Abbreviation for Moist Adiabatic Adjustment.
The last of six ages in the
Late Cretaceous epoch, lasting
from 74.5 to 66.4 Ma. It is preceded by
the Campanian age and
followed by the Danian age of
the Paleocene epoch.
It is characterized by chalk limestones throughout western
Abbreviation for Man and the Biosphere program, a
Acronym for Multi-center Airborne Coherent Atmospheric Wind Sensor,
an airborne, pulsed, scanning, coherent, Doppler laser radar (lidar)
that directly measures wind velocity and aerosol backscatter
distribution in a 3-D volume in the troposphere and lower
stratosphere. It flies on the NASA DC-8 research aircraft.
MACAWS Web site.
- Mach number
Acronym for the Meteorological and Climatological Information
Server Searcher, a suite of software that collects the addresses
of servers, extracts information from the servers, and adds this
information to a searchable database. MACISS searches servers
that are thought to contain a meteorological, climatological,
or atmospheric science component. See the
MACISS Web site.
Evolution above the species level.
Acronym for Middle Atmosphere in the Climate System, an
Acronym for Mediterranean Assistance and Data Management in
Oceanography, an initiative to set up and run an infrastructure
to provide assistance in the field of oceanographic data
management to the MTP, including the
different subprojects and associated
The general objective of MADAM is to compile and produce an
up-to-date dataset, the MTP Data Set, comprising data from
the MTP as well as a set of basic tools for the scientific
use of the data. Secondary objectives include managing and
making available the data set during the course of MTP,
set up and running a network to provide links between associated
scientists, and providing support for subprojects for specific
data handling problems. See the
MADAM Web site.
- Madeira Mode Water
A type of Mode Water formed north of
Madeira in the North Atlantic Ocean. It is characterized by
a summer thermostad at 70-150 m
depth and provides a major contribution to the formation of
North Atlantic Central Water (NACW).
See Siedler et al. (1987).
Acronym for Measurements for Assessing the Effects of
Stratospheric Aircraft, a program whose focus was to
provide information about stratospheric photochemistry and
transport for assessing the potential environmental effects
of stratospheric aircraft. It was conducted in concert with
ASHOE in four phases through the
Antarctic winter of 1994.
MAESA Web site.
A northwesterly wind in the Adriatic, most frequent on the western
shore and in summer. This is also applied to northwesterly winds
in other parts of the Mediterranean.
Acronym for Marine Aerosol and Gas Exchange, an IGAC activity.
- magnetic declination
The difference between Magnetic North (South) and Geographical
- magnetic field reversals
Cooling lava flows acquire a direction of magnetization
parallel to that of the earth's magnetic field as the iron-rich
particles within align themselves parallel to that field.
The discovery of this effect by Bernard Brunhes in 1906
led to the measurement of the direction of magnetization of
many ancient lava flows and, eventually, to the realization
that the earth's magnetic field must have reversed itself
in the past and, indeed, many times.
Skepticism concerning the multiple and worldwide nature
of these reversals was eventually allayed by the use of
methods to date lava flows above and below reversals in
samples from widespread locations and demonstrate the
synchroneity of the events. These fixed dates provided
a framework on which to build a
magnetostratigraphic time scale for the previous 4.5 million
- Magnetic North
The direction in which the North pole of a pivoted magnet will
point. It differs from Geographical North by an angle called
the magnetic declination.
- Magnetic South
The direction in which the South pole of a pivoted magnet will
point. It differs from Geographical South by an angle called
the magnetic declination.
- magnetostratigraphic time scale
A time scale based on inferred periodic
magnetic field reversals
in the Earth's geomagnetic field.
If a rock contains suitable
minerals, then it will retain the magnetic orientation induced
by this field at its time of formation, the orientation being
described as either a normal or reversed state of the field.
The correlation of these normal and reversed patterns among
many different successions of rocks at widespread geographic
locations has resulted in a sequence of orientations that,
when combined with a dating method such as potassium-argon
dating, provides a magnetostratigraphic time scale measured
in units of normal or reversed polarity. The scale presently
extends back to the Early Jurassic (about
The basic unit for this scale is the polarity
epoch or, more recently (and officially), polarity chron
and represents a time period over which the magnetic field is
constantly or predominantly of one polarity. Smaller and
larger units are called, respectively and unsurprisingly, polarity subchrons
(previously called polarity events).
and polarity superchrons.
Stratigraphy based on the geomagnetic
polarity reversals on which the
magnetostratigraphic time scale is based.
Acronym for Measurements of Anthropogenic Gases and Natural
Emissions from Tall Towers, a
NOAA CMDL program
which uses existing tall (> 400 meters) towers as sampling
platforms for in situ and flask sample analyses of atmospheric
trace gases. The program began in June 1992.
MAGNETT Web site.
Acronym for the Mackenzie River GEWEX Study, a series
of large-scale hydrological and related atmospheric and land-atmosphere
studies to be conducted within the Mackenzie Basin in Canada. More
information can be found at the MAGS Web site.
