Pa-Pm

 

Pacific-Antarctic Basin

One of three major basins in the Southern Ocean. It extends from its western border with the Australian-Antarctic Basin at the longitude of Tasmania (about 145 E) to its eastern border with the Atlantic-Indian Basin at the Scotia Ridge and Drake Passage (about 70 W). It consists of the Amundsen, Bellingshausen, and Mornington Abyssal Plains and is separated from the basins further north in the Pacific by the Pacific-Antarctic Ridge and the East Pacific Rise in the east and by the Chile rise in the east.

 

Pacific Deep Water

In physical oceanography, a water mass type found in the Pacific Ocean in the depth range from 1000-3000 m. It does not participate much in the overall circulation and as such its properties are determined mostly by slow mixing processes. It is composed of a mixture of AABW, NADW and AAIW, and has a characteristic salinity from 34.60-34.65 and a temperature around 2 C. See Tomczak and Godfrey (1994), p. 159.

 

Pacific Equatorial Water

In physical oceanography, the water mass that occupies the largest volume of the Pacific thermocline waters. The NPEW and the SPEW are two varieties of this separated, as one might guess, by the Equator. They differ in T-S properties above 8 C but merge into a single curve below this, which reaches T-S combinations showing high salinities indicative of mixing with deep water. See Tomczak and Godfrey (1994).

 

Pacific High

A center of action centered off the coast of Baja, California at about 30 N and 140 W in winter. It moves northwestward to about 40 N and 150 W and intensifies in the summer and effectively fills in the Aleutian Low. See Angell and Korshover (1974).

 

Pacific Marine Environmental Laboratory (PMEL)

A part of the NOAA ERL network the carries out interdisciplinary scientific investigations in oceanography, marine meteorology, and related subjects. See the PMEL Web site.

 

Pacific Ocean

The largest of the world oceans. More later.

The most significant surface currents of the Pacific are the cyclonic subpolar gyre in the north, the anticyclonic North Pacific subtropical gyre, the narrow and cyclonic northern tropical cell including the (NECC) NorthEquatorialCountercurrent, the westward South Equatorial Current (SEC) at the equator and to the south, the anticyclonic South Pacific subtropical gyre, and the Antarctic Circumpolar Current (ACC).

See Talley (1995).

 

PACS

Acronym for PanAmerican Climate Studies, a proposed program in the 1995-2004 time frame directed toward the goal of improving the skill of operational seasonal-to-interannual climate prediction (with emphasis on precipitation) over the Americas. It is a sequel to the NOAA EPOCS program. Further information can be found at the PACS Web site.

 

PACT

Acronym for Paleoecological Analysis of Circumpolar Treelines.

 

paedomorphosis

In heterochrony, the retention of ancestral juvenile characters by descendant adults. Paedomorphosis is if the rate of shape change is reduced or the period of operation is contracted such that a descendant adult passes through fewer growth changes and as such resembles a juvenile stage of its ancestor. This can occur by progenesis, neoteny, or post-displacement. This was coined by W. Garstang in the 1920s as part of the reaction to the Biogenetic Law when he recognized that ontogeny did not always recapitulate phylogeny but sometimes created it. The Biogenetic Law has been somewhat superseded by the concept of peramorphosis. Both processes are now recognized to play important roles in evolution. See Gould (1977) and McKinney and McNamara (1991).

 

PAGES

Acronym for Past Global Changes, an IGBP Core Project charged with providing a quantitative understanding of the Earth's past environment and defining the envelope of natural climate variability within which we can assess anthropogenic impact on the Earth's biosphere, geosphere, and atmosphere. PAGES seeks the integration and intercomparison of ice, ocean, and terrestrial paleorecords and encourages the creation of consistent analytical and database methodologies within the paleosciences. More information can be found at the PAGES Web site.

 

PALACE

Acronym for Profiling ALACE float.

 

PALE

Acronym for Paleoclimate of Arctic Lakes and Estuaries, an NSF/ARCSS and PAGES initiative to study the paleoclimate of arctic lakes and estuaries. The goal is to reconstruct Arctic climate variations over the past 150,000, 20,000 and 2,000 years and understand its interation with the global climate. More information can be found at the PALE Web site.

