On the linearity of the temperature response in Holocene: the spatial and temporal dependence
Climate of The Past Discussions(2019)
摘要
Abstract. Previous studies show that the evolution of global mean temperature forced by the total forcing is almost the same as the sum of those forced by individual forcing in the last 21 000 years as simulated in three independent climate models, CCSM3, FAMOUS and LOVECLIM. But how does the linearity of the climate response depend on the spatial and temporal scales quantitatively and in what regions the linear response tends to dominate remain unknown. Here, based on the TraCE-21ka climate simulation outputs, the spatial and temporal dependence of the linear response of temperature evolution in the Holocene is studied using correlation coefficient and a linear error index. The results show that the linear response of global mean temperature is strong on the orbital, millennial and centennial scales throughout the Holocene, but is poor on the decadal scale. The linear response differs significantly between the Northern Hemisphere (NH) and Southern Hemisphere (SH). In the NH, the linear response is strong on millennial scale, while in the SH the linear response is strong on orbital scale, such that the linear response of the global mean orbital variability is dominated by the SH response, but that of the global millennial variability seems dominated by the NH response. Furthermore, at the regional scales, the linear responses differ substantially between the orbital, millennial, centennial and decadal timescales. On the orbital scale, the linear response is dominant for most regions, even at the small area of about a mid-size country like Germany. On the millennial scale, the linear response is still strong in the NH over many regions, albeit weaker than on the orbital scale. However, the millennial variability shows relatively poor linear response over most regions in the SH. On the centennial and decadal timescales, the linear response is no longer significant in almost all the regions. The regions of strong linear response on the millennial scale are mostly consistent with those on the orbital scale, notably western Eurasian, North Africa, subtropical North Pacific, tropical Atlantic and Indian Ocean, because of a large signal-to-noise ratios over these regions. This finding can improve our understanding of the regional climate response to various climate forcings in the Holocene.
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