雪氷北信越 40号（2020）

ISSN 0918-1474䝕䜱䝇䝗䝻䝯䞊䝍䞊䛾 ᐃ᪉ᘧ䛻䜘䜛⢏ᚄ䞉ⴠୗ㏿ᗘศᕸ䛾㐪䛔㻌຾ᒣ♸ኴ㻌䠄᳃ᯘ⥲◊༑᪥⏫ヨ㦂ᆅ䠅㻌㻌䠍䠊䛿䛨䜑䛻㻌䝕䜱䝇䝗䝻䝯䞊䝍䞊䛸䛿䠈㝆Ỉ⢏Ꮚ䛾⢏ᚄ䞉ⴠୗ㏿ᗘ䜢ィ䛩䜛Ẽ㇟ ჾ䛷䛒䜛䠊⌧ᅾᬑཬ䛧䛶䛔䜛䝕䜱䝇䝗䝻䝯䞊䝍䞊䛻䛿䠈OTT 〇 PARSIVEL 䜔 Thies 〇 LPM 䛺䛹䛾ගᏛᘧ䝕䜱䝇䝗䝻䝯䞊䝍䞊䜔 2DVD 䛾䜘䛖䛺஧ḟඖ䝡䝕䜸䝕䜱䝇䝗䝻䝯䞊䝍䞊䛜ᣲ䛢䜙䜜䜛䠊䛣䜜䜙䝕䜱䝇䝗䝻䝯䞊䝍䞊䛿䛔䛪䜜䜒䝅䞊䝖≧䛾Ỉᖹ䛺ほ 㡿ᇦ䜢㏻㐣䛩䜛⢏Ꮚ䜢ィ 䛧䛶䛚䜚䠈㝆Ỉ⢏Ꮚ䛾䝣䝷䝑䜽䝇䜢ほ 䛩䜛䜒䛾䛷䛒䜛䠊䜎䛯䠈ほ 㡿ᇦ䛜❧᪉య䛾䝕䜱䝇䝗䝻䝯䞊䝍䞊䠄e.g. Ishizaka et al., 2013䠅䜒Ꮡᅾ䛧䠈䛣䜜䛿㝆Ỉ⢏Ꮚ䛾✵㛫⃰ᗘ䜢ほ 䛩䜛䜒䛾䛷䛒䜛䠊ᮏ✏䛷䛿䠈๓⪅䜢䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛸䠈ᚋ⪅䜢䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛸ୖ࿧䜆䠊䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛾䝕䜱䝇䝗䝻䝯䞊䝍䞊䛷ほ 䛥䜜䜛⢏ᚄศᕸ䛜䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛷ほ 䛥䜜䜛䛭䜜䛸␗䛺䜛䛣䛸䛜ᣦ᦬䛥䜜䛶䛔䜛䠄Adirosi et al., 2016䠅䠊䛣䜜䛿䠈䝣䝷䝑䜽䝇䜻䝱䞁ᆺ䛾ሙྜ䛿䠈ⴠୗ㏿ᗘ䛾㏿䛔⢏Ꮚ䛾䜋䛖䛜ⴠୗ㏿ᗘ䛾㐜䛔⢏Ꮚ䜘䜚䜒ほ 䛥䜜䜔䛩䛔䛯䜑䛷䛒䜛䠊ྠᵝ䛾⌮⏤䛻䜘䜚䠈䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛷ほ 䛥䜜䜛ⴠୗ㏿ᗘ䛿䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛷ほ 䛥䜜䜛䛭䜜䛸ẚ䜉䛶㐣኱䛻䛺䛳䛶䛔䜛ྍ⬟ᛶ䜒ᣦ᦬䛥䜜䛶䛔䜛䠄Katsuyama and Inatsu, 2020䠅䠊䛭䛣䛷䠈⢏ᚄศᕸ䛸䛧䛶୍⯡䛻௬ᐃ䛥䜜䜛䜺䞁䝬ศᕸ䛸⢏ᚄ䞉ⴠୗ㏿ᗘ㛵ಀ䛸䛧䛶୍⯡䛻௬ᐃ䛥䜜䜛䜉䛝஌๎䜢௬ᐃ䛧䛯䛸䛝䛻ᚓ䜙䜜䜛⢏ᚄ䞉ⴠୗ㏿ᗘศᕸ䛜䝕䜱䝇䝗䝻䝯䞊䝍䞊䛾 