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Topic: Pycnocline

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	Capotondi, Alexander, Deser and Miller (2005)
		After 1977 the pycnocline deepened in a broad band along the coast and shoaled in the central part of the Gulf of Alaska.
		The changes in pycnocline depth diagnosed from the model are in agreement with the pycnocline depth changes observed at two ocean stations in different areas of the Gulf of Alaska.
		Coastal propaga-tion of pycnocline depth anomalies is especially relevant in the western part of the Gulf of Alaska, where local Ekman pumping-induced changes are anticorrelated with the OGCM pycnocline depth variations.
	meteora.ucsd.edu /~miller/papers/goa_pyc.html (319 words)

	[No title] (Site not responding. Last check: 2007-10-25)
		A strong pycnocline, such as that prevailing in the tropics, is a very stable barrier to the mixing of the low-density water above and the high-density water below.
		The pycnocline is developed as a result of the combined effects of zones of rapid vertical changes in temperature (thermocline) and salinity (halocline).
		The pycnocline is typically not present in the high-latitude ocean because there is little difference in density of the surface waters as compared to deep waters there.
	www.geosc.psu.edu /geosc040/40.lecture_files/40L6OceanCirc.txt (600 words)

	The Insomniacs > Papers > Hypoxic Conditions in Narragansett Bay During the Summer of 2001 > Results (Site not responding. Last check: 2007-10-25)
		South of Conimicut Point, density stratification is reduced with a deeper (5-10 m) and less clearly defined pycnocline due to the absence of a distinct surface lens of low salinity water (Fig.
		Stratification is strongest at the northernmost end of the transect (in the Upper Bay) with the pycnocline gradually becoming deeper and less clearly defined as you move seaward (Fig.
		As in July, south of the low salinity surface lens, the pycnocline is deeper and less clearly defined.
	www.geo.brown.edu /georesearch/insomniacs/emilythesis-3.html (3778 words)

	[No title]
		The depth of the lower boundary of the pycnocline varies with climate from a maximum depth of 3000 m (non-glacial) to a minimum depth of 1000 m (glacial).
		From these boundary conditions, an oxygen equivalent profile for the pycnocline is generated with the possibility for both positive and negative oxygen equivalents.
		The modeling of the progressive ventilation of the ocean from 1 percent PAL to 100 percent PAL yields changing redox conditions which have geologic and oceanographic significance with respect to the initiation and sequence of evolutionary events in marine biota.
	www.marscigrp.org /ajs87.html (5826 words)

	[No title] (Site not responding. Last check: 2007-10-25)
		The overall objective of this project is to study the dynamics of momentum and energy fluxes in the upper mixed layer, and to investigate the processes that determine the stability of the pycnocline.
		Particular emphasis is placed on the response of the pycnocline to the mesoscale velocity field, internal waves, and other coherent turbulence features.
		The specific goal of this extension is to model the fluxes of heat and buoyancy associated with double-diffusive convection, and the impact of tidal currents on mixing in the upper layers of the Weddell Sea.
	www.cs.utexas.edu /users/yguan/NSFAbstracts/Abstracts/O_D/OPP.O_D.a9615524.txt (276 words)

	east sound
		From noon on 12 June through the 13th, the pycnocline descended due to inflow of water from the Frazer River.
		The descent of the pycnocline (Figure 1, above) was caused by incoming water from the Frasier River.
		As the wave train initially passed, there were two layers of high fluorescence; by the end there was a third, less concentrated one in the pycnocline.
	www.icess.ucsb.edu /biogeo/es/es98.html (428 words)

	Science, Water, and Dawaganda
		There are claims that the Qur'an discusses the pycnocline, the diffraction of light in water, the origin of ground water, and that a certain hadith speaks of subterranean seas that exist below collections of volcanic magma.
		Some Muslims have attempted to correlate these verses with the phenomenon of the pycnocline, which is a separation of waters of different densities due to temperature or salinity.
		What we see is the circular reasoning of the Muslim who champions this polemic, presupposing the author intended it as a reference to the pycnocline, and then concluding that no mere mortal could have knowledge of the pycnocline in the seventh century.
	www.geocities.com /freethoughtmecca/water.html (3645 words)

