Formation of a Cold Air Lake during the Warm Season in a Small Hollow in Mt. Inako-dake, Yatsugatake Range

Iijima, Yoshihiro; Shinoda, Masato

doi:10.4157/grj1984a.71.8_559

Cited by 2 publications

(3 citation statements)

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“…7a). Moreover, the diurnal conditions are similar to those observed during the summers of 1995 and 1997 (Iijima andShinoda 1998, 2000). Humid conditions over mountainous areas in the late afternoon are a common characteristic of central Japan and may explain the high value for downward longwave radiation after local sunset.…”

Section: Seasonal Characteristics Of Nocturnal Cooling During the Warsupporting

confidence: 77%

“…Cloudiness and water vapor pressure increased in the hollow in the summer evenings under fair weather conditions. Cloudiness and water vapor pressure were lower during autumn (Iijima andShinoda 1998, 2000). The large water vapor pressure and cloudiness in the summer evening are most likely due to the convergence of water vapor from the plain and the basin to the mountainous area through the thermally induced circulation in central Japan (Kuwagata and Kimura 1995;Kuwagata 1997;Kimura et al 1997).…”

Section: Seasonal Changes In Downward Longwave Radiationmentioning

confidence: 99%

“…However, those studies were generally conducted when the conditions were optimal-that is, under clear and calm ambient weather, based mostly on a short period not exceeding one month. With this background in mind, based on interseasonal observations made at a high mountain hollow in central Japan during the warm season, Iijima andShinoda (1998, 2000) investigated the seasonal differences in the processes of cold-air pool formation between summer and autumn, and related the differences to water vapor content. The results showed that during summer the large water vapor content in the evening delays and weakens cold-air pool formation, whereas strong cold-air pools were formed under dry air conditions during autumn.…”

Section: Introductionmentioning

confidence: 99%

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The Influence of Seasonally Varying Atmospheric Characteristics on the Intensity of Nocturnal Cooling in a High Mountain Hollow

Iijima¹,

Shinoda²

2002

J. Appl. Meteor.

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Seasonal differences in the longwave radiation balance, diurnal cycles of humidity and cloudiness, and ambient winds during the warm season were evaluated to determine their effect on the nocturnal cooling processes of a high mountain hollow in central Japan. This hollow is located at an elevation of 2230 m at the bottom, having a depth of 50-200 m with a diameter of approximately 1 km. One of the most marked seasonal changes in the atmosphere is a reduction in the downward longwave radiation from summer to autumn due to reduced water vapor. This reduction is larger than that of the upward longwave radiation due to a reduced surface temperature. This radiation balance resulted in larger (smaller) potential intensity of radiative cooling during autumn (summer). A composite analysis of diurnal variation for days in summer and autumn showed that the humidity and cloud conditions, differing between the seasons, determined the initial timing and development of nocturnal cooling. During summer (July and August), increased downward longwave radiation in the evening caused by a combination of increased water vapor and cloud cover over the mountains, suppresses and delays cooling. In contrast, dry and fair weather conditions throughout early autumn (September and October) causes strong and continuous cooling. Despite the high potential for radiative cooling during late autumn (after mid-October), nocturnal cooling was frequently disturbed by strong ambient winds exceeding 3.6 m s Ϫ1. The weak winds during summer and early autumn have a minor effect in determining the actual cooling intensity.

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Section: Seasonal Characteristics Of Nocturnal Cooling During the Warsupporting

confidence: 77%