One day in 1988, life changed for the India Meteorological
Department (IMD), a hoary institution founded in 1875 by a British
government growing increasingly panicky after three years of bad weather
destroyed harvests in its most valuable colony.
A tropical
cyclone in Calcutta (now Kolkata) in 1864, and two famines in 1866 and
1871 due to the failure of the monsoon were enough to persuade the
British that a single organization was needed, one that would peer into
the skies, across the seas and into the ground, and divine the
likelihood of another meteorological disaster.
The IMD headquarters in New Delhi.
Like
many institutions founded in the early days of British rule in India,
IMD was based in Kolkata. It was headed by Henry Francis Blanford, a
paleontologist, weather watcher and member of the Royal Geographical
Society. For the next 113 years, headed by men from Gilbert Walker,
considered by many to be the “brightest meteorologist ever”, to S.K.
Banerji, the first Indian boss of the organization, from British rule
through independence, IMD would attempt to predict the future, for the
ears of the government only. India
Meteorological Department is charged with forecasting the annual
monsoon. So why do its predictions go spectacularly wrong sometimes?
Here’s a look.
That
day in 1988, under then director general S.M. Kulshrestha, India’s
weather office dropped its habitual veil of secrecy and went public with
its prediction that the monsoon rains that year would be “excellent”.
It was right. Rainfall was indeed above average that summer. Since then,
the Met department, as it is popularly known across the country, has
lost its reputation as a reliable soothsayer—if it ever had one.
Officials at the IMD observatory in Pune.
Even
in 1988, IMD wasn’t exactly the embodiment of accuracy: for instance,
it told the government that rains would be normal in 1986. They were 13%
below normal. It said the loss would be made up in 1987, which ended up
seeing India’s worst drought.
Still, IMD’s debut on the public
stage set off a chain of events that changed the way the department
approached the iffy science of weather forecasting and the equally
recondite art of engaging with the public.
Since then, the weather
office has weathered the phenomenon called El Nino, once a minor
variable and now an entire equation unto itself; two reworkings and an
abandonment of its trusted weather models; and lay and scientific
criticism of its forecasts. It has also promised to abandon its
century-old reliance on statistics-based forecasting for the emerging
global trend of so-called dynamical forecasting.
In 2012, when
every day seems to push India closer to a drought, despite the weather
office’s insistence that the weak rainfall has not yet reached drought
levels, it looks like IMD would’ve been better off not going public with
its forecast in the first place, but in the late 1980s, the step might
not have seemed so drastic. “It wasn’t the media spectacle that we see
today,” said Ajit Tyagi, a former director general of IMD, referring to
the department’s annual forecast and updates. “It never made it to the
papers and was just an internal memo to the government.”
Predicting the unpredictable
IMD’s seismological observatory.
The
overwhelming importance of the south-west June-September monsoon, which
provides 70-80% of the country’s annual rainfall, to both Indian
agriculture and the economy has made it the focus of the efforts of at
least three generations of meteorologists—both Indian and British. While
the relative contribution of agriculture to the Indian economy may have
come down from well over 60% in colonial India to a little over 14% in
2011, it continues to be the main source of employment for more than 60%
of India’s workforce.
While droughts no longer necessarily
mean famines, a poorly distributed network of reservoirs, an inefficient
system transporting agricultural produce from farm to market, and the
lack of the right kind of seeds and fertilizers mean that poor rain
often translates into higher food prices, and hits hard rural
households, many of which make a living from farming. The monsoon, then,
is a key variable in economic calculations.
The monsoon has
always posed a strange conundrum: it is a sea breeze so regular that in
three out of every five years of the 100-odd that meteorologists have
maintained actual weather records, the total rainfall has remained
within 10% of 88cm. Yet, even a seasoned forecaster aided by gluttonous
supercomputers measuring windspeeds at various heights, surface
temperatures, heat patterns in the Pacific as well as the Indian Ocean,
can’t predict, even in late May, whether India will receive normal rains
in June. For over a century, IMD’s rather thankless task has been to
navigate a fine line between the certain and the unknowable.
An operator observes earthquake data at IMD’s seismological observatory in Pune.
Today’s
forecasters at IMD are usually postgraduates in science who have to
pass an examination administered by the Union Public Service Commission.
Once admitted, they can choose to be a forecaster or an
instrumentalist, specialists who manage weather stations.Those who choose to be forecasters follow in a long line of weather predictors.
Since
the 1680s, European scientists such as Edmond Halley—after whom
Halley’s Comet is named—have expounded on the patterns of the monsoon.
However, in 1909, it took the genius of a Cambridge mathematician
Gilbert Walker, later IMD director general, to draw a statistical
relationship between the Indian monsoon and the snowfall in the
Himalayas in May; the atmospheric pressure in South America between
March and May, and Mauritius in May; and the rainfall in Zanzibar in
April and May. Though he never lived to see his theory confirmed, Walker
was the first to suggest that the Indian monsoon was the net result of a
global, interconnected tussle between the atmosphere and the ocean.
Walker
presciently noticed that a cyclical swing in atmospheric pressure
between Darwin in Australia and Tahiti in the western Pacific Ocean had
something to do—he couldn’t precisely say what—with the occurrence of
droughts over India; the phenomenon became known as the Southern
Oscillation.
