2021

RR No.

1/2021

CRS RESEARCH REPORT

Latha Sridhar Aradhana Kumari Divya Surendran

M.R. Badwaik

O.P. Sreejith D.S. Pai

India Meteorological Department, Pune

CLIMATE MONITORING & PREDICTION GROUP OFFICE OF THE HEAD, CLIMATE RESEARCH & SERVICES

INDIA METEOROLOGICAL DEPARTMENT SHIVAJINAGAR, PUNE - 411 005

N

Development of daily gridded rainfall data sets over the Indian

Islands at 1°x1° & 0.25°x0.25° spatial resolutions for the period

(1951-2020)

Development of daily gridded rainfall data

sets over the Indian Islands at 1°x1° &

0.25°x0.25° spatial resolutions for the

period (1951-2020)

By

Latha Sridhar, Aradhana Kumari, Divya Surendran, M.R. Badwaik, O.P. Sreejith and D.S. Pai

India Meteorological Department, Pune, India

OFFICE OF THE HEAD, CLIMATE RESEARCH & SERVICES

IMD, PUNE- 411005

Table of Contents

Page Number

Executive Summary 1

Abstract 2

1 Introduction 3

2 Data and Methodology 4

3 Results and discussions 5

3.1 Inter-annual variability and trend of seasonal and annual

rainfall over the Indian Islands 6

3.2 Trends in frequency of extreme rainfall events over the

Indian Islands 7

4 Summary and Conclusions 8

Acknowledgements 9

References 9

Tables and Figures 10

1

Executive Summary

1 Document title

Development of daily gridded rainfall data sets over the Indian

Islands at 1°x1° & 0.25°x0.25° spatial resolutions for the

period (1951-2020)

2 Document type Research Report

3 Issue No. CRS Research Report No.-- 001/2021

4 Issue date

5 Security Classification Unclassified

6 Control Status Unclassified

7 No. of Pages 19

8 No. of Figures 8

9 No. of Tables 3

10 No. of reference 8

11 Annexure -.

13 Distribution Unrestricted

14 Language English

15 Authors/ Editors Latha Sridhar, Aradhana Kumari, Divya Surendran,

M.R. Badwaik, O.P. Sreejith and D. S. Pai

16 Author’s affiliations India Meteorological Department

17 Originating

Division/Group

Climate Monitoring & Prediction Group, Office of the Head,

Climate Research & Services, India Meteorological

Department, Pune

18 Reviewing and Approving

Authority

Head, Climate Research & Services ,

India Meteorological Department, Pune

19 End users Forecasters, Disaster Managers, Modellers and Researchers

etc.

20 Abstract Given in a separate sheet (Page No.2)

21 Key Words Daily gridded rainfall, Islands, Seasonal Extreme rainfall

events, Long term trends

2

Abstract

Andaman & Nicobar in the Bay of Bengal and Lakshadweep Islands in the

Arabian Sea are integral parts of India which are situated in climate hazardous areas

influenced by monsoonal rain bursts and tropical cyclonic disturbances formation. In

order to examine various rainfall variability and trend features over India, long time

series of daily gridded rainfall was developed by Rajeevan et al. (2010) at 1o X1o

spatial (latitude X longitude) resolution and by Pai et al. (2014) at 0.25o X0.25o

resolution. However, these gridded data were from the Indian main land and the two

main Island areas (Lakshadweep and Andaman & Nicobar) on either side of the

main land were ignored.In this study, we discuss the development of daily gridded

rainfall data set for the Indian islands for the period 1951 to 2020 in two spatial

resolutions, viz. 1°x1° and 0.25°x0.25°in order to fulfil the user community’s

demands of including these islands data in gridded format with the existing spatial

resolutions of IMDs gridded rainfall data sets.Statistical analyses of rainfall over

these island areas using both the gridded data sets have also been presented here.