 

paleobiogeography

The study of the spatial distribution of ancient organisms, including analysis of the ecological and historical factors governing this distribution. In contrast to paleoecology, most paleobiogeographical studies have dealt with distributions of individual taxa or with questions of global or regional provincialism. See Briggs and Crowther (1990), pp. 452-460.

 

paleobiology

The science dealing with the fields of evolution, ecology and the subsequent taphonomy of extinct animals and plants. See Briggs and Crowther (1990).

 

paleocalibration method

A method for calculating the relationship between paleoclimates and the future climate. For a given time interval, one obtains both the difference from present-day globally averaged surface temperature (DT) and the difference from the present-day globally averaged radiative forcing (DQ). DT is obtained from whatever geologic proxies are available. DQ is obtained by calculating or estimating the total effect of the heat trapped by greenhouse gases and the changes in absorption of solar radiation due to changes in solar luminosity, surface albedo and atmospheric aerosol content. Finally, the ratio DT/DQ is defined as the climate sensitivity, i.e. the global temperature response to the radiative forcing. See Covey et al. (1996).

 

Paleocene

The first of five epochs in the Tertiary period, lasting from 66.4 to 57.8 Ma. It is preceded by the Late epoch of the Cretaceous period and followed by the Eocene epoch.

 

paleoecology

The branch of science that deals with the ecology of extinct and fossil plants and animals.

 

Paleogene

A time interval of the Cenozoic era, lasting from 66.4 to 23.7 Ma and incorporating the Paleocene (66.4-57.8 Ma), Eocene (57.8-36.6 Ma), and Oligocene (36.6-23.7 Ma) epochs. If the Tertiary is designated as an era, then the Paleogene and the Neogene are its two periods.

 

paleolimnology

The branch of limnology that studies of past fresh water, saline and brackish environments. This is done in large part by taking cores from a limnological sediment system and examining the geological, biological and chemical components preserved in the core.

 

The Paleontological Society

An international organization devoted exclusively to the advancement of the science of paleontology. It was founded in 1908 and is currently incorporated as a nonprofit organization in the District of Columbia. It publishes the ``Journal of Paleontology'' and is one of several societies that sponsors the production and revisions of the ``Treatise on Invertebrate Paleontology.'' See the Paleontological Society Web site.

 

paleontology

The branch of science that deals with discovering and analyzing biological patterns in the history of lineages and biotas over long periods of time, as well as their relationship to their environments and chronology of Earth's history.

 

paleopathology

The branch of paleontology dealing with cataloging and illustrating pathological conditions. Paleopathological indicators includes such things as shell injury and repair, evidence of parasitic worm infections, regenerated arms, and dwarfism. See Moodie (1923) and Tasnadi-Kubacska (1962).

 

paleosol

A buried soil horizon of the geologic past. See Sellwood and Price (1994).

 

paleothermometry

The use of various paleoclimate proxy data to attempt to gauge paleotemperatures.

 

paleowind

A wind of the geological past. The practical geological indicators of paleowind are several scalar properties (bed thickness, grain size and sorting, mineral proportions) and directional structures (dune forms, yardangs and wind furrows, dune cross-bedding, windblown trees, wind ripples, adhesion ripples, flues and grooves). Such an indicator can be an effective paleoclimatic tool only if it is reasonably common, of high geological preservation potential, easily recognized and measured, and capable of unique or at least statistical interpretation. See Allen (1994).

 

Paleozoic

The earliest of three eras of the Phanerozoic eon, lasting from 570 to 245 Ma. It is preceded by the Precambrian interval and followed by the Mesozoic era, and consists of the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian periods.

 

palynology

The study of organic-walled microfossils such as pollen and spores as well as their living counterparts, as distinguished from micropaleontology. This was originally developed from and is occasionally used in a more restrictive sense to refer to pollen analysis. See Jansonius and McGregor (1996).

 

pampero

A name given in Argentina and Uruguay to a severe storm of wind, sometimes accompanied by rain, thunder and lightning.

 

PAN

Acronym for Peroxyacetyl Nitrate.

 

PANASH

Acronym for Paleoclimates of the Northern and Southern Hemispheres program, a proposed project of PAGES.

 

Pangaea

A supercontinent that existed from about 200 to 300 Ma before breaking up into two smaller supercontinents called Gondwanaland and Laurasia. This term was coined by Alfred Wegener.

