Paul Wennberg

Last updated
Paul Wennberg
NationalityAmerican
Alma mater Oberlin College, Harvard University
Known foratmospheric science, carbon cycle
SpouseCheryl Margaret Wold
Awards MacArthur Fellow
Scientific career
Fields atmospheric scientist
Institutions California Institute of Technology
Doctoral advisor James G. Anderson
Website www.gps.caltech.edu/content/paul-o-wennberg

Paul O. Wennberg is the R. Stanton Avery Professor of Atmospheric Chemistry and Environmental Science and Engineering at the California Institute of Technology (Caltech). [1] He is the director of the Ronald and Maxine Linde Center for Global Environmental Science. [2] He is chair of the Total Carbon Column Observing Network [3] and a founding member of the Orbiting Carbon Observatory project, which created NASA's first spacecraft for analysis of carbon dioxide in the atmosphere. [4] He is also the principal investigator for the Mars Atmospheric Trace Molecule Occultation Spectrometer (MATMOS) to investigate trace gases in Mars's atmosphere. [5]

Contents

Wennberg's research focuses on the atmospheric chemistry of planets, including air quality, photochemistry, and the carbon cycle. [2] He designs and builds remote-sensing and in-situ scientific instruments which are used in field investigations supported by the National Science Foundation and NASA. [5] His scientific instruments have made it possible to measure radicals in the atmosphere at concentrations that could not previously be detected. He measures atmospheric trace gases, making it possible to accurately describe the exchange of carbon dioxide and other gases between the atmosphere and the land and ocean. [6] His research has substantially advanced understanding of the atmospheric chemistry of the troposphere and the stratosphere. [7]

Education

Paul Wennberg grew up in Waterbury Center, Vermont. He received a B.A. from Oberlin College in 1985, and a Ph.D. from Harvard University in 1994. [8] At Harvard, he worked with James G. Anderson, professor of atmospheric chemistry. [9] His doctoral thesis was In Situ Measurements of Stratospheric Hydroxyl and Hydroperoxyl Radicals. [10]

Career

Wennberg joined Caltech in 1998. He was an associate professor of atmospheric chemistry and environmental engineering science from 1998 to 2001, becoming a full professor in 2001. In 2004, he was appointed as the R. Stanton Avery Professor of Atmospheric Chemistry and Environmental Science and Engineering. [2] Wennberg has been associated with the Ronald and Maxine Linde Center for Global Environmental Science at Caltech since it was established in 2008. [11] He served as the director from 2008 to 2011, acting director from 2012 to 2014 and director from 2014 onwards. [2]

Research

While still at Harvard, Wennberg developed advanced airborne sensors to measure radicals in the atmosphere, in particular the odd-hydrogen radicals OH and HO2. [12] The laser-induced fluorescence instrument that he developed was placed in the nose of a NASA ER-2 aircraft to measure radicals during flight. [13] [14] It has been used to measure radicals in both the troposphere and the stratosphere. [13]

Wennberg's sensor was used in several NASA missions, beginning with the SPADE mission in 1993. [13] SPADE obtained the first simultaneous in situ measurements of OH, HO2, NO, NO2, ClO, and BrO from the lower stratosphere. The data were used to calculate ozone loss rates and showed that HOx dominated stratospheric ozone loss, a result that had not been previously observable. [15] NASA's ASHOE/MAESA mission (1994) took measurements of HOx from latitudes of -70°S to 70°N, reaching nearly from the south pole to the north pole. The STRAT mission (1995–1996) was the first to record measurements of HOx in the upper troposphere, and demonstrated that the concentration of HOx considerably exceeded expected levels. [16] The POLARIS mission in 1997 obtained measurements all the way to 90° N latitude, the North pole. [14] As of 2004, Wennberg's instrument was modified for in situ measurements of water vapour and its Isotopologue HDO, and became the basis of the Harvard "Hoxotope". [17] [13]

Using these tools, he overturned the long-held belief that lower stratospheric ozone is destroyed principally by nitrogen oxides; Wennberg showed that odd-hydrogen catalysis represents a quantitatively more important process. By contrast to the stratosphere, a significant fraction of tropospheric ozone results from the presence of nitric oxide delivered to the atmosphere by aircraft and surface hydrocarbon burning. Ozone in the stratosphere acts as a protective shield against ultraviolet radiation, but ozone in the troposphere significantly reduces air quality. By developing methods for measuring radical gases in situ and interpreting these results within a theoretical framework, Wennberg has advanced our understanding of atmospheric chemistry. [7]

