Late Holocene changes in precipitation in northwest Tasmania and their potential links to shifts in the Southern Hemisphere westerly winds
Late Holocene changes in precipitation in northwest Tasmania and their potential links to shifts in the Southern Hemisphere westerly winds
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塔斯马尼亚西北部全新世晚期降水变化及其与南半球西风变化的潜在联系
DOI：
10.1016/j.gloplacha.2012.04.005
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发表时间：
2012
影响因子：
5.2
通讯作者：
M. Grosjean
中科院分区：
文献类型：
--
作者：
K. Saunders;C. Kamenik;D. Hodgson;Stefan Hunziker;L. Siffert;D. Fischer;M. Fujak;J. Gibson;M. Grosjean
对易受干旱影响地区未来气候变化的准确预测取决于对过去气候变化及其驱动过程的良好理解。在缺乏长期仪器数据的情况下，需要古气候数据。在这项研究中，我们开发了一个Rebecca Lagoon（41°11′S，144°41′E），塔斯马尼亚西北部的降水重建。首先，沉积物芯在可见光谱（380- 730 nm）和仪器降水记录（1912-2009年）的扫描反射光谱测量之间的关系被用来开发一个模型来重建降水的时间。结果表明，660和670 nm之间的反射率比（即，660 nm反射率/670 nm反射率;颜料成岩作用的量度）与年降水量显著相关。建立了一个校正模型（R=-0.56，pauto<0.001，RMSEP=43.0mm yr-1，5年三角形滤波数据，校正期1912-2009）。其次，利用该模型重建了近3000年来晚全新世降水量的变化。这显示了从大约2000年开始的相对干燥的条件。3100-2800 cal yr BP，潮湿条件，2800-2400 cal yr BP，干燥条件约为2400-2000 calyr BP，以及此后的可变条件。相对潮湿的条件发生在ca。500 cal yr BP到公元1800年代后期（约。50卡年BP）。降水重建表明，与过去的3000年相比，世纪的气候条件相对干燥。特别是，近几十年来测量的干旱期是至少在过去500年中最强烈的时期之一。由于该地区的降水主要是由南半球西风驱动的，这些变化进行了讨论的西风强度和/或位置的变化。
Accurate projections of future climate changes in regions susceptible to drought depend on a good understanding of past climate changes and the processes driving them. In the absence of longer term instrumental data, paleoclimate data are needed. In this study we develop a precipitation reconstruction for Rebecca Lagoon (41°11′S, 144°41′E), northwest Tasmania. First, the relationship between scanning reflectance spectroscopy measurements of sediment cores in the visible spectrum (380–730nm) and instrumental precipitation record (1912–2009) was used to develop a model to reconstruct precipitation back in time. Results showed that the ratio of reflectance between 660 and 670nm (i.e., reflectance at 660nm/reflectance at 670nm; a measure of pigment diagenesis) was significantly related to annual precipitation. A calibration model was developed (R=−0.56, pauto<0.001, RMSEP=43.0mm yr−1, 5year triangular filtered data, calibration period 1912–2009). Second, this calibration-in-time model was used to reconstruct late Holocene precipitation changes over the last ~3000years. This showed relatively dry conditions from ca. 3100–2800cal yr BP, wet conditions from ca. 2800–2400cal yr BP, dry conditions from ca. 2400–2000calyr BP, and variable conditions after this. Relatively wet conditions occurred from ca. 500cal yr BP to the late AD 1800s (ca. 50cal. yr BP). The precipitation reconstruction indicates that conditions were relatively dry for the 20th century compared to the last ~3000years. In particular, the dry period measured in recent decades is one of the most intense in at least the last 500years. As precipitation in this region is primarily driven by the Southern Hemisphere westerly winds, these changes are discussed in terms of shifts in westerly wind strength and/or position.
影响因子：
18.3
作者：
Lamy, Frank;Kilian, Rolf;Steinke, Tatjana
通讯作者：
Steinke, Tatjana