NII Journal No. 2 (2001.3)

研究論文

The Collection of Typhoon Image Data and the Establishment of Typhoon
Information Databases Under International Research Collaboration between
Japan and Thailand
日本とタイの国際共同研究に基づく台風画像データの収集および台風情報データベー
スの構築
Asanobu KITAMOTO
National Institute of Informatics
北本 朝展
国立情報学研究所
Kinji ONO
National Institute of Informatics
小野 欽司
国立情報学研究所

ABSTRACTThis paper describes our ongoing project under international research collaboration between Japan (National Institute ofInformatics) and Thailand (Asian Institute of Technology) for the collection of typhoon image data and the establishment of
typhoon information databases. Statistics on past typhoon records reveal that approximately one thirds of the typhoons formedin the Northwest Pacific basin have entered into South East Asia and this fact indicates the importance of the research into theanalysis and prediction of typhoons in order to prevent or reduce massive damage from typhoons in this vulnerable region.
Our challenge to this goal is unique in that our approach is mainly based on the informatics paradigm, namely based on ideas
and techniques developed in the informatics community, in contrast to the traditional paradigm based on meteorology. The
underlying infrastructure in this new paradigm is the large collection of typhoon images created from Japanese meteorologicalsatellite GMS-5 Himawari. However, when observing South East Asia through this satellite, satellite images tend to show
degradation in effective resolution and shape distortion due to earth curvature. Hence we demonstrate that satellite images
from another type of satellite called NOAA can compensate the drawbacks of GMS-5, and can provide high quality typhoon
imagery over South East Asia. We also point out that NOAA data received in Thailand are relevant data source for thiscombination, and that effective infrastructure for exchanging huge amount of satellite data is the SINET international link
between Thailand and Japan.
要旨
本論文は、日本（国立情報学研究所）とタイ（アジア工科大学）の国際共同研究として進められているプロジ
ェクト、すなわち台風画像データの収集および台風情報データベースの構築に関する報告である。過去の統計データによると東南アジア地域は、北西太平洋で発生する台風の約3分の1が通過する。この危険地域における台風
災害を防止し損害を軽減するためには、台風解析と予報という問題に徹底的に取り組むことが重要である。本プ
ロジェクトのユニークな点は、この問題に対して気象学の手法に基づく従来のパラダイムではなく、情報学の分野で発展したアイデアや手法を援用した情報学パラダイムに基づき、台風画像の大規模コレクションを研究の土台として挑戦するという点にある。本論文ではこのコレクションを主に気象衛星 GMS-5「ひまわり」の衛星画像から作成する。ただし GMS-5 を用いて東南アジア地域を観測する場合、衛星画像の実質的な解像度が低下し、雲形状が歪むという欠点が避けられない。そこで本論文では、別の種類の衛星画像、すなわちタイで受信する

15

The Collection of Typhoon Image Data and the Establishment of Typhoon Information Databases Under International
Research Collaboration between Japan and Thailand

NOAA 衛星画像を組み合わせることにより、お互いの欠点を補完しつつ高品質な台風画像が生成できることを示す。さらにこのような大量の衛星データをネットワーク経由で交換するための基盤として、日本とタイの間で運用される SINET 国際回線が有効であることを述べる。
[Keywords]
Typhoon Image Database, Geostationary Satellite, Polar Orbiting Satellite, South East Asia,
International Research Collaboration[キーワード]
台風画像データベース、静止衛星、極軌道衛星、東南アジア、国際共同研究“If there is a hurricane, you always see the signs ofHere GMS-5 (Geostationary Meteorological Satellite 5),

it in the sky for days ahead, if you are at sea.”

which is also well known by its nickname Himawari, is theErnest Hemingway,most popular geostationary satellite in Japan. As will be“The Old Man and the Sea,” 1952.

stated later, this satellite is the most powerful satellite forthe monitoring of typhoons because of favorable properties

Introduction

1such as wide coverage, frequent observation, and fixedscan range; its data are therefore utilized as our main data

“NACSIS 1 -Thai Project” is the name of the projectsource. However we will also discuss feasibility for en-

whose purpose is to promote international research col-hancing the quality of typhoon imagery created fromlaboration between Japan and Thailand through the inten-

GMS-5 over South East Asia by incorporating satellite data

sive usage of 2 Mbps SINET international link between

from another type of satellite called NOAA.

