1+ *3 1,+,/+ * +,, - - - + +32+ *0,0 / // cm cm - / +30+ +32* 0 +33+ : Key wors: long-erm observaion, fros eph, groun freezing, snow cover perio, hawing of frozen soil + - / + +33* + * 2//* - +2 2, +*- **+, + - +1 * : *0- *2*- - F - *2/ 2///, ++
242 1+ *3 D cm cm * F ay *+ D a + : : : a +32* ; +33, 2 *+ Berggren Johnson, +32+ Nixon an McRobers, +31- Berggren Alrich, +3/0 + +32+ *0 D l D l k +30+ +32* L 0 F +33*, N, /,,, E+- +* +0 10 m +32+ Anersson, +30 /* / m +313 ; +33* +/ cm +30+ cm +32, /* cm +332 +33+, 3
1+ *3 243 - D F 2,, / cm */ *0, 1*1 ay +331 * -+ cm D F **/ p*3 -+,, -, cm +32, ; *+ cm cm cm +32+ +330 +,, + /* +331 ++ + / -+ */ +, +322 - - -+ / +32+ +330 -++ +* 1 +331 */ -- +32+ *0 F ay D cm - +32+ +321 1 +*0 ay -3, cm -+- +32+ *0 +322 +330 3 +30+ +32* 0-3 ay,3* cm cm +, + +331 * 2 3,, ay
244 1+ *3 0 /* cm 3 - -,+ /* cm /* cm c +30 +, /* cm a b c +32, +30+ *0 + +32+ *0 / c +30 *1a a +322 -, +, +320 +32, b, *+ +, cm D cm
1+ *3 245 + +30+ *0
246 1+ *3 / a b c *1a F + D F 0 *- cm * cm - / 1 cm D cm F *0/ p**+ F -+- c a,2 *23 p**+ D cm F, D eph cm F F D F +30+ */3 p**+ F F 0 eph S +/,/ -*
1+ *3 247 - b F +0* ay a * -** ay +/* ay cm D -- --+ D D 1 +333 *, * 1 D D 1 D D, D *2/ D 30 *3/ p**+ D D c - 0 --, 2 D T, T T ay D 0 2 1 T T D +33+ +33 + cm +333 *, * F D T D D Db + D D T b,1 *2- p**+ D
248 1+ *3 +,0 l l k 0- cm, /1 cm,/ 2 - +33+ +/ + 3 * */ a, */ b, *0, *1 a, *1 b, *2 +33 + +30+ +32* +, * mm cm F D D T, 0 km Berggren +32+ *0 F, cm F F + *30 F Sharra cm e al, +333 ; Iwaa e al, *2 *2 *1 +30+ *0 3 a,2 + b,1 +30+ +32* +32+ *0 F T b a +1, D D Berggren +32* 0 3 +30+ *0 D F
1+ *3 249 +* +30+ *0 +, D +* ++ F +* +- +30+ *0 ** 11 ay ** *0 213 ay *2 +* +* +* +33/ +, +30+ +33* -* +30+ +* -+ 1-2, cm +33+ **,- cm, ** *0 +0 2 cm *+ *0 0 +* +* a +31* Hiroa e al, *0 0 +33* b +- -,0 + c +32+,+ +* + +30+ +33* ++ -* +33+ *0 +30+ +31* +31+ +32* +32+ +33* +0 02 cm +33+ ** +31* 2, cm, *+ *0 3, cm 2** ay +* +30+ +310 +33* 3, 30, ay +33+
250 1+ *3 Anersson, S, +30 : Physical suies in culivae soil IV Suies of freezing fros eph an hawing in i# eren arable soils wih an wihou naural / snow cover Grunforbaring, +1, +21,+ +33/ : + +32+ *0 0,2pp +30+ +32* +33* : 0+/ pp +33 :,- -+* pp,0 / // cm +32, : cm / /0 // 1 - / +32* :, 1+ 2* +310 : 3 /* -- 2/ 3+ +30+ : cm +/ +/1 Hiroa, T, Iwaa, Y, Hayashi, M Suzuki, S, Hamasaki, T, Sameshima R an Takayabu, I, *0: Decreasing soil-fros eph an is relaion o climae change in Tokachi, Hokkaio, Japan J Meeor Soc Jpn, 2, 2,+ 2-- +30+ +32* Iwaa, Y, Hayashi, M an Hiroa, T, *2: Compari- *1a son of snowmel infilraion uner i# eren soilfreezing coniions influence by snow cover Vaose 0 Zone Journal, 1, 1320 +* Johnson, GH (e), +32+ : Freezing an hawing pro- blems, permafros-engineering esign an consrucion John Wiley & Sons, +0 +03 +33+ */ a: CD-ROM */ b: +0 CD-ROM *0 : +1 CD-ROM *1a:, CD-ROM *1 b: +2 CD-ROM *2 : +3 CD-ROM *2 :,1 1* /0+ /1* +33* : +30pp Alrich, HP, +3/0 : Fros permanen below highway +33+ : an airfiel pavemen Highway Res B Bull, +-/,, pp +, +3 Nixon, JF, an McRobers EC, +31-: A suy of
1+ *3 251 some facors a# ecing he hawing of frozen soils Can Geoech J, +,,,3-3 Sharra, B, Benoi, G, Daniel, J an Saricka, J, +333 : Snow cover, fros eph, an soil waer across a prairie pohole lanscape Soil Science, +0, 2-3, +320 : +00pp *+ : +-+ +-0 +313 : +332 : ++ /,3 /-3 0*,+-,, Characerisics of groun freezing an hawing uner snow cover base on long-erm observaion Yusuke H *, Fujio T, Kazuo T an Toshimi M + ),, - - - ARADA SUCHIYA AKEDA UNEOKA + ) The Unie Grauae School of Agriculural Sciences, Iwae Universiy, +22, Uea - chome, Morioka, Iwae * 2//*,) Snow Research Cener, +-+1, Nihonbashi-horiome-cho, Chuo-ku, Tokyo +*- **+, * Presen a$ liaion : Hokkaio Branch, ARGOS Inc, Daisan-eiwa Builing F, 01,, ken-- jo- chome, Nishi-ku, Sapporo *0- *2*- -) Obihiro Universiy of Agriculure an Veerinary Meicine Nishi, ++, Inaa-cho, Obihiro Hokkaio *2* 2/// Absrac: Observaions of fros an snow ephs were conuce a he Obihiro Universiy sie locae in easern Hokkaio, Japan, from November +32+ o April *1, an he characerisics of groun freezing an hawing uner snow cover were analyze The resuls inicae ha he annual imum fros eph range from / o // cm uring he,0 winers Fros eph is influence by seasonal changes in snow eph, an i was confirme ha i is proporional o he square roo of he freezing inex when snow eph reaches cm The hawing of frozen groun sars from he surface a he seasonal en of snow cover an finishes from lae March o early May (las fros ay) A linear relaionship was foun beween he vanishing fros eph an he imum fros eph Furher, he vanishing fros eph was foun o be proporional o he square roo of he hawing inex Base on hese finings, he seasonal imum fros eph, vanishing fros eph, an las fros ay were calculae using meeorological aa from +30+ o +32* obaine from Obihiro Meeorological Observaory Taken ogeher, we can conclue ha he annual imum fros eph has ecrease in he las half cenury an ha he las fros ay has shife from mi o early April *2 +*,+ *3 +, *3 - *3 + +* + +/