During the period June 8–19, 1979, an intensive expendable bathythermograph survey of a Gulf Stream ring was made. After mapping the irregularly spaced data onto a regular grid, and azimuthally decomposing the temperature field at constant depth into Fourier constituents einθ, we find the n = 2 mode to be the dominant one. We calculate the geostrophic stream function utilizing the hydrostatic equation and the measured temperature/salinity curves. The stream function is expressed in cylindrical polar coordinates (r, θ, z) and decomposed into a steady, azimuthally independent part ψ(r, z) and a temporally varying disturbance part ϕ(r, θ, z, t) with azimuthal dependence. The quasi‐geostrophic energy equation for ϕ contains source terms representing the interaction of the ψ and ϕ fields by baroclinic and barotropic processes. We find that ∼90% of the total disturbance energy flux results from baroclinic processes, and the remainder from the barotropic exchanges. The time scale of this energy flux into the disturbance ϕ is of the order of 16 days, while the time scale of an energy loss from the disturbance is ∼4.5 days.
Thermistor chain measurements of internal wave motions below the thermocline in the western North Atlantic have been spectrally decomposed in vertical-horizontal wave number space. The measured two-dimensional spectrum exhibits a systematic deviation from the corresponding Garrett and Munk model for internal wave spectra.
Eighteen temperature sections were obtained during August 1977 using expendable bathythermograph probes along a 110 km tract oriented perpendicular to the mean direction of the Gulf Stream off Onslow Bay. Concurrent velocity and temperature measurements were obtained beneath the Stream from an Aanderra current meter moored 48 m above the bottom (620 m depth). The measurements revealed the passage of a Gulf Stream meander with a period of approximately 5 days, vertical changes in isotherm level as large as 200 m, and a lateral meander amplitude of approximately 39 km as defined by the 16°C isotherm at 200 m. A study of the meander amplitude as a function of depth is carried out in terms of the migration of the sloping frontal surface. The envelope of frontal migration is defined by curves which are found to approximate the bottom slope down to the ‘knee’ in the bottom topography at 700 m. The peak‐to‐peak meander amplitude decreases from 39 km near the sea surface to 26 km at a depth of 700 m, which suggests that the meander process off Onslow Bay is not confined to the upper slope. A strong correlation exists between the current and temperature field at the moored near‐bottom sensor and frontal migration at the 200 m level with the overall impression that the meander process has an extensive horizontal correlation scale, comparable to the width of the Gulf Stream. A downstream phase speed of 25 cm/s is derived for the meander based on a relationship between characteristics of the temperature field and characteristics of the velocity field.
ABSTFACTMultibeam bathymetric systems offer t o r e v o l u t i o nize our understanding of the ocean bottom and i t s major s t r u c t u r a l f e a t u r e s by providing highljr detailed neasurelcents of the bottom. F u r t h e r , multibean measurements yield bottom depth 2s a function of both spztiai coordinates (i.e. alongt r a c k 2nd a c r o s s -t r a c k ) . The depth resolution is s u f f i c i e n t l y f i n e t h a t c o n v e n t i o n a l c o n t o u r c h a r t s vould never incorporate a l l the information availa b l e i n t h e a u l t i b e a n data. As a n a l t e r n a t i v e t o s,Jch de'erminlszic presentations, i: can be suggeste d t h a t s t a t i s t L C e l c h a r s c t e r i z a t i m s ' De developed f o r t o p o g r a p h i c v a r i a b i l i t y a t h o r i z o n t a l s c a l e s which a r e small i n comparisor. t o t h e o v e r a l l dimensions of the feature of i n t e r e s t . Ve here discuss the stlldy of roagh topography on several seamounts by means of multibean bathymetry. The bottom topography I s analyzed in terms of numerous samples of 1503 m x 1600 n extent. A. primary quantity of intere s t i s t h e rms value of t h e r e s i d u a l :opogra?hy. The AwAt;erc of v a r i a b i l i t y f o r t h e rzs values i s 3es.ribed for several seanoucts and shown t o have c e r t a i n o v e r a l l similerities. INTROCLJCTIOPi Multibeam bathymetric swath napping systems such as SeabPam a r d S.A.S.S. o f f e r t o r e v o l u t i o n i z e our understanding of the ocean bottom and i t s major s t r u c t :~r a l f e a t u r e s by p r w i d i n g h i g h l y d e t a i l e d measurements of t h e bottom. P r i o r t o t h e 6 e v e l o pment of these systems xost af the bathynetric i n f o r m t i o n e x i s t e d i n t h e form of wide beam echo-sounder surveys from which only botton information i n t h e a l o n g t r a c k d i r e c t i o n o f t h e s:lmejr could be readily extracted. MLtibeam systems, however yield bottom depth as a function of b o t h t h e a l o n g t r a c k a n d c r o s s t r a c k d i r e c t i o n s of a silrvef and as a r e s u l t p r o v i d e a h i g h l y d e t a i l e d two-dimensional description of the ocean floor. h r t h e r m o r e , t h e d e p t h reso1u:ion of modern multibeam systems i s s u f f i c i e n t l y f i n e t h a t c o n t o u r c h a r t s et conventional scales of p r e s e n t a t i o n w i l l probably never incorporate a l l of t h e i n f o r m t i o n a v a i l a b l e f r o n t h e system. A s a n a l t e r n a t i v e t o such Presentations, it can be suggested that s t a t i s t i c a l c h a r a c t e r i z a t i o n s ought t o be developed f o r t o p o g r a p h i c v a r i a b i l i t y a t h o r i z o n t a l s c a l e s whlch a r e small i n comparison t o t h e o v e r a l l dimensions of t h e l a r g e s c a l e f e a t u r e s of i n t e r e s t . Thus the information available from multibeam bathyaetric systems can be divided into two c h a r a c t e r i z a t i o n s , one d e t e r m i n i s...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.