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Prof. P. KOTESWARAM AND 50 YEARSOF TROPICAL EASTERLY JETSTREAM
Dr. P.V.JosephProfessor Emeritus, Department of Atmospheric
Sciences, Cochin University of Science and Technology
e-mail: [email protected]
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Prof Pancheti Koteswaram was born on 25 March 1915 He obtained
D.Sc degree in Physics of the University of Madras in 1939 In 1940
he joined the India Meteorological Department (IMD) as Asst.
Meteorologist at Calcutta (now Kolkata) In 1969 he became Director
General of Meteorology of IMD and continued in the post till 1975.
During this period as permanent representative of India, he was
elected vice- president of WMO in 1971
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High lights of Prof. Koteswarams Work in IMD (1940-1975) Prof.
Koteswaram learned Meteorology while working in the operational
offices of IMD as at that time there was no formal met. training
school in IndiaDuring his 35 years in IMD he worked hard to improve
IMD and make it a world class institution in weather forecasting
and warning services, in meteorological research and in
international co-operationPersons like me who were associated with
him for many years knew him as a good operational meteorologist
(forecaster), a good research worker, a good administrator cum
manager and above all a person deeply interested in the welfare of
the officers and staff working with him
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High lights of Prof. Koteswarams Work in IMD (Contd.) As
Director of aviation services in IMD Prof. Koteswaram set up
extended analysis and prognosis centers at Bombay, Calcutta, Madras
and New Delhi As Deputy DGM at Pune he developed a computerized
Climatological data center at that office He persuaded the Global
Atmosphere Research Programme (GARP) to take up research on Asian
summer monsoon. His voice was heard and an agreement was reached
that MONEX (Monsoon Experiment) would be a part of the First GARP
Global Experiment (FGGE) to be conducted late in 1970 s
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High lights of Prof. Koteswarams Work in IMD (Contd.) The most
important work of Prof. Koteswaram as DGM of IMD was to organize
cyclone detection, tracking and warning as an efficient operational
system He set up 10 Cyclone Detection Radars (S-band), 4 along the
west coast and 6 along the east coast of India (IMD is now
converting them to Doppler radars) He also worked very hard and set
up Cyclone Distress Mitigation committees in all the coastal states
of India comprising of administrators (Government), engineers and
meteorologists with the task of drawing up contingency plans,
educating the public, prompt evacuation of costal population from
cyclone risk areas, construction of cyclone shelters and arranging
for fast and reliable communication of cyclone warnings
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Prof. Koteswaram In the International Arena He was Visiting
Professor at the University of Miami in 1965, and worked at the
National Hurricane Research Laboratory and the National Centre for
Atmospheric Research at Boulder in USA. During the Sixth World
Meteorological Congress in 1971, as a follow-up to the UN
Resolution on Tropical Cyclones which followed the unprecedented
loss of life in Bangladesh, he was designated as chairman of a WMO
committee of experts to develop a plan that launched the WMO
Tropical Cyclone Project. As a member of the WMO Commission for
Aeronautical Meteorology he contributed actively to the preparation
of Procedures for Air Navigation Services: Meteorology
(PANSMET).
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Research contributions of Prof. Koteswaram Dr Koteswaram has
made significant contributions not only to Indian meteorology and
economic development but also to international meteorology.
During 19551956, he discovered the existence of the Tropical
Easterly Jetstream (Tellus 1958) and found that it was a constant
feature between the East China Sea and the Atlantic ocean during
the Asian summer monsoon, being strongest over the Indian
subcontinent. This discovery won him international recognition and
acclaim. We will see more about this feature soon
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Prof Koteswaram receives Padma Bhushan It was a proud moment for
Prof Koteswaram, for his family and friends in the meteorological
and hydrological communities when the President of India conferred
on him the prestigious title of Padma Bhushan in January 1975, in
recognition of his outstanding services in the field of atmospheric
sciences.The commitment, determination and foresight of Prof
Koteswaram as well as his affable personality should be a source of
inspiration to meteorologists, hydrologists and indeed the whole
scientific community.