 

Panthalassa

The Early Mesozoic world ocean. It was a single ocean reaching from pole to pole, probably consisting of single southern and northern gyres, deep water formation at both poles, and slothlike deep-water circulation. See Bowen (1991).

 

PAR

Abbreviation for Photosynthetically Available Radiation, a quantity used in studies of photosynthesis as a measure of total available light. It is defined as a flux of quanta rather than energy and is usually considered to be the total photon flux between 400 and 700 nm (with the lower limit sometimes moved to 350 nm). This is around 38% of the total extraterrestrial solar irradiance. PAR is defined, as a function of depth, by

where is Avagadro's constant, h is Planck's constant, c the speed of light, the wavelength, and E the irradiance. The units of PAR are einsteins per square meter per second, and it is measured underwater using a device called a quantum meter.

 

parabolic approximation

See Mei (1990).

 

Parallel Community Climate Model (PCCM)

A parallel version of the NCAR Community Climate Model (CCM2) implemented for MIMD massively parallel computers using the message passing programming paradigm. It can be implemented on a massively parallel machine supporting message passing or across a network of machines with the PVM software package. See the PCCM Web site.

 

parameter aggregation

An averaging procedure used in some SVAT models wherein the value of a parameter, e.g. the albedo, in a grid box is calculated by linearly averaging (although the averaging can be more complicated) the range of albedo exhibited by various plant and soil types within the box. This is necessitated by the spatial inhomegenity of the land surface characteristics within individual grid boxes. Contrast with flux aggregation. See Houghton and Filho (1995).

 

parameterization

In numerical modeling, the method of incorporating a process by representation as a simplified function of some other fully resolved variables without explicitly considering the details of the process. The classic example is the representation of sub-grid scale turbulence as the product of a function of the velocities at the local grid points and an empirically derived eddy viscosity coefficient (in analogy to the molecular viscosity coefficient). This analogy has been known to fail. See, for example, the classic (and wonderfully titled) monograph of Starr (1968).

 

PARCA

Acronym for Program for Arctic Regional Climate Assessment, a NASA project initiated in 1995 to combine previous efforts at assessing whether airborne laser altimetry could be applied to measure ice-sheet thickness changes. The main goal is to measure and understand the mass balance of the Greenland ice sheet. See the PARCA Web site.

 

particulate matter

The suspended particle load that controls the chemistry of the oceans. The physical and chemical properties of the particles control how rapidly a chemical species is removed from solution and incorporated in sediment. The four main sources of this in the oceans are: (1) fluvial input of terrigenic material; (2) aeolian input from wind erosion of continental masses, volcanism and anthropogenic sources; (3) resuspension of sedimentary material by current erosion, earthquakes and slumping; and (4) authigenic production by biota, submarine volcanism and the precipitation of inorganic minerals. See Simpson (1982).

 

PASE

Acronym for Polar Air Snow Experiment.

 

PASEX

Acronym for Polar Atmosphere Snow Experiment, a SCAR project.

 

PASH

Acronym for Paleoclimate in the Southern Hemisphere, an INQUA project to investigate the paleoclimates of the Southern Hemisphere. Its main scope is to correlate Africa, South America and Australasia.

 

PATHS

Acronym for Pacific Transport of Heat and Salt, a joint program among Canada, Japan and the U.S. See WMO (1983).

 

PAWE

Acronym for Program for the Analysis of World Ecosystems.

 

PBL

Abbreviation for planetary boundary layer.

 

PBL-LIB

This is a collection of programs that deal with data pertaining to the PBL. See the PBL-LIB Web site.

 

PC

In meteorological and climate modeling, an Abbreviation for penetrative convection.

 

PCA

Abbreviation for principal component analysis, usually used synonymously with EOF.

 

PCCM

Abbreviation for Parallel Community Climate Model.

 

PCIS

Abbreviation for Pacific Climate Information System, a comprehensive information system containing statistical information on rainfall clmiatology and variation with the ENSO cycle for almost 300 Pacific islands. See the PCIS Web site.

 

PCMDI

Abbreviation for the Program for Climate Model Diagnosis and Intercomparison, whose mission is to develop improved methods and tools for the diagnosis, validation and intercomparison of global climate models. See the PCMDI Web site.

 

pCO2

The equilibrium partial pressure of CO2.

