and t he shift to ESB have been occurri ng earlier in recent years.
When t he wind system pattern with predominan t south wind is appeared , the extension of the Pacific Hi gh to the south of Japan becomes pr omi nent , resulting in a pressur e patter n wit h strong southwest wi nd ar ound the Kant o region. In recent years, t he ext ensi on of the Pacifi c Hi gh after the rai ny season has been biased towar d the south of Japan, wit h southwest winds occurri ng in t he Kant o region . This is li kely relat ed t o t he i ncr ease i n t he relati ve frequency of categori es with pr edominant sout h wind .
In the wi nd syst em pattern with predominant south wi nd an d weak east wind components, hi gh temper atures wer e obser ved in a wi de area in the inland ar ea and t he coast of Kashi ma -nada. While t he temper ature di fference between t he norther n and sout hern Kanto region became greater, hi g h temperatur es were obser ved in the southern Kanto r egion ar ound Tokyo, wher e geostrophic wind was weak and t ypicall y sea breeze system was predomi nant . As descr ibed above, local wind systems over the Kanto Plain on sunny li ght -wind days in summer ar e cl os el y related t o the pr essure gr adient around Japan because of t he differ ences that occur i n the pr essure patterns affecting the speed of the penetrati on of the sea br eeze front and t he speed at which the ESB tr ansit ion becomes dominant . In addition, on sunn y li ght -wind days when the Foehn phenomenon does not appear, it was consi dered that the appear ance f requency of t he pressur e pattern t hat appear s t he Pacific Hi gh ridge t o t he sout h of Japan increased, and that this is associated with the hi gh temperatur es that have been recorded in the inland area of t he Kanto Pl ain i n
recent year s , through the changes i n t he wi nd system over the Kanto Plain .
References
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Figures & Tables
Fi g. 1. Map of the st udy ar ea showing distri bution of obser vatories .
Elevation:
Fi g. 2. Distribution map showing obser vatories used f or t he anal ysi s of temperatur e.
Elevation:
Fi g. 3. The obser vational hei ght of the wi nd speed at each obser vator y.
(a) 1981; (b) 2009 .
Obser vat ories surrounded by red border s indicate that t he obser vati onal hei ght was changed during the peri od 1981 –2009.
(b)
(a)
Fi g. 4. The roughness paramet er and the correction fact or f or adj ustment of wind speed at each obser vator y.
(a) 1976; (b) 1987; (c) 1997; ( d) 2006.
The correction factor in 1976 was calcul ated fr om t he obser vati onal hei ght at each obser vat or y in 1981.
(c) (d)
(b)
(a)
Fi g. 5. Difference s between 1981 and 2009 in the wind speed at t he hei ght of anemometer f or each obser vator y when t he wind speed at the standar d hei ght (50 m) i s 10 m/s.
Obser vat ories where t he obser vati onal hei ght was changed during t he peri od 1981–2009 were excl uded .
Fi g. 6. Distribution map showi ng obser vatories used for select ion of sunny light -wind days.
Sea level pressure
(calculation of geostrophic wind) Precipitation and sunshine duration
Elevation:
Fi g. 7. Distributi on maps showing composite wind bar bs and convergence/ di vergence on sunny li ght -wind days.
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15:00 JST ; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Elevation:Fi g. 8. Distribution maps showi ng t he fact or loading of t he EOF anal ysi s for the hourl y convergence/ di vergence amount on sunny li ght -wind days . (a) the 1st pri ncipal component (contribution rate: 1 3.4%); (b) t he 2nd
principal component ( 11.2%); and (c) the 3r d pri ncipal component ( 7.5%).
(a) (b) (c)
Elevation:
Fi g. 9. Ti me series of hourl y mean EOF scor e on sunny li ght -wind days.
(a) the 1st princi pal component; (b) t he 2nd principal component ; and (c) t he 3rd princi pal component.
EOF score was nor mali zed by t he standard devi ation of each pri ncipal component .
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
9 10 11 12 13 14 15 16 17 PC1
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
9 10 11 12 13 14 15 16 17 PC2
-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
9 10 11 12 13 14 15 16 17
(a) (b) (c) PC3
Time (JST) Time (JST) Time (JST)
Fi g. 10. Distri buti on maps showing composit e wi nd barbs and convergence/ di vergence on days wit h positi ve anomal y of EOF1 score . (a) 09: 00 JST ( 105 days); (b) 11:00 JST (126 days); ( c) 13:00 JST (129 days);
(d) 15:00 JST (117 days); (e) 17:00 JST (95 days) .
