In Memoriam: Sergei A. Kitaigorodskii, 1934—2014

Abstract

Professor Sergei A. Kitaigorodskii, one of the pioneers of air-sea interaction studies, passed away on 4 December 2014 in Helsinki, at the age of 80. He had a clear vision of the fundamental problems of marine boundary layer physics. His bold ideas opened new paths more than a half century ago, and they continue to stimulate active research. In particular, he made significant progress on the difficult problem of estimating gas transfer rates through gas-liquid interfaces and contributed to many of the Gas Transfer at Water Surfaces conferences.Kitaigorodskii was born in Moscow on 13 September 1934. His father, Professor Alexander Kitaigorodskii, was a well-known physicist. Sergei Kitaigorodskii completed his undergraduate studies at Moscow State University in 1956, and he continued his postgraduate studies on the theory of turbulent mixing at the Academy of Sciences, Moscow, where he was awarded his Ph.D. from the Institute of Physics of the Atmosphere in 1960.As a post-doctoral fellow at the Institute of Oceanology of the Academy of Sciences, he formulated the Kitaigorodskii similarity hypothesis for the wind-generated wave spectrum in 1961. He later recounted how, as a young student, he had been impressed by the simple and at the same time fundamental results of O. M. Phillips, and he had wanted to follow that path by combining it with the Russian tradition, the Kolmogorov similarity hypothesis of turbulence. The Kitaigorodskii hypothesis immediately showed its value when W. J. Pierson Jr. and L. Moskowitz were able in 1964 to collapse their empirical data into a single dimensionless curve, and to formulate the Pierson-Moskowitz spectrum for fully developed seas. At the same time Kitaigorodskii continued his studies of the atmospheric side and showed how swell could influence the marine boundary layer, a topic upon which his ideas remain important.In 1962 Kitaigorodskii became a Senior Scientist at the institute and turned his main interest back to turbulence of the oceanic mixed layer. Here he again made fundamental contributions. These, combined with his earlier studies of waves and the air-sea boundary layer, were summarized in his thesis for the Russian degree of Doctor of Science in 1968. This work was the basis of a monograph, Physics of Air- Sea Interaction, published in 1970 and translated into English in 1973; it was used widely as a textbook. In the same year, 1973, he received the Rosenstiel gold medal, and in 1978 the Liege University Award.Between 1968 and 1977 Kitaigorodskii was head of the Laboratory of the Physics of Ocean- Atmosphere Interaction in the Institute of Oceanology.During the 1970s Kitaigorodskii established contacts with the Finnish geophysics community. His Finnish wife had completed her term as a press correspondent in Moscow, and she returned to Helsinki with their twin daughters. The Soviet system allowed Kitaigorodskii to visit his family every other year, and he used this opportunity to lecture and conduct research at several Finnish institutes.