two countries. Since the inception of this project in 1994,

This paper is organized as follows. Firstly, Section 2 re-National Institute of Informatics (NII) and Thai researchminds you of what is typhoon, and its influence in Southinstitutions have established several joint research projects,

East Asia. Its influence, from the viewpoint of disasters

and the authors have also been involved in this project forcaused by typhoons, is then briefly sketched in Section 3,

a few years under an individual project on exchanging

and some research issues on typhoon analysis and forecast

satellite data through the Internet with collaborators inare introduced as well. Next Section 4 addresses design

Asian Institute of Technology (AIT), which has been oper-

considerations necessary to be settled before actually mak-ating the reception and the archive of satellite data since

ing typhoon image databases. The next section, Section 5,

1997. Our ongoing research, “digital typhoon” [1]-[3] bene-

describes the main challenge in this paper; that is, we try tofits from this collaborative research in terms of two points.

enhance the quality of typhoon imagery through the com1.

bination of satellite data from two different types of satel-

In South East Asia, as well as in Japan, typhoons of-lites − geostationary satellites and polar orbiting satel-

ten cause massive damage and devastating losses,

lites. Section 6 summarizes our international research col-which leads to shared interest in the analysis and pre-laboration between Japan and Thailand, and the history of

diction of typhoons.
2.

our joint research called NACSIS-Thai project. Finally

For the monitoring of typhoons over South East Asia,

Section 7 concludes the paper.

the Japanese geostationary satellite GMS-5 has a limited capability in obtaining high quality data. To solve2

this problem, satellite data from a polar orbiting satel-

Typhoons in South East Asia

lite, received in Thailand, can be combined with

The terms “hurricane” and “typhoon” are regionally spe-

GMS-5 satellite data to enhance the quality of ty-

cific names for a strong “tropical cyclone.” A tropical cy-

phoon imagery.

clone is the generic term for a non-frontal synoptic scale
low-pressure system over tropical or sub-tropical waters
with organized convection and definite cyclonic surface

1 National Center for Science Information Systems (NACSIS) is thename of the antecedent of National Institute of Informatics (NII).

16

NII Journal No. 2 (2001.3)

100˚

0

120˚

0

0

140˚

160˚

180˚

7 44 51 52 25 21

40˚

40˚

0

0 14 121 239 218 169 91 31

0 76 267 357 376 260 141 56 19
20˚

20˚

4 150 366 433 420 308 142 52 20
3 17 17 39 80 81 62 35 12
0˚
100˚

120˚

140˚

160˚

0˚
180˚

Figure 1: Grid-based occurrence profile of typhoons (tropical cyclones from Category 3 through 5). Total 1,320 typhoons
formed in the period from 1951 through 1999 are analyzed, where one typhoon is counted once in one grid but may be
counted in several grids along with its motion.
wind circulation. The term “typhoon” is specifically given

phoons found in this grid tend to choose one of two

to tropical cyclones occurred in the Northwest Pacificcourses; either heading north towards the southern part of(NWP) basin, and among severe tropical cyclones in the

China or going west towards such countries as Vietnam,

world such as hurricanes, cyclones, etc., typhoons are

Malaysia and Thailand. They are usually not very strong

known to be the most active ones.

typhoons, but at least they are typhoons with strong winds,

The “cradle” of typhoons appears to be off the coast ofheavy rainfall, and tidal waves. Hence they often cause

Philippines as illustrated in Figure 1. In particular, the griddevastating destruction on people’s daily lives and the wide

(10ﾟN, 120ﾟE)−(20ﾟN, 130ﾟE) has seen more typhoons

range of industry, among which agriculture may be thethan any other grids, as many as 433 typhoons among

most vulnerable industry in South East Asian countries.

1,320 typhoons formed from 1951 through 1999. If we are

Assuming that some of the disasters can be prevented fromalso reminded of the fact that very strong typhoons, orearly warning, we claim that typhoon analysis and predic-

super-typhoons, are often found in this area of the Pacifiction are important subjects of research in order to reduce

Ocean, the most dangerous and vulnerable country against

extensive losses from typhoons.

2the strike of typhoons is likely to be Philippines .

Motivation of the Project3

However, if you also pay attention to other regions suchas South China Sea and South East Asia, you may notice

3.1

Disasters Caused by Typhoons

that those regions are almost as frequently struck by tyNot only South East Asian countries but also many

phoons as the Philippine region. For example, the grid (10ﾟcountries in the world are suffered widespread and massive

N,110ﾟE)−(20ﾟN,120ﾟE) has seen 366 typhoons or as

damage from typhoons. Phenomena listed in the following

many as 28% of typhoons formed in these 49 years. Ty-

are likely to bring massive disasters during or after the
strike of typhoons.

