MPI-ESM-wiso simulations data for preindustrial and mid-Holocene conditions@en

We present here the first results, for the preindustrial and mid-Holocene climatological periods, of the newly developed isotope-enhanced version of the fully coupled Earth system model MPI-ESM, called hereafter MPI-ESM-wiso. The water stable isotopes H216O, H218O and HDO have been implemented into all components of the coupled model setup. The mid-Holocene provides the opportunity to evaluate the model response to changes in the seasonal and latitudinal distribution of insolation induced by different orbital forcing conditions. The results of our equilibrium simulations allow us to evaluate the performance of the isotopic model in simulating the spatial and temporal variations of water isotopes in the different compartments of the hydrological system for warm climates. For the preindustrial climate, MPI-ESM-wiso reproduces very well the observed spatial distribution of the isotopic content in precipitation linked to the spatial variations in temperature and precipitation rate. We also find a good model-data agreement with the observed distribution of isotopic composition in surface seawater but a bias with the presence of surface seawater that is too 18O-depleted in the Arctic Ocean. All these results are improved compared to the previous model version ECHAM5/MPIOM. The spatial relationships of water isotopic composition with temperature, precipitation rate and salinity are consistent with observational data. For the preindustrial climate, the interannual relationships of water isotopes with temperature and salinity are globally lower than the spatial ones, consistent with previous studies. Simulated results under mid-Holocene conditions are in fair agreement with the isotopic measurements from ice cores and continental speleothems. MPI-ESM-wiso simulates a decrease in the isotopic composition of precipitation from North Africa to the Tibetan Plateau via India due to the enhanced monsoons during the mid-Holocene. Over Greenland, our simulation indicates a higher isotopic composition of precipitation linked to higher summer temperature and a reduction in sea ice, shown by positive isotope-temperature gradient. For the Antarctic continent, the model simulates lower isotopic values over the East Antarctic plateau, linked to the lower temperatures during the mid-Holocene period, while similar or higher isotopic values are modeled over the rest of the continent. […]本文首次报道了全新开发的同位素增强型完全耦合地球系统模型MPI-ESM的首个研究结果，该结果针对工业革命前与中全新世（mid-Holocene）气候时期，下文简称该模型为MPI-ESM-wiso。已将稳定水同位素（water stable isotopes）H₂¹⁶O、H₂¹⁸O及HDO集成至该耦合模型框架的全部组分中。中全新世为评估模型对不同轨道强迫条件引发的太阳辐射季节与纬度分布变化的响应提供了理想契机。本研究通过平衡态模拟结果，得以评估该同位素模型在暖气候背景下，模拟水文系统不同分区内水同位素时空变化的性能表现。针对工业革命前气候场景，MPI-ESM-wiso能够精准复现观测到的降水同位素含量空间分布特征，该分布与温度及降水速率的空间变化显著相关。本研究同时发现，模型与观测得到的表层海水同位素组成分布吻合度较高，但在北冰洋区域存在模拟表层海水过于贫¹⁸O的系统性偏差。相较于此前的ECHAM5/MPIOM模型版本，上述结果均得到了显著优化。水同位素组成与温度、降水速率及盐度的空间关联特征与观测数据高度一致。针对工业革命前气候场景，水同位素与温度、盐度的年际关联特征在全球范围内均弱于其空间关联特征，这一结果与既往研究结论相符。中全新世条件下的模拟结果与冰芯及大陆石笋的同位素测量结果吻合度良好。受中全新世季风增强影响，MPI-ESM-wiso模拟得到从北非经印度至青藏高原的降水同位素组成呈逐步降低的趋势。在格陵兰区域，模拟结果显示降水同位素组成偏高，这与夏季温度升高及海冰消退密切相关，表现为正的同位素-温度梯度。在南极大陆，模型模拟得到东南极高原区域的同位素值偏低，这与中全新世时期的低温环境相关；而大陆其余区域的同位素模拟值则与观测值相近或偏高。[…]