Hasselmann Seventy Years of Exploration in Oceanography

A Prolonged Weekend Discussion with Walter Munk
1. Auflage 2010
ISBN: 978-3-642-12087-9
Verlag: Springer
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 137 Seiten, eBook

It all began with Markus Jochum approaching one of us (HvS) – “when you guys are doing interviews with senior scientists from oceanography and related sciences, why are you not doing Walter Munk?” Indeed, why not? Walter Munk, an icon in oceanography, had just given a wonderful talk in a symposium in honor of his 90th birthday, sweeping a grand circle from his earliest work with Chip Cox on airborne measurements of ocean surface roughness to the latest satellite data – not simply a review, but the struggle of an active scientist opening up new perspectives – as inspiring and stimulating as when one of us (KH) rst met him at the Ocean Waves Conference in Easton in 1961 (Fig. I. 1). Walter immediately agreed to share with us his recollections on the nearly seventy years of his path-breaking contributions in a sheer amazing range of topics, from ocean waves, internal waves, ocean currents, tides, tsunamis, sea level, microseisms and the rotation of the earth to ocean acoustic tomography. With “you guys” Markus was referring to HvS and the various partners HvS had 1 invited to join him in conducting a series of interviews of retired colleagues.

Zielgruppe

Research

Autoren/Hrsg.

Hasselmann, Klaus

Inhaltsverzeichnis

Foreword – Carl Wunsch.- Foreward – Paul Gaffney.- Preface.- Acknowledgements.- Waves and wave spectra.- Oceanographers learn about power spectra.- Wave prediction.- Where the swell begins.- Coming to America.- Coming to America.- Caltech.- Serving in the Army.- Clearance problems.- Bikini (1946) and Eniwetok (1951).- Settling down at Scripps.- Munk finally gets his degree.- Wind-driven ocean circulation.- From waves to tides 1958-1968.- 6 Deep sea tides 1964.- The alleged suicide of Aristotle.- 7 Internal waves 1971 – 1981.- Ocean Acoustics 1974 .- The Gulf Stream sheds eddies.- The Mode experiments.- Ocean Acoustic Tomography.- Heard Island.- Whales.- The last twenty years.- Mohole 1957 – 1964.- The wobbling earth 1950 – 1960.- IGPP. 1962.- The Cambridge connection.- Finding the faculty.- Building the Laboratory.- Navy.- Finis.- Appendix.

Leseproben

"Chapter 1 Waves and Wave Spectra (p. 1-2)

1.1 Oceanographers Learn About Power Spectra

Hasselmann: Many of the topics you spearheaded in oceanography and geophysics were driven by your knowledge of time-series analysis, of spectral analysis and so forth. You were one of the first people to develop a general spectral analysis program, the BOMM (Bullard, Oglebay, Munk, and Miller) system [91]. And you applied that program to explore the ocean wave spectrum. Could you say a few words how you came to become interested in applying these spectral analysis techniques to oceanographic phenomena?

Munk: I first became aware of the problem in connection with wave prediction. During the war a remarkable UK group under George Deacon (later Sir George) had developed an analogmethod of getting power spectra for waves. Norman Barber from New Zealand did the pioneering work. He recorded on a film half black half white, with a wavy boundary that represented the wave record. The film was viewed through a vertical slit by a photocell whose output was the fraction of white film (the wave elevation). The film was mounted on a spinning wheel that was allowed to slow down by friction. The output of the photocell through a resonant RLCcircuit was recorded on paper. So as the wheel spun down, lower frequencies got into resonance. These were the first power spectra of ocean processes.

Hasselmann: I find this hard to believe. The acousticians knew about power spectra long before then.

Munk: Indeed they did. So did the optical people. They were monitoring in frequency space (pitch and color) in the first place. But I believe there was not a single oceanographer that knew how to handle time series of random phase processes. There were a few clumsy attempts to apply tidal analysis to represent wave records by a few fixed-phase frequencies.

We oceanographers depended on Barber’s wheel to lift the low wave frequencies of order 0.1Hz by four order of magnitudes to the 1000Hz resonant frequencies of RLC-circuits. But we were not the only ones who could not handle phase-incoherent processes. Meteorologists were in the same boat. So were seismologists, as we learned rather painfully during the test ban negotiations. So were geologists. But for the geologists random phase wave analysis was not such a useful tool (unless you think of ripples on the sea bottom). It is not fruitful to think of Yosemite’s Half Dome as a randomphase process."