Vassilis Angelopoulos

2001 James B. Macelwane Medal Winner

Vassilis Angelopoulos was awarded the James B. Macelwane Medal at the AGU Spring Meeting Honors Ceremony, which was held on 29 May 2002, in Washington, D.C. The medal recognizes significant contributions to the sciences by a young scientist of outstanding ability.


“Any discussion of Dr. Vassilis Angelopoulos’ contributions to space physics must begin with ‘bursty bulk flows,’ or BBFs. His Ph.D. thesis work was the first to identify this phenomenon, but more important, to understand its critical importance to energy flow in Earth’s magnetosphere. He has the remarkable ability to blend a keen theoretical eye with a knack for data analysis, which has served him well throughout his professional career. His Ph.D. and subsequent work provided a stunning new context for theorists and experimentalists alike and helped establish a renewed sense of progress in magnetospheric physics, an area that, in retrospect, had remained stagnant for many years. The term ‘BBF,’ now squarely associated with Angelopoulos, is a new paradigm by which space physicists view the dynamics of the Earth’s magnetotail.

“Dr. Angelopoulos’s BBF insights breathed new life into many old problems. He showed that energy transport in the magnetosphere is accomplished by short-lived, spatially localized pulses of energy flow from the Earth’s magnetotail toward the near-Earth environment. His recent work tied these flows directly to geomagnetic substorms, a phenomenon that has long been a geophysical enigma. He identified a new class of underdense bursty flows that were postulated to relieve the puzzle of the so-called ‘pressure balance inconsistency’ in the Earth’s tail, a long-standing theoretical problem. These latter flows he linked to activations of the poleward edge of the auroral oval, another phenomenon in auroral physics that defied simple explanation. His work on BBFs revitalized interest in the near-Earth neutral line model for substorms and tied together, in a quantitative and unifying manner, substorm physics with the global plasma circulation in Earth’s space environment.

“In a more theoretical realm, Dr. Angelopoulos showed that the magnetotail’s instantaneous circulation pattern is ~10 times more variable than its average and exhibits non-Gaussian probability distributions, explainable as intermittent turbulence. This work renewed interest in plasma turbulence and in the role of self-organized criticality and thereby contributed significantly to understanding phenomena and resolving theoretical dilemmas that had been open for twenty or more years. In short, his research did not merely push the discipline ahead in one focused area; rather, it helped reshape our comprehensive view of magnetotail physics and, more generally, the physics of magnetized plasmas.

“In addition to being a proven theorist and data analyst, Dr. Angelopoulos reinvented himself one more time to become a recognized experimentalist. His contributions to geophysics as an experimentally minded scientist have already been significant. Dr. Angelopoulos has repeatedly pointed out that both the bursty bulk flows and the instantaneous plasma fluctuation field are spatially undersampled with present satellite missions. He has been a strong advocate of a new line of space missions to explore the wave number space of magnetospheric plasma processes, termed ‘constellation class’ missions. He has vigorously pointed out the importance of dense multi-point sampling of magnetospheric plasmas at grid-size ranges of 0.5-10 RE. Dr. Angelopoulos also established his own experimental program to help identify the technologies needed to enable such missions; as such he became an expert in small satellites.

“Dr. Angelopoulos has been a strong community advocate for missions whose objectives extend beyond his own interests. He suggested the formation, and participated in the deliberations, of a NASA science and technology definition team that delineated the scientific objectives of future multipoint missions. He also helped mobilize the science and technology community on this matter (for example, by organizing a special Fall 1997 AGU Meeting session on the magnetospheric constellation missions), and he edited a book that incorporated the community’s suggestions.

“In short, Vassilis Angelopoulos’ accomplishments belie his youth. He is an internationally recognized theoretician, data analyst, and experimentalist with a paradigm-changing accomplishment already to his credit. He is a leader among leaders.”