Since his move to Caltech, Wennberg has been deeply involved in two inter-related long-term instrumentation and data-collection projects: the Orbiting Carbon Observatory, and its ground-based counterpart, the Total Carbon Column Observing Network. [10] Goals include better understanding of the carbon cycle, validation of data from space-based instruments, and establishing a standard for ground-based in situ networked data collection. [18]

In 2002, [10] Wennberg was elected chair of the Total Carbon Column Observing Network (TCCON). [3] In 2004, the first TCCON site was established. [19] The Total Carbon Column Observing Network is a group of about 20 ground-based sites worldwide that host Fourier transform spectrometers. The spectrometers examine near-infrared (NIR) solar absorption spectra and measure atmospheric column abundances of CO2, CH4, CO, N2O and other molecules in terrestrial ecosystems. [20] Data enables researchers to identify and study local carbon "sources" and "sinks", and by pooling data across the system, to better understand mechanisms of carbon exchange involving the atmosphere, the land, and the ocean. [19] Data from the sites is used to understand carbon dynamics and to validate data from space-based measurements of atmospheric CO2 and CH4. Both terrestrial and atmospheric data are used to study carbon transfer within the atmosphere. [20] [18] Methane emissions from the Aliso Canyon gas leak were detected by TCCON within a day of the start of the leak. [21] "TCCON has pioneered a key element of the ground segment measurements required to provide the evidence base for policy making for the next 100 years." [19]

Wennberg is a founding member of the Orbiting Carbon Observatory and its successor, the Orbiting Carbon Observatory-2. The first satellite failed to separate from the Orbital Taurus XL rocket used as its launch vehicle on February 24, 2009, and was destroyed during reentry. The second satellite, a near duplicate, was launched successfully by NASA on July 2, 2014, using a ULA Delta II 7320-10C rocket. [6] [4] [22] Spectrometers on the satellite can map the distribution of CO2 particles across the planet by measuring the average amount of CO2 above specific locations. [6]

Wennberg is the principal investigator for the development of the Mars Atmospheric Trace Molecule Occultation Spectrometer (MATMOS), a collaboration between Caltech and the Canadian Space Agency with NASA support. MATMOS will be flown on the ExoMars Trace Gas Orbiter and take spectra of the sunlight through Mars' atmosphere as the spacecraft goes through its orbital sunrise and sunset. MATMOS will be able to measure trace gases in Mars's atmosphere at a concentrations of parts per trillion. [5]

Awards and honors

Wennberg received a Presidential Early Career Award for Scientists and Engineers (PECASE) in 1999 from President Bill Clinton. [23] He was named a MacArthur Foundation Fellow in 2002. [7] [24]

Related Research Articles

<span class="mw-page-title-main">Satellite temperature measurement</span> Measurements of atmospheric, land surface or sea temperature by satellites.

Satellite temperature measurements are inferences of the temperature of the atmosphere at various altitudes as well as sea and land surface temperatures obtained from radiometric measurements by satellites. These measurements can be used to locate weather fronts, monitor the El Niño-Southern Oscillation, determine the strength of tropical cyclones, study urban heat islands and monitor the global climate. Wildfires, volcanos, and industrial hot spots can also be found via thermal imaging from weather satellites.

<span class="mw-page-title-main">Ground-level ozone</span> Constituent gas of the troposphere

Ground-level ozone (O3), also known as surface-level ozone and tropospheric ozone, is a trace gas in the troposphere (the lowest level of the Earth's atmosphere), with an average concentration of 20–30 parts per billion by volume (ppbv), with close to 100 ppbv in polluted areas. Ozone is also an important constituent of the stratosphere, where the ozone layer (2 to 8 parts per million ozone) exists which is located between 10 and 50 kilometers above the Earth's surface. The troposphere extends from the ground up to a variable height of approximately 14 kilometers above sea level. Ozone is least concentrated in the ground layer (or planetary boundary layer) of the troposphere. Ground-level or tropospheric ozone is created by chemical reactions between NOx gases (oxides of nitrogen produced by combustion) and volatile organic compounds (VOCs). The combination of these chemicals in the presence of sunlight form ozone. Its concentration increases as height above sea level increases, with a maximum concentration at the tropopause. About 90% of total ozone in the atmosphere is in the stratosphere, and 10% is in the troposphere. Although tropospheric ozone is less concentrated than stratospheric ozone, it is of concern because of its health effects. Ozone in the troposphere is considered a greenhouse gas, and may contribute to global warming.

