Engineering topics

Atkinson, L. P.

Publications and source records attributed to Atkinson, L. P..

6 records

NASA NTRS1988

Variability of surface pigment concentrations in the South Atlantic Bight

A time sequence of surface pigment images of the South Atlantic Bight (SAB), derived from the Nimbus 7 CZCS for the period between November 1978 and October 1979, was correlated with in situ observations of hydrographic parameters, fresh-water discharge, sea level, coastal winds, and currents in order to couple physical processes and the spatial and temporal variability of the surface pigment fields. A definite seasonal modulation of the surface pigment fields was found, with the concentrations in the Georgia Bight being highest in summer, and those north of Cape Romain highest in winter. This phase difference was found to be the result of variations in wind fields, Gulf Stream-shelf interactions, and fresh-water discharge patterns. At some locations (e.g., near Charleston) the alongshore band of high pigment concentrations increased in width throughout the year; at other locations (near Jacksonville), the alongsore band exhibited a minimum width in the summer and a maximum width in the fall of 1979.

Mcclain, Charles R.↗

NASA NTRS1986

Wind-driven upwelling in the vicinity of Cape Finisterre, Spain

Observations and numerical simulations of the evolution of upswelling and the resultant coastal circulation in response to two wind events occurring along the Galician coast of Spain during the April 18-26, 1982 period are presented. In situ measurements include shipboard determinations of hydrographic and biological parameters, and wind stress estimates obtained from the ship winds and from surface pressure charts. Sea surface temperature information was derived from NOAA 7 satellite images, and pigment concentration information was acquired from the Nimbus 7 coastal zone color scanner. The indication from the simulations that the greatest upswelling will occur either at Cape Finisterre or along the northern coast was confirmed by observations, and it is suggested that wave disturbances propagate northward along the coast at a speed of 120-160 km/day, and that organic material formed north of Cape Finisterre is advected out to sea northwest of the cape.

Mclain, C. R.↗

NASA NTRS1985

A note on the Charleston Gyre

The deflection of the Gulf Stream caused by a topographic feature - the Charleston Bump, located offshore of Savannah, Georgia - results in a quasi-stationary cyclonic eddy - the Charleston Gyre which is situated over the continental slope east of Charleston and Cape Romain. Occasionally, the upwelling associated with this eddy produces an enhancement in the surface layer primary production that is great enough to be detected by the Nimbus 7 coastal zone color scanner (CZCS). In this note a CZCS image with simultaneous hydrography, current, and wind observations is presented that documents an unusual manifestation of the gyre. In addition to the CZCS image a Seasat synthetic aperture radar (SAR) image is included that clearly indicates the presence of the eddy adjacent to the Gulf Stream front.

Mcclain, C. R.↗

NASA NTRS1983

Observations of a loop current frontal eddy intrusion onto the west Florida shelf

Data were examined to determine the structure of this intrusion (April 1-7, 1982) and to investigate its effects on water masses in the outer shelf region. A frontal eddy, made up of a warm filament separated from the main current by a region of cooler water, propagated southeastward at 30 cm/s, intruding onto the shelf near 26 deg N between April 4 and 6. It was found from temperature-salinity (T-S) properties that water in the filament was Loop Current water that had been contiguous with Loop Current water 80 m deeper in the main body of the current. It is noted that water in the cold region was Continental Edge water, a transitional water mass with cooler, fresher T-S characteristics. Under this region, upwelling of deeper Loop Current water occurred, and elevated nutrient concentrations were found in the upwelled dome under the cold region.

Paluszkiewicz, T.↗

NASA NTRS1980

Ocean chlorophyll studies from a U-2 aircraft platform

Chlorophyll gradient maps of large ocean areas were generated from U-2/OCS data obtained over test sites in the Pacific and the Atlantic Oceans. The delineation of oceanic features using the upward radiant intensity relies on an analysis method which presupposes that radiation backscattered from the atmosphere and the ocean surface can be properly modeled by using a measurement made at 778 nm. The calculation of atmospheric radiance was performed by using a method developed by Dave. An estimation of the chlorophyll concentration is performed by properly ratioing radiances measured at 472 and 548 nm after removing the atmospheric effects. The correlation between the remotely sensed data and the in situ surface chlorophyll measurements has been validated in two sets of data. The results show that the correlation between the in situ measured chlorophyll and the derived quantity is a negative exponential function, and the correlation coefficient was calculated to be -0.965.

Kim, H. H.↗

NASA NTRS1979

Ocean Chlorophyll Studies from a U-2 Aircraft Platform

Chlorophyll gradient maps of large ocean areas were generated from U-2 ocean color scanner data obtained over test sites in the Pacific and Atlantic Oceans. The delineation of oceanic features using the upward radiant intensity relies on an analysis method which presupposes that radiation backscattered from the atmosphere and ocean surface can be properly modeled using a measurement made at 778 nm. An estimation of the chlorophyll concentration was performed by properly ratioing radiances measured at 472 nm and 548 nm after removing the atmospheric effects. The correlation between the remotely sensed data and in-situ surface chlorophyll measurements was validated in two sets of data. The results show that the correlation between the in-situ measured chlorophyll and the derived quantity is a negative exponential function and the correlation coefficient was calculated to be -0.965.

Kim, H. H.↗