2 In terms of country-based statistics, however, China suffers from more
landfalls than any other countries in the world.

17

The Collection of Typhoon Image Data and the Establishment of Typhoon Information Databases Under International
Research Collaboration between Japan and Thailand

Strong Winds By definition, strong winds are the symbol

3.2

of typhoons. On the land, weak buildings and houses

Typhoon Forecasts

Unfortunately, typhoon forecasts have not yet reached toare directly destroyed by strong winds or partly dam-mature level. One of the fundamental reasons is the chaotic

aged by flying debris; while on the sea, strong winds

nature of the atmosphere − the deficiency of observation

make storm surges, resulting in shipwreck in the mid-stations in the middle of the ocean leads to unreliable esti-

dle of the ocean without any havens nearby3.
Heavy Rainfall Typhoons also bring heavy rainfall, result-mation of initial conditions for numerical weather predic-

ing in floods over low lands and landslides over moun-tion models. However, the importance of typhoons stimu-

tainous areas. Also some industry, in particular agricul-

lated meteorologists to investigate and improve typhoon

ture (rice crop, etc.) in South East Asia, may be se-forecasts in three domains as follows:verely affected by floods.

1.

Cyclogenesis forecast

2.

Intensity forecast

ric pressure, of which the former plays the major role.

3.

Track forecast

Tidal waves sometimes result in extraordinary devasta-

For example, tropical cyclogenesis has long been an im-tion on low-lying deltas, such as that occurred in Bang-

portant topic in meteorological research and there are sev-

Tidal Waves Tidal waves, or storm surges, are caused by
the mixed influence of strong winds and low baromet-

ladesh in 1970 that killed at least 300,000 people.

eral conditions thought to be necessary for tropical cyclogenesis. However, a particular tropical disturbance may

However, those phenomena can be predicted to some ex-never develop to a typhoon although all the necessary con-tent by means of the state-of-the-art weather prediction

ditions are met. [5] Thus you cannot tell a chance of a par-technology. Moreover, appropriate weather advisory, subse-

ticular cloud cluster developing to a typhoon or ending as aquent evacuation procedures, and other special precautions

short-lived cluster, which fact indicates that sufficient con-before the strike of the typhoon, are important factors for theditions for tropical cyclogenesis are still unclear. On thesignificant reduction of possible damage that may otherwise

other hand, Emanuel [6] remarks on intensity forecast as

be caused. One of the reasons of dramatic decrease in re-follows:

cent years in the amount of losses from typhoons can be

Forecasters claim little skill in predicting the in-ascribed to technological advances in early warning sys-

tensity of hurricanes beyond simple extrapolation

tems, and to the development of communication via radio

and climatological experience. For many hurri-

and television, as well as the improvement of infrastructure

canes, extrapolation is good enough because theyagainst extreme weather events. However, we hope thatstrengthen or weaken slowly. However, in someearly warning systems will play further important role insituation, a phenomenon known as “rapid deep-

the future as the world evolves to more efficient and so-ening” occurs − the central, sea-level pressurephisticated society with increased vulnerability to natural

fell suddenly as winds increased.

disasters. In this regard, we are interested in developing an
early warning system that might be less reliable than or-Thus simple extrapolation, which gives fairly good fore-

thodox numerical weather prediction models, but morecast in most cases, may suddenly provide fallacious fore-

foreseeable so as to provide some information on the con-cast in rare cases such as rapid deepening4. This failure

fidence of the forecast and the risk we should have in mind

suggests an ironic situation that rare cases, or the mostbefore taking or not taking some actions in the very early

unpredictable cases, are in fact the most dangerous and thestage of typhoon’s life cycle. As Ernest Hemingway put it,

most important cases. Here one fundamental question

we believe that “if there is a hurricane, you always see thearises: how can we tell such rare cases by discovering

signs of it in the sky for days ahead,” and we want to dis-some hints on typhoon cloud patterns in satellite imagery?

cover some signs from satellite images.

3 The Perfect Storm [4] and its recent movie (by Warner Brothers Pictures)
illustrates the dreadful shipwreck occurred on the Atlantic Ocean causedby an unexpectedly re-intensified (recovered) hurricane.

