Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 1 1 2001 10.5194/acp-1-61-2001 http://www.atmos-chem-phys.net/1/61/2001/ http://www.atmos-chem-phys.net/1/61/2001/acp-1-61-2001.html http://www.atmos-chem-phys.net/1/61/2001/acp-1-61-2001.pdf 61 71 2001-12-28 Nitrous oxide emissions from the Arabian Sea: A synthesis H. W. Bange M. O. Andreae S. Lal C. S. Law S. W. A. Naqvi P. K. Patra T. Rixen R. C. Upstill-Goddard Max Planck Institute for Chemistry, Mainz, Germany Physical Research Laboratory, Ahmedabad, India Plymouth Marine Laboratory, Plymouth, United Kingdom National Institute of Oceanography, Dona Paula, Goa, India University of Hamburg, Hamburg, Germany University of Newcastle, Newcastle upon Tyne, United Kingdom now at Institute for Marine Research, Kiel, Germany now at Frontier Research System for Global Change, Yokohama, Japan now at Center for Tropical Marine Ecology, Bremen, Germany We computed high-resolution (1º latitude x  1º longitude) seasonal and annual nitrous oxide (N₂O) concentration fields for the Arabian Sea surface layer using a database containing more than 2400 values measured between December 1977 and July 1997. N₂O concentrations are highest during the southwest (SW) monsoon along the southern Indian continental shelf. Annual emissions range from 0.33 to 0.70 Tg N₂O and are dominated by fluxes from coastal regions during the SW and northeast monsoons. Our revised estimate for the annual N₂O flux from the Arabian Sea is much more tightly constrained than the previous consensus derived using averaged in-situ data from a smaller number of studies. However, the tendency to focus on measurements in locally restricted features in combination with insufficient seasonal data coverage leads to considerable uncertainties of the concentration fields and thus in the flux estimates, especially in the coastal zones of the northern and eastern Arabian Sea. The overall mean relative error of the annual N₂O emissions from the Arabian Sea was estimated to be at least 65%.