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Tropical Easterly jet Stream at 200 hPa on 25 July 1955 Jet axes
marked by heavy broken lines. The subtropical Westerly Jetstream is
seen at top left. from Koteswaram (1958), TELLUS
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RS/RW stations whose data were used for the study
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Schematic model of the vertical circulation in the Asian summer
monsoon - Koteswaram (1958), Symposium, Monsoons of the World
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Importance of the discovery of TEJ Research on monsoon in India
till the 1950s was restricted to the Indian subcontinent.
Researchers studied features of the Indian monsoon like Monsoon
Depressions, Monsoon Trough and its north south oscillations,
Active and Break monsoons, influence of orography on rainfall,
off-shore troughs and vortices and droughts and floods in the
monsoon. Discovery of the TEJ showed for the first time that a
feature connected with the monsoon (TEJ) extended from the south
China sea to west Africa In the 1960 s and later several
discoveries came making Indian monsoon a global feature
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1) Tropical cyclones are conspicuous by their absence over the
areas overlaid by the Easterly Jetstream (Arabian sea and Bay of
Bengal). Such storms generally occur in these two sea areas either
before the setting of the Easterly Jet (pre-monsoon season) or
after its withdrawal (post-monsoon season) . We now know that it is
so because of the high vertical wind shear under the TEJ during
monsoon.In his paper presented at the Symposium of Monsoons of the
World where Prof. Koteswaram gave a schematic model of the vertical
circulation of the monsoon, he had suggested two ideas
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2) The location of the Easterly Jetstream seems to influence the
pattern of monsoon rainfall. Climatological distribution of rain
over south Asia indicates its occurrence down stream from the
region of highest winds to the left of the jet stream and upstream
to the right. This is found to be true even on individual
occasions. The concept of a high speed center in TEJ and the
convergences and divergences in its four sectors (Jet entrance and
Jet exit both left and right) have been illustrated in a recent
article by Webster and Fussulo (2003) in a six volume encyclopedia
of Atmospheric Sciences edited by JR Holten, JA Curry and JA Pyle
.
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The Globalisation of Indian Monsoon continued during the 1960
s.Ramaswamy (Tellus 1962) showed that breaks in the Indian summer
monsoon as a phenomenon of interaction between the Easterly and the
Subtropical Westerly JetstreamsResearch by Bunker (1965), Joseph
and Raman (1966), and Findlater (1969) showed that lower
tropospheric monsoon circulation is dominated by a cross equatorial
Low Level Jetstream
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Deep troughs in Westerlies intrude into India during Break
Monsson in the middle and upper troposphere (Ramaswamy 1962,
Tellus)
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Cross-equatorial Low Level Jetsream wind (Findlater 1969)
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Horizontal and vertical wind shears in Low Level Jetstream over
India in July- Joseph and Raman 1966
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Work in late 1960s by Koteswaram showed that the meridional wind
in the TEJ has maximum strength over the equator. If he knew this
in 1958 and if he knew about the cross equatorial Low Level
Jetstream he would not have put the downward limb of the Reverse
(Monsoon) Hadley Cell at the equator.
