Author(s): Nobuo Ono; Isao Yakuwa; Jin Yoshimura; Jun’Ichi Takahashi
Linked Author(s): Nobuo Ono
Keywords: No Keywords
Abstract: Lake Haruna is a caldera lake of Mt. Haruna located at 36°28'N and 138°52'E in the central Honshu, Japan. About 1.3 square kilometers in area, the lake has a mean depth of about 8 meters, and its surface is covered with ice in winter. The lake has been subjected to an investigation as to characteristics of ice growth, using data since 1960 of daily mean air temperature and daily thickness of the ice cover (I), and calculating degree-days of frost (R), beginning from the day when cumulative daily mean air temperature culminated each winter, which are used as absolute values. Analizing the data using the Stefan's law, I 2 = a (R-R 0), two constants a and R o were chosen as the parameters of ice growth characteristics, where R o is the value of degree-days of frost on the day of first freeze-over. These parameters have varied with the year since the winter of 1973-74 toward a trend in which the date of first freeze-over delays and the ice growth rate decreases. Considered to be the cause of the variation is an increase in amount of heat from warm water inflow which changes thermal conditions for lake ice growth.
Year: 1988