2000-2001 Report to President

The Department of Earth, Atmospheric, and Planetary Sciences (EAPS) has broad intellectual horizons that encompass the solid earth, its fluid envelopes, and its diverse neighbors throughout the solar system and beyond. We seek to understand the fundamental processes defining the origin, evolution and current state of these systems and to use this understanding to predict future states. The department comprises 37 faculty, including two with primary appointments in Civil and Environmental Engineering, 195 graduate and undergraduate students, and over 100 research staff, postdoctoral appointments and visiting scholars. EAPS is notable for its collaborations with other MIT Departments and Schools to address complex interdisciplinary problems. In this vein, the Department is an enthusiastic supporter of the new Earth Systems Initiative. On a sad note, Professor John Marmion Edmond FRS passed away suddenly during the spring and will be missed by all.

Educational Activities

EAPS has vigorous graduate educational programs in geology and geochemistry, geophysics, atmospheres, oceans, climate, and planetary science. Each disciplinary area of EAPS continues to be ranked among the top graduate programs in the country, with most areas being rated either first or second nationally. The EAPS graduate program currently focuses on the Ph.D. degree, which is the goal of about 90 percent of its graduate students. During the past academic year, 161 graduate students were registered in the department including EAPS students in the MIT/Woods Hole Oceanographic Institution (WHOI) Joint Program. Of these 119 are U.S. citizens and 42 are international students. Women constitute 42 percent of the graduate student population. Fifteen Ph.D. and 14 S.M. degrees were awarded during the past academic year.

The new EAPS Master's Degree Program in Geosystems graduated its fourth class this year. The program's novel curriculum is designed to educate geoscientists in system-level analysis and prepare them for professional careers in high-technology industries concerned with complex geosystems. All three of the 2000-2001 entering students successfully completed the course work in two semesters. Another relatively new degree program is administered by the department's Program in Atmospheres, Oceans and Climate (PAOC). This new Ph.D. in Climate Physics and Chemistry has 11 students currently enrolled.

A biannual prize has been developed to recognize and reward the efforts of outstanding EAPS Graduate Teaching Assistants. Winners during the past year include Matthew Reuer, Janet Wu, Bridget Bergquist, and Philip Tracadas.

EAPS continues to maintain a strong presence within the undergraduate program at MIT. It offers a wide variety of Freshman Advising Seminars each fall with about 10 faculty members participating each of the past three years. A new undergraduate seminar has been developed to introduce newly declared sophomore majors to the broad research interests of the faculty. This seminar was very well received during its inception and is now being modified and expanded to include one-on-one mentoring by faculty members in the areas of technical writing and oral communication. This year EAPS gained 14 new majors which is a very significant increase above the previous year (five new majors). Professor Kip Hodges developed and launched a new freshman-level educational experience (12.000 "Solving Complex Problems") with support from the d'Arbeloff Fund for Educational Excellence. A multidiciplinary learning collaboration involving freshmen, upperclassmen, graduate students, and alumni, the inaugural offering of the subject won very positive reviews from its participants.

The EAPS Independent Activities Program (IAP) continues to be one of the most vibrant at MIT, and faculty have maintained a healthy Undergraduate Research Opportunities Program (UROP). Opportunities for IAP field experience included trips to the world's largest geothermal field and the wind farms in California, the Lowell Observatory in Flagstaff, Arizona, the NASA Goddard Space Flight Center in Maryland, and a geoscience field camp in Nevada.

The Bachelor of Science curriculum was reorganized several years ago to include three areas of concentration: geoscience, physics of atmospheres and oceans, and planetary science and astronomy. Each concentration encompasses a set of required courses, a sequence of field and laboratory subjects, and independent study or thesis

preparation. Historically, students have primarily chosen to specialize in either geoscience or planetary science and astronomy. In the past three years however, there have been an increasing number of students (five to six) pursuing studies in the physics of atmospheres and oceans. Within this concentration area, a popular new Institute Laboratory course has been developed by Professor Marshall and Dr. Illari that permits undergraduates to develop and perform experiments related to the general circulation of the atmosphere and the day-to-day sequencing of weather events. EAPS undergraduate enrollment comprised 34 majors and 15 minors during 2000-2001.


