Browsing by Autor "Takeshi Yamazaki"

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    Energy balance analysis of a tropical glacier in the Andes and identification of key meteorological variables for empirical melt estimates
    (Cambridge University Press, 2025) Yoshihiro ASAOKA; Genki Saito; Takeshi Yamazaki; Edson Ramírez; Walter W. Immerzeel
    Abstract This study investigated surface energy fluxes of the Huayna-Potosí Glacier in Bolivia to validate existing empirical melt estimates, including degree-day models and enhanced temperature-index models. A multilayer energy balance model of the snowpack was employed to estimate melt energy and analyze its correlation with meteorological variables. The energy balance analysis revealed that melt energy peaked in October and November, the period corresponding to the progressive development toward the core wet season. Most of the net radiation was consumed by the conductive heat flux into the snowpack or glacier ice, contributing to surface temperature increases. The remaining energy was used for melt. An analysis of diurnal variation indicated that atmospheric longwave radiation suppresses melt during the dry season while driving melt during the wet season. Variables such as specific humidity and relative humidity, which are related to atmospheric longwave radiation, emerged as primary controlling factors after solar radiation in estimating melt based on meteorological variables. This study highlights that a combination of solar radiation and specific humidity outperforms existing empirical melt models that depend exclusively on temperature or a combination of temperature and solar radiation.
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    HEAT BALANCE ANALYSIS ON THE GLACIER WITH SUMMERPRECPITATON SEASONALITY AND EFFECT OF SNOW -A CASE STUDY OF ANDEAN TROPICAL GLACIER-
    (2013) Yoshihiro ASAOKA; Takeshi Yamazaki; Shunsuke Miyata; So Kazama; Edson Ramírez
    The tropical glacier in Andes Mountain has summer precipitation seasonality. A multi-layer snow model was applied to Zongo glacier, Bolivia to evaluate the heat balance on the glacier and the effect of snow on glacier melt. Model simulation at observation point successfully accounted for variations in surface temperature on the glacier in both dry and wet season. Main components of melt heat were shortwave radiation in the dry season and long wave radiation in wet season. Melt flux in mid-wet season was lower than in early-wet season due to continuous snow cover and its high albedo. Moreover, simulation results showed that snow cover on the glacier decline the melt rate in the wet season. This result suggests that mass balance is affected by summer precipitation seasonality and vulnerable to temperature rise.