Subfossil pollen and plant macrofossil data derived from 14 C-dated sediment profiles can provide quantitative information on glacial and interglacial climates. The data allow climate variables related to growingseason warmth, winter cold, and plant-available moisture to be reconstructed. 123Clim Dyn (2011) 37:775-802 DOI 10.1007 surface-pollen assemblages are shown to be accurate and unbiased. Reconstructed LGM and MH climate anomaly patterns are coherent, consistent between variables, and robust with respect to the choice of technique. They support a conceptual model of the controls of Late Quaternary climate change whereby the first-order effects of orbital variations and greenhouse forcing on the seasonal cycle of temperature are predictably modified by responses of the atmospheric circulation and surface energy balance.

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July mean temperature and annual precipipation during the last 9900 cal. yr BP were reconstructed from pollen assemblages preserved in a sediment core from northern Finland. Quantitative reconstructions were performed using a modern pollen-climate calibration model based on weighted-averaging partial least squares regression. The predictive ability of the model was evaluated against modern meteorological data using leave-one-out cross-validation. The prediction error for July mean temperature is c. 1.0°C and for annual precipitation 340 mm. The July mean temperatures during the earliest Holocene were low, c. 11.0°C, and annual precipitation was high, c. 600-800 mm. Between 8200 and 6700 cal. yr BP July mean temperatures reached their maxima, 12.5-13.0°C, which are c. 1.4-1.7°C higher than at present. At the same time precipitation decreased. During the late Holocene, July mean temperatures declined and the last 2000 years have been the coolest since the early Holocene. Precipitation has slightly increased. The spatial coherence between our results and of several other climate reconstructions from northern Europe indicates that the Holocene climate was strongly influenced by North Atlantic oceanic and atmospheric circulation patterns. We propose that the distinctly oceanic climate of the early Holocene was due to enhanced westerly (latitudinal) airflow which was replaced at c. 8200 cal. yr BP by a more meridional flow pattern and by the development of predominantly anticyclonic summer conditions.

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Abstract-Nonlinear effects in single-crystal silicon microresonators are analyzed with the focus on mechanical nonlinearities. The bulk acoustic wave (BAW) resonators are shown to have orders-of-magnitude higher energy storage capability than flexural beam resonators. The bifurcation point for the silicon BAW resonators is measured and the maximum vibration amplitude is shown to approach the intrinsic material limit. The importance of nonlinearities in setting the limit for vibration energy storage is demonstrated in oscillator applications. The phase noise calculated for silicon microresonator-based oscillators is compared to the conventional macroscopic quartz-based oscillators, and it is shown that the higher energy density attainable with the silicon resonators can partially compensate for the small microresonator size. Scaling law for microresonator phase noise is developed.[1246]