Calibrating climate-δ18O regression models for the interpretation of high-resolution speleothem δ18O time series
Calibrating climate-δ18O regression models for the interpretation of high-resolution speleothem δ18O time series
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DOI：
10.1029/2007jd009694
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发表时间：
2008-09
影响因子：
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通讯作者：
M. Fischer;P. Treble
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文献类型：
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作者：
M. Fischer;P. Treble
要提供年际-千年时间尺度上过去气候变化的估计，需要在气候和气候代用指标之间建立适当的回归模型。许多代理似乎显示与气候的关系是时间尺度依赖。任何代理气候模型都应该能够复制在多个时间尺度上观察到的主要模式。在这里，我们开发了一个新的气候-同位素回归模型的洞穴沉积物从中纬度网站。在低至中纬度地区，降水同位素的日变化（在个别月份内）与日降雨量呈显著负相关。然而，在年代际时间尺度上，这种关系似乎是不稳定的。这两点为一个新的气候-同位素回归模式提供了理论基础，在这个模式中，一个给定月份的δ 18 O日-P日线的斜率和截距受到气候变率的有组织模式的调制，如热带外波（包括环形模式）。在构建这个新的回归模型时，我们展示了如何仅使用月δ 18 O数据和日降雨量来估计日降水-δ 18 O关系。新的回归模型提供了一个一致的图片18 O的变化在一个时间尺度范围内，这并没有与任何以前的气候同位素回归模型的情况。
Providing estimates of past climate changes on interannual-millenial timescales requires suitable regression models between climate and climate proxies. Many proxies appear to show relationships with climate that are timescale dependent. Any proxy-climate model should be able to replicate the major patterns that are observed at multiple timescales. Here we develop a new climate-isotope regression model for speleothems from a middle latitude site. In the low to middle latitudes, daily variation in precipitation isotopes (within individual months) is largely negatively correlated with daily rainfall amount. On interdecadal timescales, though, this relationship appears to be nonstationary. These two points provide a theoretical basis for a new climate-isotope regression model in which the slope and the intercept of a δ 18 O day -P day line for a given month are modulated by organized patterns of climate variability, such as the extratropical zonal waves (including the annular modes). In constructing this new regression model, we show how daily precipitation-δ 18 O relationships can be estimated using only monthly δ 18 O data and daily rainfall amounts. The new regression model provides a consistent picture of 18 O variability over a range of timescales, and this has not been the case with any previous climate-isotope regression model.