• Journal of the Korean earth science society
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• v.30 no.1
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• pp.58-68
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• 2009

Three-dimensional distributions of longwave radiation flux for the April-September 1998 period are generated from radiative transfer calculations using the GEWEX Asian Monsoon Experiment (GAME) reanalysis temperature and humidity profiles and International Satellite Cloud Climatology Project (ISCCP) cloudiness as inputs to understand the effect of cloud radiative forcing in the monsoon season. By subtracting the heating of the clear atmosphere from the cloudy radiative heating, cloud-induced atmospheric radiative heating has been obtained. Emphasis is placed on the impact of horizontal gradients of the cloud-generated radiative heating on the Asian monsoon. Cloud-induced heating exhibits its maximum heating areas within the Indian Ocean and minimum heating over the Tibetan Plateau, which establishes the north-south oriented differential heating gradient. Considering that the differential heating is a ultimate source generating the atmospheric circulation, the cloud-induced heating gradient established between the Indian Ocean and the Plateau can enhance the strength of the north-south Hadley-type monsoon circulation. Cooling at cloud top and warming at cloud bottom, which are the vertical distributions of cloud-induced heating, can exert on the monsoon circulation by altering the atmospheric stability.

• Journal of the Korean earth science society
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• v.24 no.6
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• pp.558-567
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• 2003

The regional dependency of cloud-radiative forcing at the top of atmosphere is studied using ERBE (Earth Radiation Budget Experiment), ISCCP (International Satellite Cloud Climatology Project) and NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalysis data for 60 months from January 1985 to December 1989 over tropical ocean. In the interannual time scale, the dependency of cloud-radiative forcing on the sea surface temperature over the equatorial eastern Pacific ocean is about 7.4Wm$^{-2}$K$^{-1}$ for longwave radiation and about -4.4Wm$^{-2}$K$^{-1}$ for shortwave radiation, respectively. This shows that the net cloud-radiative forcing due to the increase of sea surface temperature over the equatorial eastern Pacific ocean heats the atmosphere. But the dependency is reversed over tropical oceans with -3.4Wm$^{-2}$K$^{-1}$ for longwave and 1.9WmWm$^{-2}$K$^{-1}$ for shortwave radiation, indicating that the net cloud-radiative forcing cools the atmosphere over tropical oceans. In raw data including seasonal cycle, the dependency of cloud-radiative forcing over the equatorial eastern Pacific ocean is very similar to that in interannual time scale in both the magnitude and the sign. But the dependency of cloud-radiative forcing on the sea surface temperature over tropical oceans is about 0.2Wm$^{-2}$K$^{-1}$ for longwave and 2.7Wm$^{-2}$K$^{-1}$ for shortwave radiation, respectively. These results represent that the role of seasonal cycle on the cloud radiative forcing is gradually more important than role of interannual time scale as the ocean area is broadening from the tropical central Pacific to the tropical ocean.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.439-440
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• 2001

대기 중의 에어러솔 입자들은 직접적으로는 빛의 산란, 흡수 등 복사 평형에 영향을 미치며, 간접적으로는 구름 응결핵(CCN)으로 작용함으로써 알베도와 구름의 수명에 영향을 미치게 된다. 자연적인 에어러솔은 인위적 활동에 따른 황 화합물, 질소 화합물, 유기물. 매연 그리고 토양 먼지의 증가에 의해 사실상 교란되어 왔다. 인위적인 에어러솔에 의한 복사 강제력(radiative forcing)은 현재 전 지구적 평균이 -0.3~-3.5Wm$^{-2}$ 정도로 추정되며, 이것은 온실 기체에 의한 강제력인 +2.0~+2.8Wm$^{-2}$ 와 비교될 만 하다(IPCC, 1995). (중략)

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.210-214
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• 2000

대기 중 에어로졸은 지구표면에 도달하는 태양복사에너지를 흡수 또는 산란시키는 직접 효과 및 대기물리작용에 의한 구름의 형성 및 구름 수명에 영향을 미치는 간접 효과를 통해 지구복사 평형에 불균형을 초래함으로써 전지구적인 기후변화에 영향을 미친다(Toon, 1995). 이들 에어로졸은 온실기체와는 달리 -0.4~-3.0 W/$m^2$ 의 지구 평균 복사강제력을 나타내면서(IPCC, 1995) 대기 중에 냉각 효과(whitehouse effect)를 일으킨다(Schwartz, 1996). (중략)

• 한국지구과학회:학술대회논문집
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• 2003.09a
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• pp.112-125
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• 2003

