recent research pr（）jects． The su血ce air temperature was measured in a spatial resolution of 50r

GEOGRAPHICAL REPORTS

OF TOKYO METROPOLITAN UNIVERSITY 43（2008）115−121

IMPROVEMENTS OF HEAT ISLAND MONITORING NETWORK IN TOKYO

Chieko SUZUKI

Abs〃 act Some meteorological observation netWorkS for urban climate stUdy were developed in

recent research pr（）jects． The su血ce air temperature was measured in a spatial resolution of 50r

2．5㎞，which was higher肋1伽㎞出e exis血g rou血e netWorkS． The research projectS improved measurement methodology in developing these netWorkS． More improvements were archived rather than those in hlst㎜ents；erroneous measurement was reduced by an accomplished methodology in planning the site location． The results obtained in these pr（）jects

suggest that the quality control for long−term measurementS is an issue to be resolved in the血ture．

Key words：a辻temperature， observation netWork， Tbkyo， urban heat island

1．introduction

  Our daily life dependS on daily weather conditions． Jal）an Meteorological Agency（JMA）has two observation netwod（s：one manned station and seven unmamed stations in the Tbkyo

Me噸1i伽Area． The unmanned automatic observation equipment was named Automated

analyzhlg these data． First， their databases are not easily accessible， and the researchers have to wait several months to obtain data． The second issue is with regard to the data quality． Most of the

  Tb solve these problems and di伍culties， three research pr（）jectS have established their observation netWorkS in the Tokyo MetropOlitan Area and elucidated the heat island phenomena．

Other than high spatial resolution， these netWorkS have succeeded in a implementing a long−te㎜

measurement． It enabled us tO analyze the seasonal variation in the heat island， although many preVious stUdies focus on the heat island only d曲g s−These projectS have been repOrted in mass media fbr their unique me｛hod f（）r aセtemperature measurement They have cooperated 輌th elemen伽y schcols and installed thermometers into the exis血g thermome敏shelters， which

＊Chiba PrefectUra1 Urayasu High School

一115一

were also used for educational purposes．、       ・

  This anicle describes how these pr（）jec s have improved the measurement netwo1kS． The

discussion will be mainly held on the air tempera加e measurement in Core Research Pr（）ject f〈）r

2．Outline of Three Projects

Tokyo air°temperatUre measurement pmoject

  A collaborative research pr（）ject was conducted by Tbkyo Metropolitan University and Tbkyo MetropOli伽Research lnstitUte for Environmental Protection（hereafter refereed to as TAT92）．

The pr（）ject measured the air temperature at l OO sites in Tbkyo丘om August 1992 to JUIy l 993．

The sites were 10cated血2．5㎞帥d8、㎞血e cen血1 p飢of T晦o and 5㎞鄭㎞出e

surround血g area． The grid siZes were detemiined by the spatial representativity and spatial scale

of the heat island． Consideねble efR）rt was made to select an elementary school or other othcia萱 institUte that was nearest to the grid pOint and was facilitated with a thermometer shelter． The data were distdbuted to the pr（）ject pani［cipants．

CREST（Monitor血g and Management of Urban Heat ISIand）

  A research project named Monitoring and Management of Urba l Heat lsland was con（加cted with the support ofthe Japan Science and Technology Corp（）ration（JST）丘om l 996 to 2000． This

pr（）ject aimed to evaluate and develop the effective methodS for heat island mitigation． A su血ce

pardcularly with regard to its relationship with ant㎞叩ogenic heat waste and the mesoscale wind system． The network had two types of sites；in this a血cle， they are known as CREST−A and CREST−B． Both CREST，A and CREST−B sites were facilitated with a the㎜ometer−hygrometer installed in a止emiometer shelter in the elementary schoo1． hl addition， CREST・B site was equipped also with an anemometer and a whld vane． Based on the result obtained by TAI「92， the number of sites was increased to 1 19 and the measurement area血creased by 10 km toward the no血and 5 km toward the south of血e W92膿a． The TAT92 area was limited to the Tokyo administration area， and they could not clarify the diuma1 movement of wamier air（Ushiyamaθ al．，1999）． The netWork started fUnction血g in summer 1997 and cont血ued㎜dl sp血g 2000． The

data was distributed to the pr（）ject participants under the rules of JST．

Me伽po肢伽EnVironmental TemperatUre and Rainfa皿Observa on System

  The tWo groups that organized TAT92 also developed ano止er measurement netWork named Metropolitan Environmental Temperature and Ra血制ObservaUon System（hereafter referred to as METROS）丘om 2002 to 2004． They developed two types of sites． The first type was used fbr su血ce a廿tempelature measurement at approx廿nately 100 sites（METROS 100）． These sites were also used the thermometer shelters in the school． The second one was a 20−site netWotk named METROS20 that measured a辻temperature， wind， precipitation， and a廿pressure at the building

rooflevel． The data were available to the researchers who were not involved in the pr（）ject．