<span class="mw-page-title-main">Mars 96</span> Failed Mars mission

Mars 96 was a failed Mars mission launched in 1996 to investigate Mars by the Russian Space Forces and not directly related to the Soviet Mars probe program of the same name. After failure of the second fourth-stage burn, the probe assembly re-entered the Earth's atmosphere, breaking up over a 320 km (200 mi) long portion of the Pacific Ocean, Chile, and Bolivia. The Mars 96 spacecraft was based on the Phobos probes launched to Mars in 1988. They were of a new design at the time and both ultimately failed. For the Mars 96 mission the designers believed they had corrected the flaws of the Phobos probes, but the value of their improvements was never demonstrated due to the destruction of the probe during the launch phase.

SCISAT-1 is a Canadian satellite designed to make observations of the Earth's atmosphere. Its main instruments are an optical Fourier transform infrared spectrometer, the ACE-FTS Instrument, and an ultraviolet spectrophotometer, MAESTRO. These devices record spectra of the Sun, as sunlight passes through the Earth's atmosphere, making analyses of the chemical elements of the atmosphere possible.

<span class="mw-page-title-main">Upper Atmosphere Research Satellite</span> NASA-operated orbital observatory (1991-2011)

The Upper Atmosphere Research Satellite (UARS) was a NASA-operated orbital observatory whose mission was to study the Earth's atmosphere, particularly the protective ozone layer. The 5,900-kilogram (13,000 lb) satellite was deployed from Space Shuttle Discovery during the STS-48 mission on 15 September 1991. It entered Earth orbit at an operational altitude of 600 kilometers (370 mi), with an orbital inclination of 57 degrees.

<span class="mw-page-title-main">National Institute of Water and Atmospheric Research</span> New Zealand national research institute

The National Institute of Water and Atmospheric Research or NIWA, is a Crown Research Institute of New Zealand. Established in 1992, NIWA conducts research across a broad range of disciplines in the environmental sciences. It also maintains nationally and, in some cases, internationally important environmental monitoring networks, databases, and collections.

<span class="mw-page-title-main">Atmosphere of Mars</span> Layer of gases surrounding the planet Mars

The atmosphere of Mars is the layer of gases surrounding Mars. It is primarily composed of carbon dioxide (95%), molecular nitrogen (2.85%), and argon (2%). It also contains trace levels of water vapor, oxygen, carbon monoxide, hydrogen, and noble gases. The atmosphere of Mars is much thinner and colder than Earth's having a max density 20g/m3 with a temperature generally below zero down to -60 Celsius. The average surface pressure is about 610 pascals (0.088 psi) which is less than 1% of the Earth's value.

<span class="mw-page-title-main">Venera-D</span> Proposed Russian lander to Venus

Venera-D is a proposed Russian space mission to Venus that would include an orbiter and a lander to be launched in 2029. The orbiter's prime objective is to perform observations with the use of a radar. The lander, based on the Venera design, would be capable of operating for a long duration on the planet's surface. The "D" in Venera-D stands for "dolgozhivuschaya," which means "long lasting" in Russian.

<span class="mw-page-title-main">Atmospheric chemistry observational databases</span> Aspect of atmospheric sciences

Over the last two centuries many environmental chemical observations have been made from a variety of ground-based, airborne, and orbital platforms and deposited in databases. Many of these databases are publicly available. All of the instruments mentioned in this article give online public access to their data. These observations are critical in developing our understanding of the Earth's atmosphere and issues such as climate change, ozone depletion and air quality. Some of the external links provide repositories of many of these datasets in one place. For example, the Cambridge Atmospheric Chemical Database, is a large database in a uniform ASCII format. Each observation is augmented with the meteorological conditions such as the temperature, potential temperature, geopotential height, and equivalent PV latitude.

<span class="mw-page-title-main">Atmospheric infrared sounder</span> Science instrument on NASAs Aqua satellite

The atmospheric infrared sounder (AIRS) is one of six instruments flying on board NASA's Aqua satellite, launched on May 4, 2002. The instrument is designed to support climate research and improve weather forecasting.

