Last Glacial Maximum Sea Surface Temperature Reconstruction Grid: Readme file --------------------------------------------------------------------- NOAA Paleoclimatology Program and World Data Center for Paleoclimatology, Boulder --------------------------------------------------------------------- NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!! NAME OF DATA SET: Last Glacial Maximum Sea Surface Temperature Reconstruction Grid LAST UPDATE: 5/2001 (Original Receipt by WDCA Paleo) CONTRIBUTORS: Alan Mix, Oregon State University IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2001-041 SUGGESTED DATA CITATION: Hostetler, S.W. and Mix, A.C., 2001, Last Glacial Maximum Sea Surface Temperature Reconstruction Grid, IGBP PAGES/World Data Center for Paleoclimatology, Boulder Data Contribution Series #2001-041. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCES: Hostetler, S.W. and A.C. Mix, 1999. Reassessment of ice-age cooling of the tropical ocean and atmosphere. Nature 399, 673-676. (this paper used the grid files as a boundary condition for an atmospheric general circulation model) Mix, A.C., A. E. Morey, N. G. Pisias and S. W. Hostetler, 1999. Foraminiferal faunal estimates of paleotemperature: Circumventing the no-analog problem yields cool ice age tropics. Paleoceanography, Vol. 14, No. 3, 350-359. (this paper developed the temperature estimates, and created the gridded data sets). FUNDING SOURCE: National Science Foundation, USA. GEOGRAPHIC REGION: Global Ocean PERIOD OF RECORD: Last Glacial Maximum, 18 KYrBP LIST OF FILES: Readme_Hostetler1999.txt (this file), climap_anom_3col.txt, climap_anom_mtx.txt, climap_lgm_3col.txt, climap_lgm_mtx.txt, climap_modern_3col.txt, climap_modern_mtx.txt, grid_code_anom_3col.txt, grid_code_lgm_3col.txt, grid_code_modern_3col.txt, osu_anom_nosmooth_3col.txt, osu_anom_nosmooth_mtx.txt, osu_anom_smooth_3col.txt, osu_anom_smooth_mtx.txt, osu_lgm_nosmooth_3col.txt, osu_lgm_nosmooth_mtx.txt, osu_lgm_smooth_3col.txt, osu_lgm_smooth_mtx.txt (tab-delimited ASCII format), climap_anom.hdf, climap_lgm.hdf, climap_modern.hdf, osu_anom_nosmooth.hdf, osu_anom_smooth.hdf, osu_lgm_nosmooth.hdf, osu_lgm_smooth.hdf (NCSA HDF binary format). DESCRIPTION: Oregon State University Last Glacial Maximum Sea Surface Temperature Reconstruction Grid files using the Down-core Transfer Function Method. 1) GRID CODE FILES: These files are CODE MASKS, modified from the seasonal CLIMAP (1981) masks, to identify regions of land, land ice, and sea ice. The files are: grid_code_anom_3col.txt This is the code mask for the ANOMALY map, (LGM-Modern). grid_code_lgm_3col.txt This is the code mask for the LGM map. grid_code_modern_3col.txt This is the code mask for the MODERN map. These ascii files have three columns each, tab delimited: Latitude -- negative is south Longitude -- negative is west Code -- as follows: 0 = ocean -222 = seasonal sea ice (from averaging a data value (=0) with -444) -444 = sea ice -555 = land ice -999 = land Note: In some cases in the original CLIMAP (1981) files there was a code conflict between seasons for the same grid point (-999 land in feb, but -444 sea ice in aug, for example). Unless there was a clear reason to choose one or the other, the more negative codes number was accepted over lower codes. Code -222 (seasonal sea ice) is used here for grid points in the original CLIMAP (1981) files that had sea ice in one season and ocean in the other. 2) Annual sea-surface temperature maps: Separate files are given for the CLIMAP (1981) reconstruction, and the OSU reconstruction of Mix et al., (1999). The files are given in three forms: a) _3col.txt -- ascii 3 column (latitude, longitude, value; tab delimited ascii text) b) _mtx.txt -- ascii Matrix format (ascii text grid for Spyglass Transform, version 3.3, PC version) c) .hdf -- .hdf format (binary grid for Spyglass Transform, version 3.3, PC version) CLIMAP DATA FILES: CLIMAP files were created by averaging the CLIMAP 1981 seasonal files, removing the codes, then re-applying the codes using the masks created as described above (to maintain code consistency). The files are in three formats noted above. Note that these files include the appropriate code masks. The files were created so that: MODERN SST + ANOMALY SST = LGM SST The filenames for the 3 column text files are: climap_anom_3col.txt climap_lgm_3col.txt climap_modern_3col.txt The filenames for the text matrix files are: climap_anom_mtx.txt climap_lgm_mtx.txt climap_modern_mtx.txt The filenames for the .hdf format are: climap_anom.hdf climap_lgm.hdf climap_modern.hdf OSU DATA FILES OSU files below were created by taking the annual-average version of the CLIMAP 1981 reconstruction (above), and replacing the data in the region 140W-20E, 20N-20S with OSU estimates. The files are in both 3 col (lat, lon, value) tab delimited ascii format, text matrix format (again, compatible with Spyglass Transform (version 3.3): top line = longitude, left column = latitude, matrix = values), and .hdf format. All of these these files include code masks. The files were created so that: CLIMAP Modern + OSU LGM-MODERN = OSU LGM. The grid files are provided in both smoothed and unsmoothed forms. Smoothing was done by averaging the grid cell with the eight adjacent ocean grid cells (nine cells total -- center, up, up-right, right, down-right, down, down-left, left, up-left) with two passes through the array. The primary purpose of this smoothing was to minimize discontinuities at the edge of the region being modified from CLIMAP (1981). The file names for the 3-column text files are: osu_anom_nosmooth_3col.txt osu_anom_smooth_3col.txt osu_lgm_nosmooth_3col.txt osu_lgm_smooth_3col.txt The file names for the text matrix files are: osu_anom_nosmooth_mtx.txt osu_anom_smooth_mtx.txt osu_lgm_nosmooth_mtx.txt osu_lgm_smooth_mtx.txt The file names for the .hdf matrix files are: osu_anom_nosmooth.hdf osu_anom_smooth.hdf osu_lgm_nosmooth.hdf osu_lgm_smooth.hdf