############################################################################## # ISLSCP II Global River Fluxes of Carbon and Sediments to the Oceans # ############################################################################## Within this data set the term Continental Flux refers to global estimates of the consumption of CO2 by continental erosion, while the term Oceanic Flux refers to global estimates of the riverine flux of carbon sediments into the oceans. A) Continental Flux Data Files ----------------------------- The continental flux data files represent gridded estimates for the consumption of atmospheric CO2 by continental erosion based on empirical models. The units are tC/km2/yr for all carbon species, and t/km2/yr for sediment fluxes. File Name Description --------- ----------- cont_flux_co2rw_XX_map.asc bicarbonate export (atmospheric origin), also called "atmospheric CO2 consumption by rock weathering" cont_flux_doc_XX_map.asc dissolved organic carbon (DOC) export cont_flux_hco3_XX_map.asc bicarbonate export cont_flux_poc_XX_map.asc particulate organic carbon (POC) export cont_flux_tss_XX_map.asc sediment export Here "XX" identifies the spatial resolution of the data set, where hd and 1d stand for a spatial resolution of 1/2 and 1 degrees in both latitude and longitude, respectively. The original spatial resolution of this data set is 0.5 degrees. B) Oceanic Flux Data Files ------------------------- The original oceanic flux data set has a spatial resolution of 2.5 x 2 degrees latitude/longitude, and was provided in a tabular format with four columns. The units of these data are TgC/yr for the carbon fluxes, and %g/yr for the sediment fluxes. These original files are named: ocean_flux_co2rw_2d.dat bicarbonate export (atmospheric origin) ocean_flux_doc_2d.dat dissolved organic carbon (DOC) export ocean_flux_hco3_2d.dat bicarbonate export ocean_flux_poc_2d.dat particulate organic carbon (POC) export ocean_flux_tss_2d.dat sediment export The four columns of each file contain: 1) Longitude of the center of a cell in decimal degrees. 2) Latitude of the center of a cell in decimal degrees. 3) Flux of carbon (in TgC/yr) or sediment (in Tg/yr) into the oceans 4) The continental area that is drained to each grid cell The ISLSCP II staff has created global maps in text format (ASCII) at spatial resolutions of 1/2 and 1 degree from the original data. The mapped data are named as follows, where "XX" is the same as for the continental flux data sets in A) above: ocean_flux_co2rw_XX_map.asc bicarbonate export (atmospheric origin) ocean_flux_doc_XX_map.asc dissolved organic carbon (DOC) export ocean_flux_hco3_XX_map.asc bicarbonate export ocean_flux_poc_XX_map.asc particulate organic carbon (POC) export ocean_flux_tss_XX_map.asc sediment export In addition, the authors have provided graphical versions of their 1/2 degree resolution data for visualization purposes. These GIF format files are named with the same format as the continental and oceanic files with the exception that they end in the extension ".gif", and they are located in the /comp directory. An additional file showing the flow directions used in the river routing is also provided (flow_dir.gif file). All of these files can be viewed with most standard image display programs. ############################################################################## ASCII File Format ----------------- All of the data files in the ISLSCP Initiative II data collection are in the ASCII, or text format. The map file format consists of numerical fields of varying length, which are delimited by a single space and arranged in columns and rows. The map files at different spatial resolutions each contain the following numbers of column and rows: One degree: 360 columns by 180 rows 1/2 degree: 720 columns by 360 rows All files are gridded to a common equal-angle lat/long grid, where the coordinates of the upper left corner of the files are located at 180oW, 90oN and the lower right corner coordinates are located at 180oE, 90oS. Data in the map files are ordered from North to South and from West to East beginning at 180 degrees West and 90 degrees North. A) Continental Flux Data Sets ------------------------------------------- Oceanic or water grid points are assigned the value -99. All parts of the continents which are covered by ice have specific carbon and sediment fluxes of 0.000. B) Oceanic Flux Data Sets -------------------------- The 2.5x2 degree (2d) Oceanic Flux Tables: These ASCII tables contain 4 columns: longitude, latitude, carbon or sediment fluxes, and the continental area in km2 that is drained to the grid (large values indicate that the grid is in front of a large river basin). The structure of these files is different since only the coastal grid elements receiving river inputs are included. Each grid element is identified by the coordinates of the grid center: Sample data records can be found in Section 8.3 of the documentation. Oceanic Flux Maps: These data have the same format as the Continental flux files. For these files however, land values are assigned the value of -88 while areas of open ocean or water away from coastlines are assigned the value -99. WARNING: Both of the Continental flux 1 degree data set and the Oceans map products are recommended for browse use only. These data files were created from the original data sets submitted by the Principal Investigator(s). Use these data with caution and always refer to the original tabular data files for specific information.