3-DIMENSIONAL VISUALIZATION OF ORBITAL FORCING AND CLIMATIC RESPONSE - INTERACTIVELY EXPLORING THE PACEMAKER OF THE ICE AGES

Recent developments in continuous core-logging techniques now permit u s to recover the high-resolution time series necessary for the detaile d spectral analyses of paleoclimatic proxy records. When applied to lo ng records recovered by scientific drilling (5-10 Ma) they enable us t o look at the long-term history and evolution of the ocean's response to orbital forcing. A serious limitation in these studies is the need to display the complex, multidimensional spatial and temporal interact ions of the ocean-climate system in an easily comprehensible manner. W e have addressed this issue by developing a series 3D visualization to ols which permit visualization of the role of the orbital parameters i n determining the latitudinal variation of insolation as well as the i nteractive exploration of multidimensional data sets. The ORBITS tool allows us to visualize the effect of orbital eccentricity, precession, and tilt on the latitudinal distribution of insolation on the earth a t the solstices and the equinoxes for any time over the past 5 Ma (for Berger's orbital model) or 10 Ma (for Laskar's orbital model). The ef fect of the orbital parameters on insolation can be viewed individuall y, in pairs, or all three together. By moving the model steadily throu gh time, the rate at which orbitally induced changes in insolation occ ur can also be visualized. To look at the ocean's response to orbital forcing we take the long time series generated from our paleoclimatic proxies and calculate their spectrum over a fixed, but sliding, time w indow. To view the complex multidimensional relationships found in the se evolutionary spectral analyses, we use another interactive 3D data exploration tool developed at the University of New Brunswick (Canada) . This tool (FLEDERMAUS) uses a six-degrees-of-freedom input device (B AT) and a series of software modules for color coding, shading, and re ndering complex data sets, to allow the user to interactively ''fly'' through the multidimensional data. Through the use of color, texture, and 3D position, as many as six or seven variables can be explored in a simple and intuitive manner. With special liquid-crystal display gla sses, the scene can be viewed in true ''stereo.'' We use these tools t o explore the relationship between orbital forcing and the response of the benthic isotope and calcium carbonate record at ODP Site 846 (90 degrees W and 5 degrees S) This analysis shows an equatorial Pacific c arbonate record which has a large component of linear response to tilt , but little linear response to precession. There is a major shift in response, from a carbonate-dominated response to an isotope (ice volum e)dominated response at approximately 4.5 Ma, and as expected, there i s a large nonlinear response at the lower frequencies (400 and 100 kyr ) during the past 800 kyr to 1 Ma