 

PCRF

Abbreviation for the Planetary Coral Reef Foundation, whose aim is to further knowledge about the world's coral reefs by studying reefs in a global context, to provide new ideas for ecological management of marine wilderness areas, and to provide hands-on experience in expeditions and coral reef research. See the PCRF Web site.

 

PCSP

Abbreviation for Polar Continental Shelf Project, a Canadian program.

 

PDF

Abbreviation for probability density function.

 

PDR

Abbreviation for Precision Depth Recorder.

 

PDSI

Abbreviation for the Palmer drought severity index, an index used for assessment of long-term drought conditions in the U.S. It categorizes moisture conditions in increasing order of intensity as near normal, mild to moderate, severe, or extreme for drought or wetness. It is affected by both long-term moisture shortages and excesses and by variability of temperature-driven evaporation from soils and transpiration from plants. Similar climate indexes are the CEI and the GCRI. See Karl (1986).

 

PDW

See Pacific Deep Water.

 

PE

Abbreviation for primitive equations.

 

PEAC

Acronym for Pacific ENSO Applications Center, a NOAA project established to conduct research and produce information products on climate variability related to the ENSO climate cycle in the U.S.-affiliated Pacific Island. See the PEAC Web site.

 

PECHORA

Acronym for Paleo Environment and Climate History of the Russian Arctic.

 

PEGASUS

A current profiling system.

 

PEQUOD

Acronym for the Pacific Equatorial Dynamics Experiment.

 

peat

An unconsolidated deposit of semi-carbonized plant remains in a water saturated environment. It has a persistently high moisture content (at least 75%) and is considered an early stage in the development of coal. Its carbon content is about 60% and it forms via plant decomposition in stagnant water with small amounts of oxygen.

 

peatland

A wetland that accumulates more than 30 cm (40 cm in Canada) of highly organic peat. These originate in two major ways: by the filling in of shallow water bodies and their invasion by semiaquatic peat-forming plants, or by the swamping and waterlogging (paludification) of unsaturated mineral soils in upland situations, with the latter being areally more important than the former. See Gorham (1995).

 

Peclet number

A dimensionless number expressing the ratio of advection to thermal diffusion. It is expressed by

where U is a velocity scale, L a horizontal length scale, and the thermal diffusivity. Molecular diffusion of heat is negligible when . In practice, the Peclet number is almost always large except for extremely small-scale phenomena with low velocities. This is similar to the Reynolds number except that the kinematic viscosity has been replaced by the thermal diffusivity . See Kraus and Businger (1994), p. 32.

 

pedosphere

The soil-bearing or solid portion of the Earth's surface.

 

pelagic

Descriptive of organisms that inhabit open water, as opposed to benthic. This is sometimes divided into five separate ecological zones which are, proceeding from the surface to the bottom, the epipelagic, mesopelagic, bathypelagic, abyssopelagic and hadopelagic zones. See Bruun (1957).

 

Pelagic Fisheries Research Program (PFRP)

A research program established in 1992 to provide scientific information on pelagic fisheries to the Western Pacific Regional Fishery Management Council (WPRFMC) after the Magnuson Fishery Conservation and Management Act of 1976 was amended to include highly migratory fish. It is located at JIMAR at the University of Hawaii. See the PFRP Web site.

 

Pelecypoda

A class of marine invertebrates in the phylum Mollusca. This class includes clams, oysters and mussels which all have a hatchet-shaped foot usually used for digging. All animals in this class are benthic and are usually either sessile or burrow in mud, rock or wood. Their soft parts ae enclosed in hinged shells and food is transported to the mouth via the action of cilia setting up currents. About four fifths of the known species are marine.

 

PELICON

Acronym for Project for Estimation of Long-Term Variability in Ice Concentration.

 

penetrative convection

In meteorology, a situation wherein air parcels rise quickly enough to overshoot (via inertia) the limit of convection (LOC) height at which they become cooler than their environment and should cease vertical motion.

 

PENGUIN

Acronym for Polar Experiment Network for Geophysical Upper-atmosphere Investigations.

 

peramorphosis

In heterochrony, this is the process whereby if the rate of shape change of an organism is increased, or its period of operation is extended, the descendant adult passes morphologically beyond the ancestor. This can occur by hypermorphosis, acceleration, or pre-displacement. The concept of peramorphosis somewhat equates and supersedes the Biogenetic Law. Compare to paedomorphosis. See Briggs and Crowther (1990), pp. 111-119.

