English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We have contrived a regional model (K, o, n, #, A) for the distribution of low frequency variability energy in horizontal wavenumber, frequency, vertical mode and geography. We assume horizontal isotropy, 4D(K, w, n, #, A) = 27K (k, 1, w, n, #, A), with K designating the amplitude of total horizontal wavenumber. The parameters of 1(K, w, n, #, A) can be derived from observations: (i) satellite altimetry measurements yield the surface eddy kinetic energy wavenumber and frequency spectra and the geographic distribution of surface eddy kinetic energy magnitude, (ii) XBT measurements yield the temperature wavenumber spectra, (iii) current meter and thermistor measurements yield the frequency spectra of kinetic energy and temperature, (iv) tomographic measurements yield the frequency spectra of rangeand depth-averaged temperature, and (v) the combination of satellite altimetry and current meter measurements yields the vertical partitioning of kinetic energy among dynamical modes. We assume the form of the geography-independent part of our model 4(K, w, n) oc Kroq. The observed kinetic energy and temperature wavenumber spectra suggest p = 3/2 at K < Ko and p = -2 at K > Ko for the barotropic mode, and p = -1/2 at K < Ko and p = -3 at K > Ko for the baroclinic mods, where Ko is the transitional wavenumber of the wavenumber spectra. The observed frequency spectra of temperature and kinetic energy suggest that q = -1/2 for w < wo and q = -2 for w > wo, where wo is the transitional frequency of the frequency spectra. The combination of satellite altimetry and current meter measurements suggests the vertical structure of the low frequency variability is governed by the first few modes. The geography-dependent part of our model is the energy magnitude. Although we have shown analytically that the tomographic measurements behave as a low-pass filter, it is impossible to identify this filtering effect in the real data due to the strong geographic variability of the energy magnitude and the vertical gradient of the mean temperature. The model wavenumber spectrum is appropriate only where the statistical properties are relatively homogeneous in space. Thesis Supervisor: Carl Wunsch Title: Cecil and Ida Green Professor of Physical Oceanography Acknowledgments I would first like to thank my advisor, Carl Wunsch, for his encouragement and constructive criticism throughout the course of this work. I am extremely grateful to him for reading this thesis several times, even during weekends and holidays, and for providing feedback promptly. I benefited greatly from his illuminating comments. Above all, he constantly taught me how to communicate effectively. Many members of the physical oceanography departments at MIT and WHOI have made contributions to this work. In particular, Detlef Stammer generously provided me surface kinetic energy spectra and was ready to talk with me whenever I asked. Glenn Flierl, Nelson Hogg, Rui Xin Huang, Joe Pedlosky and Mike Spall gave me many useful comments. Karl Helfrich kindly supported my first year in the Joint Program. I am indebted to Dimitris Menemenlis, Brian Dushaw (University of Washington) and Bruce Cornuelle (Scripps Institution of Oceanography) for providing me tomographic data and XBT data. Charmaine King gave me particular support in processing the data and in computing. I am indebted to my many fellow students. In particular, Brian Arbic, Albert Fischer, Christophe Herbaut and Francois Primeau didn't mind taking all the trouble to read my thesis and to listen to my talks many times. Alexandre Ganachaud was always ready to do me a favor. My special thanks go to my wife, Bibo Lai, for her love and care. My first year in the Joint Program was supported by the National Science Foundation under grant OCE 92-16628, then were supported by the National Science Foundation under grant OCE 95-29545.

Space and time scales of low frequency variability in the ocean