Why
do you think your paper is highly cited?
The paper describes results from a major international
experiment that used aircrafts, satellites, computer models,
and advanced instrumentation to characterize the composition
of the North American troposphere (0-12 km) in great detail
and followed the North American
pollution
outflow over the Atlantic to study its transport and
transformation. Many of the findings were unique and
unexpected.
Does
it describe a new discovery, methodology, or synthesis of
knowledge?
An unexpected finding was the observation of frequent
episodes of Asian pollution over North America. The upper
troposphere (7-12 km) was found to be as polluted as the
lower troposphere and the lightning-induced nitrogen oxides
(LNOx) source was nearly four times larger than
expected. This was one of the first experiments to
extensively validate satellite observations of tropospheric
composition and combine these with in situ airborne
and surface data using complex models.
Would
you summarize the significance of your paper in layman’s terms?
Both industrialized and developing nations are
contributing enormously to the burden of atmospheric
pollution. In many cases, this burden now overwhelms the
natural cycles. These pollution sources are so large that
they can be transported on intercontinental scales,
impacting air quality and regional climate thousands of
kilometers downwind. Currently, no regulatory mechanisms
exist to control such pollution influences.
How
did you become involved in this research, and were there any
problems along the way?
I have studied the composition and chemistry of the
atmosphere for the past 25 years and have published more
than 190 scientific papers and edited one textbook in this
area. My primary research goal has been to better understand
the impact of human activities on the chemistry and climate
of the earth’s atmosphere through direct observations and
data analysis.
I was the chief scientist of the INTEX-A experiment and
closely involved in its conception and development. Because
of the large resources required, it was necessary to develop
a consensus among the broader scientific community in order
to secure funding. Advanced scientific instrumentations from
many institutions around the world had to be assembled to
achieve mission objectives. The experiment was performed a
year late because of delays in satellite launches. However,
in the end, all problems were overcome and a very successful
mission was performed.
Where
do you see your research leading in the future?
The chemical composition of the atmosphere is rapidly
changing, with serious consequences affecting both air
quality and climate change. A follow-up to this experiment
will be performed next year (2008) to investigate the impact
of Eurasian pollution transport on the pristine Arctic, a
region known to be extremely sensitive to environmental
change. Another area in which this research is headed
involves observing the chemical composition of the earth’s
atmosphere remotely from space.
Are
there any social or political implications for your research?
Climate change (global warming) is a topical issue of
much debate and concern, as it will impact various regions
of the earth unevenly and holds the potential for
catastrophic impacts. Pollution also adversely impacts human
health and agricultural productivity. Because these
phenomena are simultaneously local and global, there are
many political implications that will require nations to
work together. Politically, clean air remains a priority in
all nations of the world.
Dr. Hanwant B. Singh
NASA Ames Research Center
Moffett Field, CA, USA
