• Ocean and Polar Research
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• 제37권2호
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• pp.141-147
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• 2015

Snow albedo can be decreased if there are any impurities on the snow surface other than the snow itself. Due to the decrease of snow albedo, melting rates of surface snow can increase, which is very crucial in climate change and hydrogeology in many parts of the world. Anthropogenic black carbons caused by the incomplete combustion of fossil fuel affect snow and tephra particles generated by geologic volcanic activities reduce snow albedo. In this study, we investigated isotopic compositions for snow covered by tephra particles and compared with this with clean snow. Isotopic compositions of snow with tephra statistically show more enriched than those of clean snow (p<0.02). This can be explained by the fact that snow becomes enriched in $^{18}O$ or D relative to meltwater as melting rates are increased. In addition, the slopes of the linear regression between oxygen and hydrogen for snow with tephra and clean snow are 6.7 and 8, respectively, and the latter is similar to that of the global meteoric water line of 8. Therefore, we can conclude that snow impurities control the isotopic compositions of snow, which is very crucial in the study of climate change and hydrogeology. To quantitatively explain these observations, melting experiments and numerical approaches are required.

• 천문학회지
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• 제36권spc1호
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• pp.83-91
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• 2003

There are terrestrial signatures of the solar activity cycle in ice core data (Ram & Stoltz 1999), but the variations in the sun's irradiance over the cycle seem too small to account for the signature (Lean 1997; Goode & Dziembowski 2003). Thus, one would expect that the signature must arise from an indirect effect(s) of solar activity. Such an indirect effect would be expected to manifest itself in the earth's reflectance. Further, the earth's climate depends directly on the albedo. Continuous observations of the earthshine have been carried out from Big Bear Solar Observatory since December 1998, with some more sporadic measurements made during the years 1994 and 1995. We have determined the annual albedos both from our observations and from simulations utilizing the Earth Radiation Budget Experiment (ERBE) scene model and various datasets for the cloud cover, as well as snow and ice cover. With these, we look for inter-annual and longer-term changes in the earth's total reflectance, or Bond albedo. We find that both our observations and simulations indicate that the albedo was significantly higher during 1994-1995 (activity minimum) than for the more recent period covering 1999-2001 (activity maximum). However, the sizes of the changes seem somewhat discrepant. Possible indirect solar influences on the earth's Bond albedo are discussed to emphasize that our earthshine data are already sufficiently precise to detect, if they occur, any meaningful changes in the earth's reflectance. Still greater precision will occur as we expand our single site observations to a global network.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권5호
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• pp.16-25
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• 2015

The City of Boulder is located at an average elevation of 1,655 m (5,430 feet), the foothills of the Rocky Mountains in Colorado. Its daily air temperature is much varying and snow is very frequent and heavy even in spring. This paper examines characteristics of shallow (surface and depth = 10 cm) soil temperatures measured from January to May 2015 in the high elevation city Boulder, Colorado. The surface soil temperature quickly responded to the air temperature with the strongest periodicity of 1 day while the subsurface soil temperatures showed a less correlation and delayed response with that. The short-time Fourier of the soil temperatures uncovered their very low frequencies characteristics in heavy snow days while it revealed high frequencies of their variations in warm spring season. The daily minimum air temperature exhibited high cross-correlations with the soil temperatures without lags unlike the maximum air temperature, which is derived from its higher and longer auto-correlation and stronger spectrums of low frequencies than the maximum air temperature. The snow depth showed an inverse relationship with the soil temperature variations due to snow's low thermal conductivity and high albedo. Multiple regression for the soil temperatures using the air temperature and snow depth presented its predicting possibility of them even though the multiple r² of the regression is not that much satisfactory (r² = 0.35-0.64).

• 한국지구과학회지
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• 제33권2호
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• pp.139-147
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• 2012

몽골의 태양-기상자원지도는 위성자료 및 재분석 자료를 이용하여 개발되었다. 태양복사량은 단층 태양복사모델을 이용하였으며 입력자료는 SRTM, MODIS, OMI, MTSAT-1R 등의 위성관측자료와 전구모델의 재분석자료를 이용하였다. 계산된 결과는 NCEP/NCAR 재분석 DSWRF 자료를 이용하여 계산된 일사량을 검증하였다. 몽골은 서부의 산악지역과 중남부의 사막 및 반사막지대로 이루어져 있으며 대륙 내부에 위치하여 강수량이 적고 맑은 날이 많아 동일 위도상의 다른 지역과 비교하여 높은 일사량이 나타난다. 서부 산악지역은 고도가 높아 태양에너지가 많이 도달되는 곳임에도 불구하고 일사량이 낮게 나타난다. 그 이유는 산악지역에 존재하는 연중 적설이 위성자료의 구름탐지 알고리즘에서 구름으로 오탐지 되기 때문이다. 따라서 청천지수뿐만 아니라 일사량 또한 낮게 계산된다. 남부지역은 상대적으로 높은 가강수량과 에어로솔 광학두께가 나타났으나 다른 지역에 비해 위도가 낮고 청천지수가 높아 일사량이 높게 나타나는 것으로 분석된다. 계산된 월 누적 일사량은 547.59 MJ로써 전 지점에서 약 2.89 MJ로 높게 계산되었으며 상관성은 0.99였고 평방근오차(Root Mean Square Error; RMSE)는 6.17 MJ 이었다. 월별 통계 값을 계산하였을 때 상관성이 가장 높은 월은 10월로 0.94였고 3월은 0.62로 가장 낮게 나타났다.