American Geophysical Union (AGU) Convention

JPL scientists Dr. David Halpern and William L. Sjogren have been elected Fellows to the American Geophysical Union (AGU), an international scientific society dedicated to advancing the understanding of Earth and our Solar System. The AGU has a membership of approximately 36,000 scientists in 130 countries.

Halpern was recognized for his pioneering work on El Nino and his research of equatorial and coastal currents and for scientific and organizational leadership in programs to study interactions between the ocean and atmosphere.

Halpern joined JPL in 1986 and is a senior research scientist and manager of JPL's Climate Variability Program. He has also managed the NASA Ocean Data System based at JPL and has published more than 275 scientific articles. He is now using data from JPL instruments to study monsoons and middle-latitude influences of El Nino, including the strange occurrence of three El Nino episodes from 1991 to 1995.

He received bachelor's degrees in geology and physics with honors from McGill University in Montreal and a doctorate in physical oceanography from the Massachusetts Institute of Technology, then pursued postdoctoral research at the National Institute of Oceanography in England.

Halpern has also been named a Fellow of the American Meteorological Society and of the California Academy of Sciences, as well as being awarded a U.S. Department of Commerce Silver Medal in 1981 for technological developments that created the present-day El Nino Buoy Watch and eight Scientific Achievement Awards from the National Oceanic and Atmospheric Administration.

He was a visiting professor at the California Institute of Technology, Pasadena, CA, and is currently an adjunct professor at the University of California, Los Angeles, where he teaches physical oceanography.

Halpern and his wife, Tema, live in La Canada, California. They have two children.

Sjogren was honored by the AGU for his pioneering work studying planetary gravity fields using radio data from orbiting spacecraft.

Sjogren joined JPL in 1962 and is a senior research scientist in the navigation and flight mechanics section. He has worked on the Ranger, Surveyor, Lunar Orbiter and Mariner planetary missions. He was principal investigator for gravity field determination on the Apollo 12, 14, 15, 16, 17 missions; Viking I and II; the Pioneer Venus Orbiter; Magellan and NASA's Mars Global Surveyor.

He was a co-discoverer of the Lunar Mascons, the very large unexpected gravity highs located in the circular maria basins. The discovery placed stringent constraints on the internal structure of the moon. He is the recipient of two NASA Scientific Achievement Awards and has published more than 130 scientific articles. He is presently estimating the gravity fields of the four Galilean satellites of Jupiter.

He received a bachelor's degree in civil engineering from the University of Miami (magna cum laude) and a master's degree in applied math from Northwestern University.

Sjogren lives in La Canada with his wife, Mary Alice. They have four children and six grandchildren.

JPL is a division of the California Institute of Technology, Pasadena, CA.

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