[A-CG59] Biogeochemical linkages between the surface ocean and atmosphere

[ACG59-P02] Influence of deposition of atmospheric nitrogen compounds on the surface marine ecosystem at the Japan Sea

*Fumikazu Taketani¹, Maki Noguchi Aita¹, Takashi Sekiya¹, Kazuyo Yamaji^1,2, Kohei Ikeda³, Makio Honda¹, Kazuhiko Matsumoto¹, Kosei Sasaoka¹, Yugo Kanaya¹ (1.Japan Agency for Marine-Earth Science and Technology, 2.Kobe University, 3.National Institute for Environmental Studies)

Keywords:Nitrogen compounds, deposition, Japan Sea, marine ecosystem

The sensitivity of the atmospheric deposition of inorganic nitrogen compounds to the surface chlorophyll-a mass concentration at the Japan Sea was investigated using a 3-D lower trophic-marine ecosystem model (NEMURO) combined with an atmospheric regional chemical transport model (WRF-CMAQ). The monthly mean values for the wet and dry deposition of nitrogen compounds including gases (HNO3 and NH3) and aerosol particles (NO3- and NH4+) over the Japan Sea were determined using the WRF-CMAQ, indicating that wet deposition was dominant in all seasons. These values were input into the surface of ocean of NEMURO as a new nitrogen source. The annual average of surface chlorophyll-a mass concentration at the Japan Sea was increased from 0.26 to 0.35 mg/m3. The growth ratios of chlorophyll-a mass concentration in summer was factor of ~2.1, while that in wintertime was factor of ~1.1, indicating that the atmospheric deposition of inorganic nitrogen compounds highly influence to the surface chlorophyll-a mass concentration in summer.