1. An Investigation of Several Thunderstorms During
Southern Monsoon Over Tawau Area
Wayan Suparrta*¹, M. N. Syamim Idris², Wahyu S.Putro³
Space Science Centre(ANGKASA),Institute of Climate Change, Universiti Kebangsaan Malaysia,Bangi,
Selangor,Malaysia
Abstract-This paper presents to investigate the
occurrence of thunderstorm in Tawau area during
Southern Monsoon for finding the suitable location of
the space launcher in future. An attempt was made by
analyze and compare the cloud cover (Octas) data,
wind speed and direction data, PTH data, RSPWV
data and thunderstorm frequency data taken in the
year of 2011, 2012 and 2013. It shows that events
occur during winter monsoon, the frequency of
thunderstorm occur is high especially in the month of
December, January and February. While during the
summer monsoon, can be seen a dry season occur
which no frequent of thunderstorm occur especially
in the month of late May 2011 to August 2013.Thus,
based on this result, suggestion can be made if any of
space activities should be occur during this period.
Keywords—Convective System, Tawau area,
Artificial Neural Network (ANN), Surface
Meteorological, Rainfall, and precipitation
I. Introduction
1.1 BACKGROUND
The convective system is like a complex of
thunderstorm or electrical storm with hydrostatic
approximation, geotropic and wind gradient [1]. The
development early warning systems it can help the
human to forecasting weather especially
thunderstorm activity. A lot of parameters and
variables use to develop model forecasting and
estimation. In the line with this development, we
focused on East Malaysia (Borneo) region especially
Tawau area. Tawau is one of state in the Sabah
Malaysia has a severe Convective System activity
during the summer monsoon in June, July and August
(JJA) months [2].
It know that the summer monsoon with a clear day is
crucial to estimate the variation of rainfall and
precipitation to develop an early warning system for
the space activity programme. For this purpose, we
constructed the estimation rainfall and precipitation
using surface meteorology data. The model of
estimation is an alternative to seeing the variation of
rainfall and precipitation measurement over
convective system activity when the thunderstorm
data is absent. In the current study of convective
system activity, Suparta et al. [3] was found the
activity of Mesoscale Convective System (MCS) has
increased during December, January and February
(DJF) months over Tawau area. Pielke [4] studied the
mesoscale convergence as the environment's
precondition for thunderstorm development. His
study demonstrates link between surface moisture
and heat fluxes and cumulus convective rainfall.
2. Methodology
A. Dataset and Location
The location of this study was Tawau Station (96481)
area with coordinate of Latitude 4° 19' N / longitude
118° 07' E, with Mean Sea Level (M.S.L) of 17.5
m.To investigate the thunderstorm occurrence over
Tawau area, some parameters need to be finding and
recorded .The parameters are wind speed(knots) and
direction data, cloud cover (octas) data, thunderstorm
data, pressure(Pa), temperature(°Celsius) and
humidity (mm) data, and Radiosonde Precipitable
Water Vapor,RSPWV(mm) data. The data was taken
in three different years which are from 2011 to 2013.
The cloud cover (Octas) data, thunderstorm
occurrence data, wind speed and direction data was
taken from Meteorological Malaysia .The pressure,
temperature and humidity(PTH) data was taken from
surface meteorological weather underground website
with duration per hour .The RSPWV data was taken
from the Wyoming University also with duration per
hour.
B. Data Analyzing
The surface meteorological data pressure,
temperature and humidity (PTH) ,thunderstorm and
cloud cover (Octas) data taken were plotted and
RSPWV data also were plotted in three different
years in the same plotted figure.Then, the data was
compared and correlated with thunderstorm to be
analyzed and estimate the thunderstorm occur
specifically over Tawau area.
3. Results and Discussion
Figure 1 shows that the trending and variation of the
wind speed distribution over Tawau area in the year
of 2011, 2012 and 2013. From the data, each year
experienced of wind speed class three (4-7knots)
from south direction which can be harm to the space
launcher to depart into the south direction.