<span class="mw-page-title-main">SBUV/2</span>

The Solar Backscatter Ultraviolet Radiometer, or SBUV/2, is a series of operational remote sensors on NOAA weather satellites in Sun-synchronous orbits which have been providing global measurements of stratospheric total ozone, as well as ozone profiles, since March 1985. The SBUV/2 instruments were developed from the SBUV experiment flown on the Nimbus-7 spacecraft which improved on the design of the original BUV instrument on Nimbus-4. These are nadir viewing radiometric instruments operating at mid to near UV wavelengths. SBUV/2 data sets overlap with data from SBUV and TOMS instruments on the Nimbus-7 spacecraft. These extensive data sets measure the density and vertical distribution of ozone in the Earth's atmosphere from six to 30 miles.

The Stratospheric Aerosol and Gas Experiment (SAGE) is a series of remote sensing satellite instruments used to study the chemical composition of Earth's atmosphere. Specifically, SAGE has been used to study the Earth's ozone layer and aerosols at the troposphere through the stratosphere. The SAGE instruments use solar occultation measurement technique to determine chemical concentrations in the atmosphere. Solar occultation measurement technique measures sunlight through the atmosphere and ratios that measurement with a sunlight measurement without atmospheric attenuation. This is achieved by observing sunrises and sunsets during a satellite orbit. Physically, the SAGE instruments measure ultraviolet/visible energy and this is converted via algorithms to determine chemical concentrations. SAGE data has been used to study the atmospheres aerosols, ozone, water vapor, and other trace gases.

<span class="mw-page-title-main">Greenhouse gas monitoring</span> Measurement of greenhouse gas emissions and levels

Greenhouse gas monitoring is the direct measurement of greenhouse gas emissions and levels. There are several different methods of measuring carbon dioxide concentrations in the atmosphere, including infrared analyzing and manometry. Methane and nitrous oxide are measured by other instruments. Greenhouse gases are measured from space such as by the Orbiting Carbon Observatory and networks of ground stations such as the Integrated Carbon Observation System.

<span class="mw-page-title-main">SAGE III on ISS</span>

SAGE III on ISS is the fourth generation of a series of NASA Earth-observing instruments, known as the Stratospheric Aerosol and Gas Experiment. The first SAGE III instrument was launched on a Russian Meteor-3M satellite. The recently revised SAGE III was mounted to the International Space Station where it uses the unique vantage point of ISS to make long-term measurements of ozone, aerosols, water vapor, and other gases in Earth's atmosphere.

<span class="mw-page-title-main">Total Carbon Column Observing Network</span>

The Total Carbon Column Observing Network (TCCON) is a global network of instruments that measure the amount of carbon dioxide, methane, carbon monoxide, nitrous oxide and other trace gases in the Earth's atmosphere. The TCCON began in 2004 with the installation of the first instrument in Park Falls, Wisconsin, USA, and has since grown to 23 operational instruments worldwide, with 7 former sites.

OSIRIS is an instrument that measures vertical profiles of spectrally dispersed, limb scattered sunlight from the upper troposphere into the lower mesosphere. OSIRIS is one of two instruments on the Odin satellite, launched February, 2001 into a Sun-synchronous, 6 pm/6 am local time orbit at 600 km. This restricts OSIRIS sunlit observations to the Northern hemisphere in May, June, July and August, and the Southern hemisphere in November, December, January and February. Global coverage from 82°S to 82°N occurs on the months adjoining the equinoxes. OSIRIS measurements began November, 2001 and continue to the present.

<span class="mw-page-title-main">Meteor-3M No.1</span>

Meteor-3M No.1 was the first and only of the Meteor-3M series polar-orbiting weather satellites. It was launched on 10 December 2001 at 17:18:57 UTC from the Baikonur Cosmodrome in Kazakhstan. The satellite is in a Sun-synchronous orbit with an ascending node time of about 9AM.

<span class="mw-page-title-main">Space-based measurements of carbon dioxide</span> Used to help answer questions about Earths carbon cycle

Space-based measurements of carbon dioxide are used to help answer questions about Earth's carbon cycle. There are a variety of active and planned instruments for measuring carbon dioxide in Earth's atmosphere from space. The first satellite mission designed to measure CO2 was the Interferometric Monitor for Greenhouse Gases (IMG) on board the ADEOS I satellite in 1996. This mission lasted less than a year. Since then, additional space-based measurements have begun, including those from two high-precision satellites. Different instrument designs may reflect different primary missions.