ᐃ᪉ᘧ䛻䜘䛳䛶䛹䛾䜘䛖䛻␗䛺䜛䛾䛛䜢 Katsuyama andInatsu (2020) 䛻䜘䜛❧ᘧ䛻ἢ䛳䛶⌮ㄽⓗ䛺ഃ㠃䛛䜙♧䛩䠊䛭䛧䛶䠈䝕䜱䝇䝗䝻䝯䞊䝍䞊䛻䜘䜛ほ 䝕䞊䝍฼⏝䛻䛴䛔䛶䠈䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛸䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛾㐪䛔䛻䜘䜛ほⅬ䛛䜙␃ព䛩䜉䛝Ⅼ䛻䛴䛔䛶㆟ㄽ䛩䜛䠊䛸䛺䜛䠊䛣䛣䛷䠈ܸ䛿ⴠୗ㏿ᗘ[m s-1]䜢䠈ߪ ଶ 䛿ⴠୗ㏿ᗘ䛾ศᩓ䜢⾲䛩䠊ᘧ䠄䠍䠅䠄䠏䠅䜘䜚䠈⢏ᚄ䞉ⴠୗ㏿ᗘ䛾ྠ᫬ศᕸ䛿䠈㻌© 2020（公社）日本雪氷学会(4)䛸䛺䜛䠊䛣䛣䛷䠈ࣂ ൌ ௧ሺܽܾߪ ଶ ߤߣሻ 䛷䛒䜛䠊ᮏ✏䛷䛿䠈䛣䜜䜢䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛾ほ 䝕䞊䝍䛜ᚑ䛖⢏ᚄ䞉ⴠୗ㏿ᗘศᕸ䛸䛩䜛䠊㻌䠏䠊䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛾⢏ᚄ䞉ⴠୗ㏿ᗘศᕸ㻌䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛾ሙྜ䛻䛴䛔䛶䜒䠈䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛾ሙྜ䛸ྠᵝ䛻䠈⢏ᚄศᕸ䛸䛧䛶䜺䞁䝬ศᕸ䜢䠈ⴠୗ㏿ᗘศᕸ䛸䛧䛶ṇつศᕸ䜢௬ᐃ䛩䜛䠊䛣䛾᫬䠈䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛾䝕䜱䝇䝗䝻䝯䞊䝍䞊䛿䠈ᘧ䠄䠐䠅䛷⾲䛥䜜䜛㝆Ỉ⢏Ꮚ䛜ⴠୗ㏿ᗘܸ䛷㠃✚‫ܣ‬䛾ほ 㡿ᇦ䜢㏻㐣䛩䜛䛸䛝䛭䛾⢏Ꮚ䜢䜹䜴䞁䝖䛩䜛䛣䛸䛛䜙䠈䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛾⢏ᚄ䞉ⴠୗ㏿ᗘศᕸ䛿䠈㻌‫ܣ‬ȟ‫ܸܰݐ‬௧௢௧ ሺܸǡ ‫ܦ‬ȁࣂሻ(5)㻌‫ܮ‬䛸䛺䜛䠊䛣䛣䛷ȟ‫ݐ‬䛿ほ ᫬㛫[s]䜢䠈‫ܮ‬䛿䜹䜴䞁䝖䛥䜜䛯ྜィ⢏Ꮚᩘ䜢䠈ܰ௧௢௧ 䛿⢏Ꮚ✵㛫⃰ᗘ[m-3]䜢⾲䛩䠊ྜィ⢏Ꮚᩘ䛿䠈㻌‫ܮ‬㻌ୗ ሺܸǡ ‫ܦ‬ȁࣂሻ ൌஶ㻌ஶൌ න ቈන ‫ܣ‬ȟ‫ܸܰݐ‬௧௢௧ ሺܸǡ ‫ܦ‬ȁࣂሻ ܸ݀቉ ݀‫ܦ‬଴