2. During winter monsoon, (November to March) in
north direction the wind speed is in class two (1-
4knots) frequently happening and sometimes in class
three (4-7knots). However, in south direction every
month had class three speeds. Consider the wind
speed class three as can harm the space launcher if
want to takeoff during the month of winter monsoon
whether in north or south direction.
While during summer monsoon (late May to
September), the wind speed is in class two in the north
but not frequently as during winter monsoon. But, in
south direction the wind speed had class three and
frequently happened. Hence, it is suitable for the
space launcher to takeoff during summer monsoon in
north direction because of the wind speed in north is
not high as much as during winter monsoon and south
direction in summer monsoon.
In Figure 2 shows the cloud cover (octas) over Tawau
area .It was nearly correspond to the wind speed and
direction. During the Southeast monsoon, in August
the cloud cover is in between 5 to 7 octas which
indicates that there is event occur with 5 octas cloud
cover as the wind speed during that month is
frequently low (class 1 and 2) in north and high (class
3) in south direction. In contrast, during the
Northwest monsoon can be seen in the month of
December where the cloud cover is in between 6 and
7 octas hourly and also the wind speed is in class two
frequently same as in the month of March. However,
in the month of January and February there are some
event occurs where the cloud cover is 8 octas(fully
covered).
This is same as the statement of C. J. G. Morris [10]
where the cloud cover increase as the wind speed
increases
Figure 3 shows that the thunderstorm frequency over
Tawau area. During the southeast monsoon as a case
study, in year 2012 and 2013 the thunderstorm in June
and July had clearly same of 11 thunderstorm and 8
thunderstorm occurrence in the month respectively.
In July, it indicates among the lowest frequent of
thunderstorm occur in a month compare to others
hence possibly had a dry season in that month.
The thunderstorm data can be related with the cloud
octas data. During Southeast Monsoon in August of
2011 and 2012 when the octas is decreased, the
thunderstorm frequency is increased. This is not same
as the statement of C. Panneerselvam [11] in India
where the same events occur relating the
thunderstorm occurrence and the octas value stated
that there is an increased of thunderstorm occur with
the increase of the octas value.
In order to identify the thunderstorm occurs as in
figure 3, the pressure(P),Temperature(T) and
Humidity(PTH)of the air were plotted as in figure 4.
During Southeast monsoon in July of 2011,2012 and
2013, the temperature is increase as the pressure and
humidity are decreased and hence this correlated with
the thunderstorm in July where it has 8 thunderstorm
occur fewer than any other month.
In contrast, in the early of August 2013, the
temperature had decreased rapidly (very minimum
compared to others temperature value in 2011,2012
and 2013) ,contribute to the very high humidity and
also increased in presurre in the air.However, after
that events in 2013 the temperature had increased but
fluctuated effected the humidity and pressure in vice
versa .Hence related with the thunderstorm
data,indicates there is thunderstorm occur when the
first decrease of temperature,and increase humidity
and pressure before the thunderstorm not frequently
occur in the middle and late of August 2013 explained
only seven thunderstorm occur during that month.
In figure 5, the RSPWV data shows correlated with
the thunderstorm events during Southeast monsoon.
It is found that there is an increased of RSPWV during
late of May to early of June similarly there is
thunderstorm occur frequently during that time in
each year. It reached the maximum of RSPWV
recorded in early of June 2011 where it can be seen
that time in figure 4 PTH Data also there is
temperature decreased, pressure and humidity
increased contribute to the occurrence of
thunderstorm.
However, the RSPWV has minimum value in the
early of August 2013 where it decreased to had almost
zero value .During that time, there is slightly
decreased of temperature value but consistently
increase of humidity and pressure indicates that there
is a day in that month that had possibility of
thunderstorm occur. According to this, there is not
necessarily that thunderstorm will not occur if there
is decreased of RSPWV.There is a theory that there is
possibility there is only thunderstorm in the evening
on that day but not in the morning .This can be found
from Suparta[13] statement that the lightning will
occur when the PWV was increased in the evening by
at least 5 mm.

3. A. Wind Speed and Wind Direction Data over Tawau area
Years Wind Direction Wind Speed (Frequency class distribution)
2011
2012
2013
Figure 1 : Wind Rose variation over Tawau area in the year of 2011, 2012 and 2013.
B. Cloud Cover(Octas) Data.