Acronym for Middle and High Latitude Ocean Variability Study.
- Makaroff Deep
See Guiana Basin.
- Maluku Sea
See Molucca Sea.
- Malvinas Current
A jet-like northward looping extension of the
Antarctic Circumpolar Current located in the southwest Atlantic
Ocean. The cold waters of this current form an intense front
with the warm waters of the
Brazil Current as it separates
from the continental shelf at around 35 S.
This is also called the Falkland Current.
See Tomczak and Godfrey (1994).
Acronym for Mediterranean Association of Marine Biological
Oceanography, an ICSU project.
A member of the class Mammalia.
A class of the subphylum Vertebrata
of the phylum Chordata.
These are warm-blooded, air-breathing animals with hair and
The orders that include marine mammals include
Members of this class include sea otters, seals, walruses,
sea cows, manatees, whales and dolphins.
Acronym for Multispectral Atmospheric Mapping Sensor, a multispectral
scanner which measures reflected radiation from the Earth's surface
and clouds in eight
visible/near-infrared bands, and thermal
emission from the Earth's surface, clouds and atmospheric
constituents (primarily water vapor) in four infrared bands.
It is an airborne sensor developed and flown in 1985 to verify
small-scale water vapor features observed in
VAS imagery aboard GOES.
The data collected from MAMS will be used to identify mesoscale
atmospheric moisture variations and provide visible and infrared
measurements of thunderstorms. The data will also be used to
characterize the structure of these features and to derive integrated
water content (precipitable water) measurements for these features.
See the MAMS Web site.
- map projections
Any of an extremely large number of methods for mapping, or projecting,
the spherical (well, almost) Earth onto a two-dimensional surface.
An overview of map projections
is available on the Web.
1. Acronym for Measurement of Air Pollution from Satellites, an
experiment to measure the global distribution of carbon monoxide
in the free troposphere. See the
MAPS Web site.
2. Acronym for Mesoscale Analysis and Prediction System, a
regional data assimilation and forecast system which provides
high-frequency (i.e. at least every 3 hours) analyses of
conventional and new data sources over the contiguous U.S.
and short-range forecasts (out to 12 hours) in support of
aviation and other mesoscale forecast users.
MAPS Web site.
Abbreviation for Mapped Atmosphere-Plant-Soil System, a global biome
model including resource limitation and competitive balance effects,
i.e. a so-called ``second-generation'' model.
See Neilson (1994).
- marginal ice zone
An area between solid sea ice and the open ice-free sea that is
only partially covered by dispersed ice floes. This can represent
a large portion of the total sea area covered by ice.
Acronym for Margin Experiment, an
Antarctic CRC experiment along
the continental shelf and slope region of Antarctica from
80 to 165 E whose objectives include:
(1) estimating the rate of formation of surface and Antarctic
Bottom Water (AABW) masses; (2) defining the evolution and
modification of Antarctic water masses along the shelf and
slope in this region; (3) estimating the relative importance
of air-sea interaction and advection of surface and deep
waters on property changes in the major water masses; and (4)
constructing numerical models of the formation and dynamics of
water masses south of the Antarctic Convergence over the full
MARGINEX Web site.
- Margules' equation
In physical oceanography, an equation that allows the estimation of
the slope of the surface density discontinuity associated with
in the sea and of fronts in the atmosphere
from a knowledge of the component speeds of geostrophic motion along
the interface and the density difference across the interface. The
equation is given by
where is a finite increment of vertical distance,
a finite increment of horizontal distance along the dip
of the interfacial slope, f the
g the gravitational acceleration,
the density, and c the geostrophic velocity parallel with one
side of the interface, and the primed variables the values of
corresponding properties on the other side.
This equation is helpful in clarifying the sometimes confusing
problem of estimating the change of frontal slope as a function of
latitude or a change in density contrast across the front at the
same latitude but with different velocities of flow.
See Von Arx (1962).
- marine biogeography
See Hedgpeth (1957a).
- marine bioluminescence
See Tett and Kelly (1973).
- marine palynology
The study of pollen deposits in marine sediment records.
See Stanley (1969).
- marine pollution
See Duursma and Marchand (1974).
- marine snow
Oceanic particles which are amorphous, heterogeneous aggregates
greater than 500 m and composed of detrital material,
living organisms and inorganic matter.
See Alldredge and Silver (1988).
- Marine Technology Society (MTS)
An international, interdisciplinary society devoted to ocean and
marine engineering, science and policy.
Its objectives are to disseminate marine science and
technical knowledge, promote and aid education of scientists
and other involved in marine fields, and advance the development
of tools to explore, study, preserve and exploit the oceans.
MTS publishes the ``MTS Journal.''
MTS Web site.
Acronym for the MARine Information Service, a project in the
Netherlands to improve the overview of and access to marine
expertise, information, and data related to the sea and its
uses. See the
MARIS Web site.