Professor Rafael Bras has been elected to the National Academy of Engineering.

Professor Clark Burchfiel has been nominated unopposed for Vice President, then President, of the Geological Society of America.

Professor Kerry Emanuel was elected to give the honorific Charney Lecture at the 2001 American Geophysical Union Spring Meeting.

Professor Brad Hager was selected for the 2001 George P. Woollard Award of the Geological Society of America. The Woollard Award is given annually to an individual who has contributed in an outstanding manner to geology through the application of the principles and techniques of geophysics.

Professor Julian Sachs was awarded the Henry L. and Grace Doherty career development professorship in ocean utilization to support work on paleothermometry in oceanic sediments to determine abrupt climate change mechanisms.

Professor Peter Stone was elected a Fellow of the American Association for the Advancement of Science.

Professor Jack Wisdom has been given the 2002 Dirk Brouwer Award by the Division of Dynamical Astronomy of the American Astronomical Society "for his fundamental contributions and leadership in the field."

Professor Maria Zuber was elected a Fellow of the American Geophysical Union and has received the NASA Group Achievement Awards for the Mars Global Surveyor Mission, Mars '98, and the Mars Mission Failure Investigation Board.

Over the past year several vigorous searches have led to four exciting new faculty appointments. Roger Summons, whose work in "molecular fossils" is widely recognized and lauded, has been appointed Professor of Geobiology. Julian Sachs, an accomplished young paleoclimatologist, has joined the faculty as the Doherty Assistant Professor. David Mohrig, who has made notable contributions to sedimentary geomorphology, was named Assistant Professor of Geology. Most recently, James Hansen, who is doing innovative research on optimal observing and forecasting has joined us as Assistant Professor of Atmospheric Science.

The department currently has active faculty searches in six exciting areas. The first is in Planetary Science which is making dramatic advances toward understanding the formation and evolution of our solar system and other planetary systems. The second faculty search is for another faculty member in Geobiology. We envision this emerging new field to encompass research that includes the origin of life, evolutionary and developmental biology, microbial biology, and the interactions between ecosystems and climate.. The time is right for the expansion of the department into this exciting new field which is directly relevant to the proposed Earth Systems Initiative. The third faculty search is in Oceanic and Climate Sciences. We aim to enhance our existing programs in oceanography and climate research including ongoing work in the Center for Global Change Science's Climate Modeling Initiative.

The fourth faculty search is in Experimental Geophysics and Geochemistry. We are seeking an outstanding scientist in the area of experimental geophysics and geochemistry who studies the physics and chemistry of Earth materials. The fifth faculty search is in Seismology. This area, which provides fundamental information on the structure and dynamics of the earth, is entering an exciting new era incorporating new measurement networks. The sixth and newest search is in Atmospheric Chemistry. The current coupled challenges of air pollution and climate have increased the demand for new knowledge of chemical processes.

The department continues to pioneer work in new interdisciplinary areas. The Earth Resources Laboratory is broadening its base to include a wider range of geophysical, geological, and environmental topics. The Center for Global Change Science (including the Climate Modeling Initiative) and the Program in Atmospheric, Oceans and Climate continue to foster cross-fertilization among all areas of the earth sciences that control the climate system. Research activities are gradually broadening so that geologists are now working with oceanographers and atmospheric scientists, and models of the climate system have been constructed both for the modern system and for times deep in the geological past. A large new faculty group interested in co-evolution of the geosphere and biosphere has formed and is participating in the definition of the new earth systems initiative. Department faculty also continue to play leading roles in the MIT Joint Program on the Science and Policy of Global Change.

Current Research

Professor Edward Boyle's group has shown for the first time that a large fraction of oceanic iron, an element that is essential to marine life but is in short supply, occurs as colloids less than 0.2 micrometers in diameter; this work has implications to the bioavailability of iron. His group has also obtained data from five sites in the North Atlantic and North Pacific ocean which demonstrate that during the past two decades lead (Pb) has decreased in the upper two kilometers in the ocean as a result of the phasing out of leaded gasoline.

