southwest monsoon 2010

219 Pages·2011·6.92 MB·English

GOVERNMENT OF INDIA
IMD Met. Monograph No. :
MINISTRY OF EARTH SCIENCES
Synoptic Meteorology No. 10/2011
INDIA METEOROLOGICAL DEPARTMENT
Monsoon
2010
AA RReeppoorrtt
Edited by
Ajit Tyagi, A. B. Mazumdar and D. S. Pai
Monsoon
2010
AA RReeppoorrtt
DESIGNED & PRINTED AT
OAOTHDFFE DFMI ICMTEIEETO ETONEOFAOR LTRO HDOLEIROLOEGCGYTI C(ORAREL S GOEEFANFREICCREHA )PL,P RUENSES, NDIIA METEOROLOGICAL DEPARTMETN ADNDAITTIIOONNOAAFLLF DICCILREIE MOCAFTT OTEHR CE GEENNTREREAL
NATIONAL CLIMATE CENTRE OF METEOROLOGY (RESEARCH),PUNE
NATIONAL CLIMATE
CENTRE
IMD Met Monograph:
Synoptic Meteorology No: 10/2011
Government of India
India Meteorological Department
Edited by
Ajit Tyagi, A. B. Mazumdar and D. S. Pai
National Climate Centre
India Meteorological Department
PUNE- 411 005
INDIA
Copyright © India Meteorological Department, 2011
The right of publication in print, electronic or any other form reserved by the India
Meteorological Department.
Short extracts may be reproduced, however the source should be clearly indicated.
DISCLAIMER & LIMITATIONS
The contents published in this report have been checked and authenticity assured within
limitations of human errors.
India Meteorological Department is not responsible for any errors and omissions.
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List of Authors
Ajit Tyagi Director General of Meteorology,
India Meteorological Department
A. B. Mazumdar Additional Director General of Meteorology
(Research),
India Meteorological Department, Pune
Ananda Kumar Das, V.R. Durai, Office of the
S.D. Kotal, M Mohapatra, Naresh Director General of Meteorology,
Kumar, D. R. Pattanaik, S.K. Roy India Meteorological Department, New Delhi
Bhowmik, O. P. Singh, C. S.
Tomar, B. P. Yadav
D. S. Pai, O.P. Sreejith and A.K. Office of the
Srivastava Additional Director General of Meteorology
(Research),
India Meteorological Department, Pune
Medha Khole, Sunitha Devi. S. Office of the
DeputyDirector General of Meteorology
(Weather Forecasting)
India Meteorological Department, Pune
Manish Ranalkar Office of the
DeputyDirector General of Meteorology
(Surface Instruments)
India Meteorological Department, Pune
C
o n t e n t s

