J. Jpn. Soc. Soil Phys.
No. +*3, p. /+/0 ,**2®

¯*ῌ°±²*ῌ³P´µ*Improvement of the Measurement Apparatus for ConvectiveVelocity of Ponded Water in Paddy FieldsSusumu HANAYAMA*, Tatsuaki KASUBUCHI* and Takeyuki ANNAKA** Faculty of Agriculture, Yamagata University, +῏,- Wakaba-machi,Tsuruoka, Yamagata, 331῏2///, JapanAbstractWe improved the measurement apparatus for convective velocity of ponded water in paddyﬁelds, proposed by Fujimaki et al. (,***).

Since the e#ect of air bubbles accumulated along thesensor on the measurement values was observed, we developed a new equipment to prevent airbubbles from accumulating along the sensor.

Another improvement was that the power sourcesof all measurement devices in the apparatus were exchanged from AC power supplies to DCpower supplies.

This improvement allowed us to measure convective velocity of ponded waterin paddy ﬁelds without AC power supplies.

The good performance of the improved apparatuswas veriﬁed by the measurement of convective velocity of ponded water in a paddy ﬁeld.
Key words : ponded water, convective velocity, bubbles, DC power supply+HI75 JK0 6.-5LMNO6P* Q7R,-?MNO*#ST787AU>?%VWXY Z[\;.*]?^_ 3- >MNO`ST0 P Z[

#  *a48b'8'->?#cdeK8'-\+afg[hi\h*a48jk- MNOlmRose and Chapman, +302 ; Mowjood et al., +331 ;*+,-Zn0MNOlmopqr6steMowjood and Kasubuchi, +332 0uvw*+x ypex5MNOVzh*]{|6+a}~?

'8 _&b?78 ~-5L 0K- 77 MNO`ST*?]&U*+,- ῏῏ uvw+af./<`{|0>KA%K8'&'ῌb*+'8&6r578'-?
KFujimaki et al. ,*** 06./~

A5 Fujimaki et al. ,*** ./BCDE0FG./6bex-*6?~-5L!"#$%&'()*+,-./012%345-Q6y7 %;.<6cd78'- %0 ῌ MNO*ST~-#./*+a}./0 MNOzh*+,-V~{|6~->? ῍ +afZ 6h6 @?75Q£ ῎ £eK5./BCDE75]%3- ~& ¡ ¢/ypex5MNO6¤P*Q¥?_ ¤*¦78M6789:()%;.<6=->?6 @?75NOV0zh~- >MNOVzh*?]&,UMNOzh6./~->?%3- 0 §

6¨78# *.+῏+.. mm s+ ©ª%, +zb~->?cd~-??]* ./*+,-«¬6Fujimaki et al. ,*** ./Q­**  331῏2///  +῏, :    \] ^ +*3 _ ,**252ῌ+ %&'()* Fujimaki et al., ,*** +,Fig. + Outline of measurement apparatus for convective velocity (Fujimaki et al., ,***)`a b- ,῏+ V'(c;dP+e. fi#. jNk. l m DCA+++F, DEICY. En(o , p PA+2-+.,A, KENWOOD. AD8- V+. R+ G@H R, (gh . ῎ @e e45R67- 89:.  ;$ $ qr @?stVuvawxR Vuvy8Greenkit22. ESD.  !"#$# PC32*+UV, NEC. e 4z- {. J&Vuvawx?st|}B- f i#. EF *.+* mm. I /**V~ B. AWXR Vy8e e 5-mm  ABCB DEFG@HI,,   ;$ $  EF *.++ mm e9 S XR< ;$ $ v a- f<. S  @  ;$ $ ?si#J [* . #$#;$ $ R<JB @? ;$ $ '-   '(<#M;M jNk!"l m4# .  !"#$,῏+  P+ ¤q . ;$ $ ?strJ 2 cm8@>Je. A r f i#[* . f i# SR<¡¢'(<- '(£J? +20

<- f i# S  rJ UTP, ¤ABCB G© e+.

