Maniac Talk by P.K. Bhartia -- March 28, 2012
A "story teller" is what I would call our Maniac talk speaker Dr P. K. Bhartia. Dr. Bhartia has been involved with the remote sensing of ozone for many years. In this exciting series of Maniac talks, Dr Bhartia's talk was yet another rare and complete story of its own kind. Woven together meticulously, he presented the history, science, and technicality behind satellite-based retrievals of total column ozone amount from the past 45 years.
He began by introducing early ground-based measurements by Dobson based on the sun-photometry technique. Next he moved on to the theoretical work of Dave and others in the 1960s, which established the possibility of ozone remote sensing from space and introduced concepts such as Lambert-equivalent reflectivity, which are still in use today for applications not envisioned when they were created. From there he discussed the Total Ozone Monitoring Spectrometer (TOMS), which has flown on several satellites, and related instruments.
The
last section of his talk concerned the discovery of the Antarctic ozone hole by Joe Farman and colleagues in the early 1980s, and the story of its confirmation and
monitoring with the TOMS data, including the trials and tribulations which
happened while trying to confirm whether or not this unexpected (at the time)
phenomenon was real.
Dr. Bhartia offered a chance, probably
the first for many in audience, to look through the lenses of a retrieval
expert on how NASA both did and did not discover the famous Antarctic
"Ozone Hole" from its satellite observations. It turns out that Dr
Bhartia and his colleagues did see very low ozone values from the TOMS
instrument in summer of 1984 when they processed the data from October 1983
(due to available computer power at the time, there was a considerable lag
between data acquisition and processing). The data was quickly scrutinized and
instrument, algorithm and satellite errors were ruled out. For the lack of
agreement between ground based S. Pole data and the satellite observations, and
the lack of a priori ozone profile for low ozone concentration (below 225 DU), the
satellite algorithm flagged out the low Ozone retrievals! In August of 1985, Dr Bhartia presented these
results at the Symposium on Dynamics and Remote Sensing of the Middle
Atmosphere held in Prague. However, the results were not published as they were
thought to be a meteorological anomaly of some sort. This story behind the
story of Ozone hole was a unique peek into a very interesting regional
phenomenon that was discovered, recognized, and mitigated to avoid a global
impact. The speaker, Dr Bhartia, very conscientiously made his point on how
important it is for us to learn the lessons from history, and insure our future
with regards to climate change!
by Falguni & Andy --- Edited by Pawan