- Maritime Province Current
See Mid-Japan Sea Current.
- Marmara Sea
A marginal sea centered near 28.5 E and 40.5 N
whose primary significance is to serve as part of the connection between
the Black Sea and the
It reaches 75 km in width, 250 km in length, has a surface area
of about 11,500 km , and a maximum depth of 1390 m.
It is located between the
Bosporus Strait to the northeast
(which connects to the Black Sea) and the
Dardanelles to the west (which connects
to the Aegean Sea).
The northern part of the Marmara comprises three topographic
depressions. The eastern (1240 m), central (1389 m) and
western (1097 m) basins are connected by sills about 750 m
and widths (from west to east) of 20 km and 40 km.
The southern continental shelf is shallow (100 m) and
wide (30 km), while the northern shelf is much narrower
(< 10 km).
The mean upper layer circulation is a basin scale anticyclonic
gyre driven mainly by the sea level differences between the
Black Sea and the
Aegean Sea. This gyre is modified
by the Bosphorous jet during high outflow conditions in spring
and early summer and by the wind stress during the winter.
See Besiktepe et al. (1994).
See Hasselmann and Shemdin (1982).
- Count Marsigli (1658-1730)
See Peterson et al. (1996), p. 32.
Abbreviation for Marvor float, a multicycle
RAFOS type float developed by
IFREMER and TEKELEC (now MARTEC).
A MARVOR float cycles several times between the surface and its
planned depth during its mission. When it surfaces it sends the
data collected to the ARGOS satellite
which relays it to land-based stations.
It is equipped with a hydraulic system that controls its depth
by transferring oil from an internal reservoir to the external
See Ollitrault and et al. (1994) and the
MARVOR Web page
at the IFREMER Web site.
Acronym for Millimeter-wave Atmospheric Sounder, an instrument
designed to study the formation and distribution of ozone by measuring
emission lines of ozone, water vapor, and chlorine monoxide from the
Space Shuttle. The MAS scans the limb of the earth to produce
maps of the global distribution of these trace molecules as a function
of altitude. See the
MAS Web site.
Abbreviation for Mesoscale Air-Sea Interaction Group.
Abbreviation for meters above sea level.
- Massenerhebung effect
The tendency for mountains to significantly modify the prevailing climate.
See Collinson (1988).
- mass spectrometry
A method for making isotope abundance measurements
on gases in geochemical work. The instrument separates and detects
ions on the basis of the motions of charged particles with different
masses in magnetic or electrical fields.
Acronym for MArine Science and Technology, a research program of
the European Union. THe aim of this program is to develop the
scientific and technological bases for the sustainable
exploitation of marine systems and determine their precise
role in global change. See the
MAST Web site.
Acronym for the Midocean Acoustic Transmission Experiment, a
project of the APL of the
University of Washington Department of Oceanography.
It was conducted
near Cobb Seamount in the Northeast Pacific Ocean about 450 km
off the coast of Washington during June-July 1977.
In this experiment simultaneous measurements of temperature
and velocity time series, vertical and horizontal temperature
profiles, and acoustic transmissions were performed to
attempt to ascertain the effects of internal waves on
See Ewart and Reynolds (1984).
- Matuyama Magnetic Epoch
Reverse polarity time interval extending from 0.6 to 2.4 million
years ago. See Bowen (1991).
- Maunder butterly
A graph of the distribution of sunspots
showing heliographic latitude with time that is shaped not unlike
the wings of a butterfly. See Burroughs (1992).
- Maunder Minimum
An extended period of limited sunspot
activity lasting from
1645 to 1715. It is named after the British astronomer who first
called attention to it in 1890.
See Eddy (1976) specifically and Foukal (1990) and
Wigley (1988) generally.
- Maury, Matthew Fontaine (1806-1873)
See Peterson et al. (1996), p. 79.
Modified Atlantic Water.
- Maximum Entropy Spectral Analysis
A method of analyzing time series which uses
autoregressive methods to extract the
maximum amount of information from the available data.
- Mayr's Rules
These are ecogeographical rules
that apply to birds. In colder climates, the number of eggs in a
clutch are larger, the wings longer, and migratory behavior is
more developed than in warmer climates. These were published
by Ernst Mayr in 1942.
1. Abbreviation for Marine Biology Laboratory, located at
2. Abbreviation for marine boundary layer.
Abbreviation for moist convective adjustment.
Abbreviation for mechanical current meter.
Abbreviation for multichannel sea surface temperature, a satellite
data set derived from the TIROS-N/NOAA series satellite
See Wick et al. (1992).
A statistical property of n numbers that is their sum divided by
m. The mean of a
is called its expected value.
Constrast with median and
- mean meridional circulation
An average circulation feature or cell defined to consist of the zonal-mean
meridional and vertical velocities. In the tropics and subtropics this
mean meridional circulation cell is known as the
Hadley cell and in midlatitudes as
the Ferrel cell.
- mean noon
The instant at which the mean Sun crosses the
meridian at upper culmination at any place. The meridian of
Greenwich is usually meant.