It was observed that the 0.25°x0.25° data set is more comparable with the IMD

official rainfall time series for the island subdivisions and hence using the

0.25°x0.25° data set, trend analysis has been carried out for extreme rainfall events

for the Indian Islands in the climate change scenario for the periods 1951-2020 and

1971-2020 for all the seasons. Extreme rainfall (ER) events were classified into two

categories MR (≥5mm to 100mm), HR (≥100mm) events. Signs and magnitude of

the long-term trends in frequency of ER events (and its 2 categories) showed

significant changes during the period 1971-2020. However, when islands rainfall

were included for the calculation of rainfall time series of India as a whole, not much

of difference in the All India rainfall time-series has been observed, the reason being

that the area of the islands is negligible when compared with that of the Indian

mainland.

3

1. Introduction

The first daily gridded rainfall data set for the Indian mainland at the spatial

grid of 1°x1° for the period 1951-2003 was initially developed by Rajeevan et al.

(2006) using a fixed network of 1803 rain gauge stations having minimum 90% data

availability during the analysis period. To improve the data quality over northern part

of India, Rajeevan et. al., (2010) reconstructed the data set of Rajeevan et al. (2006)

using a fixed network of 2140 having minimum 90% data availability and the data

period was extended up to 2007. This data set is being widely used by the

researchers worldwide. Pai et al. (2014) developed a daily rainfall data set at the

spatial grid of 0.25° x 0.25° using rainfall from a network of 6955 stations and

compared it with that of Rajeevan et. al., (2006), Rajeevan et. al., (2009), Rajeevan

et. al., (2010) and Yatagai et. al., (2012).

Andaman & Nicobar and Lakshadweep Islands are integral parts of India and

form independent subdivisions out of the 36 meteorological subdivisions of India

(Fig. 1), numbered 1 and 36 respectively. Andaman & Nicobar and Lakshadweep

Islands are situated in climate hazardous areas influenced by monsoonal rain bursts

and tropical cyclonic disturbances formation. The studies related to rainfall over

these islands are important because they are situated in the warm pool tropical

region over which the Inter Tropical Convergence Zone (ITCZ) crosses twice in a

year (May and October–November). Examining trends in the rainfall over warm pool

tropical region are also important for understanding long term change and decadal

variability of the rainfall. Since grids over these islands had been excluded by

Rajeevan et al (2010) & Pai et al. (2014), in the preparation of daily gridded rainfall

data sets, in the present study, daily rainfall gridding has been carried out for these

two island meteorological subdivisions of India, for the period 1951-2020 using a

network of 14 stations (8 over Andaman &Nicobar Islands and 6 over Lakshadweep

islands).

There are limited studies related to variability and trend of rainfall and its

extremes over these two Indian island subdivisions, which lay in the warm pool

tropical region. Kumar et. al (2012) observed a statistically significant decreasing

trend (95 %) for yearly rainfall averaged over the Andaman & Nicobar Islands for a

40-year period of 1961-2000. Sreekesh (2016) examined the rainfall trends over

Amini and Minicoy stations of the Lakshadweep islands for the period 1951-2004

and observed insignificant positive trends of rainfall during JJAS and OND seasons.

4

The main object of the present study is to examine various features of the

rainfall over both the island areas such as climatology, variability at different

temporal scales, extreme rainfall analysis and trends using the gridded rainfall at two

different resolutions (1°x1° and 0.25°x0.25°) developed.

2. Data and Methodology

For developing the daily gridded rainfall data sets of 1°x1° and 0.25°x0.25°

resolutions over the Indian Islands, daily station rainfall data for a fixed network of 14

stations (8 over Andaman & Nicobar scattered across 572 islands and 6 over

Lakshadweep scattered over about 10 inhabited and other small islands) archived at

the National Data Centre, IMD Pune for the period 1951-2016 have been used and

for the period 2017-2020 real-time station rainfall data for these 14 stations have

been used.

Multi-stage quality control of observed rainfall data was carried out before

interpolating station rainfall data into regular grids of 1°x1° and 0.25°x0.25°

Latitudes/Longitudes.