(c) (d)
(b) (a)
(e)
Elevation:Fi g. 11. Distributi on maps showing composite wind barbs and convergence/ di vergence on days wit h negat ive anomal y of EOF1 score . (a) 09: 00 JST ( 10 days); (b) 11:00 JST (53 days); (c) 13:00 JST (130 days);
(d) 15:00 JST (178 days); (e) 17:00 JST (187 days) .
(c) (d)
(b) (a)
(e)
Elevation:Fi g. 12. Distri buti on maps showing composit e wi nd barbs and convergence/ di vergence on days wit h positi ve anomal y of EOF2 score . (a) 09: 00 JST (35 days); (b) 11:00 JST (21 days); (c) 13:00 JST ( 51 days); (d)
15:00 JST (135 days); (e) 17:00 JST ( 208 days) .
(c) (d)
(b) (a)
(e)
Elevation:Fi g. 13. Distri buti on maps showing composit e wi nd barbs and convergence/ di vergence on days wit h negat ive anomal y of EOF2 score . (a) 09: 00 JST ( 25 days); (b) 11:00 JST ( 162 days); (c) 13:00 JST (170 days);
(d) 15:00 JST (57 days); (e) 17: 00 JST ( 20 days) .
(c) (d)
(b) (a)
(e)
Elevation:Fi g. 14. Distri buti on maps showing composit e wi nd barbs and convergence/ di vergence on days wit h positi ve anomal y of EOF3 score . (a) 09: 00 JST ( 135 days); (b) 11:00 JST ( 90 days); (c) 13: 00 JST (80 days);
(d) 15:00 JST (116 days); (e) 17:00 JST (1 36 days).
(c) (d)
(b) (a)
(e)
Elevation:Fi g. 15. Distri buti on maps showing composit e wi nd barbs and convergence/ di vergence on days wit h negat ive anomal y of EOF3 score . (a) 09: 00 JST ( 20 days); (b) 11:00 JST (72 days); (c) 13:00 JST (145 days);
(d) 15:00 JST (167 days); (e) 17:00 JST (115 days) .
(c) (d)
(b) (a)
(e)
Elevation:Fi g. 16. The dendr ogr am of c luster anal ysis r epresent ing t he process of linking the cl usters.
Fi g. 17. Ti me seri es of hourl y mean EOF score on each categor y classified by the cl uster anal ysis .
(a) the 1st princi pal component; (b) t he 2nd principal component; and (c) t he 3rd princi pal component.
EOF score was nor mali zed by t he standard devi ation of each pri ncipal component .
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
9 10 11 12 13 14 15 16 17 A B C D E -2.0 平均 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
9 10 11 12 13 14 15 16 17 A B C D E -2.0 平均 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
9 10 11 12 13 14 15 16 17 A B C D E
平均Mean of sunny light-wind days
PC1 PC2 PC3
(a) (b) (c)
Time (JST) Time (JST) Time (JST)
Fi g. 18. Zonal and meridional components of the geostrophic wind on each sunny li ght -wind days for each cat egor y.
Shades i ndicate t he s t andar d deviati onal ell ipse f or each categor y.
Fi g. 19. Distri buti on maps showing composit e wi nd barbs and convergence/ di vergence on Categor y A days.
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15:00 JST ; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Elevation:Fi g. 20. Distri buti on maps showing composit e wi nd bar bs and convergence/ di vergence on Categor y B days.
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15:00 JST ; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Elevation:Fi g. 21. Distri buti on maps showing composit e wi nd barbs and convergence/ di vergence on Categor y C days.
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15:00 JST; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Elevation:Fi g. 22. Distri buti on maps showing composit e wi nd barbs and convergence/ di vergence on Categor y D days.
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15 :00 JST; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Elevation:Fi g. 23. Distri buti on maps showing composit e wi nd barbs and convergence/ di vergence on Categor y E days.
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15:00 JST; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Elevation:Fi g. 24. Di stributi on of vertical wind speeds at 975 hPa and surface wi nd barbs at 15: 00 JST on each categor y of sunny li ght -wi nd days ( 2006–2011) . (a) Categor y A ( 29 days); (b) Categor y B (12 days); ( c) Cat egor y C (16 days);
(d) Categor y D (12 days); (e) Categor y E (13 days) .