<span class="mw-page-title-main">SPRITE (spacecraft)</span> Proposed NASA Saturn atmospheric probe mission concept

SPRITE was a proposed Saturn atmospheric probe mission concept of the NASA. SPRITE is a design for an atmospheric entry probe that would travel to Saturn from Earth on its own cruise stage, then enter the atmosphere of Saturn, and descend taking measurements in situ.

Nadir and Occultation for MArs Discovery (NOMAD) is a 3-channel spectrometer on board the ExoMars Trace Gas Orbiter (TGO) launched to Mars orbit on 14 March 2016.

References

  1. ↑ "Paul O. Wennberg". Caltech. Archived from the original on 24 August 2018. Retrieved 10 May 2016.
  2. 1 2 3 4 "Paul O. Wennberg". Environmental Science and Engineering. Retrieved 10 May 2016.
  3. 1 2 Griffith, D. (2014). "Near Infrared remote sensing of atmospheric composition from the ground and space: the Total Carbon Column Observing Network (TCCON), GOSAT and OCO-2". Light, Energy and the Environment, OSA Technical Digest: ETh4A.2. doi:10.1364/E2.2014.ETh4A.2. ISBN   978-1-55752-756-1 . Retrieved 12 May 2016.
  4. 1 2 Crisp, D.; Atlas, R.M; Breon, F.-M; Brown, L.R; Burrows, J.P; Ciais, P.; Connor, B.J; Doney, S.C; Fung, I.Y; Jacob, D.J; Miller, C.E; O'Brien, D.; Pawson, S.; Randerson, J.T; Rayner, P.; Salawitch, R.J; Sander, S.P; Sen, B.; Stephens, G.L; Tans, P.P; Toon, G.C; Wennberg, P.O; Wofsy, S.C; Yung, Y.L; Kuang, Z.; Chudasama, B.; Sprague, G.; Weiss, B.; Pollock, R.; et al. (2004). "The Orbiting Carbon Observatory (OCO) mission". Advances in Space Research. 34 (4): 700–709. Bibcode:2004AdSpR..34..700C. doi:10.1016/j.asr.2003.08.062. S2CID   16804121.
  5. 1 2 3 Oliwenstein, Lori (2010). "Caltech, Canadian Space Agency Awarded NASA Project to Develop Spectrometer Headed to Mars". Caltech News. Retrieved 12 May 2016.
  6. 1 2 3 Morin, Monte (June 30, 2014). "NASA makes second attempt to launch CO2-measuring satellite". Los Angeles Times. Retrieved 10 May 2016.
  7. 1 2 3 The John D. and Catherine T. MacArthur Foundation. "MacArthur Fellows September 2002" . Retrieved 2007-06-02.
  8. ↑ Wennberg, Paul. "Paul Wennberg / Caltech". Caltech. Retrieved 10 May 2016.
  9. ↑ "Anderson Research Group". Harvard College. Retrieved 10 May 2016.
  10. 1 2 3 "Paul O. Wennberg (C.V.)" (PDF). Caltech. Retrieved 12 May 2016.
  11. ↑ "Linde + Robinson Laboratory at Caltech". Los Angeles Conservancy. Retrieved 10 May 2016.
  12. ↑ Wennberg, P. O.; Cohen, R. C.; Hazen, N. L.; Lapson, L. B.; Allen, N. T.; Hanisco, T. F.; Oliver, J. F.; Lanham, N. W.; Demusz, J. N.; Anderson, J. G. (1994). "Aircraft-borne, laser-induced fluorescence instrument for the in situ detection of hydroxyl and hydroperoxyl radicals" (PDF). Review of Scientific Instruments. 65 (6): 1858–1876. Bibcode:1994RScI...65.1858W. doi:10.1063/1.1144835.
  13. 1 2 3 4 North, Gerald R.; Pyle, John A.; Zhang, Fuqing (2014). Encyclopedia of atmospheric sciences. Elsevier Academic Press. pp. 393–394. ISBN   9780123822253 . Retrieved 11 May 2016.
  14. 1 2 "HOx Research Group". Anderson Group. Archived from the original on 29 June 2016. Retrieved 12 May 2016.