Professor Clark Burchfiel's nine year program to monitor crustal movements in eastern Tibet and South China has been completed. The crustal velocity map shows velocities from India to Eurasia are locally absorbed within the Tibet plateau region, but relative to a fixed Eurasia there appears to be an eastward movement of eastern Tibet coupled with eastern China beyond the plateau. This result is different from nearly all existing tectonic models for this region.

Professor Jim Elliot, student Susan Kern, and their colleagues at Lowell Observatory have discovered over one hundred and twenty Kuiper Belt objects in the course of their Deep Ecliptic Survey, which being carried out at Cerro Tololo and Kitt Peak National Observatories. Follow-up observations of one of the objects (2001 KX76) with MIT's MagIC camera on Magellan-in collaboration with Dr. David Osip-shows that it may be the largest Kuiper Belt object presently known. Work is continuing to characterize the physical properties of these bodies, which lie beyond the orbit of Neptune.

Professor Frederick Frey is obtaining an understanding of the Kerguelen Plateau, a very large submarine province in the south Indian Ocean, by geochemical studies of lavas cored during an Ocean Drilling Program expedition. Although this plateau formed after breakup of Australia, India and Antarctica, it is evident that the mantle-derived magmas were affected by microcontinental fragments that became isolated in the newly formed Indian Ocean Basin.

Professor Kerry Emanuel's recent research has focused on a theory for multiple stable climate regimes, which has the potential to explain a number of enigmatic features of the earth's climate, including sensitivity to orbital variations, sudden transitions, and polar warmth during such periods as the early Eocene and late Cretaceous.

Professor Tim Grove and his colleagues have carried out experiments in their MIT laboratory that reproduce the earliest crystallizing minerals in the Shergotty meteorite; one of 15 Meteorites believed to have come from Mars. They have determined that the Shergotty magma contained ~ 2 wt. percent water prior to eruption on the Martian surface. This result points to volcanic recycling as a possible mechanism for getting water to Mars's surface.

Professor Brad Hager and his group developed a procedure to estimate more reliably slip rates and locking depths of fault systems using geodetic data, with applications in California, Turkey, and the Tien Shan Mountains of Central Asia. In California and the Tien Shan, there is excellent agreement with slip rates inferred independently from geologic studies. In the region near Istanbul, Turkey, their results suggest that the most likely maximum earthquake moment release is a factor of two smaller than previously believed.

Professor Kip Hodges' activities over the past year have focussed on the development of a new laboratory for (U-Th)/He geochronology, a technique especially well-suited for exploring the evolution of topography in modern mountain systems. At the same time, he has continued tectonics research in the Nepalese Himalaya.

Professor Richard Lindzen is studying climate feedbacks, in cooperation with colleagues at NASA's Goddard Space Flight Center. They are attempting to combine various satellites in order to get adequate spatial, temporal and spectral resolution. Climate sensitivity is being looked at by examining the time response of surface temperature to changes in atmospheric regime. Rapid response is associated with low sensitivity. Also, in cooperation with a student, Pablo Zurita, they are studying how the eddies that transport heat equilibrate nonlinearly.

Professor John Marshall continues his research into the role of the ocean in climate variability. His group has been investigating possible patterns of ocean circulation and biogeochemistry in warm periods in earth history, such as the Cretaceous and the Permian. With Professor Alan Plumb, he has been preparing an undergraduate text book in atmosphere and ocean dynamics.

Professor Reginald Newell and colleagues John Cho and Erik Lindborg have studied variations in the lower stratosphere of temperature and ozone using aircraft data to distinguish the direction of energy and scalar variance

flux between the scales of motion. In related work, a layer of high potential vorticity from the stratosphere was observed to trap below a pollution plume rising from the boundary layer and the mechanics were studied.

Professor Ronald Prinn and Colleagues have been studying long-term variations of the hydroxyl radical (OH) which is the dominant oxidizing chemical in the atmosphere. Global measurements of 1,1,1-trichloroethane provide an accurate method for determining the global and hemispheric behavior of OH. Analysis of these measurements shows that global OH levels were growing between 1978 and 1988, but the growth rate was decreasing so that OH levels began declining after 1988. These variations imply important and unexpected gaps in current understanding.