The interpolation method proposed by Shepard (1968) has been used for

interpolating station rainfall data into regular grids including the directional effects

and barriers, as in Rajeevan et. al.,(2006).

One of the additional data set used for this study was the IMD official Rainfall

time series of rainfall over the two island subdivisions during various months,

seasons and annual (1951–2020). IMD official rainfall series contains monthly rainfall

data for the period 1901-2012 from delayed mode computation using all available

stations and 2013-2018 from real time data series (District Rainfall Monitoring

Scheme). District rainfall values have been computed using simple arithmetic mean

of stations values. Met sub-divisions rainfall values have been calculated based on

district area weighted method. This IMD official Rainfall time series has been used

for comparing with 1°x1° and 0.25°x0.25° data sets for the Indian islands.

The area in sq. kms of Lakshadweep islands is about 32.62 and that of

Andaman &Nicobar Islands is 8,249. The number of stations of Andaman & Nicobar

Islands from which data is being received is very less when compared with the areas

of these islands. Also, the total area of the inhabitant and other small islands of

Lakshadweep is lesser than that of the area developed in gridded format. However,

5

to fulfil the user community’s demands the necessity of including the islands data in

gridded format with the existing resolutions of IMDs gridded rainfall data sets has

arisen and hence the rainfall data in gridded format for these two islands have been

prepared in 1°x1° and 0.25°x0.25° resolutions keeping into consideration that at

least one representative station falls in one grid.Fig.2a & Fig.2b show the number of

grids of 1°x1° and 0.25°x0.25° resolutions over the Indian Islands marked for

Andaman & Nicobar and Lakshadweep Islands, taken for preparing rainfall data

series. However, for the computation of rainfall time series, the fractional area of land

falling in the respective grids only has been considered avoiding the ocean part.

3. Results and Discussions

In the present study, comparison of mean rainfall (mm) for the period 1961-

2010 between IMD official data set and the present data sets for Andaman & Nicobar

Islands and Lakshadweep are is shown in Table-1 (a & b). The climatology of rainfall

for all the months and seasons of 0.25°x0.25° data set was more comparable with

IMD official rainfall time series than 1°x1° data set. Hence, for further analysis, the

0.25°x0.25° data set was used.

Over Andaman & Nicobar Islands, the wettest year 2011 received 3824 mm of

rainfall and driest year 1979 received 2084 mm of rainfall. The heaviest grid-point

rainfall recorded in 24 hours is 374 mm on 31st December 1976. Over the

Lakshadweep Islands, the wettest year 1961 received 2435 mm of rainfall and driest

year 1958 received 979 mm of rainfall. The heaviest grid-point rainfall recorded in

24 hours is 297 mm on 15th October 1999.

The seasonal and annual rainfall and the number of respective ER events

over the two island subdivisions were significantly and positively correlated and

major portion (about 98-99%) of rainfall during ER events for annual and all the

seasons over both the islands were received in the form of MR events.

The mean annual cycle in the number of MR & HR events over Andaman &

Nicobar and Lakshadweep Islands are shown in Fig.3 (a) and (b) respectively. It can

be seen from Fig.3 (a) that over Andaman & Nicobar Islands, the maximum MR

events (15-20) occurred between mid-May to mid-October. Mid-April to mid-May and

Mid-October to mid-December, the MR events ranged between 5 and 15, and were

less than 5 during January to mid-April. The HR events were more than 1 during few

days of May & June, and for the other days, mean HR events were less than 1. It

6

can be seen from Fig.3 (b) that over Lakshadweep Islands, the mean MR events

ranged between 0-2 during January to April, increased progressively through May,

ranging between 2-6, thereafter increased to the range of 6-12 during June and July.

The mean MR events decreased gradually and ranged between 4-8 from August to

October and between 0-4 during November and December. The mean HR events

were less than 1 throughout the year.