ିஶ

(6)

Ȟሺߤ ൅ ܾ ൅ ͳሻൌ ‫ܰݐ߂ܣ‬௧௢௧ ܽߣି௕㻌Ȟሺߤ ൅ ͳሻ䛷䛒䜛䛛䜙䠈䛣䜜䜢ᘧ(5)䛻௦ධ䛧䛶㻌㻌䠎䠊䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛾⢏ᚄ䞉ⴠୗ㏿ᗘศᕸ㻌⢏ᚄศᕸ䛸䛧䛶ḟ䛾䜺䞁䝬ศᕸ䜢௬ᐃ䛩䜛䠊㻌ߣఓାଵ ‫ܦ‬ఓ㻌(1)ሺ‫ܦ‬ȁߤǡ ߣሻ ൌሺെߣ‫ܦ‬ሻ㻌Ȟሺߤ ൅ ͳሻ䛣䛣䛷䠈ሺ‫ܦ‬ȁߤǡ ߣሻ䛿ᙧ≧ẕᩘߤ䛸ᑻᗘẕᩘߣ䛾䜒䛸䛻䛚䛡䜛⢏ᚄ‫[ ܦ‬mm]䛾᮲௳௜䛝☜⋡ศᕸ䜢⾲䛩䠊Ȟ䛿䜺䞁䝬㛵ᩘ䜢⾲䛩䠊⢏ᚄ䞉ⴠୗ㏿ᗘ㛵ಀ䠈䛩䛺䜟䛱䠈ᖹᆒⴠୗ㏿ᗘ䛿䠈䜉䛝஌๎㻌㻌(2)ܸሺ‫ܦ‬ሻ ൌ ܽ‫ܦ‬௕ 㻌䜢௬ᐃ䛧䠈ⴠୗ㏿ᗘ䛿ṇつศᕸ䛻ᚑ䛖䛸䛩䜛䛸䠈ⴠୗ㏿ᗘศᕸ䛿䠈㻌ሺܸȁ‫ܦ‬ǡ ܽǡ ܾǡ ߪ ଶ ሻሺܸ െ ܽ‫ܦ‬௕ ሻଶͳ㻌(3)ൌ ቈെ቉㻌ଶଶʹߪξʹߨߪሺܸǡ ‫ܦ‬ȁܽǡ ܾǡ ߪ ଶ ǡ ߤǡ ߣሻൌ ሺܸȁ‫ܦ‬ǡ ܽǡ ܾǡ ߪ ଶ ሻ ൈ ሺ‫ܦ‬ȁߤǡ ߣሻ 㻌ൌ ሺܸǡ ‫ܦ‬ȁࣂሻୗ ሺܸǡ ‫ܦ‬ȁࣂሻܸ㻌ൌܲሺܸǡ ‫ܦ‬ȁܽǡ ܾǡ ߪ ଶ ǡ ߤ ൅ ܾǡ ߣሻܽ‫ܦ‬௕(7)䛜ᚓ䜙䜜䜛䠊䛴䜎䜚䠈䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛾䝕䜱䝇䝗䝻䝯䞊䝍䞊䛷ィ 䛥䜜䜛⢏ᚄ䞉ⴠୗ㏿ᗘศᕸ䛿䠈䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛾䝕䜱䝇䝗䝻䝯䞊䝍䞊䛷ィ 䛥䜜䜛䛭䜜䛸ẚ㍑䛧䛶䠈⢏ᚄศᕸ䛾ᙧ≧ẕᩘߤ䛿ܾ䛰䛡␗䛺䜚䠈☜⋡ศᕸ䛿ⴠୗ㏿ᗘ䛾㏿䛔᪉ྥ䛻ṍ䜐䠊䛣䛾䛯䜑䠈䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛾䝕䜱䝇䝗䝻䝯䞊䝍䞊䛷ほ 䛥䜜䜛ᖹᆒⴠୗ㏿ᗘ䛿䠈㻌ஶ‫ܸܲ ׬‬ௌ ሺܸǡ ‫ܦ‬ȁࣂሻ ܸܸ݀ௌ ሺ‫ܦ‬ሻ ൌ ିஶஶ‫ି׬‬ஶ ܲௌ ሺܸǡ ‫ܦ‬ȁࣂሻ ܸ݀ 㻌
㻌
(8)
ɐଶ௕ൌ
൅ ܽ‫ ܦ‬ܽ‫ܦ‬௕䛸䛺䜚䠈䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛾䝕䜱䝇䝗䝻䝯䞊䝍䞊䛷௬ᐃ䛧䛯䜒䛾䜘䜚䜒ߪ ଶ Τܽ‫ܦ‬௕ 䛰䛡㏿䛔ⴠୗ㏿ᗘ䛸䛺䜛䠊㻌ᅗ䠍䛻㝆Ỉ⢏Ꮚ䛸䛧䛶䛒䜙䜜䠄Locatelli and Hobbs, 1974䠅䛸