  15. ↑ Wennberg, P. O.; Cohen, R. C.; Stimpfle, R. M.; Koplow, J. P.; Anderson, J. G.; Salawitch, R. J.; Fahey, D. W.; Woodbridge, E. L.; Keim, E. R.; Gao, R. S.; Webster, C. R.; May, R. D.; Toohey, D. W.; Avallone, L. M.; Proffitt, M. H.; Loewenstein, M.; Podolske, J. R.; Chan, K. R.; Wofsy, S. C. (1994). "Removal of Stratospheric O3 by Radicals: In Situ Measurements of OH, HO2, NO, NO2, ClO, and BrO". Science. 266 (5184): 398–404. Bibcode:1994Sci...266..398W. doi:10.1126/science.266.5184.398. PMID   17816682. S2CID   2520718.
  16. ↑ Wennberg, P. O.; Hanisco, T. F.; Jaegle, L.; Jacob, D. J.; Hintsa, E. J.; Lanzendorf, E. J.; Anderson, J. G.; Gao, R.; Keim, E. R.; Donnelly, S. G.; Negro LAD; Fahey, D. W.; McKeen, S. A.; Salawitch, R. J.; Webster, C. R.; May, R. D.; Herman, R. L.; Proffitt, M. H.; Margitan, J. J.; Atlas, E. L.; Schauffler, S. M.; Flocke, F.; McElroy, C. T.; Bui, T. P. (1998). "Hydrogen Radicals, Nitrogen Radicals, and the Production of O3 in the Upper Troposphere". Science. 279 (5347): 49–53. Bibcode:1998Sci...279...49W. doi:10.1126/science.279.5347.49. PMID   9417019.
  17. ↑ St. Clair, J. M.; Hanisco, T. F.; Weinstock, E. M.; Moyer, E. J.; Sayres, D. S.; Keutsch, F. N.; Kroll, J. H.; Demusz, J. N.; Allen, N. T.; Smith, J. B.; Spackman, J. R.; Anderson, J. G. (2008). "A new photolysis laser-induced fluorescence instrument for the detection of H2O and HDO in the lower stratosphere" (PDF). Review of Scientific Instruments. 79 (6): 064101–064101–14. Bibcode:2008RScI...79f4101S. doi:10.1063/1.2940221. PMID   18601418.
  18. 1 2 Wunch, D.; Toon, G. C.; Blavier, J.-F. L.; Washenfelder, R. A.; Notholt, J.; Connor, B. J.; Griffith, D. W. T.; Sherlock, V.; Wennberg, P. O. (2011). "The Total Carbon Column Observing Network". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 369 (1943): 2087–2112. Bibcode:2011RSPTA.369.2087W. doi: 10.1098/rsta.2010.0240 . PMID   21502178.
  19. 1 2 3 Stoller-Conrad, Jessica (2014). "Integrating Carbon from the Ground Up: TCCON Turns Ten" (PDF). The Earth Observer. 26 (4): 13–15. Retrieved 12 May 2016.
  20. 1 2 "Carbon cycle and ecosystems funded research". National Aeronautics and Space Administration. Retrieved 12 May 2016.
  21. ↑ Fesenmaier, Kimm (April 18, 2016). "Aliso Canyon, Methane, and Global Climate: A Conversation with Paul Wennberg". Science and Technology Research News. Retrieved 12 May 2016.
  22. ↑ Frankenberg, C.; Pollock, R.; Lee, R. A. M.; Rosenberg, R.; Blavier, J.-F.; Crisp, D.; O'Dell, C. W.; Osterman, G. B.; Roehl, C.; Wennberg, P. O.; Wunch, D. (2015). "The Orbiting Carbon Observatory (OCO-2): Spectrometer performance evaluation using pre-launch direct sun measurements". Atmospheric Measurement Techniques. 8 (1): 301–313. Bibcode:2015AMT.....8..301F. doi: 10.5194/amt-8-301-2015 .
  23. ↑ "President names outstanding young U.S. scientists". The White House. February 10, 1999.
  24. ↑ Maugh II, Thomas H. (September 25, 2002). "Eight Californians Win MacArthur Fellowships". Los Angeles Times. Retrieved 12 May 2016.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.