 

percolation zone

One of five glacier zones defined in terms of the ice temperature and the amount of melting. This is a zone in which some surface melting occurs, which can percolate a short distance into lower layers before it refreezes. If it encounters an impermeable layer it will spread laterally and freeze into an ice layer or lens. Vertical water channels can also freeze into pipe-like structures called ice glands. The latent heat released by the refreezing process raises successively deeper snow layers to the melting point, and there exists a point where, by the end of the present summer, all the snow deposited since the end of the previous summer has been raised to the melting temperature. This is called the saturation line and forms the boundary between this zone and the lower soaked zone. The upper limit to the percolation zone, which separates it from the dry snow zone, is called the dry snow line.

 

perigee

The nearest point to Earth in the orbit of a satellite, artificial or otherwise.

 

periglacial

The climatic and geomorphological zone peripheral to the ice sheets and glaciers at high latitudes, and occupying nonglacial environments at high latitudes.

 

perihelion

The point in a satellite's orbit at which it is nearest to the Sun.

 

peristaltic pumping velocity

See eddy-induced transport velocity.

 

permafrost

A layer in the ground that remains frozen throughout the year that generally occurs where the annual mean air temperature is below -1 C. Most permafrost lies below an active layer that thaws for periods of weeks to months in the summer. Permafrost is continuous over most land north of 65 N and discontinuous south to about 50 N in Canada and to about 47 N in eastern Asia. The total area covered is about 7.6 million km2 of continuous and 17.3 million km2 of discontinuous permafrost, with the total volume equivalent to a sea level change of 0.08-0.18 m.

 

permanent thermocline

A relatively sharp change in temperature (and therefore density) beneath the seasonal thermocline maintained by a balance between downward diffusion of heat and the gradual upwelling of deep, cool water.

 

Permian

The final period of the Paleozoic era, lasting from 286 to 245 Ma. It precedes the Triassic period of the Mesozoic era and follows the Carboniferous period, and is comprised of the Early (286-258 Ma) and Late (258-245 Ma) epochs. It is named from the province of Perm in Russia and characterized by vulcanicity, an on-going mountain-building movement called the Variscan (Appalachian in North America), and the end of the Southern Hemisphere glaciation.

 

Persey Current

See Pfirman et al. (1994).

 

Persian Gulf

A marginal sea of the Indian Ocean centered at approximately 52 E and 27 N. It is surrounded by Iran to the north, Kuwait, Saudi Arabia, Qatar, and the United Arab Emirates to the east and south, and connects with the Gulf of Oman (and on into the Arabian Sea) through the Strait of Hormuz to the east. It has a length of 990 km, ranges in width from 56 to 338 km, covers an area of 241,000 km , occupies a volume of 10,000 km , has a mean depth of 40 m, and a maximum depth of abuot 170 m.

 

Peru Current

A component of the eastern limb of the counterclockwise-flowing southern subtropical gyre in the Pacific Ocean. The flow rate has been estimated at around 15 Sv, although variations from this can be considerable. This current is part of the most impressive upwelling system in the oceans, with the upwelling driven by prevailing winds from the east that push the surface water westward, allowing the cold, nutrient-rich water beneath to well to the surface. Without the upwelling, this current lowers the temperatures along South America several degrees belows the zonal average, and the upwelling serves to lower the temperatures without about 100 km of the coast another 2 to 4 C. The nutrient content of the upwelled water makes this region the most productive upwelling region in the world ocean, although a combination of overfishing and the effects of the El Nino phenomenon put an end to what was the largest fishery in the world before 1973. The southern part of the Peru Current is sometimes called the Chile Current, and both were originally known as the Humboldt Current. See Tomczak and Godfrey (1994).

 

Peterson grab

A type of bottom sampler used in biological oceanography to for the quantitative investigation of benthic organisms in relatively shallow waters. It comprises a set of heavy hinged jaws that are held open during descent but are released when the device hits bottom. The jaws close on an area of benthic material (usually around 0.1 m2) when the cable is drawn tight and the device returned to the surface. The organisms thus caught are screened from the bottom sediments, classifed and counted to develop statistics for organisms per square meter in the study area. See Sverdrup et al. (1942).