3.1. Inter-annual variability and trend of seasonal and annual rainfall over the Indian Islands

Fig.4a & Fig.4b show the time series of annual cycle of daily rainfall over the

Andaman & Nicobar and Lakshadweep Islands respectively. The daily rainfall over

these islands was computed as the area weighted rainfall over all the grid points

over the respective islands. As seen in the Fig.4a & Fig.4b, both inter-annual and

intra-seasonal variability are present in the daily rainfall series embedded with

extreme rainfall events over the 69-year record. Many times, very heavy rain events

are associated with cyclonic disturbances affecting Andaman & Nicobar and

Lakshadweep Islands. As seen from the Fig.4a, over the Andaman & Nicobar

Islands as a whole, the highest rainfall was observed during the end of April 2008,

owing to Cyclone Nargis. Similarly, Fig.4b shows that owing to Cyclone Maha, during

the end of October 2019, the highest rainfall was observed for the Lakshadweep

Islands as a whole. During July 1997, the peak in the rainfall activity over Andaman

& Nicobar Islands as seen in Fig.4a may be attributed to active MJO phase over

Indian Ocean.

Fig.5 (a-e) show the inter-annual variation of rainfall over Andaman & Nicobar

Islands for the period 1951-2020 with trend lines fitted for the total data period and its

sub-period 1971-2020. From the Fig.5 it can be seen that no trend was observed

during OND season for both the periods, however during MAM season, the sign has

changed from insignificantly negative (1951-2020) to insignificantly positive (1971-

2020). The insignificantly positive trend for JF season during 1951-2020 has

changed to significantly positive (95%, at 17.32 mm/decade) during 1971-2020. The

trend for JJAS and annual rainfall was insignificantly negative during 1951-2020

which have changed to insignificantly positive during 1971-2020.

Fig.6 (a-e) show the inter-annual variation of rainfall over Lakshadweep

Islands for the period 1951-2020 with trend lines fitted for the total data period and its

sub-period 1971-2020. From the Fig.6, insignificant positive trend was observed

during JJAS and OND seasons for the entire period of 1951-2020, which is agreeing

7

with Sreekesh (2016) who examined the rainfall trend over Amini and Minicoy

stations of the Lakshadweep islands for the period 1951-2004 and concluded with

similar results. However, during the sub-period 1971-2020, the sign for trend of JJAS

rainfall changed from insignificantly positive to significantly (90%, at -35.72

mm/decade) negative. Also, for JF and MAM seasons, the sign changed from

negative to positive, though statistically insignificant.

3.2. Trends in frequency of extreme rainfall events over the Indian Islands

Fig.7 shows the inter-annual variation of category wise number of ER (MR &

HR) events over Andaman & Nicobar Islands respectively for the period 1951-2020

with trend lines fitted for the total data period and the sub-period 1971-2020. Table-2

shows the trend/decade for ER events and its two categories (MR & HR) for various

seasons over Andaman & Nicobar Islands. The level of significance are marked by

(+) for 90% and (*) for 95%. From the Fig.7 and Table-2, it can be seen that

significant (95%) negative trends were observed in the number of MR events over

Andaman & Nicobar Islands for Annual, JJAS & OND seasons for the period 1951-

2020 which changed to insignificantly negative during the sub-period 1971-2020.

During JF season, the trend of MR events was insignificantly positive for the period

1951-2020, which was observed to be significant (90%) for the sub-period 1971-

2020. During the period 1951-2020, the trend for MR events for MAM season was

insignificantly negative, which changed to insignificantly positive during the second

period.

As for the HR events over Andaman & Nicobar Islands, insignificantly

negative trends were observed for Annual and MAM seasons during the period

1951-2020. However, during 1971-2020, the trend for HR events changed to positive

for Annual (significant at 90%) and MAM (insignificant). The trends for HR events for

JF, JJAS and OND seasons were observed to be insignificantly positive for the

period 1951-2020 which remained so during the sub-period 1971-2020 for JF

whereas became 95% significant for JJAS season, but changed to insignificantly

negative for OND season.

