High‐Resolution Nudged Isotope Modeling With ECHAM6‐Wiso: Impacts of Updated Model Physics and ERA5 Reanalysis Data
High‐Resolution Nudged Isotope Modeling With ECHAM6‐Wiso: Impacts of Updated Model Physics and ERA5 Reanalysis Data
复制标题
使用 ECHAM6-Wiso 进行高分辨率微调同位素建模：更新模型物理和 ERA5 再分析数据的影响
DOI：
10.1029/2021ms002532
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发表时间：
2021
影响因子：
6.8
通讯作者：
Werner Martin
中科院分区：
文献类型：
--
作者：
Cauquoin Alexandre;Werner Martin
本文介绍了1979-2018年期间，在两个不同的空间分辨率下，使用增强的ECHAM6 - wiso模型版本推动ERA5再分析的新同位素启用模拟结果。考虑海冰积雪的同位素含量，在海冰覆盖区域产生同位素比较低的地表水蒸气，并假设海洋蒸发的动力分异因子与风速无关。此外，为了更好地与南极同位素观测结果一致，过饱和方程也进行了稍微调整。除了空间分辨率外，还研究了改进的ECHAM6模型物理特性和选择更新的ERA5再分析数据集对模拟结果的影响。为此，对先前的ECHAM5 - wiso模型与ERA5再分析和ECHAM6 - wiso模型与ERA - Interim模型的模拟结果进行了详细的比较。与ERA - Interim再分析相比，向ERA5的推进并未导致全球尺度上模拟地表同位素值的实质性变化，但热带地区的水运发生了明显变化，亚马逊地区的降水量增加，对流层高层水蒸气的同位素含量也发生了相关变化。高空间分辨率（0.9°水平分辨率和95个垂直水平）的ECHAM6 - wiso模拟通常进一步改进了年平均同位素值的模拟。在高空间分辨率配置下，季节和（亚）日时间尺度上的时间同位素变化模型也略有改进。后者对于改进各种水同位素记录的解释非常有用。
We present here results of new isotope‐enabled simulations with an enhanced ECHAM6‐wiso model version nudged to the ERA5 reanalyses, at two different spatial resolutions, for the period 1979–2018. The isotopic content of snow on sea ice is considered, yielding surface water vapor with lower isotope ratios over sea ice covered areas, and the kinetic fractionation factors for oceanic evaporation are assumed as independent of wind speed. Also, the supersaturation equation was slightly re‐tuned for a better agreement with the Antarctic isotope observations. In addition to the spatial resolution, the impacts of the improved ECHAM6 model physics and the chosen updated ERA5 reanalyses data set on our simulation results are investigated. For this purpose, detailed comparisons to simulation results obtained from the predecessor ECHAM5‐wiso model nudged to ERA5 reanalyses and from ECHAM6‐wiso nudged to ERA‐Interim are performed. Compared to the ERA‐Interim reanalyses, the nudging to ERA5 does not result in substantial changes of modeled surface isotope values on a global scale but water transport over the tropics clearly changed, with increased precipitation amounts over the Amazonian area and related changes of isotopic contents in water vapor in the high troposphere. An ECHAM6‐wiso simulation at high spatial resolution (0.9° horizontal resolution and 95 vertical levels) generally further improves the modeling of annual mean isotope values. The modeling of temporal isotopic variations at seasonal and (sub‐)daily time scales is also slightly improved for the high spatial resolution configuration. The latter will be very useful for an improved interpretation of various water isotope records.