 

PEX

Acronym for Baltic Sea Patchiness Experiment, an ICES investigation which took place in the Gotland Basin during April through May in 1986 under the leadership of B. Dybern. The basic objective of the experiment was to study the heterogeneous and patchiness in the distribution of physical, chemical and biological properties in the region. Almost all of the Baltic Sea countries contributed to a total of 15 research vessels used in this experiment. The data collected during this experiment can be found at the PEX Web site.

 

PFRP

Abbreviation for Pelagic Fisheries Research Program.

 

PFZ

Abbreviation for Polar Frontal Zone.

 

phagotrophic

Descriptive of a heterotrophic phytoplankton species that feeds on phytoplankton or detritus.

 

Phanerozoic

An eon comprising the whole of geologic time since the end of the Precambrian era, as opposed to Cryptozoic before that. It is comprised of the Paleozoic, Mesozoic, and Cenozoic eras and represented by rocks in which the evidence for life is abundant. It means ``obvious life''.

 

PHDI

Abbreviation for the Palmer Hydrological Drought Index, a drought index designed using the principles of balance between moisture supply and demand. See Rind et al. (1990).

 

phenogram

One of two major types of dendrograms, a tree-like diagram used to show similarity (or otherwise) among specimens or groups of specimens. It is based only on similarities in phenotypes.

 

phenology

The study of cyclic and seasonal natural phenomena, especially in relation to climate and plant and animal life. Phenological data would refer to phenomena such as flowering times of trees, harvest times, and migration dates of biota. Not to be confused with the slightly knottier science of phrenology.

 

Phleger Bottom Sampler

A bottom sampler used for quantitative studies of foraminifera, designed to take a short core of the upper sediment layers without disturbing the surface layer. This sampler, first used in 1951, is a short weighted tube with a removable lining tube and a replaceable cutting edge. The liner is a clear plastic tube with a diameter of 3.5 cm. It can be operated with a light winch in depths up to 500 m when weighted with 35-40 pounds of molded lead, and to depths of 4600 m in more cohesive sediments. See Hedgpeth (1957b).

 

photic zone

See euphotic zone.

 

photosynthesis

The process in plants by which carbon dioxide is converted into organic compounds using the energy of light absorbed by chlorophyll, which in all plants except some bacteria involves the production of oxygen from water.

 

phototaxis

The movement of a motile organism in response to stimulation by a light source. It is called negative phototaxis when it moves away from and positive phototaxis when it moves toward the source.

 

phototrophic

Descriptive of a phytoplankton species that lives primarily by photosynthesis.

 

Phycological Society of America (PSA)

Organization for the study of phycology. See the PSA Web site.

 

phycology

The study of algae, especially seaweeds. This is also called algology. Professional organizations for phycologists are the Phycological Society of America and the British Phycological Society.

 

phylogeny

In biology, the evolutionary development of a species or other group of organisms through a succession of forms. This can also refer to the evolutionary development of a particular feature of any organism. Compare to ontogeny. See also Biogenetic Law.

 

Physical Oceanographic Real-Time System (PORTS)

An information acquisition and dissemination technology developed by the NOS in cooperation with the Greater Tampa Bay Marine Advisory Council. The Tampa Bay PORTS includes the integration of real-time currents, water levels, winds, and water temperatures at multiple locations with a data dissemination system that includes telephone voice response as well as modem dial-up and dedicated modem displays. See the PORTS Web site.

 

physical oceanography

The study of physical conditions and physical processes within the ocean, especially the motions and physical properties of the ocean. This is usually further divided into the activities of descriptive and theoretical oceanography, the former being concerned with observing the oceans to prepare maps of the spatial and temporal variations of its properties, and the latter with constructing theoretical models to attempt to explain the observations. As in most natural sciences, most significant advances are the result of the interaction between theory and observation. Physical oceanography is not a pure but an applied science in which the knowledge of many disciplines is relevant, e.g. fluid mechanics, optics (optical oceanography), acoustics (acoustical oceanography), thermodynamics and, especially in the age of satellites, electromagnetics (satellite oceanography). This is one of four sub-fields into which the general field of oceanography has been divided, the others being biological. chemical and geological oceanography.

 

phytobenthos

That part of the benthos consisting of plant life.

