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Carbon dioxide (CO 2 ) and methane (CH 4 ) were measured in a rice-barley double cropping and rice mono cropping paddy fields, which are located in the southwestern coast of Korea, over a one-year period. Net ecosystems CO 2 exchange (NEE) and ecosystem respiration (Re) were estimated by the eddy covariance (EC) method, and an automatic open/close chamber (AOCC) method was used to measure CH 4 fluxes. Environmental factors (solar radiation, air temperature, precipitation etc.) were also measured along with fluxes. After the quality control and gap-filling, the observed fluxes were analyzed. As a result, NEE was -603.0 and -471.5g C m -2 yr -1 in rice-barley double cropping and rice mono cropping paddy field, respectively. CH 4 emissions increased during the course of flooded days and were similar in two cropping paddy field. Accoding to rough results considering only fluxes of CO 2 and CH 4 , it was estimated that the carbon absorbation in rice-barley double cropping paddy field was higher than that in rice mono cropping paddy field by 128.9g C m -2 yr -1 .

The occurrence of abnormal sunshine duration was analyzed using meteorological data collected from 60 observation stations during the last 38 years . The 20 agro-climatic zones defined by the Rural Development Administration, were used as a spatial unit for the analysis.

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Rice-barley double cropping system is typical in southwestern part of South Korea. However, the information of carbon dioxide (CO 2 ) exchange for barley growing season has still limited in comparison with rice. Using the eddy covariance (EC) technique, seasonal variation of CO 2 exchange was analyzed for the barley growing season at a rice-barley double cropping field in Gimje, Korea. The effects of environmental factors and biomass on the CO 2 flux also were investigated. Quality control and gap-filling of flux data were conducted before this analysis and investigation. The results indicated that CO 2 uptake increased rapidly at tillering stage and maximum net ecosystem exchange of CO 2 (NEE) occurred at the early of May, 2012 (-11.2g ), when the heading of barley occurred. NEE, gross primary production (GPP), and ecosystem respiration (Re) during the barley growing season were -348.0, 663.3, and 315.2 g C m −2 , respectively. In this study, an attempt has been made to measure NEE, GPP, and Re with the help of the EC system for the barley growing season for the first time in Korea, focusing on CO 2 exchange between the biosphere and the atmosphere.