4 “Rapid deepening” is defined as a decrease in the minimum sea-levelpressure of a tropical cyclone of 1.75 hectopascals (hPa) / hr or 42 hPa for
24 hours.

18

NII Journal No. 2 (2001.3)

3.3

Informatics Paradigm

satellite images, we can also point out such references as
typhoon data mining by neural network, [14] and typhoon

This question is difficult to answer, or to put it correctly,

track prediction by fuzzy modeling. [15]we do not have any answers for the time being. However,various techniques that have been developed in the mete-

However, it seems that most of the research mentioned

orology community are definitely the most important andabove makes just a minor impact on meteorology due toreliable reference to begin with. For example, in terms of

their lack of meteorological frame of reference; in otherintensity estimation for tropical cyclones, there is a stan-words, their research regard meteorology as one applica-

dard technique established by Dvorak. [7][8] Even before histion of informatics-based methods available to them, but

research, satellite imagery has been the most powerful data

they do not have much interest in truly combining both

source since the launch of meteorological satellites in

informatics and meteorological frame of reference, which

1960s. The long history of experiences on satellite image

is our goal. We also conjecture that, in the informatics

interpretation that had been accumulated from the epoch

paradigm, the huge collection of typhoon related data suchleads to his technique for typhoon analysis which is now

as typhoon imagery and the best track database should

utilized operationally at most of the tropical analysis or-serve as the underlying infrastructure of the research. In

ganizations around the world. This technique basicallythis collection, the quality control of the databases should

relies on the image pattern recognition of satellite observa-

be done in accordance with requirements set for meteoro-

tions along with analyst interpretation of empirically-based

logical applications.

rules, regarding the vigor and organization of convection

Typhoon Databasesurrounding the storm center. [9] Dvorak maintains that it is4

the pattern formed by the clouds of a tropical cyclone that

4.1

is related to the cyclone’s intensity and not the amount ofBest Track

The basic information for typhoon analysis is the center

clouds in the pattern. [8] Hence research on “cloud pattern,”

position of a typhoon, because it is the representative point

or pattern recognition, plays a vital role in typhoon analysis.

on which most of typhoon analysis techniques depend.

However, the reliability of the current technique depends

When the eye of a typhoon can be observed in a clear form,on the human perception of experts, namely subjective

the tracking of a typhoon is just simple; however evenjudgment of the cloud pattern, and is not based solely on

professionals have trouble with determining the position ofrigorous theoretical foundations, or in other words, quanti-

the typhoon when a typhoon cloud pattern takes an irregu-

tative and objective judgment.

lar form. The automatic determination of typhoon center is

In this respect, we propose that, in addition to the tradi-an important challenge; however, as far as off-line typhoontional paradigm based on meteorology as summarized

analysis is concerned, we do not have to automate this

above, the informatics paradigm can also contribute to thispainstaking task and can refer to external datasets called

challenge with novel solutions, because the informatics

best track.

community has a long history dealing with this kind ofSince 1951, official records on tropical cyclones in thepattern recognition problems. Related research fields in-

NWP basin are compiled by the Japan Meteorologicalclude image pattern recognition, computer vision, com-

Agency (JMA) as a best track database. This database con-puter graphics, artificial intelligence, knowledge discovery,tains records such as center position, central barometricdata mining, information retrieval, database systems, net-pressure, and maximum sustained wind for every three towork systems, and so on. There have been not many, but at

six hours. Since those data records are determined by ex-

least a few, attempts to typhoon analysis that can be cate-

perts after all information on the typhoons is received andgorized into the informatics paradigm. For example, theassessed, we can rely on the quality and stability of the

motion of clouds is analyzed from image sequences based

data, and regard them as “quasi” ground truth data. The

on fluid dynamics [10]-[12] and tropical cyclone patterns are

best track dataset allows us to concentrate solely on theinterpreted on satellite images using dynamic link architec-

analysis of cloud pattern.

ture and active contours. [13] Referring to research without

19

The Collection of Typhoon Image Data and the Establishment of Typhoon Information Databases Under International
Research Collaboration between Japan and Thailand(a) Eulerian Point of View(b) Lagrangian Point of View

Figure 2: Two viewpoints associated with the typhoon. Those images on Typhoon 9713 are created from the infrared image(IR1) taken on 1000 UTC August 16, 1997. GMS-5 observes the earth in the form of (a). The edges of the square in (a) is
2,500km, which we define as the size of typhoon imagery. The region within this square is then cropped from the originalsatellite image to make a "well-framed" typhoon image illustrated in (b). Note that the square captures almost entire cloud
pattern of this relatively large typhoon. The approximate measurements of the typhoon are: the central barometric pressureof 945 hPa and the maximum sustained wind of 85 knots (about 40 meters/second).

