Dr.
Judith Lean, of the Naval
Research Laboratory's (NRL's) Space
Science Division has been
elected a Fellow of the American
Geophysical Union (AGU). Fellowship
in the AGU is an honor
conferred upon scientists who, in the
eyes of the AGU, have
"attained acknowledged eminence in
the geophysical
sciences."
Dr.
Lean has worked in NRL's
Space Science Division since 1986,
where her research focuses
on the mechanisms, measurements and
modeling of variations in
the Sun's radiative output at all
wavelengths, and the effects
of this variability on the Earth's
global climate and space weather.
She is a guest investigator
on NASA's Upper Atmosphere Research
Satellite (UARS), Living
with a Star (LWS) and Sun-Earth Connection
(SEC) programs, and
a co-investigator on the Solar Radiation
and Climate (SOURCE)
and Thermosphere Ionosphere Mesosphere Energetics
and Dynamics
(TIMED) space missions.
Dr. Lean and her coworkers provided
the first
quantitative study of the relative roles of sunspots
and other
smaller, more numerous solar features in controlling
the solar
constant over short (27-day) and long (11-year) solar
cycles.
Their studies completely reversed earlier theories drawn
primarily from sunspot data and moved the science of sun/climate
connections from speculative belief to one grounded in physical
understanding and solid data.
Dr. Lean's research into the
distribution by
wavelength of electromagnetic radiation, which
produces the
Sun's total brightness output, is considered by
colleagues to
be a breakthrough discovery. Dr. Lean showed that,
while
emissions from the ultraviolet portion of the spectrum
account
for only one percent of the Sun's total brightness, they
actually affect the variations in total brightness that
occur as the Sun's activity waxes and wanes by about 20
percent.
Because
the ultraviolet radiation
from the Sun is the primary source of
energy for the Earth's
atmosphere, this finding of the
disproportionately large role
of the UV spectrum in solar
brightness variations prompted a
series of studies that
investigated how ultraviolet light modulates
the upper and
lower atmosphere. Subsequent coupling within the
Earth's
atmosphere suggested a mechanism for amplifying solar
effects
on climate over alternative proposed mechanisms based
on less
physical models.
Dr. Lean is a recognized expert
on the Sun's role
in global climate change and has testified
before the US Senate
Committee on Energy and Natural Resources
on the Science of Climate
Change and the US Senate Committee
on Commerce, Science and
Transportation Subcommittee on Science,
Technology and Space on
this topic.
Dr.
Lean received a B.Sc. (Hons),
Physics in 1974 from the
Australian National University, Australia,
where she was
awarded the Priscilla Fairfield Bok Prize as the
university's
best female student in the field of science. In
1980, she
received a Ph.D. in atmospheric physics in 1980 from
the
University of Adelaide, Australia.
Dr. Lean is a member of the American
Geophysical Union, the International Association of Geomagnetism
and Aeronomy, the American Astronomical Society-Solar Physics
Division, and the American Meteorological Society. She currently
serves as a member of the National Research Council's Board on
Atmospheric Science and Climate and the National Science
Foundation's
(NSF's) Advisory Committee for Geosciences, and
has previously
served on numerous panels and advisory groups
for NASA, NRC and
NSF.
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