Potential analogues for paleoclimatic variations in eastern interior Alaska during the past 14,000 yr: atmospheric-circulation controls of regional temperature and moisture responses

摘要: The paleoclimatic history of a region can be viewed as series surface temperature and moisture anomalies through time. effects changes in large-scale climatic controls (e.g., insolation, major circulation controls) mediated by the influence smaller-scale topographic barriers, coastlines); this may result heterogenous responses at regional sub-regional scale. Divergent trajectories between regions explainable terms such meso-scale patterns. Using modern analogues for paleoclimate we examine how sequence variations eastern interior Alaska during interval 12,000–0 14C yr BP could have been generated specific atmospheric Fossil-pollen lake-level records document long-term trends effective region. Water-balance modelling provides additional estimates paleoprecipitation. Synoptic climatological patterns are described using (instrumental) record upper-level sea-level pressure, temperature, precipitation. At 12,000 BP, was cooler drier than present, situation today southward displacement jet stream. Conditions warmer present 9000 increased ridging north weakened westerly circulation. Warmer, wetter conditions possibly prevailed late-middle Holocene; these might reflect over troughing further west. Cool, wet feature enhanced flow into an eastward shift east Asian trough positive pressure North Pacific; they analogous to cold periods Little Ice Age. demonstrate other parts Beringia sometimes similar to, while times different from those interior. These broader spatial provide hypotheses about past climates that tested with paleoclimatological data. For example, widespread associated warm/dry (9000 BP) analogue fit expansion northward Siberian treeline. anomalously cool northeast Siberia warm/wet explain continued (late-middle Holocene) treeline advance there retreat Siberia.