	Johnson and McPhaden -- Interior pycnocline flow from the Subtropical to the Equatorial Pacific Ocean
		Inspection of the depth of this isopycnal (not shown) suggests that geostrophic shear at this surface is weak except in the far southwest portion of the region under investigation, where the subtropical pycnocline is deep.
		The mixed layer is excluded because the mean wind field over nearly the entire region dictates a poleward Ekman transport (Lu and McCreary 1995), which overwhelms the equatorward geostrophic velocity in the mixed layer.
		Our functional definition of the tropical pycnocline base in this instance is the neutral density at which the net interior meridional mass transport changes sign from equatorward above to poleward below within a 9° latitude band containing the deep cyclonic gyres in each hemisphere.
	www.pmel.noaa.gov /pubs/outstand/john1966/interior.shtml (1494 words)

	[No title] (Site not responding. Last check: 2007-10-25)
		The work proposed here is an effort to measure high frequency vertical profiles of velocity and temperature using a Rapid Sampling Vertical Profiler, a tethered sensor system developed by the principal investigator that free falls through the upper 250 meters of the ocean.
		The objective is to study the dynamics of momentum and energy fluxes in the upper mixed layer, and to investigate the processes that determine the stability of the pycnocline.
		Particular emphasis will be placed on the response of the pycnocline to the mesoscale velocity field, internal waves, and other coherent turbulence features.
	www.cs.utexas.edu /users/yguan/NSFAbstracts/Abstracts/O_D/OPP.O_D.a9317321.txt (235 words)

	Hydrography and Circulation in the Upper 1000 Meters of the Tropical Atlantic
		Within the pycnocline, southern water is distinguished by salinities that are 0.3 psu lower than their northern counterparts at the same density surface.
		During winter and spring eastward currents are found in two latitude bands, a surface current between 5 - 10N and a weaker current south of 5N that is limited to the thermocline, with no surface expression in winte r.
		The base of this layer (and t he top of the pycnocline and thermocline) is marked by a broad salinity maximum in the temperature range 21°-26 C and density range of between sigma theta=23.8 - 25.3.
	www.aoml.noaa.gov /phod/acvp/carton.htm (678 words)

	Johnson and McPhaden -- Interior pycnocline flow from the Subtropical to the Equatorial Pacific Ocean
		Under the ITCZ values peak at 10°N, 125°W and again at 11°N, This peak under the ITCZ is where the pycnocline is drawn closest to the surface by Ekman pumping associated with the large-scale wind stress curl and strengthened, perhaps by some combination of mixing and surface buoyancy flux.
		Finally, isovorts around the equator are spread in the west and pinched in the east, a pattern consistent with acceleration potential and salinity distributions that suggest equatorward interior pycnocline convergence feeding the EUC.
		In the north, equatorward flow of relatively fresh pycnocline water follows a serpentine route to skirt westward of the eastern potential vorticity maximum under the ITCZ.
	www.pmel.noaa.gov /pubs/outstand/john1966/water.shtml (2284 words)

	Johnson and McPhaden -- Interior Pycnocline Flow from the Subtropical to the Equatorial Pacific Ocean
		In the North Pacific the pycnocline shoals and strengthens dramatically under the intertropical convergence zone, separating the North Equatorial Current from the North Equatorial Countercurrent.
		Where the pycnocline is shallowest, around 12°N, the fresh surface influence of precipitation under the ITCZ may augment that of the CCW.
		The focus of this manuscript is on describing interior pycnocline pathways from the subtropics to the equator in the Pacific Ocean and quantifying mass fluxes of these pathways.
	www.pmel.noaa.gov /pubs/outstand/john1966/john1966_new.shtml (8463 words)

	Cynthia Cudaback's Thesis (Site not responding. Last check: 2007-10-25)
		The pycnocline is thinned by lateral advection on flood and thickened by vertical mixing on ebb and.
		On late flood, the pycnocline is close to the surface and quite thin; on late ebb, its center is below mid-depth and it fills 3/4 of the water column.
		Bottom friction raises the pycnocline and causes tidal variations in vertical shear, which drive the changes in pycnocline thickness.
	www4.ncsu.edu /~cncudaba/Columbia/Thesis_abst.html (346 words)