The southern sea breeze
In the 1950s,
Walker’s ideas were linked to another centuries-old anomaly, wherein
every three-seven years the waters in the Pacific Ocean off the coast of
Peru turned unusually warm, especially around Christmas, and disrupted
fish catches, an irksome phenomenon that South American fishermen
referred to as El Nino. “Among the great discoveries of meteorology was
noting that El Nino and the Southern Oscillation (ENSO) are related, a
coupling of the sea and sky, and to think that this was intimately
connected to droughts over India, several thousands of kilometres away,
was fantastic,” said Krishna Kumar, a senior scientist at the Indian
Institute of Tropical Meteorology, Pune, who’s studied the ENSO
phenomenon for decades.
A self-recording rain gauge being tested at an IMD observatory
The
Indian who accidentally brought the Southern Oscillation and the El
Nino indices to public attention and midwifed IMD’s exposure to its
inclement future wasn’t a meteorologist. A cryogenic expert with the
department of space, and then secretary in the department of science and
technology, Vasant Gowarikar had an omnivorous appetite for science. He
created a population prediction model and authored a comprehensive
encyclopaedia on fertilizers. Gowarikar led the development of a weather
model that crunched the magnificent unpredictability of the monsoon
rainfall into 16 weather variables, including the North Atlantic Sea
surface temperature and the El Nino ocean index, and in 1988 used this
to make that first publicized forecast.
“When I became
secretary in the department of science and technology, I found that 90%
of the things were already there,” Gowarikar told Down To Earth
magazine in a 1993 interview. “It was really a question of somebody who
was not conditioned by the same mindset taking the lead.” Repeated
attempts by Mint to reach the 79-year-old Gowarikar were unsuccessful.
It
was in the 1980s that the Southern Oscillation theory, which had fallen
out of fashion with meteorologists, came back into vogue, with help
from Gowarikar.
A scientific assistant marks water samples from various parts of India at the air pollution section of the Met department.
Walker
may have invoked a handful of parameters, but Gowarikar took the lead
at developing a forecast model with about 200 factors—some as strange as
the surface temperature at De Bilt in Holland—all of which had been
tested, sifted, abandoned, resurrected and statistically linked to the
performance of the south-west monsoon. IMD in the course of time had
shifted headquarters from Kolkata to Pune, then Shimla, and finally to
Delhi in 1944.
Modernization
The weather office’s
forecasting centre in the heart of Lutyens Delhi looks and is as
futuristic as it should be. The visible part of this is a multitude of
flatscreen monitors. The hidden part of it is the alliance IMD entered
into with French weather agency Meteo France to harness trillions of
bytes of supercomputing power to assimilate and predict data from across
the world, to generate hourly and daily forecasts. Every day, the IMD
website records where rainfall is likely across India, and, by evening,
it’s possible to know exactly how much rainfall each district received
during the day. “There’s been a great improvement in the way we’ve made
data accessible to the general public,” said L.S. Rathore, current
director general. “In fact, even Pakistan relies on our website for
their monitoring and forecasting purposes.”
IMD has a network of
around 6,000 rain gauges, of which it relies primarily on about 2,000.
It has also invested substantially—no numbers are available—in
transmitting the measurements of rainfall, windspeed, surface
temperature and cloud patterns from India’s fringes to IMD’s district
and state headquarters. “IMD was one of the first organizations to
employ everything from telegrams to computerized switching networks,
satellite transmission, etc.,” said S.C. Bhan, spokesperson for the
agency in Delhi.
Previously, IMD forecasters would be buried in a
flurry of charts detailing the exact windspeeds—down from the surface to
the stratosphere—and rainfall data from the 2,000 or so stations that
would gush in every four hours. “It was then a matter of calculated
guesswork,” said A.K. Bhatnagar, a former deputy director general with
IMD. “To prepare a usable forecast, you had to apply your experience.”That
would mean knowing the local weather history and finding out if there
were anomalies—such as a freak wind shear, or unexpected excess rain in a
neighbouring district. In Met jargon, such forecasts were called
“synoptic forecasts”, and, even today, IMD places a premium on synoptic
forecasts for determining the likelihood of rain, storms and cyclones.
However, the punctiliousness of its data gathering and the sturdiness of
its website notwithstanding, several experts say IMD is yet to achieve
the original objective with which the British founded it: forecasting a
drought.
In 2007, IMD introduced a new statistical forecasting
system called ensemble forecasting, using five predictors from April
research and three more from May. In an approach that would befuddle
even Wall Street financial wizards, combinations of all parameters are
mathematically crunched. Using the first five parameters, it throws up
31 different models, and those which best tally rainfall during a common
period in the past are selected. Each of them is given a further
statistical weight, just as food articles and consumer goods are given
different weights in computing inflation, which in turn generates a new
hypothetical model. “That’s the one we finally use,” said Madhavan
Rajeevan, a pioneer of the ensemble technique and a former head of IMD’s
forecasting division. “This, too, couldn’t predict the 2009 drought,
but it did indicate that rainfall would be dramatically less. That’s a
victory in itself.” Still, IMD has plenty of critics. “It doesn’t
make scientific sense to encapsulate all Indian rainfall into one
number,” said a senior weather scientist, who didn’t want to be
identified. “No other country reduces its rainfall to a number; most of
them give regional indicators.”
Perhaps it’s criticism like this that’s resulted in a Rs.
400 crore programme called the monsoon mission. The aim is to develop a
model that relies on actual weather conditions on any given day, rather
than statistics, to simulate the output. “We need as much data as
quickly as possible, more weather radars, automatic weather stations as
well as massive amounts of compu ting power,” said Shailesh Nayak,
secretary, ministry of earth sciences. “More than half of it is done.”Perhaps
that model, which officials say will be running by 2017, can finally
resolve the century-long quest to master the monsoon.
Source - Live mint
Author - jacob.k@livemint.com
Photographs - Abhijit Bhatlekar/Mint