Professor Paola Rizzoli and her collaborators have focussed on three major research issues. 1) Model-data synthesis in the Atlantic ocean to understand tropical/subtropical interactions using TOPEX and WOCE datasets in collaboration with Dr. Bussalacchi and his group at the Goddard Space Flight Center. 2) Predictability of geophysical fluid flows under a program of the Office of Naval Research which she co-directs. 3) Physical and biochemical modeling of marginal seas, with a focus on the Mediterranean and Black seas.

Professor Daniel Rothman has developed a new model for the evolution of atmospheric carbon dioxide levels for the last 500 million years. The model, which is based on the reconciliation of geochemical signals related to tectonic and biological activity, shows no systematic coupling of atmospheric carbon dioxide levels to climate at tectonic time scales.

Professor Julian Sachs deduces past sea surface temperatures from ocean sediments. Whereas records from Antarctic ice cores indicate a long term cooling into the Last Glacial Maximum (~21,000 yr ago), surface temperatures from the southeast Atlantic warmed substantially 41,000-25,000 yr ago, suggesting a strong response to changes in Earth's tilt. Evidence for 20th-century warming was observed in sediments from the Nova Scotian Margin, and a pronounced cooling inferred early in our present interglacial period in the subpolar NW Atlantic.

Professor Stone and his collaborators in the MIT Joint Program on the Science and Policy of Global Change have used multiple climate diagnostics and their optimal fingerprint detection algorithm to investigate how strong the global forcing due to anthropogenic aerosols has been over the last 50 years. They find that the 95 percent confidence interval for the forcing (cooling) is -0.3 to -1.0 W/m2, a much smaller range of uncertainty than that quoted by the Intergovernmental Panel on Climate Change in their recent assessment.

Professor Nafi Toksöz has been working on seismological techniques and fostering international cooperation for reducing earthquake risk to major population centers.

Professor Rob Van der Hilst and his group have studied the structure and evolution of Earth's deep mantle, using high resolution imaging and last year they produced the best global model for compressional wavespeed available to date. They have also begun to constrain the nature of compositional heterogeneity of the deep mantle (depth > 2000 km), but despite extensive searches evidence for sharp interfaces has not been found. The investigation of the Australian continent has shifted to determining and understanding its mechanical and seismological anisotropy.

Professor Kelin Whipple has worked on: relationships between climate, tectonic setting, rock type, and elevation and relief of mountain belts; controls on timescales of mountain building and decay; and the nature of the sediment supply delivered on-shore and off-shore during an orogenic cycle. Minimum estimates of landscape response time argue against the often-invoked steady-state assumption, the role of sediment flux in modulating river incision rates was analysed, and a river incision law was refined to predict patterns and rates of tectonic uplift.

Professor Wisdom, with Professor Gerald Sussman in EECS, has published a novel book on classical mechanics, which is used in a course. With Professor Jihad Touma (AUB), Professor Wisdom has studied the evolution of Earth and Venus through nonlinear core-mantle resonances. These are resonances between the precession of the fluid core and the motion of the planet around the Sun. They speculate that heating during resonance passage may have led to the global resurfacing of Venus that occurred 700-800 million years ago.

Professor Carl Wunsch and many of his associates continue to exploit recent global scale oceanographic data sets, combined with numerical models of the ocean, to estimate the time-varying absolute ocean circulation. The results are important for understanding of the way in which the ocean controls climate change.

Professor Maria Zuber and colleagues used their laser altimeter on the Mars Global Surveyor spacecraft to constrain the timing of formation of the massive Tharsis volcanic on Mars. The associated release of volatiles early in Martian history can explain the thicker atmosphere and extensive surface water that marked an earlier, clement climate on Mars. Zuber and colleagues also used their laser altimeter on the Near Earth Asteroid Rendezvous mission to produce the first high resolution model of the shape and internal structure of an asteroid.