(c) (d)
(b) (a)
(e)
Fi g. 25. Meridi onal and vertical component s of wind on the vertical north -sout h cross section along the 139.5°E line at 15:00 JST on each categor y of sunny li ght -wi nd days (2006 –2011).
(a) Categor y A ( 29 days); (b) Categor y B (12 days); ( c) Cat egor y C (1 6 days);
(d) Categor y D ( 12 days); (e) Categor y E ( 13 days).
Shadi ng repr esent s the verti cal wind speeds .
(c) (d)
(b) (a)
(e)
Fi g. 26. Distribution maps showing composite sea level pressur e (hPa) and surface wind vector ( m/s) on each categor y of sunny li ght -wind days.
Shaded areas i ndicate the si gnificant di ffer ence at the 95% level on sea level pressur e fr om sunny l ight -wind days mean.
Wind vector s are not shown in the area with low wind speed (less t han 2 m/s) .
A B
C
E
D
Sunny light-wind days mean
Fi g. 27. Distribution maps showing sea level pr essur e ( hPa) and surface wind vector ( m/s) on Jul y and August .
(a) 1979–1989; ( b) 1990–2000; (c) 2001 –2011; ( d) 1979– 2011 ( 33 years mean).
Shaded areas i ndicate the si gnificant di ffer ence at the 95% level on sea level pressur e fr om 33 year s mean .
Wind vector s are not shown in the area with low wind speed (less t han 2 m/s) .
(d) 1979–2011 (c) 2001–2011
(b) 1990–2000
(a) 1979–1989
Fi g. 28. Distribution maps showing sea level pr essur e ( hPa) and surface wind vector ( m/s) on 1979–1989.
(a) Jul y 1–15; ( b) Jul y 1 6–31; (c) August 1–15; (d) August 16–31.
Shaded areas i ndicate the si gnificant di ffer ence at the 95% level on sea level pressur e fr om 33 year s mean of each period .
Wind vector s are not shown in the area with low wind speed (less t han 2 m/s) .
(b) 7/16–7/31 (a) 7/1–7/15
(d) 8/16–8/31
(c) 8/1–8/15
Fi g. 29. Distribution maps showing sea level pr essur e ( hPa) and surface wind vector ( m/s) on 1990–2000.
(a) Jul y 1–15; ( b) Jul y 16–31; (c) August 1–15; (d) August 16–31.
Shaded areas i ndicate the si gnificant di ffer ence at the 95% level on sea level pressur e fr om 33 year s mean of each period .
Wind vector s are not shown in the area with low wind speed (less t han 2 m/s) .
(b) 7/16–7/31 (a) 7/1–7/15
(d) 8/16–8/31
(c) 8/1–8/15
Fi g. 30. Distribution maps showing sea level pr essur e ( hPa) and surface wind vector ( m/s) on 2001–2011 .
(a) Jul y 1–15; ( b) Jul y 16–31; (c) August 1–15; (d) August 16–31.
Shaded areas i ndicate the si gnificant di ffer ence at the 95% level on sea level pressur e fr om 33 year s mean of each period .
Wind vector s are not shown in the area with low wind speed (less t han 2 m/s) .
(b) 7/16–7/31 (a) 7/1–7/15
(d) 8/16–8/31
(c) 8/1–8/15
Fi g. 31. Dist ributi on maps showing composite temperat ure on sunny light -wind days.
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15:00 JST; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Fi g. 32. Di stributi on maps sh owi ng composite temperature anomal y on Categor y A days.
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15:00 JST; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Fi g. 33. Di stributi on maps sh owi ng composite temperature anomal y on Categor y B days.
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15:00 JST; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Fi g. 34. Di stributi on maps sh owi ng composite temperature anomal y on Categor y C days.
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15:00 JST; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Fi g. 35. Di stributi on maps sh owi ng composite temperature anomal y on Categor y D days .
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15:00 JST; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Fi g. 36. Di stributi on maps sh owi ng composite temperature anomal y on Categor y E days.
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15:00 JST; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Fi g. 37. Di stributi on maps showing composite surf ace air temper ature anomal y ( °C) on each categor y of sunny li ght -wi nd days.
Shaded areas indicate the si gnifi cant difference at the 9 5% level on temperatur e fr om sunny li ght -wind days mean.
A B
C
E
D
Sunny light-wind days mean
Fi g. 38. Distri buti on map s showing composit e wi nd barbs and convergence/ di vergence on TK - T ≥ 2.5 °C cases.
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15:00 JST; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Elevation:Fi g. 39. Distri buti on maps showing composit e wi nd barbs and convergence/ di vergence on TK - T < 1.5 °C cases.