Fig.8 shows the inter-annual variation of category wise number of ER (MR &

HR) events over Lakshadweep Islands respectively for the period 1951-2020 with

trend lines fitted for the total data period and the sub-period 1971-2020. Table-3

shows the trend/decade for ER events and its two categories (MR & HR) for various

seasons over Lakshadweep Islands. The level of significance are marked by (+) for

8

90% and (*) for 95%. From the Fig.8 and Table-3, it can be seen that insignificantly

positive trends were observed in the number of MR events for Annual and OND

seasons during the period 1951-2020. However, during 1971-2020, the trend for MR

events remained positive for Annual (insignificant) and OND (significant at 90%). For

the seasons JF and MAM, trends for MR events were observed to be insignificantly

positive during 1951-2020, changing to positive significant at 90% for JF and

insignificant for MAM during 1971-2020. The observed insignificant positive trend for

MR events during 1951-2020 changed to insignificant negative trend during 1971-

2020.

The HR events over Lakshadweep Islands showed insignificant negative

trends during 1951-2020 for Annual and MAM seasons which became insignificantly

positive for the sub-period 1971-2020. Insignificant negative (positive) trends for HR

events was observed for JJAS (OND) seasons during both the periods and JF

season for both the periods showed no trend in the number of HR events.

4. Summary and Conclusions

In this study, we discuss the development of daily gridded rainfall data set for

the Indian islands for the period 1951 to 2020 in two spatial resolutions, viz. 1°x1°

and 0.25°x0.25°. A few statistical analyses of these gridded data sets for the Indian

islands have also been made to demonstrate their use for various research

purposes. The quality of the data for the two island subdivisions has been assessed

by comparing it with the existing IMD official rainfall time series for these two islands

which are two independent meteorological subdivisions. It is observed that the

rainfall over the islands for all months and seasons are comparable with the IMD

official rainfall series for both the spatial resolution data sets. However, the

0.25°x0.25° data set is more comparable with the IMD official rainfall time series for

the island subdivisions and hence using the 0.25°x0.25° data set, trend analysis has

been carried out for extreme rainfall events for the Indian Islands in the climate

change scenario for the periods 1951-2020 and 1971-2020 for all the seasons.

During the recent years (1971-2020), owing to climate change, significant

changes were observed in the trend for MR and HR events over both the island

subdivisions. The MR and HR events trends over Andaman & Nicobar as well as

Lakshadweep Islands though insignificant in the MAM season, changed sign and

became positive for 1971-2020, which were negative for 1951-2020. The trends in

Annual HR events over Andaman & Nicobar Islands changed from insignificantly

9

negative during 1951-2020 to significantly positive at 90% during 1971-2020. Over

the Lakshadweep Islands, trends in Annual and OND HR events changed from

insignificantly negative during 1951-2020 to insignificantly positive during 1971-2020.

This study has provided opportunity to make use of observations from island

stations of the country and converting them into gridded spatial resolution format.

Since the rainfall reporting island stations are more or less very consistent on day to

day basis, real time daily preparation of the data is possible. Hence this data can

also be used for important operational services such as onset of Southwest

monsoon over the Indian Islands, and also for more accuracy wherever the rainfall of

India as a whole is taken into consideration, with the rainfall over the two island

subdivisions of the country also included.

Acknowledgements

We express our sincere thanks and gratitude to Dr. M. Mohapatra, DGM, IMD

and Dr. M. Rajeevan, Secretary, MoES and for their encouragement, guidance and

support during various stages of this work. We are also thankful to all the officers

and staff of Climate Monitoring & Prediction Group, IMD Pune for their support.

References

Kumar, N., Yadav, B.P., Tyagi, A. and Jaswal, A.K., 2012. Trend and spatial distribution of rainfall & rainy days over Andaman & Nicobar Islands. Natural hazards, 63(2), pp.575-587.

