The Indian Monsoon and
Seasonal Foreshadowing:
The Birth of Seasonal Forecasting
Long-Term Stability of the Indian Summer Monsoon
Climatological Onset Dates
Monsoon sweeps north and west
15 July
1 July
15 June
10 June
5 June
1 June
1 June
Britain’s fascination with the meteorology
of India
• India was Britain’s most important imperial and
economic possession. By the late 1860s India
absorbed 1/5th of all British exports, so its
economic importance was profound.
• India appeared to offer an ideal natural laboratory
for the science, and an ideal space in which to
demonstrate the political importance of science in
a global age.
Reference: Predicting the Weather: Victorians and the Science of Meteorology by
Katharine Anderson
Henry Francis Blanford
1st British Director (Imperial Meteorological Reporter) of the Indian
Meteorological Department (1875-1889)
‘Order and regularity are as
prominent characteristics of
our (India’s) atmospheric
phenomena, as are caprice
and uncertainty those of
their European
counterparts.’
Great Trignometrical Survey of India:
1840s onwards
Lambton's Great Theodolite used by
William Lambton and George Everest
George Everest
Great
Trignometrical
Survey of India
Blandford arrived in India in
1855 as part of the Great
Survey of India. Meteorology
had a particular bearing on one
of the trickiest challenges, the
triangulation of the wide plains
of the Indus region.
Calcutta Cyclone 1864
Massive storm surge devastated
the port and surrounding inland
regions:
• Over 70,000 deaths
• Loss of over 300,000 cattle
• Of 195 ships in Calcutta harbour,
only 23 were undamaged
• Salt losses of £141,000
• Overall losses in excess of £1M
From ‘The Indian Charivari’ – India’s equivalent of ‘Punch’: July 23, 1875
India holds the key to unraveling the laws of the
atmosphere!
Blanford argued that India offered a special situation for the study of
meteorology:
‘We are in the position of a commander who can find no eminence
from which he may gain a bird’s eye view of the combat.
Could we but find some isolated tract of mountain, plain and
ocean … girdled round by a giant mountain chain that should
completely shut in and isolate some millions of square miles of the
atmosphere, resting on a surface vast and varied enough to exhibit
within itself all those contrasts of desert and forest, of plain,
plateau and mountain ridge, of continent and sea, then the
progress of meteorology would be assured.’
Long-Term Stability of the Indian Summer Monsoon
and the Great Famine of 1876-78
Great Famine of 1876-78
Mass starvation and 6-10 million deaths. Over 5 million deaths in
the British territory. During that period Britain continued to export
grain from India.
Great Famine of
1876/78:
Conjunction of Politics
and Science
The Indian economy was
single-mindedly focused on its
grain harvests.
Indian taxes to administer the
country and pay dividends to
its investors depended entirely
on the monsoon rains.
"Disputed Empire“: Cartoon from Punch, 1877
Control of famine through
climate prediction would
mean that India could be
governed more effectively.
“On the Connexion of the Himalaya Snowfall with Dry Winds and Seasons of
Drought in India”. Henry F. Blandford, 1884, Proceedings of the Royal Society
‘.......the apparent dependence of the (1876) drought on the remarkable
and unseasonable persistence of dry north-west winds down the whole
of Western India.
The experience of recent years affords many instances of an unusually
heavy and especially a late fall of snow on the North-Western Himalaya
being followed by a period of prolonged period of drought on the plains
of North-Western and Western India.’
Snow-monsoon interactions
Model Sensitivity Study: No Snow versus Heavy Snow
~2week delay to
monsoon onset in
heavy Himalayan
snow case
No Snow
Heavy Snow
Turner & Slingo 2010
Looking further afield
• Blandford also noted that failed monsoon of 1877
was associated with abnormally high pressure in
countries surrounding the Indian Ocean.
• Contacted Charles Todd of South Australia who noted
that Australia had also experienced drought: ‘There
can be little doubt that severe droughts occur as a
rule simultaneously over the two countries’
• Concept of ‘teleconnections’ was born – the remote
influences on India of pressure variations in other
parts of the world.
• But were they just coincidences?
Sir Gilbert Thomas Walker
3rd British Director (Director General of Observatories) of the Indian
Meteorological Department (1904-1924)
‘I think that the relationships of
world weather are so complex that
our only chance of explaining them is
to accumulate the facts empirically.’
Pioneered statistical forecasting formed a ’human computer’ with
Indian staff performing a mass of
statistical correlations using data from
around the world
Introduced the terms Southern
Oscillation, North Atlantic Oscillation,
and North Pacific Oscillation
Correlations in Seasonal Variations of Weather
Memoirs of the Indian Meteorological Department
Dr. Gilbert T. Walker FRS
Simla, 1910-1915
Gilbert Walker’s regression equation:
Monsoon Rainfall = -0.20 (snow accumulation) – 0.29 (Mauritius pressure)
+0.28 (South American pressure) – 0.12 (Zanzibar rainfall)
where correlation (r) between observed and predicted rainfall is 0.58 – so potentially useful?
BUT:
Standard deviation of monsoon rainfall is only 2.76 inches and Walker argued that the
standard error described by this correlation was 2.76*Sqrt(1-r2) = 2.25inches.
‘This is not a very great reduction on a causal variation of 2.76 inches, and does
not look hopeful for the success of the method. But the unfortunate fact is that
correlation is of very little use for the purpose of forecasting unless the coefficients
concerned are very high.’
Gilbert Walker also looked at sunspot activity as a possible factor but without any success.
Seasonal ‘Foreshadowing’
G. T. Walker, 1930: Seasonal Foreshadowing, QJRMS
Sir Gilbert Walker: In general the object of prediction is to assist the
layman , and it is the opinion formed by him that decides whether
they succeed or fail. Hence I regard it as foolish to issue a prediction
except in the years when the indications of an excess or defect are so
strongly marked as to give a 4:1 chance of success. Even with a
coefficient of 0.75 this will occur only in about half the years, and as
the claim to “forecast” the seasons arouses the expectation of
annual prediction, I advocate the word “foreshadow” as expressing
a smaller ambition.
Sir Richard Gregory: No doubt this is the surest plan of securing
public confidence, for the press is more inclined to direct attention to
failures than to successes, however sound the principles of arriving
at correlation coefficients may be.
El Nino, Southern Oscillation
and the Walker Circulation
Walker & Bjerknes
‘Predictability of Monsoons’
J. G. Charney and J. Shukla, 1981
‘It is shown by numerical simulation that the variability of average
pressure and rainfall for July due to short-period flow instabilities
occurring in the absence of boundary anomalies can account for
most of the observed variability at mid-latitudes but not at low
latitudes.
On the basis of the available evidence it is suggested that a large
part of the low-latitude variability is due to boundary anomalies in
such quantities as sea surface temperature, albedo and soil
moisture, which, having longer time constants, are more
predictable than the flow instabilities.’
Possible Players in Monsoon Prediction
(+++ Level of confidence/knowledge)
• El Nino/Southern Oscillation (+++)
• Eurasian and Himalayan snow amounts (+)
• Indian Ocean sea surface temperatures and
heat content (+)
• Intra-seasonal variability e.g. active/break
cycles (++)
How far have we come in the last 130 years?
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