4.2

Selection of Viewpoints

weather change at a particular geographical location such

The viewpoint employed for creating a “well-framed”

as Tokyo. However, the analysis of a moving object re-typhoon image differs from the one commonly used for thequires creating image sequences that always capture apresentation of meteorological imagery. Borrowing a frame

moving object within the frame; thus Eulerian viewpoint is,of reference from the field of flow dynamics, a well-in general, not suitable for the time-series analysis of aframed typhoon image is one example of “Lagrangian

moving object, such as a typhoon.

point of view.” This viewpoint focuses on the time evolu-

Figure 2 compares two different viewpoints associatedtion of a particular mass or object over a specified timewith the typhoon. Since a geostationary satellite always

period. The coordinate system of the typhoon image moves

observes the earth from a fixed location above the equator,

along the typhoon so that the center of the image always

we always obtain the disk image of the earth. On the othercoincides with that of the typhoon. In this manner, we canhand, the well-framed typhoon imagery always capture theseparate the evolution of typhoon cloud pattern from thetyphoon cloud pattern inside its frame in a concise manner.

global motion of typhoon cloud system, of which the for-In the following, we discuss additional design considera-

mer is our main concern.

tions associated with the creation of typhoon imagery in
Lagrangian point of view.

On the other hand, another viewpoint, “Eulerian point ofview,” describes the time evolution of cloud pattern in such

4.3

a way that all the measurement is taken from a fixed loca-

Additional Design Considerations

tion. Presentation of satellite imagery on TV weather pro-

Mapping Projection

grams usually take this form because it naturally corre-tion scheme is another design consideration for the crea-

sponds to the way a geostationary satellite observes thetion of typhoon imagery. The mapping projection we haveearth, and also because people are usually interested inchosen in this paper is azimuthal equivalent projection

20

The selection of mapping projec-

NII Journal No. 2 (2001.3)

Table 1: Channels, wavelength, IFOV and GFOV of VISSR on GMS-5 satellite.

ChannelWavelength (μm) IFOV (μrad)

GFOV(km)

Quantization

VIS (VISible)

0.55 ～ 0.90

35 × 31

1.25

6 bitsIR1 (InfraRed)

10.5 ～ 11.5

140 × 140

5.0

8 bitsIR2 (InfraRed)

11.5 ～ 12.5

140 × 140

5.0

8 bits

6.5 ～ 7.0

140 × 140

5.0

8 bitsIR3 (Water Vapor)

Table 2: Channels, wavelength, IFOV and GFOV of AVHRR on NOAA satellite.

ChannelWavelength (μm) IFOV (mrad)

GFOV(km)

Quantization

CH1 (visible : green)

0.58 ～ 0.68

1.39

1.1

10 bits

CH2 (reflected infrared)

0.725 ～ 1.05

1.41

1.1

10 bits

CH3 (reflected/thermal infrared)

3.55 ～ 3.92

1.51

1.1

10 bits

CH4 (thermal infrared)

10.3 ～ 11.3

1.41

1.1

10 bits

CH5 (thermal infrared)

11.5 ～ 12.5

1.30

1.1

10 bits(Lambert azimuthal equal-area projection) [16]. This map-

Figure 2 (b) validates the selection of parameters, whereping projection is suitable for the description of typhoon

most of the core cloud systems of the typhoon is captured

imagery because of the following two reasons.

in the image. Note here that we do not perform any further
normalization in terms of scale, because the actual size of1.

Since this projection is equal area, the area of ty-

the cloud pattern itself suggests some hints on the intensity

phoon clouds can be directly compared with that inof the typhoon.

other images by counting the number of image pix-2.

els, irrespective of the geographical location of ty-

Sensor Wavelengthphoons.

select infrared channels because of the following properties

The distortion of shape is in proportion to the dis-favorable for typhoon analysis.

