A Kinematics-based GIS Methodology to Represent and Analyze Spatiotemporal Patterns of Precipitation Change in IPCC A2 Scenario James Bothwell University of Oklahoma JamesBothwell@ou.edu May Yuan University of Oklahoma myuan@ou.edu ABSTRACT A kinematics-based GIS methodology is applied to represent and analyze spatiotemporal patterns and pattern transitions in very large data sets. A use case is built from two precipitation data products projected for the A2 scenario by the International Panel for Climate Change (IPCC): (1) the Community Climate System Model (CCSM3) from the National Center for Atmospheric Research (NCAR, USA, Boulder Colorado), and (2)the global ocean-atmosphere coupled system (CM3) from the Center National Weather Research (CNRM, METEO-France, Toulouse). The study takes a predefined threshold to delineate regions of interest, calculates shifts of the regions between years, and characterizes the pattern change. The research focus was the topics as tropical changes affect extra- tropical climate [12]. The dominate factor affecting tropical climate is the Walker circulation which showed trends in all GCMs when examined for periods of longer than 20 years [19]. The 30 year duration insures that trends are gradual and lead to changes amenable to analysis. The study uses precipitation over 213 cm/year in 2001 and 2048 to illustrate the kinematics approach to comparing precipitation patterns predicted from the CCSM3 and CM3. Even though the precipitation data in 2001 and 2048 cannot be considered temporally continuous, the differential used here was to identify the patterns of precipitation shifts between the two years under the assumption that changes to spatial patterns of precipitation for 213 cm/year were gradual from 2001 to 2048. The 213 cm/year precipitation threshold is only met by a large number of precipitation events during the years of interest. Hence, this threshold appears stable from year to year although lesser thresholds would be discontinuous. The kinematics approach quantifies divergence, rotation, and deformation about changes to precipitation patterns and enables the search for precipitation regions influenced primarily by local conditions or by general circulation patterns of water vapour transport. The study demonstrates that the kinematics approach is able to discern transitional patterns from a continuous field of geographic properties over time by defining objects through thresholds and analyzing the object’s internal and external movement patterns in space and time. Categories and Subject Descriptors H2.8 [Database Management]: Database Applications – Spatial Databases and GIS General Terms Algorithms Keywords Temporal GIS, space-time objects, geographic kinematics, internal change, motion, and Geographic Information Science. 1. INTRODUCTION Many climatological studies examine aggregated patterns from climate events to generalize spatially the overall outcome of climate change at the regional or global scales (Carelton 1999). Van Ulden and Oldenborgh [18] studied five GCMs and discovered significant differences in circulation patterns leading to differences in precipitation patterns. This research seeks an effective way to address spatiotemporal patterns, specifically, precipitation patterns projected in A2 scenario defined by the International Panel for Climate Change (IPCC). Elicitation of precipitation patterns out of massive GCM data products is non- trivial. From the perspective of information sciences, effective detection of patterns relies heavily on the design of representation schemes and analytical methods [22]. Instead of examining precipitation patterns at individual time frames, the research revises and applies a kinematics-based GIS method originally designed for the analysis of changes in temperature patterns, to emphasize spatiotemporal transitions of precipitation by the authors. By adopting the idea of kinematics, the GIS method identified areas of high precipitation and characterized the direction and distance of movement for these areas, conceptualized as an object, over space and time. The shift patterns of precipitation are then examined through linking these objects across time steps as in a flow field defined by Theisel and Seidel [17]. Shifts measured by the rates of emergence, dissipation, splitting and merging may be indicative of the effects of large scale circulation patterns on precipitation. Measures for the area’s internal spatiotemporal characteristics and transitions draw new insights into precipitation patterns projected by two General Circulation Models (GCMs). The near fifty year interval revealed changes in tropical precipitation that resulted in changes that can be analyzed for shifts of objects defined by isohyets. Climatic data are analyzed to determine the location, type and rate of internal change of precipitation objects. These measures can effectively summarize and contrast precipitation patterns suggested by different GCM models or for different climate change scenarios. All GCMs produce massive climate projection products, and the essence of predicted climate patterns and the differences among data outputs from models are difficult to discern. The kinematics GIS approach can facilitate the elicitation and summary of changes in spatiotemporal precipitation patterns Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Conference’10, Month 1–2, 2010, City, State, Country. Copyright 2010 ACM 1-58113-000-0/00/0010…$10.00.