Acknowledgements
Preface
Executive Summary
Chapter- 1 Onset, advance and withdrawal of southwest monsoon
Chapter- 2 Semi Permanent Systems and Synoptic Features
Chapter- 3 Rainfall Statistics
Chapter- 4 Global and Regional Circulation Anomalies
Chapter- 5 Performance of Operational NWP Short Range Forecasts –
Southwest Monsoon 2010
Chapter- 6 Performance of Global Forecast System of IMD In the Medium
Range Time Scale During Summer Monsoon 2010
Chapter- 7 Performance of Extended Range Forecast during Southwest
Monsoon 2010
Chapter- 8 Verification of the operational and experimental Long Range
Forecasts
Chapter- 9 Features of Southwest Monsoon -2010 as observed In Satellite
Products
Chapter- 10 Utility of Automatic Weather Station (AWS) data for monitoring
and prediction of Cyclonic Disturbances during 2010
Chapter- 11 Summary and Conclusions
ACKNOWLEDGEMENTS
The editorial team could complete this report in time and in detail only
due to the whole hearted support of all the authors and co-authors of various
chapters of this report. The editorial team expresses sincere thanks to all of
them. The report was prepared in the Office of the ADGM(R), IMD, Pune.
The officers and staff of the Long Range Forecasting Section and National
Climate Center provided the technical assistance. We are particularly
thankful to Shri. S. M. Jamadar, Smt. Madhuri Musale, Smt. Latha Sridhar,
Shri. C.N. Shaligram, and Shri. Bhushan Patkar for their technical support.
We are also thankful to Shri. Philipose Abraham and other staff
members of the Printing and Documentation Section of the Office of
ADGM(R), IMD, Pune for designing, type setting and printing and publication
of the report. Our sincere thanks are also due to the officers and staff of
DGM (Hydromet), New Delhi for providing the station rainfall data
extensively used in this report.
PREFACE
The 2010 southwest monsoon season was a normal monsoon season with the season
(June-September) rainfall over the country as a whole of 102% of its long period average
(LPA). Out of the total 36 meteorological subdivisions, 31 subdivisions constituting 85% of
the total area of the country received excess/normal season rainfall and the remaining 5
subdivisions (15% of the total area of the country) received deficient season rainfall. The
monthly rainfall over the country as a whole during all the months of the season
except June was above the LPA value. The monsoon set in over Kerala on 31st
May, one day earlier than its normal date of 1st June and covered the entire country
by 6th July, earlier than its normal date of 15th July. However, the withdrawal of
monsoon from west Rajasthan was delayed and it commenced only on 27th
September compared to its normal date of 1st September. After 2002 (a deficient
monsoon year), this was the only year when no depressions formed over the Indian
monsoon region during the entire season. The monsoon rainfall was impacted by the
different regional and global features such as moderate to strong La Niña conditions over
equatorial Pacific, weak negative Indian Ocean Dipole and strong activities of Madden Julian
Oscillations in the equatorial Indian Ocean. The mid latitude wave activities north of Indian
region had also significant bearing on the rainfall distribution over the country. Thus the
2010 monsoon season witnessed many anomalous rainfall and circulation features
which call for more focused studies for improving our understanding of monsoon
and its predictability.
The main objective of bringing out the monsoon monographs every year is to document
various challenging aspects of each monsoon for quick reference to both operational and
research communities. The present report has been divided in different chapters each of
which discusses specific aspects of the 2010 southwest monsoon like progress and
withdrawal of monsoon, synoptic systems over the Indian region, large scale regional and
global thermal, circulation and convective features observed during the season, rainfall
statistics, forecasts at various scales and its verification etc. The report also includes
chapters on the utility of the satellite and automatic weather station data in monitoring and
prediction of monsoon. There is no doubt that this report provides useful and authentic
information about the 2010 southwest monsoon season.
I sincerely appreciate all the authors for their valuable contribution. I also appreciate
the efforts made by Dr. D. S. Pai and other officers/ staff of the office of the ADGM(R ), IMD,
Pune in bringing out this met. monograph, which is sixth in the series of monographs.
Ajit Tyagi
Director General of Meteorology
India Meteorological Department
Executive Summary
1 Document title Monsoon 2010 Report
2 Document type Meteorological Monograph
3 Issue No. Synoptic Meteorology No.10/2011
4 Issue date 17.02.2011
5 Security Classification Unclassified
6 Control Status Unclassified
7 Document type Scientific Report
8 No. of Pages 212
9 No. of Figures 131
10 No. of references 28
11 Distribution Unrestricted
12 Language English
13 Editors Ajit Tyagi, A. B. Mazumdar and D. S. Pai
Originating National Climate Centre, Office of ADGM (R), India
14
Division/Group Meteorological Department, Pune
Reviewing and Director General of Meteorology, India Meteorological
15
Approving Authority Department, New Delhi.
Operational Forecasters, Modelers and Researchers,
16 End users
Government Officials etc.
The 2010 southwest monsoon was a normal with season
rainfall of 102% of long period average (LPA) over the
county as a whole. Monsoon set over Kerala close to its
normal date but covered the entire country nearly one
week before the normal date. No break events were
observed and no depressions were formed during the
season. In association with the evolution of La Nina
during the season, the rainfall of the second half of the
season was more than that in the first half. Monthly
rainfall except in June was above its LPA. The rainfall
over most of the subdivisions, except 5 (deficient)
17 Abstract
subdivisions over eastern part of the country was normal
or excess. Region wise, rainfall over south Peninsula
was excess and that over northeast India was deficient.
The rainfall over northwest India and central India was
normal. The first 10 chapters of this report discusses
various important aspects of the 2010 SW monsoon such
as the rainfall, regional and global features,
verification of forecasts at different temporal and
spatial scales, satellite & AWS analysis of the
events etc. The summary and conclusions of the
report are given in the Chapter 11.
Southwest Monsoon, La Niña, Multi-model Ensemble,
18 Key Words
Forecast Verification, Rainfall, Satellite Imageries.
1
ONSET, ADVANCE AND WITHDRAWAL
OF SOUTHWEST MONSOON
Medha Khole, A. B. Mazumdar, Sunitha Devi. S. and B.P. Yadav
The Monsoon Onset over Kerala (MOK) and the further advance of the South West
monsoon exhibit inter annual as well as intra seasonal variability. The advance of the
monsoon is often not very systematic and regular. It is marked by phases of rapid advance
and periods of hiatus in the advance. These phases are largely modulated by strength of the
south westerly winds [cross equatorial flow] over north Indian Ocean, which, in turn, is
governed by placement and intensity of components of monsoon and also the tele-
connections of monsoon. This chapter discusses the various meteorological aspects of
onset, advance and withdrawal of southwest monsoon 2010.
1.1 Arrival of southwest monsoon current over the Andaman Sea
Southwest monsoon set in over the Andaman Sea on 17th May, 3 days prior to
normal date in association with a severe cyclonic storm (Laila, 17th–21stMay 2010) over the
Bay of Bengal. The southwest monsoon further advanced over parts of Comorin area and
some more parts of Bay of Bengal on 21st May and thereafter, there was a hiatus in the
monsoon advance lasting for more than a week, due to a temporary weakening of the cross
equatorial flow.
1