4. Figure 2 : Cloud Cover (Octas) Data in 2011, 2012 and 2013
C. Thunderstorm Data
Figure 3 : Thunderstorm frequency data over Tawau area in year 2011, 2012 and 2013
D. Thunderstorm in association with PTH Data

5. Figure 4 : The PTH Data taken by weather underground website in year 2011, 2012 and 2013.
E. Thunderstorm in association with Radiosonde PWV (RSPWV)Data.
Figure 5 : RSPWV Data taken from Wyoming University in year 2011, 2012 and 2013.

6. 5. Conclusion
The correlations between the thunderstorm and PTH,
RSPWV, cloud cover (Octas) and wind speed and
direction can be simply concluded. Based on the
result, we can say that:
I. The condition space launcher over Tawau
area during Southeast Monsoon event is must
be wind speed to class two(1-4knots), and
the space launcher depart from south area to
the north as the wind speed is frequently high
in south direction .
The correlation between the parameters
shown in the results also consistently related
.This can be summarized as the space
launcher departs must be in certain events.
The events correlated are with high
temperature, low pressure and humidity
(PTH), gives the lower in Radiosonde
Precipitable Water Vapor (RSPWV) and
hence contributed to no thunderstorm occur.
II. This parameter mentioned earlier contributed
to some events and characteristics of Tawau
area during Southeast Monsoon which is
averagely dry or summer day.
Hence, the suggestions suitable for the space
launcher to depart during Southeast
Monsoon are during middle of June to July,
and also middle of August(JJA).
REFERENCES
1. Kuk, B., H. Kim, J. Ha, H. Lee and G. Lee, 2012:
A Fuzzy Logic Method for Lightning Prediction
Using Thermodynamic and Kinematic Parameter
from Radio Sounding Observation in South
Korea. Wea. Forecasting, 27, 205-217.
2. Lippmann, R.P., 1987: An Introduction to
computing with neural nets. IEEE Acoustics,
Speech Signal Process. Mag., 4, 4-22.
3. Suparta, W. and K. M. Alhasa, 2013: Estimation
of precipitable water vapor using an adaptive
neuro-fuzzy inference system technique. ICT,
Lecture Notes in Computer Science, 7804, 214-
222.
4. P. Sr. Roger, 2013: Mesoscale Meteorological
Modeling; Second Edition-Department of
Atmospheric Science; Colorado, State University
Fort Collins.
5. W. Suparta, A. Iskandar, M. S. Jit Singh, M. A.
Mohd Ali, B. Yatim and A. N. M. Yatim, 2013:
Analysis of GPS Water Vapor Variability during
the 2011 La Niña Event over the Western Pacific
Ocean. Annals of Geophysics 56, 489.
6. Lin, J. Y., Cheng, C. T., Sun, Y. G., & Chau, K.,
2005: Long-term prediction of discharges in
Manwan hydropower using adaptive-network-
based fuzzy inference systems models. Lecture
Notes Computer Science, 3612, 1152–1161.
7. Jang, J. S. R., Sun, C. T., & Mizutani, E., 1997:
Neuro-fuzzy and soft computing: A
computational approach to learning and machine
intelligence (3th ed.). New Jersey: Prentice Hall.
8. Jang, J. S. R., 1993: ANFIS: Adaptive network-
based fuzzy inference systems. IEEE
Transactions on Systems Man and Cybernetics,
23, 665–685.
9. Takagi, T., & Sugeno, M., 1985: Fuzzy
identification of system and its application to
modeling and control. IEEE Transactions on
Systems Man and Cybernetics, SMC-15, 116–
132.
10. C. J. G. Morris, I. Simmonds, & Plummerb,
2001: Antification of the Influences of Wind and
Cloud on the Nocturnal Urban Heat Island of a
Large City, Allen Press, Inc
11. C. Panneerselvam, K. U. Nair, C. Selvaraj, K.
Jeeva, C. P. Anil Kumar, & Gurubaran, 2007:
Diurnal variation of atmospheric Maxwell current
over the low-latitude continental station,
Tirunelveli, India (8.7°N, 77.8°E), Springer-
Verlag
12. W Suparta, J Adnan, MAM Ali, 2011 :
Monitoring the Association between Lightning
Activity during the 2009 Winter Monsoon over
Bangi Malaysia.IEEE