抄録
郊外に水田域と果樹園域が広がる長野県小布施町において,自動車による水蒸気圧の移動観測を1996年9月から1997年10月にかけて非積雪期において延べ111回行った.その結果,夜間も日中も市街地は郊外に比べ低水蒸気圧であった,市街地と郊外の水蒸気圧差は灌水期の夏季日中に大きく,郊外を水田域とした水蒸気圧差は果樹園域としたものより2倍程度である.夜間では市街地と郊外の水蒸気圧差は郊外の地点の取り方の違いによる差異は認められない.市街地内外の水蒸気圧分布において,市街地上にはヒートアイランドによく似た'低水蒸気圧の島'が見られた.水田域とそれ以外の土地被覆との境で等水蒸気圧線が密になる現象は,夏季日中の観測21例中11例で見られた,さらに,風速が大きくなると市街地と郊外の水蒸気圧差は小さくなることが分かった.
Automobile traverses were used to gather 111 times water vapor pressure distributionsin Obuse, Nagano, in which rural there are paddy fields and orchards from September 1996 to October 1997. The water vapor pressure in urban is lower than that in rural at day and night. The urban/rural water vapor pressure difference is the maximum at daytime in summer. The difference of water vapor pressure between urban and paddy field is roughly twice as large as that between urban and orchard. The effect of selection of rural sites in water vapor pressure difference can't be seen at night. There is low water vapor pressure island over urban area, similar to heat island, with steep water vapor pressure gradients between paddy field and urban, which can be seen in 11 cases among 21 summer daytime cases. Winds have emerged as an important parameter in controlling the urban/rural water vapor pressure difference.
