Oxygen stable isotope ratios from British oak tree-rings provide a strong and consistent record of past changes in summer rainfall
Oxygen stable isotope ratios from British oak tree-rings provide a strong and consistent record of past changes in summer rainfall
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DOI：
10.1007/s00382-015-2559-4
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发表时间：
2015
期刊：
影响因子：
4.6
通讯作者：
G. Young;N. Loader;D. McCarroll;Roderick J. Bale;Joanne C. Demmler;D. Miles;N. Nayling;K. Rinne;I. Robertson;C. Watts;Matthew C. Whitney
中科院分区：
文献类型：
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作者：
G. Young;N. Loader;D. McCarroll;Roderick J. Bale;Joanne C. Demmler;D. Miles;N. Nayling;K. Rinne;I. Robertson;C. Watts;Matthew C. Whitney
英国夏季以反气旋环流为主，其特点是天空晴朗、气温温暖、降水总量少、空气湿度低，降水中的氧同位素比（δ 18 O）更丰富。这种情况通常会导致相对更积极的（丰富的）氧同位素比率在树叶糖，并最终在树轮纤维素形成的那一年，匡威亦然，在凉爽，潮湿的夏季为主的西风气流和气旋条件。因此，树轮δ 18 O和夏季降水量之间应该有很强的联系。在英国8个地点取样的40棵橡树的晚材纤维素的稳定氧同位素比产生了一个平均δ 18 O年代学，该年代学与夏季总剪切涡度、表面气压和英国英格兰和威尔士地区夏季降水量指数密切相关。基于同位素的降雨信号更强，随着时间的推移比基于橡树环宽度的重建更稳定。使用最近开发的精确、高效和高成本效益的方法，可以同时测量同一树木年轮纤维素的碳（δ 13 C）和氧（δ 18 O）同位素比值。在我们的研究区域，这两个测量从多棵树可以用来重建夏季温度（δ 13 C）和夏季降水量（δ 18 O）有足够的独立性，使这些气候参数的演变，以高水平的信心重建。不列颠群岛上存在着长时间的、复制良好的橡树年轮年表，这意味着现在应该有可能重建数百年甚至数千年来的夏季温度和降水。
United Kingdom (UK) summers dominated by anti-cyclonic circulation patterns are characterised by clear skies, warm temperatures, low precipitation totals, low air humidity and more enriched oxygen isotope ratios (δ18O) in precipitation. Such conditions usually result in relatively more positive (enriched) oxygen isotope ratios in tree leaf sugars and ultimately in the tree-ring cellulose formed in that year, the converse being true in cooler, wet summers dominated by westerly air flow and cyclonic conditions. There should therefore be a strong link between tree-ring δ18O and the amount of summer precipitation. Stable oxygen isotope ratios from the latewood cellulose of 40 oak trees sampled at eight locations across Great Britain produce a mean δ18O chronology that correlates strongly and significantly with summer indices of total shear vorticity, surface air pressure, and the amount of summer precipitation across the England and Wales region of the United Kingdom. The isotope-based rainfall signal is stronger and much more stable over time than reconstructions based upon oak ring widths. Using recently developed methods that are precise, efficient and highly cost-effective it is possible to measure both carbon (δ13C) and oxygen (δ18O) isotope ratios simultaneously from the same tree-ring cellulose. In our study region, these two measurements from multiple trees can be used to reconstruct summer temperature (δ13C) and summer precipitation (δ18O) with sufficient independence to allow the evolution of these climate parameters to be reconstructed with high levels of confidence. The existence of long, well-replicated oak tree-ring chronologies across the British Isles mean that it should now be possible to reconstruct both summer temperature and precipitation over many centuries and potentially millennia.