구름의 몬순의 활동에 있어서 직접적으로나 간접적으로 영향을 준다. 본 연구에서는 이러한 구름이 몬순의 활동에 어떠한 영향을 주는지를 알아보기 위해 ISCCP 구름자료와 GAME 재분석 자료를 입력자료로한 장파 복사 모델을 수행하였다. 모델 수행의 결과로 얻어진 대기 상부에서의 플럭스는 CERES 관측치와 비교하였으며, 구름에 의한 가열율은 몬순활동을 해석하기 위해 사용하였다. 구름이 몬순에 끼치는 영향을 파악하기 위해 맑은 대기의 가열율과 구름을 포함한 평균 대기의 가열율의 차이를 구하였으며, 이를 수평과 연직분포의 관점에서 해석하였다. 가열율의 지리적 분포는 수평적으로는 인도양에서 장파 복사 가열율의 최대가 나타났으며, 가열의 최저 (냉각)은 티벳고원에 나타났다. 이러한 공간적 분포는 구름이 남북방향으로 차등가열을 유발시키고 있음을 보여주고 있어 구름의 분포가 열적인 몬순순환을 강화시켜주고 있음을 시사하고 있다. 이러한 차등가열의 강화는 동서방향으로도 나타나 구름이 동서방향 순환에도 영향을 줄 수 있음을 보여준다. 구름에 의한 복사 가열의 연직구조는 운정에 의한 냉각과 운저에 의한 가열이 일어날 수 있음을 보여주고 있으며, 이로 인해 대기의 불안정성이 높아져 연직 운동을 향상시킬 수 있는 역할을 하고 있음이 밝혀졌다. 즉 몬순순환에 의해 생성된 구름은 구름 생성의 원인이 되었던 순환을 더욱 강화시키고 있음을 보이고 있다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.277-278
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• 2001

대기 중 에어로졸은 지구표면에 도달하는 태양복사에너지를 흡수 또는 산란시키는 직접 효과 및 대기물리작용에 의한 구름의 형성 및 구름 수명에 영향을 미치는 간접 효과를 통해 지구복사 평형에 불균형을 초래함으로써 전지구적인 기후변화에 영향을 미친다. 이들 에어로졸은 온실기체와는 달리 -0.4~-3.0 W/$m^2$의 지구 평균 복사강제력을 나타내면서(IPCC, 1995) 대기 중에 냉각 효과(white- house effort)를 일으킨다(Schwartz, 1996). (중략)

• Atmosphere
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• v.23 no.3
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• pp.283-291
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• 2013

This study investigates the changes in the atmosphere-ocean interactions over the South China Sea (SCS) by analyzing their variables in the period of 1979~2011 during the boreal summer (June-July-August). It is found that a simultaneous correlation coefficient between sea surface temperature (SST) and precipitation over SCS during summer is significantly changed before and after the late-1990s. That is, the variation of precipitation over SCS is negatively (positively) correlated with the SST variations before (after) the late-1990s. Our further correlation analysis indicates that the atmospheric forcing of the SST is dominant before the late-1990s accompanying with wind-evaporation feedback and cloud-radiation feedback. After the late-1990s, in contrast, the SST forcing of the atmosphere through the latent heat flux from the ocean to the atmosphere is dominant. It is found that the change in the relationship of atmosphere-ocean interactions over SCS are associated with the changes in the relationship with Northeast Asian summer precipitation. In particular, a simultaneous correlation coefficient between the precipitation over SCS and Northeast Asia becomes stronger during after the late-1990s than before the late-1990s. We argue that the increase of the SST forcing of the atmosphere over SCS may lead a direct relationship of precipitation variations between SCS and Northeast Asia after the late-1990s.

• Journal of the Korean earth science society
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• v.32 no.2
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• pp.239-247
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• 2011

The United Nations Framework Convention on Climate Change and the corresponding national low-carbon policy should be grounded on the scientific understanding of climate sensitivity to the increase in CO2 concentration. This is, however, precluded by the fact that current estimates of the climate sensitivity highly vary. To understand the scientific background, limitations, and prospects of the climate sensitivity study, this paper reviews, as objectively as possible, the most recent results on the sensitivity issue. Theoretically, the climate sensitivity hinges on climate feedbacks from various atmospheric and surface physical processes. Especially cloud and sea-ice processes associated with shortwave radiation are known to have largest uncertainty, resulting in an inaccurate estimation of climate sensitivity. For this reason, recent observational studies using satellite data suggest sensitivity lower than or similar to those estimated by climate models (2-5 K per doubled CO2).