o

一116。

Table 1  0bservation netvvod（s f（）r u烈）an cl㎞ate study

Networks

A    B

METROS

lOO   20 Sites  Number

     Average distance

Measurements

     Period

■

100 5km＋

Interval Parameters

  Air temperature O

101

5km＋

18 97    20

2．5km

August l 992−August l 997−   August 2002−

July l 993  March 2000   March 2005

15min    15 min 15 min＋＋10min lOmin

  Wind direction ×   Wind speed   ×

○   ○   ○

○   ○   ○

×   ○   ×

×   ○   ×

×    ×    ×

×    ×    ×

Natural Natural Natural M    A，M   M

＊＊       ＊＊       ＊＊

○

○

○

○

○O

Forced

A

＊＊

＋：2．5㎞舳ec㎝副卿s of恥域oヂH：Wind speed and direction are measured at 10 m血intervals，

M：Manually acquire￠ A：Automatically f（）rwarded via cellular phone，

＊：lnterpolation with the reciprocal of distance， and＊＊：Depends on each user

3．Comparison of Measurement NetWorks

  The details of each netWork are given i血this section． Figure l shows the distribution of the sites in the three observation netWorkS． Table 1 summariZes the meas−t resultS．

TAT92

  The air重empera加re was measured with the nat㎜レventilation−type shelter that was the existing facility童n the elementary schoo1（Fig．」a）． The㎞st㎜erにused was battery」operated automatic logging themiometer（Micro Data Logger， IBC Co．， Lrd．）． The air temperature was measured at 15 min intervals and stored in the memory． Data were manually acquired from the logger every 3 months． The thermometer used was calibrated血three temperature ranges before and after the measurement． The calibrated and quality−checked data was stored in the database（lto

θ 01．，1994）．

CREST−A and CREST−B      伽

  After TAT92， the natural−ventilation−type shelter in the school was used fbr the temperature measurement in both CREST−A and CREST−B（Fig．1b）． An飢omatic lo細血g the㎜ometer

−hygrometer（SK−O l SArO Keiryouki Mfg． Co．， Ud．）was installed in the shelter The measurement ihterval was l 5 min， an山he data were manually acqμired丘om the logger every other month． CREST・B site was also equipped with an anemometer and a vane at 3 m above the

gromd level． Wind data were automatically transferred to the host computer via a cellular phone．

一117 一

 The the㎜ometeFhygrome重er was calibrated at 5°C  ilterva ls bef（）re and after the m6asurement．

However， the correction of p mper耳ture was carried out by the i ldividua1 user． Quality control was also per茸）rmed in every analysis．

甑TROS100 and MEM．OS20

 The MEROS 100 site also measured the air temperature hl the natura1−ventilation−type sheher in the schoo1（Fig．1c）． The measurements were carried out using an automa廿c logging thermomete晦grometer（3（S41， HIOKI E．E． Corp．）副O m血inten・als． Data acqUisition was manually performed tWice in three months．

「働ぞ制一、

く 殴＼まノ・

F鱈．la Location map ofTAT92 sites（Sh㎞oyama l 996）．

F喀．1b Location map of CREST sites（Ushiyama et al．1999）．

一ll8。

Fig．1c

・5

         萌6，

       ∀郵轡 囎：離・搬1浸獣、

・餓灘．灘燦く雛TeeSiea］

㍉

゜ノ

賊

Location map ofMETROS sites（sma 11 cir℃les indicate METROS 100，

la㎎e circles㎞dicate METROS20）（Ando et al． 2004）．

The METROS20 site was血stalled on the building r∞f， where， commercial electric power s叩ply was available． The measured parameters were air ternperature， relative humidity， w血d speed and曲ection， precipitation and baromeUic pressure． A fbrced−v㎝緑1ation−type the㎜ometer shelter was used， which was one of the improvements over the previous two netWorkS． The measurement interval was 10 min， and the data were transferred to the host computer automatically via a cellular phone． Quality control eliminated the erroneous and ambiguous values

（Andoθ o∠2003）．

4。DiScussion

Improvement of observation netWorks in伽ee projects

  Table 1 shows some improvementS in tl te netWork performanoe that were achieved in these

three pr句ects． One is the increase in the measUrement periOd． The TAr92 pr（）ject encountered an

island in the El Nii50 year and other years． Due to its succession fbr 3 years， the METROS pr（）ject

  The second improvement is the increase in the number of measurement parameters． Al血ough only血e air temperatUre was measured in TAT92， the parameters for humidity and舳d were added in CREST． Further， pressure and preciphation were measured in METROS20；this allowed 食）r the investigation of the heaVy urban rain． These improvements should lead to a reduction血 cost of the inst㎜ents． Upgraded instnumentS enable us to conduct more frequent measurements

（a resolution of 15 min in TAT92 and CREST−A and a finer resolution of 10 min in CREST−B and METROS）and automatic data acquisition．