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Zonal winds in mean TEJ at 150 hPa. Isotachs at 2m/s intervals-
from Koteswaram (1969). (Easterlies by dotted lines)
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Meridional winds in mean TEJ at 150 hPa. Isotachs at 2m/s
intervals- from Koteswaram (1969) (Northerlies by dotted lines)
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Weakening of Monsoon Wind Flow through Peninsular India1950 to
2003 at 850hPa (1.5 Km ASL)Joseph and Anu Simon, (2005) Current
Science & Clivar Exchanges
Chart1 (2)
9.7263425
8.9108375
9.53936
9.53623759.9789092857
11.1180759.9982532143
9.62039510.3031767857
11.401117510.5543896429
9.8617510.5820232143
11.045302510.8438267857
11.2978510.9486221429
9.729672510.7202142857
12.950710.6269471429
10.353962510.2757275
9.80226259.7402289286
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10.5473059.6415432143
9.57570759.5105357143
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9.400679.5800814286
9.34999.5073032143
10.56271259.4426292857
8.08085259.4213507143
10.03785759.404
9.122999.45451
9.39447259.2068732143
9.2792159.3042360714
9.703478.9636321429
8.8292558.8909414286
8.76239258.8251164286
7.653638.9606053571
8.6141558.9354525
8.93369758.8499096429
10.22763758.6888232143
9.52749.1719835714
8.2304559.12496
7.63478759.0084292857
11.03575258.90739
8.284998.6490396429
8.11798258.7919528571
9.52036258.9135403571
7.71894758.6736628571
9.23084758.7221060714
8.48598.8633546429
9.35661
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Chart1
9.7263425
8.9108375
9.53936
9.53623759.9789092857
11.1180759.9982532143
9.62039510.3031767857
11.401117510.5543896429
9.8617510.5820232143
11.045302510.8438267857
11.2978510.9486221429
9.729672510.7202142857
12.950710.6269471429
10.353962510.2757275
9.80226259.7402289286
9.208889.8455535714
8.5867659.3668292857
7.549369.2025442857
10.4669459.2689285714
9.599639.3521075
9.20396759.3205142857
10.26695259.7487921429
9.79113259.6214725
8.36561259.6134428571
10.5473059.6415432143
9.57570759.5105357143
9.54342259.6207614286
9.400679.5800814286
9.34999.5073032143
10.56271259.4426292857
8.08085259.4213507143
10.03785759.404
9.122999.45451
9.39447259.2068732143
9.2792159.3042360714
9.703478.9636321429
8.8292558.8909414286
8.76239258.8251164286
7.653638.9606053571
8.6141558.9354525
8.93369758.8499096429
10.22763758.6888232143
9.52749.1719835714
8.2304559.12496
7.63478759.0084292857
11.03575258.90739
8.284998.6490396429
8.11798258.7919528571
9.52036258.9135403571
7.71894758.6736628571
9.23084758.7221060714
8.48598.8633546429
9.35661
8.6240925
9.1067225
U Wind (m/s)
Mean U=9.45m/sTrend line y = -0.0312x + 10.309Corr. Coeff. =
-0.46
Sheet1
19509.736.8147089907-0.4618808657
19518.916.8147089907
19529.546.8147089907
19539.546.81470899079.98
195411.126.814708990710.00
19559.626.814708990710.30
195611.406.814708990710.55
19579.866.814708990710.58
195811.056.814708990710.84
195911.306.814708990710.95
19609.736.814708990710.72
196112.956.814708990710.63
196210.356.814708990710.28
19639.806.81470899079.74
19649.216.81470899079.85
19658.596.81470899079.37
19667.556.81470899079.20
196710.476.81470899079.27
19689.606.81470899079.35
19699.206.81470899079.32
197010.276.81470899079.75
19719.796.81470899079.62
19728.376.81470899079.61
197310.556.81470899079.64
19749.586.81470899079.51
19759.546.81470899079.62
19769.406.81470899079.58
19779.356.81470899079.51
197810.566.81470899079.44
19798.086.81470899079.42
198010.046.81470899079.40
19819.126.81470899079.45
19829.396.81470899079.21
19839.286.81470899079.30
19849.706.81470899078.96
19858.836.81470899078.89
19868.766.81470899078.83
19877.656.81470899078.96
