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Rapid Arctic warming has altered the regional hydrological cycle through reduction in Arctic sea ice. Observational and modeling efforts provided evidence that the enhanced evaporation from the Arctic Ocean could lead to changes in hydrological cycle over high latitude terrestrial zones. However, its amount and temporal variations from seasonal to decadal timescales need further investigations with attention to the moisture source regions. This study, thus, developed atmospheric moisture transport model that is driven by reanalysis dataset as forcing, and investigated the moisture exchange across the Arctic coastal regions. Atmospheric moisture that originated from Arctic Ocean evaporation has increased significantly in autumn to early winter during 1981–2019 when substantial sea ice retreat was observed. The enhanced Arctic moisture content is found in western Siberia in September. In the Arctic region, the fraction of atmospheric moisture originated from Eurasian and North American continents have increased during summer. Our results denote moisture exchange between Arctic Ocean and surrounding regions has undergone changes associated with Arctic warming., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

We developed a CANDLES-III system to study the neutrinoless double beta (0νββ) decay of Ca48. The proposed system employs 96 CaF2 scintillation crystals (305 kg) with natural Ca (Canat) isotope which corresponds 350 g of Ca48. External backgrounds were rejected using a 4π active shield of a liquid scintillator surrounding the CaF2 crystals. The internal backgrounds caused by the radioactive impurities within the CaF2 crystals can be reduced effectively through analysis of the signal pulse shape. We analyzed the data obtained in the Kamioka underground for a live-time of 130.4 days to evaluate the feasibility of the low background measurement with the CANDLES-III detector. Using Monte Carlo simulations, we estimated the background rate from the radioactive impurities in the CaF2 crystals and the rate of high energy γ-rays caused by the (n,γ) reactions induced by environmental neutrons. The expected background rate was in a good agreement with the measured rate, i.e., approximately 10−3 events/keV/yr/(kg of Canat), in the 0νββ window. In conclusion, the background candidates were estimated properly by comparing the measured energy spectrum with the background simulations. With this measurement method, we performed the first search for 0νββ decay in a low background condition using a detector on the scale of hundreds of kg of nonenriched Ca. Deploying scintillators enriched in Ca48 will increase the sensitivity strongly. Ca48 has a high potential for use in 0νββ decay search, and is expected to be useful for the development of a next-generation detector for highly sensitive measurements.