In terms of sensor selection, wetance between a pixel and the image center. This1.

property indicates that the effect of distortion is

activity of a storm continuously night and day.

less harmful to circular objects such as typhoons.
2.
Size Parameters

Infrared channels enable the analyst to monitor the

The creation of a well-framed typhoon

The altitude of cloud top can be derived from theradiance of thermal infrared channels.

image involves determining a few parameters related to thesize of a framed image. The following describes parameterOn the other hand, a visible channel has superior properties

values we have chosen.

in terms of greater ground resolution and better readability
for the manual inspection of cloud texture for thin clouds

1.

and convective clouds. Hence we utilize visible channel

The width of super-typhoons sometimes reaches

data as additional datasets.

beyond 2,000 km. Hence, with some margins, wechoose the actual size of the frame to be 2,500 km.
2.

Size of the Database

The ground resolution of GMS-5 at the subsatellite

We have already collected morethan 20,000 typhoon images for approximately 110 ty-

point is approximately 5.0 km for infrared images.

phoon sequences from 1995 through 1999. This database

Then the image size of 512×512 is almost equiva-

has been used for several types of typhoon analysis such as

lent to the actual size of 2,500 km ×2,500 km as

diurnal cloud pattern analysis, typhoon eye detection, thementioned above.

content-based typhoon image retrieval system, and so on.

21

The Collection of Typhoon Image Data and the Establishment of Typhoon Information Databases Under International
Research Collaboration between Japan and Thailand

14˚ 00'13˚ 30'13˚ 00'100˚ 00'

100˚ 30'101˚ 00'

Figure 3: Scan spots of GMS VISSR in Bangkok area on 0000 UTC December 12, 1998. A white circle represents a scanspot, whose diameter is equivalent to the GFOV of NOAA AVHRR, about 1.1km.

Enhancing the Quality of Typhoon Imagery

5
5.1

which a satellite series operated by National Oceanic andGeostationary and Polar Orbiting

Atmospheric Administration (NOAA) in the United States

Meteorological Satellites

is most widely used in the world. On board it has a sensor
called Advanced Very High Resolution Radiometer (AVHRR),

Now we summarize the properties of interesting satel-from which we can acquire observation data in relatively

lites and how we take advantages of both satellites to en-high resolution through High Resolution Picture Transmis-

hance the quality of typhoon imagery. Firstly, the geosta-

sion (HRPT) as shown in Table 2. An average IFOV (In-tionary satellite is, in general, the best satellite for the

stantaneous Field of View) of 1.3 miliradians or an averagemonitoring of typhoons because of frequent observation,

GFOV of 1.1 km at nadir when viewed from the nominal

wide coverage, and fixed scan range. The Japanese geosta-

orbit altitude of 833 km degrades to an average GFOV oftionary satellite, GMS-5, has a sensor called Visible and

6+ km at edge of scan.

Infrared Spin Scan Radiometer (VISSR) with one visible

Polar orbiting satellites observe the earth from lower alti-channel and three infrared channels as shown in Table 1.

tude than geostationary satellites do, and, roughly speaking,The ground field of view (GFOV) of infrared channels is

this lower altitude leads to higher resolution satellite images

approximately 5 km at nadir from a height of 35,790 km

from polar orbiting satellites. Moreover, there are some areas

above the equator at 140ﾟE. Normally it operates in hourly

where polar orbiting satellites are better suited to the moni-

observation mode, which frequency is fairly sufficient for

toring of the earth. One representative example is arctic re-tracking the global motion of the typhoon cloud system,

gions invisible from geostationary satellites due to earth

but not enough for the accurate estimation of surface winds

curvature, while polar orbiting satellites can observe thosewhirling around the typhoon center.

regions from zenith. However, polar orbiting satellites are

Another type of meteorological satellites of interest is ausually inferior to geostationary counterparts in terms of low

polar orbiting environmental satellites (POES), amongobservation frequency and narrow scan range. In summary,

22

NII Journal No. 2 (2001.3)

those two types of satellites have their own advantages andits scan range. Since Typhoon 9921 is positioned in the rightdisadvantages, and our idea is to compensate the degrada-edge of the scan range, overall cloud pattern is not observ-

tion of GMS-5 imagery with high resolution NOAA im-able through this sensor. In contrast, Figure 4 (b) shows theagery.

map projected typhoon imagery and Figure 4 (d), its scan
range, in which overall cloud pattern is captured because of

5.2

Combination of Satellite Data from Two
Satellites

the wide coverage GMS VISSR. However, notice that somepixels in the left edge of Figure 4 are slightly blurred.