- 30 -

雪氷北信越 40号（2020）

ISSN 0918-1474

㞼⢏௜䛝㞷∦䠄▼ᆏ䠈1995䠅䜢ᶍ䛧䛯⢏ᚄ䞉ⴠୗ㏿ᗘศᕸ䜢♧䛩䠊㻌 䛒䜙䜜䛾ሙྜ䛿ࣂ ൌ ௧ሺͳǤ͵ͲǤ͸͸ͲǤͲͺʹʹǤͷሻ 䜢䠈㞼⢏௜䛝㞷∦䛾ሙྜ䛿ࣂ ൌ ௧ሺͲǤͺʹͲǤͳʹͲǤͲͺʹͳǤͷሻ 䜢᮲௳䛸䛩䜛☜⋡ศᕸ䜢ᘧ䠄䠐䠅䛸ᘧ䠄䠓䠅䜢⏝䛔䛶ィ⟬䛧䛯䠊䛒䜙䜜䛾ሙྜ䛿䠈䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛾☜⋡ศᕸ䜘䜚䜒䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛾☜⋡ศᕸ䛾᪉䛜⢏ᚄ䛸ⴠୗ㏿ᗘ䛾኱䛝䛔᪉ྥ䛻ᗈ䛜䛳䛶䛔䜛䛣䛸䛜䜟䛛䜛䠊䛣䜜䛿䠈䛒䜙䜜䛾ሙྜ䛿䝟䝷䝯䞊䝍ܾ䛜኱䛝䛔䛯䜑䠈ᙧ≧ẕᩘߤ䛜䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛸䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛸䛷኱䛝䛟␗䛺䜛䛯䜑䛷䛒䜛䠊ᖹᆒ䛾ⴠୗ㏿ᗘ䛿኱䛝䛺ᕪ䛜䛺䛔䠊୍᪉䛷䚸㞼⢏௜䛝㞷∦䛾ሙྜ䛿䠈䝟䝷䝯䞊䝍ܾ䛜ᑠ䛥䛟䠈ᙧ≧ẕᩘߤ䜈䛾ᙳ㡪䛜䜋䛸䜣䛹䛺䛔䛯䜑䠈䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛾☜⋡ศᕸ䛿ⴠୗ㏿ᗘ䛾኱䛝䛔᪉ྥ䛻䛾䜏䜔䜔೫䛳䛶䛔䜛䛣䛸䛜䜟䛛䜛䠊ᖹᆒ䛾ⴠୗ㏿ᗘ䛻䛴䛔䛶䛿䠈ᘧ䠄䠔䠅䛛䜙᫂䜙䛛䛺䜘䛖䛻䠈ⴠୗ㏿ᗘ䛾㐜䛔✀㢮䛾㝆Ỉ⢏Ꮚ䛾ሙྜ䛻ߪ ଶ Τܽ‫ܦ‬௕ 䛜኱䛝䛺್䛻䛺䜚䜔䛩䛔䛯䜑䠈䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛸䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛾ሙྜ䛸䛷␗䛺䜛ⴠୗ㏿ᗘ䛸䛺䜛䛣䛸䛜䜟䛛䜛䠊䛧䛛䛧䠈ᅗ䠍䛻䛚䛔䛶䛿䠈䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛸䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛾ሙྜ䛾ᖹᆒⴠୗ㏿ᗘ䜢ẚ㍑䛩䜛䛸䠈䛭䛾ᕪ䛿⣙ 0.1 m s-1 䛸ഹ䛛䛷䛒䜛䠊㻌 㻌䠐䠊䜎䛸䜑䛸㆟ㄽ㻌㻌 ⢏ᚄศᕸ䛸䛧䛶䜺䞁䝬ศᕸ䜢䠈ⴠୗ㏿ᗘศᕸ䛸䛧䛶ṇつศᕸ䜢௬ᐃ䛧䛯ሙྜ䛾䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛸䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛾䝕䜱䝇䝗䝻䝯䞊䝍䞊䛻䜘䜛⢏ᚄ䞉ⴠୗ㏿ᗘศᕸ䛾㐪䛔䜢⌮ㄽⓗ䛺ഃ㠃䛛䜙♧䛧䛯䠊䛭䛾⤖ᯝ䠈䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛾ሙྜ䛾⢏ᚄ䞉ⴠୗ㏿ᗘศᕸ䛿⢏ᚄ䛸ⴠୗ㏿ᗘ䛭䜜䛮䜜䛜኱䛝䛔᪉ྥ䜈ᗈ䛜䜛䛣䛸䛜ศ䛛䛳䛯䠊≉䛻䠈䛒䜙䜜䛾䜘䛖䛺ⴠୗ㏿ᗘ䛾኱䛝䛔✀㢮䛾㝆Ỉ⢏Ꮚ䛾ሙྜ䛿䠈⢏ᚄศᕸ䛜኱䛝䛟␗䛺䛳䛯䠊ᖹᆒⴠୗ㏿ᗘ䛻䛴䛔䛶䜒䝕䜱䝇䝗䝻䝯䞊䝍䞊䛾 ᐃ᪉ᘧ䛻䜘䛳䛶␗䛺䜛䛣䛸䛜♧䛥䜜䛯䛜䠈䛭䛾ᕪ䛿㞷∦䛾䜘䛖䛺ⴠୗ㏿ᗘ䛾㐜䛔✀㢮䛾㝆Ỉ⢏Ꮚ䛾ሙྜ䛷䜒⣙
0.1 m s-1 ⛬ᗘ䛸ഹ䛛䛰䛳䛯䠊㻌 㻌㻌 ௨ୖ䛾⤖ᯝ䛛䜙䠈䝕䜱䝇䝗䝻䝯䞊䝍䞊䛾䝕䞊䝍䜢฼⏝䛩䜛ୖ䛷䠈䛭䛾 ᐃ᪉ᘧ䛻␃ព䛩䜛䜉䛝ᚲせ䛜䛒䜛䛾䛿⢏ᚄศᕸ䜢ᢅ䛖ሙྜ䛷䛒䜛䠊≉䛻䠈䝺䞊䝎䞊Ẽ㇟Ꮫ䜔㞼≀⌮Ꮫ䛷ᢅ䜟䜜䜛⢏ᚄศᕸ䛿䠈୍⯡䛻✵㛫ᩘ⃰ᗘ䛾䛣䛸䜢ᣦ䛧䛶䛚䜚䠈䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛾䝕䜱䝇䝗䝻䝯䞊䝍䞊䛷ほ 䛥䜜䜛⢏ᚄศᕸ䜢᝿ᐃ䛥䜜䛶䛔䜛䠊୍᪉䛷䠈ᬑཬᆺ䛾䝕䜱䝇䝗䝻䝯䞊䝍䞊䛿䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛾䛯䜑䠈䛣䛾ሙྜ䛿ᘧ䠄䠓䠅䜢౑䛔ᙧ≧ẕᩘ䜢ኚ᥮䛩䜛ᚲせ䛜䛒䜛䠊䛯䛰䛧䠈䛣䛾ኚ᥮䛿⢏ᚄศᕸ䛜䜺䞁䝬ศᕸ䜢௬ᐃ䛷䛝䜛ሙྜ䠈䛛䛴䠈⢏ᚄ䞉ⴠୗ㏿ᗘ㛵ಀ䛜᪤▱䛾ሙྜ䛻㝈䜛Ⅼ䛻ὀព䛥䜜䛯䛔䠄cf. Adirosi
et al., 2016䠅䠊㻌