 

phytochorion

A phytogeographic term used as the unit of flora, i.e. a floristic unit. The plural is phytochoria. The top phytochoric level or realm is that of floral region, with floral province and flora district following in the hierarchy. See Collinson (1988).

 

phytogeography

The branch of biogeography dealing with the geographic distribution of plants.

 

phytoplankton

One of two groups into which plankton are divided, the other being zooplankton. Phytoplankton comprise all the freely floating photosynthetic forms in the oceans, i.e. they are free-floating microscopic plants which, having little mobility, are distributed by ocean currents. Most marine phytoplankton are found in one of five Phyla: Cyanophyta, Chrysophyta, Chlorophyta, Cryptophyta, and Pyrrophyta. See Johnson (1957) and Riley and Chester (1971).

 

phytosociology

The study of plant communities. See McIntosh (1978).

 

Piacenzian

The second of two ages in the Pliocene epoch (coincidental with the Late Pliocene), lasting from 3.4 to 1.6 Ma. It is preceded by the Zanclean age and followed by the Calabrian age of the Pleistocene epoch.

 

PIC

Abbreviation for particulate inorganic carbon.

 

PICES

Abbreviation for North Pacific Marine Science Organization, whose purpose is to promote and coordinate marine scientific research in order to advance scientific knowledge of the living resources in the North Pacific. It was founded in 1992 and the members now include Canada, Japan, the People's Republic of China, the USA, the Russian Federation and the Republic of Korea. This is sort of a version of the ICES but for the North Pacific rather than the North Atlantic. See the PICES Web site.

 

PICOLO

Acronym for Production Induite en Zone de Convergence par les Ondes Longues, a program to attempt to understand how a heavy catch of tun occurs in a region considered biologically poor although prone to tropical instability waves.

 

PIK

Acronym for the Potsdam Institute for Climate Impact Research, whose mission is to investigate the consequences of global climate change as a paradigm for the unfolding fundamental crisis between the ecosphere and humanity. More information can be found at the PIK Web site.

 

PILPS

Acronym for Project for Intercomparison of Landsurface Parameterization Schemes, a joint research activity sponsored by GEWEX and WGNE of WCRP project. See Henderson-Sellers and Dickinson (1992), Henderson-Sellers et al. (1993) and Henderson-Sellers et al. (1995) as well as the PILPS Web page for further information.

 

PIM

Abbreviation for Particulate Inorganic Matter.

 

Piora oscillation

This refers to an advance of glaciers in Europe in the last 500 years or so of the Atlantic period. It was a sharper oscillation twards cold climate conditions than any for several thousand years previously. See Lamb (1985), p. 372.

 

PIP

Abbreviation for principal interaction patterns, a method of reducing the complexity of a full covariance matrix by combining an EOF-type pattern expansion in the spatial domain with an ARMA-type dynamical modeling approach in the time domain. This technique is useful for constructing simple dynamical models for forecasting or diagnostic purposes and as an approximate multivariate spectral compression technique. See Hasselmann (1988) and Hasselmann (1993).

 

PIPOR

Acronym for Program for International Polar Oceans Research.

 

PIPS

Acronym for Polar Ice Prediction System.

 

PIRATA

Acronym for Pilot Research Moored Array in the Tropical Atlantic, a plan for an observing system to support tropical Atlantic climate studies from 1997-2000. The purpose of PIRATA is to remedy the crucial lack of oceanic and atmospheric data in the tropical Atlantic. The scientific goals are to provide an improved description of the seasonal-to-interannual variability in the upper ocean and at the air-sea interfaece, to improve understanding of the relative contributions of the different components of the surface heat flux and ocean dynamics to the seasonal and interannual variability of SST within the tropical Atlantic basin, and to provide a data set that can be used to develop and improve predictive models of the coupled Atlantic climate system. These goals are to be accomplished by designing, deploying, and operating a pilot array of moored oceanic buoys and by collecting and transmitting via satellite in real-time a set of oceanic and atmospheric data. A pilot phase is proposed for 1997-2000 to be followed, if successful, by a long-term operational system to monitor the area maintained by GOOS and GCOS. See the PIRATA Web site.

 

Pisces

A class of marine vertebrates of the subphylum Vertebrata of the phylum Chordata. This comprises the true fishes with a bony endoskeleton, paired fins, and an operculum covering the gills. Most species are marine and pelagic, although there are some benthic examples.