e, ª%Be+V+R+ῌR+RNi e,V+R+ῌR+RG=8> ~<- f i# +0 cm/ -3 cm/ +* cm $-P, ¤¥ e ¦§@>¨ B- P+ ¤t VD Z~ B- AS VῌJKLMNOP QR. A S TUK V«¬­®¯ Tz~@ °±<- ²³῏+ f i# S V <¡¢´a- S V <¡¢G@H & f i# S. R+  R . RNi . RGV8aµ `a . ABCB - '('( <-  ;$ $ . V+'( Ga jNk z #$# jNk z- B @e. P+ ¤zABCB +./ V, -.* VP, ¤¥ e  e+ Fujimaki et al. ,*** WXYZe, ª «  B-eV+R+1+ῌR+RNi2+ῌR+RNiR3. RGRNiR῍<- R  ;$ $ =8>?  @- . R,R+RNieV+R+ῌR,1+ῌ+R, ῌR3῍ ῎,῏ , fi#sS<- B¶[( <-@ <WXe. f i# S '(¶ G@· V9h<- '¸¹h0* )#$#z . +** )h+2* )¥G©f i# S R<µº*S8aµ+, +*ῌ uvy8<- S

X @ ?V S V&'( ) :ῌ+ * + ,53ῌ, Photo + Sensor with bubbles accumulatedFig. , E#ect of air bubbles accumulated alongsensor on measurement for convectivevelocity of ponded water-./012345.3 67.8R 
9: e 9:6;<=> ?@3 -, 2A-BCD E>F6.Fujimaki et al. ,*** GHIJKB- -++TUS/ FFKBF>=SVW*+6*KUX^_XU^cLM)2NO P QR+S 6- AC SK!

+ #FK `h** defdga323b6. #FK ijMk:+b +./ V B !" # $ %ῌ-  r!"stuῌ, v+Y S KZK[./\] Y/01 + lmnoj K , pqA-QR> Owx yP b - V Bhz6#" , p ?

${!|m}M~H . ~ ~| }M~./7 K . pqA-QR F%l 6 PH M)FA-+-*RA,i P  qA-dK[28 /- +  KijMk2NO P b:+VWB#>> 0 &6 , &6 + VWWK ,.

P SB + lY , p -.* V q FS ONῌOFF j  ) SDM-CDjMkK +./1 V \= +.// V, O P K -.** V \=+0AC, Campbell Sci. K,.33 V 6 #>>bB ,ῌB , mm s+ 6 . K3 b23.5+B K+'*6-

P()MnJK+,

9_+F6K*Kb9-/-K!K[28m*\= .>+F6B+F6. ?@3*¡/¤@A-\= %ῌ. B

  #6[#>>   bB i*¡/qA-9- !" %ῌ/ 9- *c0%v+ ¢= ,**1 9-1B%ῌ/ 2£3¥¦+4¨/R+ῌR* K§@ 5KB2£ R* 6 R+ #>>2c\=£6B +.** k ..30 k.K9-1B7 / 86.© ¥¦+@KªCVW2A- 6«¬m B LM-/2N Texas Instruments Inc q­\9®7K #¯° SB 3V ± **0P lY + pq&c6 +* &cWK +6«B¬­.\A #FK5GHIJKB ³´  / &h*+28

%ῌ0 B!"m  :;²K 5 Kq+<µb *.*ῌ*.- mV -¶&.·±²=+F6v>
%ῌ + Kv> AD >¸¨2N¹º

PB'( )*+ , +*3 - ,**254ῌFig. -

Outline of equipment to lift up/down sensorῌ.

Fig. .