	Maryland DNR - Tributary Strategies
		A pycnocline is a layer in the water column where density changes rapidly between the warmer, fresher upper water, and the cooler, saltier, denser deep water.
		A strong pycnocline is common in deep areas of the Bay tributaries during the warmer months of the year.
		To determine whether the water quality is improving or worsening with time, the observed data for the study period are analyzed for annual trends using a combination of statistical tests.
	www.dnr.state.md.us /Bay/tribstrat/status_trends_methods.html (2119 words)

	Physical Oceanography - Woods Hole Oceanographic Institution (Site not responding. Last check: 2007-10-25)
		With sea-ice covering most of the study area and eliminating almost all surface wave motion, the R/VIB Nathaniel B. Palmer provided a very stable platform, allowing high-quality CTD data to be collected without significant wave-induced contamination.
		These steps are thin in the vertical, of the order of a few meters, and are separated by stratified layers that ranged in thickness from a few to tens of meters.
		A vertical heat flux across the pycnocline of 1.46 W m-2 was calculated based on volume integral budgets, (Klinck, 1998).
	www.whoi.edu /science/PO/dept/education/project_hyatt.htm (417 words)

	[No title]
		It consists of two layers that are separated by a pycnocline.
		The depth of the pycnocline H varies as a function of distance from the coast, i.e., H=H(x).
		The pycnocline becomes flat at a distance L from the coast, i.e., H(x=L)=constant=H0.
	marine.rutgers.edu /cool/education/physical.oceanography/hw14.html (112 words)

	SMIG -- Modeling Relocation of Boston's Sewage Outfall (article: Sept. 1999)
		Removing the freshwater associated with the effluent discharge in Boston Harbor is predicted to increase the mean salinity of the harbor by 0.5 psu and decrease the mean salinity by 0.10-0.15 psu within 2-3 km of the outfall.
		During the summer, effluent from the Bay Outfall induces a circulation at the pycnocline that is similar to the induced near-surface winter circulation (Figure 10b).
		This was a design consideration of the new outfall: the waters below the pycnocline have relatively high nutrient levels and are largely aphotic, thus it was determined that the nutrients in the discharged effluent would have less impact on the ecosystem if the plume received enough initial dilution to be trapped in the lower layer.
	smig.usgs.gov /SMIG/features_0999/bharbor.html (8149 words)

	[No title]
		The lower depths of the ocean have a slightly higher density than the upper levels, and there is a thin boundary layer with a continuous variation in density between the upper and lower levels.
		This boundary layer is known as the pycnocline.
		This investigation is intended to examine the effect of the pycnocline on the swimming of dolphins and the effects of internal wave resistance on a dolphin swimming in the pycnocline.
	www.clarkson.edu /honors/research/papers/Eddy-Patrick.doc (739 words)

	Figure 5 (Site not responding. Last check: 2007-10-25)
		Pa/m) (provided by CERSAT) (a); pycnocline depth anomalies estimated from TP/ERS (metres), (b); pycnocline depth anomalies from a quasi-geostrophic linear model (metres), (c); and sea level anomalies at the coast from tide gauge data (cm) (provided by TOGA Sea Level Center) (d).
		Negative values for pycnocline depth anomalies correspond to a deepening of the thermocline and a warming of the surface waters.
		The model was forced by the ERS-1/2 winds and its boundary conditions in the east correspond to thermocline depth anomalies along the South American coast between 10°S and 40°S. They were given by a high-resolution Eastern Boundary linear Model (EBM) forced by sea level data at the equator [Pizarro et al., 1999].
	topex-www.jpl.nasa.gov /science/invest-vega-fig5.html (128 words)

	HOT: Potential Temperature and Density (Site not responding. Last check: 2007-10-25)
		Seasonal variation in temperature for the upper ocean is apparent in the maximum of near-surface temperature of about 26 Deg C and the minimum of approximately 23 Deg C. Ossilations in the depth of the 5 Deg C isotherm below 500 dbar appear to be relatively large with displacements up to 100 dbar.
		The main pycnocline is observed between 100 and 600 dbar, with a seasonal pycnocline developing between June and December in the 50-100 dbar range (
		The cruise-to-cruise changes between February and July 1989 in the upper pycnocline illustrate that variability in density is not always well resolved by our quasi-monthly sampling.
	hahana.soest.hawaii.edu /hot/methods/potempd.html (154 words)