Pai D. S., Latha Sridhar, Rajeevan M, Sreejith O. P., Satbhai N. S. and Mukhopadhyay B (2014):Development of a new high spatial resolution (0.25° X 0.25°) Long period (1901-2010) daily gridded rainfall data set over India and its comparison with existing data sets over the region. Mausam 65:1, 1-18.

Rajeevan, M., J. Bhate, J.D. Kale and B. Lal, 2006 : A high resolution daily gridded rainfall for the Indian region : analysis of break and active monsoon spells, 2006, Current Science, Vol.91, No.3 pp 296-306.

Rajeevan, M. and Bhate, J., 2009: A high resolution daily gridded rainfall data set (1971-2005) for mesoscale meteorological studies; Current Science, 96, 4, 558 – 562.

Rajeevan M., SulochanaGadgiland JyotiBhate., 2010: Active and break spells of the Indian summer monsoon; Journal of Earth System Science, 119, 3, 229-247.

Shepard D., 1968: A two-dimensional interpolation function for irregularly spaced data; Proc. 1968 ACM Nat. Conf, 517-524.

Sreekesh, S., 2016. Rainfall variation in Lakshadweep Islands, Indian Journal of Geo Marine Sciences Vol. 45 (11), November 2016, pp. 1603-1609.

Yatagai Akiyo, Kenji Kamiguchi, Osamu Arakawa, Atsushi Hamada, Natsuko Yasutomi and Akio Kitoh, 2012: APHRODITE: Constructing a Long-Term Daily Gridded Precipitation Dataset for Asia Based on a Dense Network of Rain Gauges; Bull. Amer. Meteor. Soc., 93, 1401–1415.

10

Table 1(a): Rainfall climatology (in mm) (1961-2010) for various months and seasons over Andaman &Nicobar Islands.

ANDAMAN & NICOBAR ISLANDS

PERIOD IMD

OFFICIAL 1x1

DEGREE 0.25X0.25 DEGREE

DIFFERENCE DIFFERENCE

(IMD OFFICIAL –

1X1 DEGREE)

(IMD OFFICIAL – 0.25X0.25 DEGREE)

JANUARY 58.25 51.52 56.61 6.73 1.64

FEBRUARY 33.15 24.70 28.00 8.45 5.15

MARCH 36.66 35.85 41.01 0.81 -4.35

APRIL 81.34 76.06 82.76 5.29 -1.42

MAY 352.35 360.34 360.36 -7.99 -8.01

JUNE 365.44 410.60 386.70 -45.16 -21.26

JULY 355.60 403.04 379.33 -47.43 -23.73

AUGUST 360.91 402.50 376.30 -41.58 -15.39

SEPTEMBER 389.47 411.70 401.48 -22.23 -12.01

OCTOBER 289.74 285.25 290.96 4.49 -1.22

NOVEMBER 255.45 233.49 252.54 21.96 2.90

DECEMBER 162.70 146.64 160.91 16.06 1.80

JF 91.40 76.22 84.61 15.18 6.79

MAM 470.36 472.25 484.14 -1.89 -13.78

JJAS 1471.43 1627.83 1543.81 -156.40 -72.38

OND 707.89 665.38 704.41 42.51 3.48

ANNUAL 2741.08 2841.69 2816.97 -100.61 -75.89

11

Table 1(b): Rainfall climatology (in mm) (1961-2010) for various months and seasons over Lakshadweep Islands.