  The forced ventilation of出e thermometer shelter is the third improvement． METROS20

一ll9一

introduced iち although the previous netWorkS used natUra1−v㎝伽on一膿血errnometer shelters．

職e㎞ced−ventilation−type shelter requires commercial electric ． pOwer supply；however， it

㎞proves血e a㏄㎜cy of the measured te卑peIa加re． The natural−ventilation−type shelter cann（）t

prevent heat血g and cooling perfectly by radiation；thus， it causes a positive bias（warmer than the tUe air temperatUre）in the daytime and negative bias in the nighUime．

  The CREST data that were measured with the natura1−ventilation−type shelter indicate重he magnitude ofthese biases． Figure 2 shows the temperatUre difference at 41 CREST sites relative to the JMA site（Otemachi si勧． The JMA used the forced−ventiladon−type shelter． Thus， Fig．2

shows the spatial variation ofthe temperature as well as the tempera加re difference due to the types of ventilation． The brand new thermometer should 1）e error free du血g this period， although some sites were not installed at this血1e． It should be noted that the CREST temperature is an average of

hour i 1 genera1， the CREST temperatUre is larger than the JMA temperature in the daytime but it

−0．7°Cin the nightほme．

2

0 3 6 9 12 15 18 21

・一・X0％

一・

ledian

一一・P0％

Local standard time

Fig．2 Diurnal variation of血e difference血air te即erature betWeen 41 sites ofCREST and     JMA station in Otemachi（in August 1997）．

  On the other hand， the difference between the 25％and 75％po血ts is roughly less than l°C；

thi3㎞dicates the spatia1 variation hl the CREST data． Thus， the difference due to the shie豆d type

natural−ventilation−t）rPe shelter hl METROS 100．

  The fburth advancement is in the plannjng of the site location． TAr92 netwofk appears to have

an ambiguous site， where血e envko㎜ent was conside曲ly礁re血from血舳出e o出er sites

⑰．K． Shimoyama，蜘e communication）． For example，鋤ex廿emely hi帥te即e伽e was

一120一

ヤ

observed in a specific site；this must be due to血e｛msphalt pavement below the血ermometer shelter．

Based on this suggestion，1血e CREST project developed a proce（lure for site planning． The site had

etc．）and distance fr（）m the nearest buildjng（Ushiyama et al．1999）． Final1》〜llgsites were selected

】巨「utU】re Issue

  The previous two projectS（TAT92 and CREST）distゴbuted lhe data only to廿1e prqlect

members． Theref（）re， these pr（）jectS did not have a unified guideline fbr correction and quality

methodS for quality cor血ol and gap mling． The teclmical expertise was not stored in the projectS．

  In recent years， many pr（）jectS have been f｛）rced by the sponsors to release the measured data to

particular， for the long−term measurementS， the血1e trend is the main topic in the analysis． Thus，

止eproject has to fbcus signi五cant attenUon to the decrease ㎞血e data quality dur血g the measurement． Some projectS other than the ufban cl㎞ate study have attempted to develop the

guidelines for quality control． Theh・resUltS should be used in the urban climate stUdy．

  Flnall》〜one more viewpoint should be added as a fUtUre task． These three pr（）jectS mainly

f（）cused on the surface measurement that is necessary f（）r elucidating the heat island phenomena．

Howeveらwhile discussing血e fomiation process of the heat island， we require the（lata abOve the gromd level， for example， the profile in the building canopy｛and the wind speed abOve the roof level． The verdcal measurement， in conjunction with the surface measuremenち would be required

for understanding the heat island．

References

Ando， H．， Shioda， T．， Morishim礼 W．， K（）jima， S．， Ishii， K．，㎞mi， T． and Mikarni， T． 2003， Spa廿al

strpcture gf summer temperatures over血e曲…of晦in 2002．伽蜘呵

   Tokソoノレfetropolitan・Research lnstitu彪ノ1＞r Environ〃zental Pro彪ction 2003：81−87．＊＊

Ito， M， Udagawa， M． and Mikami， T」994． Tokiyo tonai no kt on bunρu ni tsui彪（Air temperature    in・T（）kyo， ver．1）． Annual Report ofTok）・o Me〃 oρolitan Research lnstitu彪for Env〃りη〃iental

Sh廿noyama， K．1996． Tokiyo t∂nai ni okera sei，彪nbi nicchu no in on bunpa tokusei（A廿temperature

   Tokyo Metropolitan University．＊

Ushiyama， M， Mikami， T． and Kim㎜， K．，1999． The spread of the high density urban climate    observation netWorl（㎞Tbkyo alrea． hLル表）η∫ω7加9 a〃d一ルlanage〃2ent of乙「rban」Heat」lsland    In彪rium Report． 4−15． Tbkyo：Japan Science and Technology Corporation．＊＊

（＊：in Japanese，＊＊：in Japanese with English abstract）

馬

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