Now we describe our main challenge in this paper;

Hence the NOAA data and the GMS-5 data taken on ap-

namely the combination of two satellites for creating theproximately the same observation time can be integrated

comprehensive collection of high quality typhoon imagery.

together for enhancing the quality of typhoon imagery. In

Typhoon imagery created from GMS-5 tends to show deg-

this scheme, the collection of typhoon imagery is composed

radation in resolution and distortion in cloud shape espe-of low resolution but frequent observation data from GMS-5

cially over South East Asia, because pixels in the edge ofand high resolution but less frequent data from NOAA.

scan are skewed from the sensor due to earth curvature.

Here we also point out that the comparison of Table 1

For example, in Figure 3, white circles represent the lo-

and Table 2 shows that IR1, IR2 of GMS VISSR and CH4,

cation of scan spots of GMS VISSR around Bangkok

CH5 of NOAA AVHRR represent almost the same wave-(Thailand) area, where the separation of neighboring scan

length. This property allows us to compare typhoon images

sports increases to about 7.5 km, which is 1.5 times larger

created from two satellites. Although the quantitative com-than that at the subsatellite point. On the contrary, the di-parison of two typhoon images is left for future works, inameter of white circles represents the ground resolution ofqualitative evaluation, we conclude that NOAA satellite

NOAA AVHRR at the subsatellite point5, namely 1.1 km,

data can provide complement data for the creation of highwhich figure shows much better resolution than that ofquality typhoon image collection over South East Asia.

VISSR.
6

This comparison indicates an advantage in using polar
orbiting satellites for improving the quality of typhoon

International Research Collaboration
between Japan and Thailand

imagery in terms of higher resolution and less distortion.

Since polar orbiting satellites move around the earth, theThe biggest disadvantage here lies in narrow scan range; theacquisition of satellite imagery over Thailand requires

scan range of 2,800 km is only marginally larger than 2,500

having at least one receiving station in Thailand or its

km, which is the size of typhoon cloud pattern. Therefore,

proximate regions. The receiving station operating at Asianunless the center of the typhoon is positioned very close to

Institute of Technology (AIT), Asian Center for Researchnadir, we cannot capture the whole picture of the typhoon.

on Remote Sensing (ACRoRS), thus plays an importantMoreover, we may lose track of cloud motion due to the lowrole in obtaining NOAA AVHRR satellite data over Southfrequency of observation − just a few times a day.

East Asia. Upon the reception of satellite data, part of them
are transferred to Japan through the Internet and concur-

5.3

Experimental Results

rently archived in Japan. On its route to Japan, SINET

Figure 4 compares two types of typhoon imagery createdInternational Link, 2 Mbps international link devoted to thefrom two meteorological satellite data. These images take

distribution of academic information between two coun-

the cloud pattern of Typhoon 9921 on 2100 UTC October 19

tries, serves as the infrastructure for exchanging huge

1999. The position of the typhoon was around (17.1ﾟN,amount of satellite data.

107.3ﾟE), near the city of Hué (Vietnam). Figure 4 (a) shows

will otherwise be realized by sending tape media by a snail

the image received from NOAA AVHRR, and Figure 4 (c),mail; in this way, near real-time monitoring of the earth

The distribution of satellite data

environment, such as typhoons, cannot be realized. Hence
this international link works as an indispensable part of this

5 The size of a scan spot of AVHRR (1.1 km) may be compared with ahuge public ground in front of the Grand Palace called Sanam Luang incentral Bangkok, which, in length, has approximately half the size of ascan spot.

collaborative research.

23

The Collection of Typhoon Image Data and the Establishment of Typhoon Information Databases Under International
Research Collaboration between Japan and Thailand(a) NOAA AVHRR (CH4)(b) GMS VISSR (IR1)(c) Scan range of (a)(d) Scan range of (b)Figure 4: Comparison of NOAA AVHRR and GMS VISSR. These images (Typhoon 9921) were taken on 2100 UTC October 19, 1999. The position of the typhoon was around (17.1ﾟN,107.3ﾟE), near the city of Hué(Vietnam). The interpolated
measurements of the typhoon are: the central barometric pressure of 996 hPa and the maximum sustained wind of 35 knots.
Scan range of (a) and (b) is represented by (c) and (d) respectively. Note the similarity of typhoon cloud shape between (a)and (b) that are taken almost on the same time.