 

PISP

Acronym for Polar Ice Sheet Program.

 

piston velocity

The velocity with which gas diffuses across the air-sea interface in the stagnant film model. It is proportional to the molecular diffusivity of the gas in sea water and inversely proportional to the thickness of the stagnant film across which it travels. The piston velocity has been found to be a function of the Schmidt number, with different dependencies at high and low wind speeds. The velocity is also a function of wind speed, increasing nonlinearly with wind speed and having a greater sensitivity to wind changes at higher wind speeds, with the change in sensivity occurring fairly abruptly at around 10 m/s. Due to the variability of real winds and this variable sensitivity, the piston velocity at the average wind speed will be lower than the average piston velocity. The general functional form of the piston velocity is usually taken to be

where Sc is the Schmidt number and V the wind speed. This is also occasionally known as the transfer velocity. See Najjar (1991).

 

PIW

Abbreviation for Polar Intermediate Water.

 

PKDB

Abbrevation for the International Paleoclimate Database (Internationale Palao Klima-Daten Bank, located at the Institut fur Botanik at the Universitat Hohenheim in Stuttgart. See the PKDB Web site (in German).

 

Planck function

The amount of radiation emitted by a body at a given temperature as a function of the wavelength of the radiation.

 

plane-parallel assumption

An assumption made in the study of atmospheric radiation transfer where variations in radiation intensity and atmospheric parameters are permitted only in the vertical direction, at least in localized areas. Absorption and emission processes are symmetrical with respect to the zenith angle when this assumption is made, and consequently the intensity is a function of only the vertical position and zenith angle. See Liou (1992).

An assumption made when modeling the radiative effects of clouds where the distribution of clouds is assumed to be uniform and infinite in the horizontal rather than its actual patchy nature.

 

planetary boundary layer

A generic term for either oceanic boundary layer (OBL) or atmospheric boundary layer (ABL). These layers are fundamentally turbulent and extend from near the surface to the boundary layer depth or height, defined as the limit to which boundary layer eddies can penetrate in the vertical.

 

planetary vorticity

See vorticity.

 

planetisimal

An asteroid, comet or meteorite.

 

plankton

One of three major ecological groups into which marine organisms are divided, the other two being the nekton and the benthos. Plankton are small aquatic organisms (animals and plants) that, generally having no locomotive organs, drift with the currents. The animals in this category include protozoans, small crustaceans, and the larval stages of larger organisms while plant forms are mainly diatoms.

 

plant succession model

A model to designate the ways in which plant communities develop from initial colonization to climax vegetation. The two main types are conceptual and mathematical. The conceptual models can be divided into four main types: (1) initial floristic composition, (2) facilitational, (3) tolerance, and (4) inhibition models. The mathematical models are significantly more varied and trusted slightly less. See Collinson (1988).

 

Pleistocene

The earliest epoch of the Quaternary period, lasting from 1.6 Ma to 8000 Ya.

 

pleuston

Marine organisms associated with the water surface or the uppermost water layer that possess special adaptations allowing them to passively float there. This term was originally used in freshwater biology to refer to microscopic plants and animals associated with the surface film and supported by surface tension, but it is now also used by marine biologists to describe organisms found in the upper 100 meters of the ocean. Pleuston was historically used especially by Soviet scientists, with their western counterparts more likely to group the pleuston in with the neuston. See Cheng (1975).

 

Pliocene

The final of five epochs in the Tertiary period, lasting from 5.3 to 1.6 Ma. It is preceded by the Miocene epoch and followed by the Pleistocene epoch of the Quaternary period. Observational evidence shows this to be perhaps the last time when global temperatures were significantly warmer than at present These observations indicate that: (1) global sea level was probably 20-30 m higher, implying a significant reduction in the Antarctic ice sheet; (2) there was a significant northward migration of the freezing line in winter Thompson (1991), and (3) tropical sea surface temperatures may have been similar to present Dowsett et al. (1991).

 

PMAP

Abbreviation for Paleoenvironment Mulitproxy Analyses and Mapping Project.

 

PMEL

Abbreviation for Pacific Marine Environmental Laboratory.

 

PMIP

Abbrevation of Palaeoclimate Model Inter-comparison Project, a PAGES project.

 

PMSE

Abbreviation for Polar Mesosphere Summer Echo.