- mean sea level
See Lisitzin (1963).
- mean solar day
The interval, perfectly constant, between two successive transits of
the mean Sun across the meridian.
- mean solar time
Time as measured by the hour angle of the mean Sun.
It is counted from midnight, and when referred to the meridian of
Greenwich is called Greenwich Mean Time.
- mean Sun
A fictitious reference point which has a constant rate of motion and
is used in timekeeping in preference to the non-uniform motion of
the real Sun. The mean Sun is imagined to follow a circular orbit
along the celestial equator
and is used to measure mean solar time.
1. Acronym for Model for Estuarine and Coastal Circulation
2. Acronym for Model Evaluation Consortium for Climate Assessment, created
in 1991 with the goals of performing numerical experiments that will
identify and quantify the uncertainties associated with predictions
of greenhouse gas-induced climate change for models used to advise
public policy, to create a protocol for analyzing the experimental
results and applying them to policy, and to communicate findings in
order to advance model development.
See the MECCA Web site.
Acronym for the Mediterranean Alpine Experiment, a part of the
GARP subprogram on airflow over and around
mountains. The primary function of MEDALPLEX was to study the
response of the western part of the Mediterranean to wind
forcing. See the
MEDALPLEX Web site.
An international research project to investigate the effects of
desertification on land use in Mediterranean Europe. See the
MEDALUS Web site.
A project to create a hydroraphic data bank for the Mediterranean
Sea. The objectives are to create a data project which includes
an update of currently available data sets, a quality control of
the data set in conformance with IOC and MAST recommendations,
revised climatological statistics for the Mediterreanean Sea, and
making the final product available electronically.
MEDATLAS Web site.
A subsurface lense of
These rotating lenses serve to transport the Mediterranean
Water in their cores as far afield as the
Sargasso Sea. Over the long
term these meddies, each slowly releasing its surplus of
heat and salt, inject their contents into and serve to
partially form the upper part of
North Atlantic Deep Water
Acronym for Measurements of Earth Data for Environmental
The value of the middle item of a group of data arranged according
to size. The median of a
is the value on the horizontal scale through which a vertical
line dividing the area into two equal parts passes. Contrast with
mean and mode.
- Medieval Maxima
A period of increased sunspot activity lasting from approximately
1120 to 1280. See Foukal (1990) and
- Medieval Warm epoch
See Little Climatic Optimum.
- mediolittoral zone
The second (from the surface) of seven zones into which the
benthos has been divided.
In this zone organisms are more or less regularly emerged
and submerged, usually by the action of the tides.
Species are here adapted to resist prolonged emersion
and are generally incapable of living if continually
See Fairbridge (1966).
- mediterranean sea
A generic term used to describe a class of ocean basins that
have limited communication with the major ocean basins and
in which the circulation is dominated by thermohaline
forcing. This causes a circulation that is the reverse of
that found in the major basins, i.e. it is driven by salinity
and temperature differences and only modified by wind action.
Mediterranean seas exhibit the dynamics of estuaries rather
than those of open oceans.
Examples include the
Arctic Mediterranean Basin,
Australasian Mediterreanan Basin, and of course the
Mediterranan seas can be further distinguished by their
balance of precipitation and evaporation. If evaporation
exceeds precipitation, the deep vertical convection occurs and
the water below the sill depth is frequently renewed. The
open ocean connection features inflow in the upper layer and
outflow in the lower layer since the inflow is driven by the
freshwater loss in the upper layer. This is called a
If precipitation exceeds evaporation, then the surplus of
fresh water in the upper layer drives an outflow of surface
water into the connecting major basin. The decrease in surface
density also results in an increased pressure difference at the
connecting sill which in turn results in inflow in the lower
layer and even more outflow in the upper layer. A very
sharp pycnocline is established which inhibits the renewal
of the deep waters. This type of basin can be depleted in
oxygen even to the point of anoxia in the lower layer.
This is known as a dilution basin.
- Mediterranean Sea
See Robinson et al. (1992).
- Mediterranean Surface Water
See Perkins and Pistek (1990).
- Mediterranean Water
In physical oceanography, a
water mass formed in the arid eastern
Mediterranean Sea that flows westward and sinks in the Algero-Ligurian
and Alboran basins to depth of about 500 m due to its relatively
high salinity of 36.5 to 39.1. It continues westward into
the Atlantic Ocean through the shallow Straits of Gibraltar (at
depths below 150 m) where it sinks to about 1000 m, forming a
distinctive water mass with a temperature of 11-12 C
and a salinity of 36.0-36.2. It can be recognized as a salinity
and temperature maximum near 1000 m. This is also denoted as
EMW or Eurafrican MW to distinguish it from Australasian MW.
See Tomczak and Godfrey (1994).
Acronym for Mediterranean Models Evaluation Experiment, whose aim is
to achieve an intercomparison of existing models that have been
applied to the Mediterranean Sea.
