Emissions from international ship traffic Contact: thomas.diehl@nasa.gov Description of the emission files We compiled a gridded inventory of emissions from international ship traffic for black carbon (BC), organic carbon (OC), SO2, and SO4 for the time period 1979-2007. The inventory is derived from a gridded dataset for SO2 for the year 2000 generated by V. Eyring and A. Lauer for the EDGAR FT2000 database and total emissions trends. These trends are provided in Eyring et al. (2005a) for the years 1970, 1980, 1995, and 2001, and in Eyring et al. (2005b) for a projection to the year 2020. Trends for years not provided in the Eyring et al. publications were derived through interpolation. For each year, a global scaling factor was calculated as emitot(year)/emitot(2000), where emitot are the total emissions for the given year. These scaling factors were then applied to all grid points to generate the gridded emissions for the individual years. We derive trends for BC, OC, and SO4 from the trends for PM10 by assuming that the fraction of each of these species of PM10 is the same as in 2001 for all years. The gridded maps for these species are then generated by assuming that, for each grid point, the ratio of the local emissions to the global emissions for SO2 is the same for the other species. The naming convention for the ship emission files is XX_ship_yyyy.nc, where yyyy is the year (1979 to 2007) and XX is BC, OC, SO2, or SO4. The horizontal resolution of the emission maps is 1x1. The following variables are included in each file: * lon: longitude at grid cell midpoints * lat: latitude at grid cell midpoints * ilon: longitude at grid cell interfaces * ilat: latitude at grid cell interfaces * XX_SHIP: amount of species XX emitted per grid box, where XX is BC, OC, SO2, or SO4; unit is kg/y. Recommendations regarding the usage of the inventory Currently, we are emitting all species into the first model level only. For regridding purposes, we recommend the NCREGRID tool, but any other code, which is mass conserving will of course be adequate as well. References: Eyring, V., H. W. Kšhler, J. van Aardenne, and A. Lauer, Emissions from international shipping: 1. The last 50 years, J. Geophys. Res., 110, D17305, doi:10.1029/2004JD005619, 2005a. Eyring, V., H. W. Kšhler, A. Lauer, and B. Lemper, Emissions from international shipping: 2. Impact of future technologies on scenarios until 2050, J. Geophys. Res., 110, D17306, doi:10.1029/2004JD005620, 2005b.