	Bibliography of the Phd dissertations written by the students of Dr. James J. O'Brien
		Model pycnocline variations at several locations are similar to the observed sea level fluctuations.
		A rapid shoaling of the pycnocline in the western tropical Pacific during each El Nino is caused by westward-propagating Rossby waves.
		Interannual pycnocline displacements in the central equatorial Pacific are determined by the superposition of Kelvin waves excited to the west and first-mode Rossby waves generated to the east.
	www.coaps.fsu.edu /lib/elninobib/phd (5630 words)

	About SoundScience
		The separation between the deep/heavier water and the surface/lighter water is known as the pycnocline.
		The pycnocline isolates the deep water so that it cannot mix with surface water which is its primary source of oxygen.
		Thus to understand the development and breakdown of hyxpoxic conditions, it is necessary to have information on the vertical structure of the Sound's water properties, the local atmospheric forcing conditions, and in fact the three-dimensional water circulation in the Sound.
	www.sunysb.edu /soundscience/background/hypoxia.html (370 words)

	Anand Gnanadesikan: Research Foci
		The basic idea is that the vast majority of the conversion of light water to dense water associated with the meridional overturning circulation occurs in the North Atlantic.
		Mesoscale eddy processes determine the partition of upwelled water in the Southern Ocean which comes from the dense water sphere vs. that which comes from the light water sphere.
		This work implies that there is a relationship between wind stress in the Southern Ocean and the depth of the pycnocline to the north of the Southern Ocean.
	www.gfdl.noaa.gov /~a1g/circulation.html (603 words)

	Hydrography Results from the Hawaii Ocean Time-series
		The main pycnocline is observed between 100 and 600 dbar, with a seasonal pycnocline develpoing between June and December in the 50-100 dbar range (Figure 2).
		The cruise-to-cruise changes between February and July 1989 in the upper pycnocline illustrate that variability in density is not always resolved by our quasi-monthly sampling.
		Figures 3 and 4 show the contoured time-series record for salinity in the upper 1000 dbar plotted against pressure and potential density.
	www.soest.hawaii.edu /HOT_WOCE/hilights/y6results.html (1035 words)

	Internal Waves. (Site not responding. Last check: 2007-10-25)
		The pycnocline, therefore, is a gradual interface between two fluids of different density.
		Since internal waves are not directly visible, they can only be detected by their surface signature and by direct measurements of the pycnocline or thermocline.
		Where the density interface is shallow enough to permit the internal wave crests to interact with the sea surface, the waves can be detected by the resulting increased roughness of the surface ocean.
	ceprofs.tamu.edu /plynett/iw/internal.htm (457 words)

	[No title]
		P_DEPTH is set at 0.5 meters above the pycnocline and is used as the cutoff depth between upper (AP) and lower (BP) water column layers.
		The pycnocline is determined to be the depth at which the greatest conductivity change is observed.
		Composited water samples pumped from 5 depths above the pycnocline and 5 depths below the pycnocline were filtered through a 44 micrometer mesh net and rinsed into a jar.
	www.nbii.gov /metadata/mdata/textfiles/epa_cbp_d_mdmicrozooplankton.txt (1448 words)

	Ocean Water: Density
		The next layer is the pycnocline, or transition zone.
		The bottom layer is the deep zone, where the water remains cold and dense.
		The polar regions are the only places where deep waters are ever exposed to the atmosphere because the pycnocline is not always present.
	www.onr.navy.mil /focus/ocean/water/density1.htm (179 words)

	Upwelling of Arctic pycnocline associated with shear motion of sea ice
		Upwelling of Arctic pycnocline associated with shear motion of sea ice
		High-resolution radar imagery shows that the dynamic response of winter sea ice to gradients in large-scale surface wind stress is often localized along quasi-linear fractures hundreds of kilometers long.
		In one event recorded during the drift of the SHEBA ice camp, we observed an intense zone of pycnocline upwelling (∼14 m) associated with significant shear motion near the camp, while upward turbulent heat flux in the ocean boundary layer reached nearly 400 W m
	www.agu.org /pubs/crossref/2005/2004GL021819.shtml (258 words)

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