—CHARLES F. KENNEL, University of California, San Diego


“I am deeply honored by this award and humbled by the legacy of previous recipients. It is a great pleasure to be nominated by Charlie, my scientific father. Charlie’s influence transcends the realm of science because by inspiring he brings out the best in you. I felt like the strangest 10-year old on the block when I would devour aviation and space magazines while vacationing in the Greek islands. Charlie taught me to appreciate how privileged we scientists are to be able to work on something we care so deeply about. I only wish I had known this back then. He also taught me that despite common perception, scientists are an utterly social breed. This honor indeed is a reflection of my profound and strong interactions with a distributed network of peers.

“At UCLA, Ferd Coroniti, Margy Kivelson, Bob McPherron and Chris Russell (another Macelwane awardee) each had a unique influence on my thinking. In particular my discussions with Charlie and Ferd on transport, turbulent flows, reconnection, tearing and ballooning modes, helped guide my analysis of BBFs using AMPTE data which Wolfgang Baumjohann was providing and enthusiastically helping interpret, albeit remotely. Supported by an IGPP/LANL grant, we proceeded to incorporate ISEE data, only to verify, to our amazement, the repeatability of our conclusions on the burstiness of magnetotail transport, on the average equatorial flow profile and on the turbulent nature of the instantaneous flow pattern. During multiple visits to LANL I interacted with a resourceful and stimulating science team. In particular Peter Gary’s contagious affection for the plasma dispersion function and Jack Gosling’s insight on electrostatic analyzers brushed off and stuck. I can undoubtedly trace the seeds of my subsequent evolution in ideas derived from these graduate school experiences as molded by our daily discussions with Charlie.

“At APL, I was introduced to the ISTP program, the Geotail satellite, and energetic particle detectors. I was fortunate to be in the company of accomplished instrumenters Don Mitchell and Nick Paschalidis and keen phenomenologists Tony Lui, Dave Sibeck and Victor Sergeev, then visiting from Russia. Amongst APL’s avant-garde engineers the ideas about feasibility of spacecraft and instrument miniaturization took hold; their importance for the field’s post-ISTP future became apparent. They were reinforced by frequent discussions with Boston University’s Harlan Spence and George Siscoe.

“Recently at SSL, I have been blessed by interactions with a group of engineers that know instruments and spacecraft inside-out and in a ‘holistic’ way. The lean academic environment forces each person to wear many ‘hats’ and encourages innovation. This cultivates the traits necessary for spacecraft miniaturization and Constellation class missions. The availability of data from Geotail, WIND, FAST and POLAR (and more recently Cluster) provided the necessary scientific ammunition to promote multipoint sampling. Forrest Mozer is my mentor and source of tremendous encouragement. Thanks to him I was able to advance my science objectives in self-organized criticality, in probing the scale-size of flow bursts, and more recently in monitoring electromagnetic coupling between the tail and the ionosphere, while simultaneously evolving in the area of instrumentation and mission design. Chuck Carlson and Bob Lin were critical in this shift, eagerly providing advice and continuously sharing experiences.

“I am forever indebted to my parents who selflessly encouraged and endured the loss of a child to science abroad. I am grateful to my wife, Mary, for her support during my frequent absence from home and absent-mindedness at home.

“I would not be here today without the American society’s openness: it empowered me, through a Fulbright fellowship, to strive to fulfill my dream. Acceptance and, indeed empowerment of diverse cultures within a competitive entrepreneurial environment are American ideals that we scientists are effective missionaries of, through our international social networks. These ideals were best portrayed by the demeanor and attitudes of my UCLA office mate and friend Max Hammond who tragically perished on September 11. But Max’s spirit does live on in the hearts and minds of all scientists. It is the active propagation of these ideals, never to be taken for granted, that will win the ideological war of the 21st century. To this American spirit I mostly credit this award; in its name I would like to accept it.”

—VASSILIS ANGELOPOULOS, Space Science Laboratory, University of California, Berkeley