19888.616.81470899078.94
19898.936.81470899078.85
199010.236.81470899078.69
19919.536.81470899079.17
19928.236.81470899079.12
19937.636.81470899079.01
199411.046.81470899078.91
19958.286.81470899078.65
19968.126.81470899078.79
19979.526.81470899078.91
19987.726.81470899078.67
19999.236.81470899078.72
20008.496.81470899078.86
20019.366.8147089907
20028.626.8147089907
20039.116.8147089907
9.45
50
50515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798990123
8.374310.1119.619499.3583410.17310.80611.23138.717879.366068.7073710.759710.14098.088159.907478.967759.755348.199599.049848.481638.834419.7922113.59747.8378510.22589.7328312.07088.763398.8696311.78868.6409311.34789.173078.621778.4156212.397710.65139.88698.363078.469310.287610.32437.884446.7574212.355211.26417.289397.891928.022888.2891110.00779.5616511.47518.765648.58916
14.359411.426413.056611.862612.797411.198514.8713.688515.751116.169710.668915.5714.955312.03668.7766314.034110.96413.451114.024514.099612.832212.023613.359213.872712.2889.1951613.171712.913211.586111.196313.40412.014111.711210.872410.881410.494911.76299.8871811.743510.594212.502314.81911.26919.8025615.221811.811511.531313.267410.384412.551211.884412.398910.304211.5448
9.3120911.453812.089813.417311.174511.415212.105811.89110.808712.703712.384413.106110.968111.931813.3726.449527.9323513.286211.98267.5380411.99979.3300610.200411.935312.852811.592510.071110.015113.610310.75711.572212.288313.379911.245412.230310.491210.22069.56068.8601811.397211.959312.497410.9735.9313911.6188.683269.1059412.64257.161029.10979.7389510.899111.29339.98246
6.859582.652153.391553.5067110.32745.061887.397375.149638.255357.610635.1056912.98587.40435.333185.719144.10813.10156.080643.909796.343826.44374.213472.0656.155423.42925.315235.596495.601675.265851.729183.827433.016493.865026.583443.304483.679623.179172.803675.383643.455796.124652.908763.92232.456.039115.355813.942774.148675.041265.254792.75862.653344.133236.31047
9.72634258.91083759.539369.536237511.1180759.62039511.40111759.8617511.045302511.297859.729672512.950710.35396259.80226259.208888.5867657.5493610.4669459.599639.203967510.26695259.79113258.365612510.5473059.57570759.54342259.400679.349910.56271258.080852510.03785759.122999.39447259.2792159.703478.8292558.76239257.653638.6141558.933697510.22763759.52748.2304557.634787511.03575258.284998.11798259.52036257.71894759.23084758.48599.356618.62409259.1067225
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Number of Break Monsoon Days in a Monsoon Season(wind through
India less than 9m/s) during 1950 to 2003Joseph and Anu Simon,
(2005) Current Science & Clivar Exchanges
ch-15-new (2)
15
9
21
24
15
5
25
16
24
31
18
26
17
8
17
14
6
19
20
21
11
16
11
21
10
16
11
5
9
24
16
7
9
9
7
1
23
1
7
6
16
20
18
6
27
10
19
25
13
16
10
10
8
Zonal wind >=15m/sMean days - 14.5 daysTrend line - y =
-0.1168x + 17.662
ch-13-new
36
30
36
43
35
20
49
34
47
59
37
59
42
22
24
21
17
37
37
32
21
33
22
43
28
26
21
26
37
32
30
31
31
22
38
13
32
9
16
13
30
39
29
24
51
19
30
44
15
31
25
26
22
Zonal wind >=13m/sMean days - 30.7 daysTrend line - y =
-0.2524x + 37.493
y =
ch-11-new
66
73
70
63
66
66
55
77
53
52
75
34
72
73
76
77
81
55
62
72
61
67
81
67
77
73
82
69
57
75
61
70
74
83
61
82
78
88
93
74
61
63
76
75
47
91
87
66
96
76
75
70
90
Zonal wind
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Mean 100 hPa Zonal Wind 1950-1959(Top) and 1990-1999(Bottom)
using NCEP data (after Sathiyamoorthy 2005)m/s
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m/sMean 100 hPa Zonal Wind (1950-1959) minus mean of (1990-1999)
using NCEP data (after Sathiyamoorthy 2005)
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THANK YOU
