PRISM 8°x10° Northern Hemisphere Paleoclimate Reconstruction: Digital Data

The PRISM 8°x10° data set represents several years of
investigation by PRISM (Pliocene Research, Interpretation, and
Synoptic Mapping) Project members. One of the goals of PRISM
is to produce time-slice reconstructions of intervals of
warmer than modern climate within the Pliocene Epoch. The
first of these was chosen to be at 3.0 Ma (time scale of
Berggren et al., 1985) and is published in Global and
Planetary Change (Dowsett et al., 1994). This document
contains the actual data sets and a brief explanation of how
they were constructed. For paleoenvironmental interpretations
and discussion of each data set, see Dowsett et al., in
press. The data sets includes sea level, land ice
distribution, vegetation or land cover, sea surface
temperature and sea-ice cover matrices.
This reconstruction of Middle Pliocene climate is organized as
a series of datasets representing different environmental
attributes. The data sets are designed for use with the GISS
Model II atmospheric general circulation model (GCM) using an
8°x10° resolution (Hansen et al., 1983). The first step in
documenting the Pliocene climate involves assigning an
appropriate fraction of land versus ocean to each grid box.
Following grid cell by grid cell, land versus ocean
allocations, winter and summer sea ice coverage of ocean areas
are assigned and then winter and summer sea surface
temperatures are assigned to open ocean areas. Average land
ice cover is recorded for land areas and then land areas not
covered by ice are assigned proportions of six vegetation or
land cover categories modified from Hansen et al. (1983).