See the MEDMEX Web site.
Acronym for MEDiterranean Ocean Circulation.
See Group (1970).
Acronym for Marine Environmental Data Service, a branch of
Canada's DFO whose mandate is to manage and
archive physical and chemical oceanographic data collected by DFO
regions or acquired through various arrangements from Canadian
researchers and from foreign research conducted in the major
ocean areas adjacent to Canada.
MEDS Web site.
Acronym for Methane and Halocarbons Intercalibrations Experiment,
and IGAC task.
Acronym for the Master Environmental Library, a distributed environmental
data access system which allows users to search for, browse, and retrieve
environmental data from distributed sources.
This project, sponsored by the U.S. Navy's
Defense Modeling and Simulation Office (DMSO), allows users to access the available environmental
data by region, date, databases and keywords.
MEL Web site.
- Menard, Henry
A marine geologist at Scripps who in 1958 suggested a
continuous process of mid-ocean ridge development.
Acronym for the Marine Ecosystem Response program, a research
initiative jointly supported by NOAA and NSF geared toward
the generation of quantitative scenarios for the impact of
the climate system on marine ecosystems such as the economically
significant fisheries in the northeast U.S. See the
MER Web site.
- Merian's formula
In the study of seiches and harbor resonance, this is an
equation that gives the natural period of a
long and narrow basin in terms
of its length and depth for the various modes of oscillation.
It is given by
where T is the period, a is the length of the basin,
n is the mode number, g gravitational acceleration,
and h the basin depth.
See Raichlen (1966).
The great circle passing through the poles of the
celestial sphere which cuts the
observer's horizon in the north and south points and also
passes through his zenith angle.
Acronym for Medium Resolution Imaging Spectrometer, an ocean color
sensor. It is a push-broom instrument that measures the radiation
reflected from the Earth's surface and from clouds in the visible
and near-infrared range during the daytime.
The 1150 km wide swatch of the instrument is divided into 5 segments
covered by 5 identical cameras having corresponding fields of
view with slight overlap between adjacent cameras.
The geophysical parameters derived from MERIS measurements
include ocean color in open and coastal waters, e.g. chlorophyll,
gelbstoffe, and other pigments, qualitative parameters such as
presence ofclouds and emerged land, and atmospheric parameters
like aerosol optical thickness, cloud albedo, Angstrom exponent,
top pressure, and water vapor column contents.
MERIS Web site.
In heterochrony, meristic characters
are individual structures produced during an organism's
Acronym for the Multi-source EnviRonmental dispLay for INternet
archives, a software system that provides access, fusion,
intercomparison, interpretation and visualization of a wide variety
of environmental data and derived products for researchers investigating
climate and global change issues. It was developed at
SSEC and further details can be found at the
MERLIN Web site.
Acronym for Mediterreanean Eddy Resolving Modeling and Interdisciplinary
Studies, a study whose main goal is to assess the internal variability
of the Mediterranean thermohaline circulation as induced by deep and
intermediate water formation processes and the inflow/outflow system
at Gibraltar on the seasonal and interannual time scales.
MERMAIDS Web site.
Acronym for Maximum Entropy Spectral Analysis.
- mesopelagic zone
One of five vertical ecological zones into which the
deep sea is sometimes divided.
This is the uppermost aphotic zone from 200 to 1000 m deep where little light
penetrates and the temperature gradient is even and gradual with
little seasonal variation. This zone contains an oxygen minimum
layer and usually the maximum concentrations of the nutrients
nitrate and phosphate.
This overlies the
bathypelagic zone and
is overlain by the
See Bruun (1957).
Plants which can withstand wilting for short periods.
To be completed.
The middle of three eras of the
Phanerozoic eon, lasting from 245 to 66.4 Ma.
It is preceded by the Paleozoic era
and followed by the Cenozoic era and consists of
the Triassic, Jurassic, and
Cretaceous periods. It was characterized
by great terrestrial disturbances such as the formation of mountains
and much volcanic activity. The fauna was notable for the number,
variety, and enormous size of the reptiles on land and in the sea,
which occasionally leads to it being called "The Age of Reptiles".
Flowering plants, deciduous trees, and the first birds appeared in
the middle of this era.
The last of six ages in the
Miocene epoch (the second of two in the
Late Miocene), lasting from 6.5 to 5.3 Ma. It is preceded by
the Tortonian age and followed by
the Zanclean age of the
Abbreviation for Multispectral Electronic Self-Scanning Radiometer.
Information describing a data set, including data user guide,
descriptions of the data set in directories, catalogs, and
inventories, and any additional information required to
define the relationships among these.
The French national weather service. See the
Meteo-France Web page for more
- meteoric water
Water produced by or derived from the atmosphere. Meteoric waters
start as precipitation in the hydrologic cycle, and the source
thereof is evaporation from oceanic surfaces.
- Meteoric Water Line
An equation expressing a correlation between deuterium and
oxygen-18 in meteoric waters. The equation is expressed as
del D = 8 * del oxygen-18 + 10. See Bowen (1991).