24

NII Journal No. 2 (2001.3)

This international link is also used by other researchers

collaboration we also had annual international workshops,

both in Japan and Thailand, some of which have been tak-

WAINS, for exchanging ideas and results about individual

ing part in the joint research project called “NACSIS-Thaiprojects. SINET international link between Japan and Thai-

Project.” As mentioned earlier, the purpose of this project

land serves as the infrastructure for this research collabora-

is to promote international research collaboration between

tion; in terms of our individual project, we benefit fromJapan and Thailand through the usage of the international

this international network for exchanging satellite data

network between those two countries. Since its establish-

between the receiving station at Asian Institute of Technol-

ment in 1994, “NACSIS-Thai Project” covered diverse

ogy and NII.

research areas such as multi-lingual and multimedia deliv-

The main part of this paper discussed methods and ideas

ery system, digital library, the collaborative development

towards the comprehensive collection of typhoon imagery.

of online dictionary, satellite data exchange using high-To prevent or reduce damage from typhoons, indispensable

speed network and advanced network technology. Anotherare powerful techniques that can analyze current cloud

activity under this project is an annual forum called “Interna-

patterns and predict typhoon evolution in the very earlytional Workshop on Academic Information Networks andstage of the life cycle of the typhoon. The uniqueness of

Systems” (WAINS) for exchanging research achievement on

our research can be characterized by the “informatics para-these topics. Since 1994, we have held 7 annual workshops

digm,” which is based on various techniques that have

either in Japan or in Thailand. In the future, we are plan-

been developed in the informatics community. The specificning to extend this project to include new areas such as

challenge in this paper was to enhance the quality of ty-

bioinformatics, robotics, and distance learning.

phoon imagery over South East Asia. The idea was to

The individual project we are involved under “NACSIS-

combine satellite data from two types of satellites, namely

Thai Project” deals with the exchange of satellite data

geostationary satellites and polar orbiting satellites. The

through the Internet. Although this exchange has currently

disadvantages in using GMS-5 in terms of resolution andreached to a stable level with a bottleneck inside Thailand,

distortion can be compensated by the incorporation of

we should also notice that there is a tendency of remark-

NOAA AVHRR data received in Thailand. The ultimate

able increase in the amount of satellite data necessary to begoal of this solution is to create the comprehensive collec-

exchanged, because new sensors tend to have more chan-tion of high quality typhoon imagery.

nels with wider bandwidth coverage, better spatial resolu-

An important future work is to apply data mining ap-

tion, and higher radiometric resolution. Hence the per-proaches to this typhoon databases to discover relevant,formance of the network should be improved in accordance

possibly hidden rules or knowledge, that ultimately lead towith the amount of satellite data distributed through thenovel typhoon analysis and prediction techniques. Among
research issues stated in Section 2, cyclogenesis forecast

network. To maintain a global network on which such huge

and intensity forecast are the most interesting research

amount of satellite data can be exchanged without too

issues. In terms of typhoon disasters, we should also pointmuch congestion, we need to develop high performanceout that the integration of typhoon information databases

broadband network technology such as caching or multi-

with geographic information systems (GIS) will be an im-

cast. Experiments on these network issues are left for fu-

portant part of our research under the conception that me-

ture work.

teorological data are one example of geographical data.
Finally, we need to develop novel network technologies for7

Conclusion

the efficient exchange of satellite data through the Internet.

We have described our ongoing research, namely thecollection of typhoon image data and the establishment of

Acknowledgement

typhoon information databases under “NACSIS-Thai Pro-

We would like to thank Prof. Kitsuregawa and Dr. Nemotoin Institute of Industrial Science, University of Tokyo, andProf. Shibasaki in Center for Spatial Information Science,
University of Tokyo, for the courtesy of allowing access to
GMS-5 satellite data. Moreover, we also would like to thankject.” This project has undergone approximately sevenyears of international research collaboration between NII
and Thai research institutions, and along with research

25

The Collection of Typhoon Image Data and the Establishment of Typhoon Information Databases Under International
Research Collaboration between Japan and Thailand

Prof. Murai, Dr. Honda and Dr. Surat in Asian Center for
Research on Remote Sensing, Asian Institute of Technology,
for providing NOAA satellite data and software support.

[10] Palaniappan, K.; Kambhamettu, C.; Hasler, A.F.;
Goldgof, D.B., “Structure and Semi-fluid Motion
Analysis of Stereoscopic Satellite Images for Cloud

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