HR: 0800h
AN: B41B-04    [Abstracts]
TI: Validation of MODIS driven clear-sky daytime net radiation over the Korean Peninsula
AU: Jang, G
EM: gjang@kangwon.ac.kr
AF: Kangwon National University, Department of Environmental Science, Chunchon, Korea, Republic of
AU: Kim, H
EM: hkim@kangwon.ac.kr
AF: Kangwon National University, Department of Environmental Science, Chunchon, Korea, Republic of
AU: Ryu, Y
EM: ryuyr77@snu.ac.kr
AF: University of California, Berkeley, Department of Environmental Science, Policy and Management, Berkeley, CA 94720-3114, United States
AU: Kim, J
EM: joon.kim@yonsei.ac.kr
AF: Yonsei University, Department of Atmospheric Sciences, Seoul, Korea, Republic of
AU: * Kang, S
EM: kangsk@kangwon.ac.kr
AF: Kangwon National University, Department of Environmental Science, Chunchon, Korea, Republic of
AB: Net radiation is the balance of the shortwave and longwave radiation in upwelling and downwelling streams, which is the fundamental quantity of energy available at the earth's surface to drive processes of evapotranspiration, air and soil heating, photosynthesis, and energy storage in vegetation. MODIS provides a challenging tool for monitoring net radiation periodically, nearly twice per daytime (i.e. onboard Terra in the morning and onboard Aqua in the afternoon). The reliable MODIS driven estimates are however hindered by multiple error sources, for examples, related to heterogeneous land cover and complex topography. In this study, we utilized MODIS atmospheric and land products as inputs to estimate daytime shortwave, longwave, and net radiations and then, reliability of the radiation estimates and their errors associated with the input variables were evaluated over the Korean Peninsula. Our results indicate that MODIS is applicable to retrieve net radiation and its input variables (i.e. air temperature, vapor pressure, albedo, and shortwave and longwave radiations) with reasonable accuracy. Overall, Aqua MODIS showed better results than Terra MODIS. For examples, net radiation was better estimated at the forest site (root mean square errors (RMSE) of 42 and 38 W/m2 for Terra and Aqua) than the farmland site (88 and 59 W/m2), while accuracy of shortwave radiation was in opposite (RMSEs of 51 and 44 W/m2 for Terra and Aqua at the forest site; 44 and 26 W/m2 at the farmland site). The large error of net radiation at the farmland site was explained by considerable discrepancies in albedo, land surface emmisivity, and land surface temperature, which were closely related to sub-pixel land cover heterogeneity. On the other hand, the large error of solar radiation at the forest site indicates that effects of sub-pixel topographic complexity on direct and diffuse radiations need to be accounted for in complex terrain areas.
DE: 0416 Biogeophysics
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 0430 Computational methods and data processing
DE: 0480 Remote sensing
DE: 0495 Water/energy interactions (1878)
SC: Biogeosciences [B]
MN: 2007 Joint Assembly