A type of feedback in which a perturbation to a system causes a damping of the process, and thus opposes itself.

 

nekton

Collective term for free-swimming organisms in aquatic ecosystems, as opposed to plankton.

 

Nemesis theory

A theory proposed to explain posited cyclic extinction events. Nemesis is a hypothesized small companion star to the Sun which orbits the Sun with a period of about 26 million years. When it passes close to the Sun it passes through the Oort Cloud, deflecting the orbits of some of the comets therein. The theory posits that these random deflections increase the number of comets passing close to and hitting the Earth which, given the 26 million period, provides a causal mechanism for the massive extinction events in the fossil record which is claimed by some to exhibit a period of around 26 million years. See Raup (1986) for a book length exposition of the genesis of the theory through events up to late 1985.

 

Neogene

A time interval of the Cenozoic era, lasting from 23.7 to 1.6 Ma and incorporating the Miocene and Pliocene epochs. If the Tertiary is designated as an era, then the Neogene and the Paleogene are its two periods.

 

NEONS

Acronym for the Naval Environmental Operational Nowcasting System, a software package that provides the capability to mange oceanographic and meteorological data in near real-time. It provides a set of tools to access, create and manage environmental data which is stored in a NEONS schema within a relational database. See the NEONS Web site.

 

NEP

1. Abbreviation for net ecosystem production, the rate at which carbon from the atmosphere (as CO ) is accumulated in the biosphere. It is equal to the NPP minus heterotrophic respiration. See Woodwell (1995a). 2. Abbreviation for National Estuary Program, an EPA program to identify problems in estuaries and recommend solutions. See the NEP Web site.

 

nephanalysis

A cartographical representation of cloud and, often, cloud type. From the Greek root ``nephos'' meaning, strangely enough, cloud.

 

NERC

Abbreviation for the U.K. National Environmental Research Council. See the NERC Web site.

 

neritic

A division of the pelagic portion of the ocean that overlies the continental shelf.

 

NESDIS

Acronym for the National Environmental Satellite, Data and Information Service, a NOAA office that manages U.S. civil environmental satellite systems as well as global data bases for meteorology, oceanography, solid-earth geophysics, and solar-terrestrial physics. NESDIS consists of the Offices of Environmental Information Services, Satellite Operations, Satellite Data Processing and Distribution, Research and Applications, and Systems Development. More information can be found at the NESDIS Web page.

 

nested modeling

In climate modeling this is a method for obtaining improved regional climate change predictions by the use of a spatial hierarchy of simulation models. Output from GCM simulations is used to provide initial and driving lateral boundary conditions for high resolution regional climate model (RegCM) simulations. There is no feedback from the ReGCM to the GCM. Different nesting techniques have been used, ranging from the standard technique of directly interpolating output from the coarse grid to the fine grid to the more sophisticated technique of spectral nesting. In the latter method the GCM forces the low wavenumber component of fields in the regional domain while the RegCM calculates the high wavenumber components. See Houghton and Filho (1995).

 

net irradiance

The sum of the irradiance and the exitance.

 

net radiation at top of atmosphere

This defined as the difference between absorbed solar radiation and emitted terrestrial radiation, or

where R is the net radiation, S the insolation, the planetary albedo, F the outgoing longwave radiation, and Q the absorbed solar radiation. See Hartmann (1993).

 

new moon

The times when the Sun and Moon have the same Earth-centered longitude, i.e. they are in conjunction. During these times the Moon is invisible since the Earth blocks the light of the Sun from illuminating it. Spring tidesspringtide occur during new moons.

 

new production

Photosynthesis due to the uptake of nitrate. It is so-called because ocean circulation is the only source of nitrate to the euphotic zone and, as such, the nitrate can be thought of as newly available to phytoplankton. See Najjar (1991).

 

Newtonian fluid

A fluid in which deformation is proportional to velocity gradients.

 

NGDC

Acronym for National Geophysical Data Center, a branch of the NESDIS division of the Office of Environmental Information Services of NOAA that manages environmental data in the fields of solar-terrestrial physics, solid earth geophysics, marine geology and geophysics, paleoclimatology, and glaciology. It operates a World Data Center for each field. More information can be found at the NGDC Web page.

 

NGWLMS

Abbreviation for Next Generation Water Level Management System, an automated system for collecting sea level and other data. The NGWLMS platform measures sea level position, air and water temperature, water density, wind speed and direction, and atmospheric pressure. Data is collected at various rates, stored every three minutes, and relayed via the NOAA GOES satellite to a central collection facility in Rockville, MD every three hours. See Beaumariage and Scherer (1987).

 

NH

Abbreviation for northern hemisphere.

 

nimbostratus

A type of dark grey layered cloud that brings almost continous rain or snow. It is formed at an altitude of approximately 19,000 feet.

 

NIOZ

Acronym for Nederlands Institut voor Onderzoek der Zee or, in translation, the Netherlands Institute for Sea Research. See the NIOZ Web site.

 

Niskin bottle

A plastic sampling bottle with water tight clsoures at top and bottom used to collect seawater samples for discrete chemical and biological measurements. It is equipped with a subsampling spigot and an air vent and can be triggered at pre-determined depths to collect samples. It is made of polyvinylchloride (PVC), an unreactive substance, to minimize possible contamination of highly sensitive measurements.

 

nitrification

The process by which ammonia formed by the bacterial decay of marine organisms or excreted by marine animals is oxidized to nitrite and then nitrate. It is inhibited by light and proceeds very slow if at all in the euphotic zone. See Najjar (1991).

 

nitrogen propagation factor

In atmospheric photochemistry, the probability that an NO2 molecule will be photolyzed rather than reacted to nitrogen products. It describes the fraction of recreated NO per total NO reacting. See Jeffries (1995).

 

nitrous oxide

This is a greenhouse gas commonly known as ``laughing gas''. It is composed of the two most common gases in the atmosphere: nitrogen and oxygen. It has an atmospheric concentration of 310 ppb (in 1990), as opposed to a pre-industrial 285 ppb (in 1880), although this relative scarcity belies its effectiveness as a greenhouse gas. A molecule of N O is 200 to 300 times more effective as is one of carbon dioxide as a greenhouse gas. It also has a longer residence time, being broken down into its constituents by light in the stratosphere after about 150 years.

The main anthropogenic sources of atmospheric nitrous oxide are combustion (of fossil fuels, wood, or other biomass) and the widespread use of fertilizers, although the estimates for the amount supplied by the latter are highly variable. Natural sources include gas release into the atmosphere by the oceans and tropical and temperate forest soils.

 

NLR

Abbreviation for nearest living relative, a technique of paleoclimatological interpretation of phytogeographic evidence that fundamentally assumes that the climatic tolerances of living taxa can be extrapolated without modification to ancestral forms of the same taxa. This assumption of evolutionary stasis may be inappropriate. See Spicer et al. (1994). This has been somewhat superseded by the physiognomic approach, a technique relating the climatic tolerances of plants to their physical form (the physiognomy of individual organs, whole plants, and vegetational units up to the scale of global biomes) with no reference to taxa.

 

NMAT

Abbreviation for Night-time Marine Air Temperature. This is a temperature defined and measured so as to avoid the effects of the daytime heating of the decks of ships, the platforms on which such things are usually measured.

 

NMC

Abbreviation for National Meteorological Center (USA).

 

NMFS

Acronym for the National Marine Fisheries Service, a program office of NOAA that administers programs that support the domestic and international conservation and management of living marine resources. More information can be found at the NMFS Web page.