Radon continuous observation on the sea surface atmosphere by using the high sensitive radon detector

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Continuous measurements of the atmospheric radon have been made in the ice breaker SHIRASE by the use of the high sensitive radon detector upon the Japan Sea from Monbetsu to Tottri(13 Sep.2004- 17 Sep.) and the Antarctic Ocean from Fremantle via SYOWA station to Sydney(13 Dec.2004 - 18 Mar.2005). The observation results of the radon will be expected to contribute for the development of the atmospheric long-range transport model to Antarctica from the other continents, South America and Africa. The results are summarized as follows.1) The observed minimum background level 0.02Bqm-^3 of the atmospheric radon concentration upon the Antarctic Ocean corresponds with the simulation results from the ocean atmospheric flux of radon 0.01Rncm-^2s^<-1>.2) The rapid increasing events of the radon concentration (radonic storm) were observed 6 events on the Antarctic Ocean. The radonic storm detection on 25-Feb 2005 was success to the parallel observation with the SYOWA station and SHIRASE, which w … More as shipped offshore Amundsen Gulf far 500km from SYOWA. Two observation points were located on the front of the depression from the NOAA satellite photographs. This radonic storm event turned out to be transport from the South America to SOYWA station with the one week by the comparison with the observation data and evaluated data of the Atmospheric transport model. The observation arrival time was coincident with the evaluation time of the model, but the radon concentrations were different with the observations, SHIRASE 0.145Bqm^<-3> and SYOWA 0.085Bqm^<-3> and evaluation 0.024Bqm^<-3>. The model failed to simulate the amplitudes of radonic storm events at SYOWA station. These high concentration events were possibly a result of filament-like horizontal structure or laminated vertical structure. The improvement of the model was expected for the radonic storm events. These radon observation results on the Antarctic Ocean will be contributed to the development of the atmospheric long-range transport model Less