- meteorological equator
The latitude of the mean annual position of the
This is located at about N rather than on the geographical
See Riehl (1954).
A European geostationary meteorological satellite operated by
The SI fundamental unit of length. It was defined
(in 1983) as the distance travelled by light in a vaccum during
the time interval of 1/299,792,458 of a second. The meter was
originally defined as 1/10**7 of the distance on the Earth's
surface between the North Pole and Equator, but later defined
as in the above.
This atmospheric trace gas is also a
and a particularly effective one.
It has a warming effect that is 21 time more on a molecule-for-molecule
basis and 58 times more on a pound-for-pound basis than does
carbon dioxide. The concentration of
this in the atmosphere (1.72 ppm in 1990) has doubled since the
advent of the industrial age, and has increased in concentration
about 8 times faster than carbon dioxide. On the plus side, its
atmospheric lifetime is only about 11 years, much less than most
other greenhouse gases.
It is produced naturally by geologic sources such as venting
by volcanoes and other breaks in the Earth's crust, although much
of atmospheric methane is biological in origin. A large source
is produced by bacteria decomposing plant and animal refuse in
natural wetlands, which is estimated to produce about one-fifth
of the annual emissions. Another source is intestinal gas produced
by ruminant (vegetation-eating) livestock, which produces about
one-sixth as much as natural wetlands. Other anthropogenic
sources include rice paddies (i.e. artificial wetlands), fossil
fuel extraction, animal wastes, sewage treatment, landfills,
and biomass burning.
The production of CH4 in organic soils as a result of anaerobic
respiration. See Schlesinger (1995).
The oxidation of CH4 by bacteria in the upper, aerobic layers
of the soil. See Schlesinger (1995).
- method of dynamic sections
See dynamic method.
- methyl bromide
A broad spectrum pesticide which is a significant ozone
depleting substance. This is at least 50 times more effective
at destroying ozone than chlorine from CFCs on a per molecule
basis, with an ozone depletion potential (ODP) of 0.6.
EPA Methyl Bromide Web site.
Acronym for the Finnish Forest Research Institute, a state research
organization with the duty to furnish research results for use
by forest policy decision makers. See the
METLA Web site.
- Metonic cycle
A period of 19 years over which the phases of the Moon recur
on the same days of the year as during the previous period.
This cycle was introduced by the Greek astronomer Meton in 433 BC
and is very nearly equal to 235 synodic months.
Abbreviation for Marine Environment Unit, a part of the Space
Applications Institute at the European Commission Joint Research
Center. Its purpose is to develop, demonstrate, and validate
methodologies for the use of data from space and airborne platforms
in both operational applications and scientific investigations
related to the marine environment. The MEU is mainly involved
in analyzing ocean color data collected by the
CZCS, investigating the sea surface temperature
of the Northwest African upwelling area, and developing hydrodynamic
models to assimilate remote sensing data for process studies and as
a contribution to global modeling.
MEU Web site.
Abbreviation for medium frequency, an electromagnetic spectrum
waveband ranging from 300 kHz to 3 MHz.
Abbreviation for Multifilter Rotating Shadowband Radiometer, an
instrument used in the ARM program
to measure direct normal, diffuse horizontal, and total
horizontal solar irradiances. The optical depth of the
atmosphere at various wavelengths can be inferred from
these measurements and, in turn, the optical depths can
be used to derive information about column abundances of
ozone and water vapor as well as atmospheric aerosols. See the
MFRSR Web site.
Abbreviation for Modeling Global Biogeochemical Cycles, an
Acronym for Man's Impact on Coastal and Estuarine Systems,
an MAB-COMAR project.
Acronym for the Miami Isopycnic Coordinate Ocean Model, a ocean
circulation model that uses isopycnic coordinates in the vertical.
MICOM Web site.
A small htmlreffossilfossil. A quasi-arbitrary distinction
is made between these and macrofossils by restricting the former to
those discrete remains whose study requires the use of a microscope.
A boundary-layer micrometeorology measurement program designed to
study radiation and dissipation properties in frontal regions.
The objectives were to: (1) determine the dissipation of
kinetic energy in the surface layer under varying conditions; (2)
determine the kinetic energy dissipation in a frontal zone as
a check on previous estimates; (3) examine the nature
of the coherent structures and microfronts for the case of
surface heating; (4) study and modify the bulk aerodynamic relationship
for use with the surface radiative temperature; (5) study the
dynamic and thermodynamic effects on the atmosphere from the
contrast between a small lake and the surrounding land; (6) observe
the occurrences of breakdowns of the stable boundary layer and the
occurrences of atmospheric gravity waves. See the
MICROFRONTS Web site.
The study of microfossils..
This term is sometimes restricted to
studies of mineral-walled microfossils to distinguish it from
Phytoplankton whose lengths range from
50 to 500 m. Compare to
Tiny particles of glassy material probably formed by the collision
between a planetisimal and the Earth.