LAKSHADWEEP ISLANDS

PERIOD IMD

OFFICIAL 1x1

DEGREE 0.25X0.25 DEGREE

DIFFERENCE DIFFERENCE

(IMD OFFICIAL –

1X1 DEGREE)

(IMD OFFICIAL – 0.25X0.25 DEGREE)

JANUARY 19.83 16.13 17.76 3.70 2.07

FEBRUARY 11.79 6.39 8.65 5.40 3.14

MARCH 11.15 6.60 9.35 4.55 1.80

APRIL 33.22 19.60 27.97 13.63 5.25

MAY 170.02 152.88 157.41 17.13 12.60

JUNE 329.81 353.85 345.88 -24.04 -16.07

JULY 294.84 314.25 309.22 -19.41 -14.39

AUGUST 225.78 226.91 226.75 -1.13 -0.97

SEPTEMBER 168.70 169.33 168.80 -0.63 -0.09

OCTOBER 146.40 145.28 149.26 1.11 -2.86

NOVEMBER 122.55 106.01 113.68 16.54 8.87

DECEMBER 62.13 49.58 53.78 12.55 8.35

JF 31.61 22.52 26.41 9.10 5.20

MAM 214.39 179.08 194.73 35.31 19.66

JJAS 1019.13 1064.35 1050.65 -45.22 -31.52

OND 331.08 300.87 316.72 30.21 14.36

ANNUAL 1596.21 1566.81 1588.51 29.40 7.70

12

Table 2: Trend/decade of ER, MR and HR events for various seasons over

Andaman &Nicobar Islands.

TREND/DECADE (Andaman & Nicobar)

SEASON EVENTS 1951-2020 1971-

2020

JF ER 1.83 20.03+

MR 1.768 20.013+

HR 0.068 0.023

MAM ER -2.252 7.183

MR -1.529 6.89

HR -0.723 0.245

JJAS ER -23.714 -10.15

MR -24.23* -13.71

HR 0.516 3.433*

OND ER -28.345* -16.615

MR -28.417* -16.588

HR 0.072 -0.192

ANNUAL ER -52.47* 0.454

MR -52.408* -3.395

HR -0.067 3.477+

Table 3: Trend/decade of ER, MR and HR events for various seasons over

Lakshadweep Islands.

TREND/DECADE (Lakshadweep)

SEASON EVENTS 1951-2020 1971-2020

JF

ER -1.75 3.474+

MR -1.83 3.474+

HR 0.073 4.802

MAM

ER -3.24 2.637

MR -3.283 2.149

HR 0.034 0.488

JJAS

ER 4.9 -10.439

MR 5.132 -10.158

HR -0.223 -0.365

OND

ER 8.65 17.032+

MR 8.566 16.577+

HR 0.089 0.455

ANNUAL

ER 8.558 12.704

MR 8.585 12.042

HR -0.027 0.662

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Fig. 1: The 36 meteorological subdivisions of India including Andaman & Nicobar and

Lakshadweep Islands

Fig.2 (a) Number of grids of 1°x1° taken into account for Andaman & Nicobar and

Lakshadweep Islands

14

.

Fig.2 (b) Number of grids of 0.25°x0.25° taken into account for Andaman & Nicobar

and Lakshadweep Islands

Fig. 3: Daily cycle of MR and HR events over Andaman & Nicobar and Lakshadweep

Islands

(a)

(b)

15

Fig.4 (a) Daily cycle of Rainfall over Andaman & Nicobar

Fig.4 (b) Daily cycle of Rainfall over Lakshadweep

16

Fig.5 (a-e) Inter-annual variation of rainfall and Trend over Andaman & Nicobar

Islands

Fig. 5(a)

Fig. 5(b)

Fig. 5(c)

Fig. 5(d)

Fig. 5(e)

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Fig.6 (a-e) Inter-annual variation of rainfall and Trend over Lakshadweep

Islands

Fig. 6(a)

Fig. 6(b)

Fig. 6(c)

Fig. 6(d)

Fig. 6(e)

18

MR Events HR Events

Fig.7 Inter-annual variation of number of MR & HR events and Trend for

various seasons over Andaman& Nicobar Islands

JF

JF

MAM

MAM

JJAS

JJAS

OND

OND

ANNUAL

ANNUAL

19

MR Events HR Events

JF

JF

MAM

MAM

JJAS

JJAS

OND

OND

ANNUAL

ANNUAL

Fig.8 Inter-annual variation of number of MR & HR events and Trend for

various seasons over Lakshadweep Islands

20