Disturbance of ponded water by liftingup/down sensorPS+**, Campbell Sci. ./01ῌ,Photo ,. Equipment to lift up/down sensor234567

89:;<=>?@ABC;D. Fujimaki et al. ,***EFGHIJK1 ?@ABC;DLMNO -* cmP !"#$%& CR+*X, Campbell Sci.+** cmQR ,* cmYZV1 #$%&C].^_V .`7V1ab.;cL +, V[\=AS .TUV W S

X>?@A : BCD3῎45EFGH῏ῌῌ/Fig. /ῌῌ0Fig. 0ΐ

55 ,**1 Circuit diagram of ampliﬁer (Nakamura et al., ,**1)ῑῌῌ1῏Fig. 1Output characteristics of ampliﬁer!"#$%Calibration of sensor using improvedmeasurement apparatusIJKLMNOPQRSTSU4RVWX-QYPZ* + [\-Q];V^P& EF* , _`a0-& EF_`* +,* b` cMdNefghGH+_` 0- :;<;WX45Vm ;HEF8*+,* b`0-& Un op* EFqr / scMdhtu EF8+vF-u -*ῌ+,* bwND NpxRy pxRyQNnzHef{|}~-0-&ῌ1 * !

EF_`*+* suND!"#$%ij0klN& EF_DNn"#$%./V^  ῏$KNnQzH*DC = / cm xNGHOsNd+R;&N-&EF* ,**1  2 Ni$M +  +.2 m'+.2 m  PQYP& 

ῌ2 *3῎45EFῒV^H& 3῎45* / _V6¡0U  :u+- _NzQo- +/ _¢p$M£¤*¥¦£¤V^  §¨©ῐ +..*7x-&g kg+ §ª©ῐ +.- g kg+ CῌN « +*.2 ῌ¬­®

()* Fujimaki et al. ,*** +,-./012-ῌ2 V,R;3῎45+[{|GH0P¯ῐ ++ cmolc kg+ V^P& EF_$M& 3῎456780698*:;<;= *.. mm s+°±* ²D³ +* cm ῍´DB0-& EF_µ0= +.0 mm s+ 0U  1[3῎45{¶* ·  +*356,**2!"#$%&'()*+, -./.012' 3456!7"#8&%9:;<=>?5@AB C, DEFGH I9JK6AL!$, +* cm 'MN&OPQ= HI/cm RS&%T6!A4'(UV'WXYZ[\]^_`a!ABῌ ῑ ῐ ῍Fujimaki, Y., Mowjood, M.I.M and Kasubuchi, T.
(,***) : Measurement of convective velocity ofponded water in a paddy ﬁeld, Soil Sci., +0/ : .*.ῌ.++.
῏ῌ2Fig. 2Mowjood, M.I.M., Ishiguro, K. and Kasubuchi, T.

Diurnal change in convective velocityof ponded water with time(+331) : E#ect of convection in ponded water onthe thermal regime of a paddy ﬁeld, Soil Sci., +0, :/2-ῌ/21.

+., mm s+ Pbc, 6!de9fbTMowjood M.I.M. and Kasubuchi, T. (+332) : DynamicsJK6Ag=+,39 Fujimaki et al.

of dissolved oxygen (DO) in ponded water of aK6A,*** K6++.- mm sPhij$Qc,Rk'M `UV9l UVPmj6!n _aP|}<+, $Q$b5= ~a9CP9&7b& .paddy ﬁeld, Soil Sci. Plant Nutr., .. : .*/ῌ.+-.

opqr stur vw x ,**1 : K6yz{ ,  p. +3*   Rose, C.W. and Chapman, A.L. (+302) : A physical.&%  .analysis of diurnal temperature regimes in clear 5 *.- mm s+ P4and turbid water layer : A problem in rice cul--./.012'-./.0 3456ture, Agric. Meteorol., / : -3+ῌ.*3.

ῒFujimaki et al. ,***῎'c%<+, _6!aUV`_c, . 58¡OPA6!"#5AOP_¢£$  _¤¥<¦b&UV_G§$, C,6!¨©G3@bª«¬_¢­$¡&®¯A6!_°na,± ²«¬A6!A4'(6!UV_`$, ³$% O`UV_&%´ ®¯A6!$,µ¶ `UV9b6!n _ aP|}<+, : ,**1  +,  1  : ,**2  .  / 