- Mid-Japan Sea Current
A slow southward cold water movement into the Polar Front in the
Japan Sea. This is also known as
the Maritime Province Current.
- Milankovitch forcing
The name given to the changes in the amount or seasonal distribution
of solar radiation that reaches the Earth as caused by the orbital
changes predicted by Milankovitch theory.
- Milankovitch theory
that changes in the geographic distribution of solar insolation
due to planetary perturbations of the Earth's orbital characteristics
are the primary driving force for the cycles of glaciation seen
in geological and fossil records. See Berger (1988).
- mild slope equation
See Mei (1990).
Acronym for MIxed Layer Dynamics EXperiment, multi-institutional
cooperative experiment which took place in a deep water region
(4700 m) about 650 km off Pt. Conception in central California.
Two ships and two floating platforms were used to make
measurements of the surface meteorological forcing and the
temperature and current response of the near-surface layers
in the ocean.
See Paduan et al. (1989).
Acronym for MIxed Layer Experiment.
Acronym for Mid-Latitude Ecosystems as Sources and Sinks for
Atmospheric Oxidants, and IGAC activity.
Abbreviation for Multifrequency Imaging Microwave Radiometer, a
passive microwave radiometer successor to the Special Sensor
Microwave/Imager (SSM/I) that provides greater frequency diversity,
improved spatial resolution, increased swatch width, and improved
antenna performance. It is used to observe atmospheric and oceanic
parameters such as precipitation, soil moisture, global ice and
snow cover, SST, wind speed, atmospheric cloud water,
and water vapor. See the
MIMR Web site.
- Mindanao Current
A southward flowing boundary current along the Philippine coast
(from about 13 to 8 N at about 127 W) that closes
the counterclockwise wind-driven gyre of which the
North Equatorial Current (NEC)
North Equatorial Countercurrent (NECC) are the northern and southern
limbs, respectively. The westward flowing NEC splits at the
Philippine coast and the Mindanao Current (MC) flows southward,
carrying North Pacific subtropical thermocline and surface waters
toward a region of confluence with South Pacific waters near
5 N. Part of the flow continues along the Philippines and on
into the Celebes Sea, with the remainder
turning eastward at the confluence and contributing to the
NECC as well as the
Equatorial Undercurrent and the
Northern Subsurface Countercurrent. This eastward turn also
serves to spin-up a recirculation feature historically called the
Mindanao Eddy, although the Eddy
may be an intermittent rather than a persistent feature.
The MC is an energetic coastally trapped jet with speeds
reaching over 0.9 m s at the shelf break, with a standard
deviation of measured velocities of less than 0.1 m s
indicating low current variability. It is
broadest at the surface and narrows to a width of 150 km at
300 m depth.
The average transport above the thermocline has been estimated from
direct measurements to be
kg s , with the estimate
from hydrographic surveys virtually identical.
The MC contains distinct cores of high salinity
North Pacific Central Water (NPCW) and low-salinity
North Pacific Intermediate Water (NPIW), with each salinity
core associated with elevated concentrations of dissolved
oxygen indicative of the source connection with the
See Wijffels et al. (1995).
- Mindanao Dome
See Mindanao Eddy.
- Mindanao Eddy
A cyclonic circulation gyre or eddy
sometimes found to the east of Mindanao
centered at about 8 N and 135 E.
The southward flowing section near the coast is part of
the Mindanao Current,
and the Eddy can be thought of as the recirculation cell
of this current.
The southward flow does not extend
beyond a depth of 250 m and is underlain by a deep western boundary current
flowing northward (from about 250 to 500 m) at a rate
of 16-18 Sv.
The transport has been estimated at
around 25-35 Sv with strong interannual variations.
At least one investigation of the Mindanao Current at
8 N noted the absence of the Eddy, and as such it
may be an intermittent feature of the circulation field.
This has also been called the Mindanao Dome.
See Tomczak and Godfrey (1994) and Wijffels et al. (1995).
- Mindanao Sea
See Bohol Sea.
- Mindanao Undercurrent
A northward flowing current beneath and offshore of the
This has been estimated by some investigators to have speeds ranging
from 0.15 to 0.30 m s and transports between
8 and 22 kg s , although others have found
it to be more of a transient phenomena than a permanent circulation
See Wijffels et al. (1995).
The Alpine name given to the Kansan
The fourth of five epochs in
the Tertiary period, lasting from 23.7 to 5.3 Ma.
It is preceded by the Oligocene epoch
followed by the Pliocene epoch, and comprised
of the Aquitanian,
and Messinian ages.
Acronym for Michelson Inteferometer for Passive Atmospheric
MIPAS Web site.
Acronym for Migration of Radioisotopes in the Geosphere.
Abbreviation for Multi-Angle Imaging Spectro-Radiometer, an
EOS instrument planned for the AM satellite
platforms. Nine CCD cameras fixed at nine viewing angles in four
spectral bands provide top-of-atmosphere, cloud, and surface
angular reflectance functions.