© 2020（公社）日本雪氷学会

㻌ᅗ䠍㻌 㻔㼍㻕㻌 䛒䜙䜜䛸㻔㼎㻕㻌 㞼⢏௜䛝㞷∦䜢ᶍ䛧䛯⢏ᚄ䞉ⴠୗ㏿ᗘศᕸ䠊➼್⥺䛿 㻜㻚㻜㻜㻝䠈㻜㻚㻜㻝䠈㻜㻚㻝 䛾➼☜⋡ᐦᗘ䜢⾲䛧䠈◚⥺䛿ᖹᆒⴠୗ㏿ᗘ䜢⾲䛩䠊㯮Ⰽ䛿ᘧ㻔䠐㻕䛷⾲䛥䜜䜛䝪䝸䝳䞊䝮䝇䜻䝱䞁ᆺ䛾ศᕸ䜢䠈㉥Ⰽ䛿ᘧ㻔㻣㻕䛷⾲䛥䜜䜛䝣䝷䝑䜽䝇䝇䜻䝱䞁ᆺ䛾ศᕸ䜢⾲䛩䠊㻌 㻌ᩥ⊩㻌
Adirosi, E., E. Volpi, F. Lombardo, and L. Baldini (2016):
Raindrop size distribution: Fitting performance of common
theoretical models. Adv. Water Resour., 96, 290–305.
▼ᆏ㞞᫛䠄1995䠅䠖㞼⢏௜㞷∦䛾ⴠୗ㏿ᗘ䛻䛴䛔䛶䠊㞷ị䠈
57䠈229–238䠊
Ishizaka, M., H. Motoyoshi, S. Nakai, T. Shina, T. Kumakura,and K. Muramoto (2013): A new method for identifying themain type of solid hydrometers contributing to snowfall frommeasured size-fall speed relationship. J. Meteor. Soc. Japan,91, 747–762.
Katsuyama, Y., and M. Inatsu (2020): Fitting precipitation
particle size-velocity data to mixed joint probability density
function with an expectation maximization algorithm. J.
Atmos. Oceanic Technol., 37, 911–925.
Locatelli, J. D., and P. V. Hobbs, (1974): Fall speeds and massesof solid precipitation particles. J. Geophys. Res., 79, 2185–2197.

- 31 -