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15:00 JST; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Elevation:Fi g. 40. Distri bution maps sh owing temperature anomal y on TK - T ≥ 2.5°C cases.
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15:00 JST; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Fi g. 41. Distribution maps sh owing temp erature anomal y on TK - T < 1.5 °C cases.
(a) 09:00 JST; (b) 11: 00 JST; (c) 13: 00 JST; (d) 15:00 JST; (e) 17:00 JST.
(c) (d)
(b) (a)
(e)
Table 1. Land utili zat ion di visions and classified categories.
Land utili zati on di visions that have the same charact eristics of the ground surface conditions and the roughness l engt h we re cl assified int o the same categor y (a–e) .
Category Category
1 Paddy field※3 a 1 Paddy field※3 a
2 Farmland※3 a 2 b
3 Orchard※4 b
4 Tree plantation b
5 Forest b 5 Forest c
6 Wasteland※3 a 6 Wasteland※3
-7 Building (Large) c 7 d
8 Building (Small) d
9 Road and railway a 9 Road and railway e
A Other※3 a A Other※3
-B Lake※1 a B a
C River A※1 a
D River B※3 a
E Beach※2 a E Beach※2 b
F Sea※1 a F Sea※1 a
G Golf course※3 b
The following Z0 values are applied when land utilization is homogeneous in the area (each land utilization of ※1～※4 covers more than 90% of the area independently):
※1: 0.1 cm, ※2: 1 cm, ※3: 5 cm, ※4: 65 cm
<Kuwagata and Kondo (1990)> <Reclassification>
Other agricultural land※3
River and lake※1 Land utilization
Building Land utilization
Table 2. Numb er of sunny li ght -wind days and relati ve frequency of each categor y on each 11 -year period .
The sunny li ght -wind days were classifi ed into fi ve categories (A –E) based on t he diurnal variati ons of t heir convergence/di vergence fiel ds.
Period Number of sunny
light-wind days A B C D E 1979–1989 108 8% 31% 30% 15% 16%
1990–2000 118 19% 27% 24% 16% 14%
2001–2011 143 35% 17% 17% 15% 16%
1979–2011 369 22% 24% 23% 15% 15%
Table 3. Number of sunny li ght -wind days and relati ve frequency of each categor y on 1979–1989.
The sunny li ght -wind days were classifi ed into fi ve categories (A –E) based on t he diurnal variati ons of t heir convergence/di vergence fiel ds.
Period Number of sunny
light-wind days A B C D E July 1–15 11 0% 45% 18% 9% 27%
July 16–31 30 3% 27% 37% 20% 13%
Au . 1–15 34 12% 35% 24% 12% 18%
Au . 16– 31 33 12% 27% 33% 15% 12%
1979–1989 108 8% 31% 30% 15% 16%
Table 4. Number of sunny li ght -wind days and relati ve frequency of each categor y on 1990–2000.
The sunny li ght -wind days were classifi ed into fi ve categories (A –E) based on t he diurnal variati ons of t heir convergence/di vergence fiel ds.
Period Number of sunny
light-wind days A B C D E July 1–15 16 13% 31% 19% 13% 25%
July 16–31 34 24% 24% 24% 24% 6%
Au . 1–15 30 10% 27% 37% 13% 13%
Au . 16– 31 38 24% 29% 16% 13% 18%
1990–2000 118 19% 27% 24% 16% 14%
Table 5. Number of sunny li ght -wind days and relati ve frequency of each categor y on 2001–2011.
The sunny li ght -wind days were classifi ed into fi ve categories (A –E) based on t he diurnal variati ons of t heir convergence/di vergence fiel ds.
Period Number of sunny
light-wind days A B C D E July 1–15 28 43% 14% 11% 14% 18%
July 16–31 28 32% 11% 21% 18% 18%
Au . 1–15 47 36% 26% 19% 11% 9%
Au . 16– 31 40 30% 13% 18% 18% 23%
2001–2011 143 35% 17% 17% 15% 16%
Table 6. Number of sunny li ght -wi nd days of each TK - T categor y and rel ati ve frequency of each cat egor y.
TK - T was defined by t he difference bet ween t he dail y maxi mum temper ature at
Kumagaya and t he dai ly maxi mum temper at ure at Tokyo.
The sunny li ght -wind days were classifi ed into fi ve categories (A –E) based on t he diurnal variati ons of t heir convergence/di vergence fiel ds.