See Diner (1991) and the
MISR Web site.
- missing carbon
This phrase refers to the difficulty in balancing the fluxes of carbon
to the atmosphere via the burning of fossil fuel, forests and other
biomass with the known sinks. The total ``missing'' is on the order
of 3-5 Pg carbon per year, although the lower bound is within the
error margins of recent estiamtes of the net oceanic sink strength,
particularly if corrections to the synoptic air-to-sea CO2 influx
or enhanced organic carbon sequestration fluxes are included.
The upper bound is out of range of current oceanic sink strength
estimates, indicating a net terrestrial sink, which implies fertilization
of forest ecosystems due to increased atmospheric CO2 levels,
of terrestrial ecosystems because of fallout of
anthropogenic NO3 and NH4 nutrients, aggradation of previously
disturbed or undisturbed terrestrial ecosystems, or some combination
See Woodwell (1995b).
- missing forcing
This refers to possibly important climate forcing mechanisms not
yet included in GCMs, whether due to neglect
or difficulty. Examples include the
indirect effects of sulphate aerosols, the radiative effects
of trace gases other than CO2, and the forcings associated with
large-scale land-use changes or the carbonaceous aerosols generated
by biomass burning.
A northwesterly or northerly wind which blows offshore along the
north coast of the Mediterranean from the Ebro to Genoa. In the
region of its chief development its characteristics are its frequency,
its strength, and its dry coldness. It is most intense on the coasts
of Languedoc and Provence, especially near the Rhone delta. Its speeds
are usually around 40 knots, but can reach over 75 knots in the delta.
- mixed layer
In oceanography, a nearly isothermal surface layer of around
40 to 150 m depth caused by wind stirring and convection. In
the winter, low surface temperatures and large waves (with
their accompanying turbulent mixing) can deepen the mixed
layer all the way to the
Higher temperatures and a less energetic wave climate in the
summer can lead to the development of a
at the base of the mixed layer that overlies the
- mixed layer ocean
See slab ocean.
- mixing length
A concept used in the parameterization of turbulent transport
processes. According the this model, fluid masses called
eddies, distinguishable from the ambient fluid, spring into
existence in some undefined way and then, after moving unchanged
over a certain path length, become indistinguishable from the
surrounding fluid. This path length, over which the eddy
mixes with the surrounding fluid, is called the mixing length.
This model is analogous to the mean free path of a molecule
or atom between collisions.
See Liou (1992), p. 219.
- mixing ratio
See water vapor mixing ratio.
marginal ice zone.
Acronym for Marginal Ice Zone Experiment.
See Quadfasel et al. (1987).
- mks system
A system of units in which the basic units are the meter, the kilogram
and the second. This is not used as often as the
Abbrevation for Marine Light-Mixed Layers, a research program
designed to study mixed layer dynamics and bioluminescent
plankton production. The program focuses on seasonal changes
in upper layer physics and the successive populations that
are responsible for bioluminescence.
See Marra (1989).
Abbreviation for the Mauna Loa Observatory Photochemistry
Experiment, a major component of the GTCP.
The objective of MLOPEX is to evaluate the budgets and photochemical
processes of ozone, odd nitrogen and some odd hydrogen speices and
to build a climatology of the distributions of photochemically
important short-lived trace species in the remote troposphere. See the
MLOPEX Web site.
Abbreviation for the Microwave Limb Sounder, a
UARS instrument that provides global
maps of ClO, the radical responsible for the Antarctic
ozone hole. It scans the atmosphere from top to bottom at the
edge, or limb, of the Earth's disc, collecting natural thermal
microwave radiation emitted by gases in the atmosphere. It is
specifically designed to measure ozone, chlorine monoxide,
and water vapor, although it also measures atmospheric temperature
and pressure. See the
MLS Web site.
Acronym for the application of high performance computing
techniques for the Modeling of Marine Ecosystems project, whose
objectives are to create an interdisciplinary forum for the
exhange of information and experience related to the projects
carried out by the participants and to facilitate collaboration
between the partners. These projects will focus on the
implementation of existing models on high performance computers,
refining the models and their algorithms, and benchmarking
parallel software and validating new models.
MMARIE Web site.
Abbreviation for the Fifth-Generation NCAR/Penn State
MM5 Web site.
Abbreviation for Mesoscale and Microscale Meteorology, one of five
science divisions at NCAR. The primary focus
of this division is on understanding atmospheric phenomena on
spatial scales ranging from micrometers to megameters and time
scales from seconds to a few days.
MMM Web site.
Abbreviation for Marine Mammal Research Program, a project designed
to provide information on the hearing capabilities of marine mammals
and sea turtles, to study the response of marine mammals and other
marine organisms to man-made sounds (from the related
ATOC project as well as from other sources
such as shipping noise), and to provide information
needed to direct policies for the long-term protection and conservation
of marine species.
MMRP Web site.
Abbreviation for Minerals and Management Service.