Short-term climate dynamics and biogeochemical processes in the Gulf of Taranto: From regional proxy variations to climate records

拟议项目的总体目标是重建过去几个世纪和全新世晚期塔兰托湾(意大利南部)的气候和相关生物地球化学循环的记录。我们预计，这些记录不仅将提供当地信息，还将记录北大西洋涛动等大范围气候模式的影响。为了实现这一目标，必须开发新的传递函数，从沉积物档案中提取环境信息。传统上，传递函数是通过在空间域中评估代理数据与环境参数之间的关系来定义的。在这里，我们提出了另一种方法，在该方法中，我们推导出一个同时检查空间域和时间域的可变性的传递函数，因此是一种更直接地从代理记录重建时间气候变化的方法。为了实现我们的目标，我们将应用1958-2013年期间的高分辨率物理和生物地球化学海洋模型，包括用目标代理变量模拟合成沉积物岩芯。在这段时间内，可以获得高质量的再分析数据来强制执行该模型。然后将模拟的时间序列与现有表层沉积物和沉积物岩心产生的高分辨率替代记录进行比较。塔兰托湾是进行这项研究的理想区域，因为海洋环境与陆地上的气候变化密切相关，沉积物以较高的速度在沉积中心积累，从而能够以不到十年的分辨率重建环境变异性。然后，我们新的时空转移函数将被用于重建仪器时期(至少自1850年以来，个别记录甚至更长)的区域气候和生物地球化学可变性，这使得能够评估重建的质量。随后，我们将把重建扩展到可用代理记录的完整长度(大约5000年)。我们计划研究地中海海洋环境对北半球大尺度气候模式的敏感性，如北大西洋涛动和大西洋年代际涛动。此外，人为对代理记录中发现的变化的贡献将被量化。

The overall goal of the proposed project is to reconstruct records of climate and related biogeochemical cycles in the Gulf of Taranto (southern Italy) for the past few centuries and the late Holocene. We expect that these records will not only yield local information but will also record the effect of large-scale climate modes like the North Atlantic Oscillation. This goal necessitates the development of novel transfer functions to derive environmental information from sediment archives. Traditionally, transfer functions are defined by evaluating the relationships between proxy data and environmental parameters in the spatial domain. Here, we propose an alternative approach, in which we derive a transfer function that examines both the variability of the spatial and temporal domains, thus being a more direct approach to the reconstruction of temporal climate variations from proxy records. In order to achieve our goal, we will apply a high-resolution physical and biogeochemical ocean model for the period 1958-2013, including simulations of synthetic sediment cores with the targeted proxy variables. For this time period, high-quality reanalysis data are available to force the model. The modeled time series will be then compared with high-resolution proxy records generated from available surface sediments and sediment cores. The Gulf of Taranto is an ideal region for this research because the marine environments are closely linked to climate changes on land and sediments accumulate in deposition centers at high rates permitting the reconstruction of environmental variability at a sub-decadal resolution. Our new spatio-temporal transfer function will then be applied for the reconstruction of the regional climate and biogeochemical variability for the instrumental period (since at least 1850, individual records even longer), which allows an assessment of the quality of the reconstruction. Subsequently, we will extend the reconstruction to the full length of the available proxy records (approximately 5000 years). We plan to study the sensitivity of Mediterranean marine environments to large-scale climate patterns of the Northern hemisphere such as the North Atlantic Oscillation and the Atlantic Multidecadal Oscillation during the late Holocene. Additionally, the anthropogenic contribution to the changes found in the proxy records will be quantified.