Modeling Present and Future Permafrost Distribution at the Seward Peninsula, Alaska
Modeling Present and Future Permafrost Distribution at the Seward Peninsula, Alaska
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DOI：
10.1029/2019jf005355
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发表时间：
2020-08
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影响因子：
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通讯作者：
M. Debolskiy;D. Nicolsky;R. Hock;V. Romanovsky
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文献类型：
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作者：
M. Debolskiy;D. Nicolsky;R. Hock;V. Romanovsky
永久冻土是北极生态系统的重要组成部分，目前正受到气候变暖的影响，预计本世纪将发生进一步重大变化。预计最显着的变化将发生在不连续和连续类型永久冻土之间的过渡带。我们应用瞬态温度动态模型来研究阿拉斯加苏厄德半岛永久冻土条件的时空演变，该地区目前的特点是北部是连续的永久冻土，南部是不连续的永久冻土。我们使用变分数据同化技术来校准模型参数，该技术利用在研究区域收集的历史地面温度测量值。然后使用一组单独的地面温度数据控制来评估模型。校准的模型参数根据生态系统类型分布在整个域中。应用于我们模型的强迫包括历史月度温度和降水数据以及基于代表性浓度路径 (RCP) 4.5 和 8.5 情景的气候预测。 2000 年至 2010 年十年间模拟的近地表永久冻土范围与现有永久冻土图和之前的阿拉斯加范围内的建模研究非常吻合。未来的预测表明，与 2000-2010 年期间相比，2090-2100 年半岛的平均地温将显着增加（RCP 4.5 下 3.0°C，RCP 8.5 下 2 m 深度为 4.4°C）。预计到 21 世纪末，近地表永久冻土层的广泛退化将使其范围缩小至仅占 RCP 4.5 下半岛面积的 43% 和 RCP 8.5 下的 8%。
Permafrost, a key component of Arctic ecosystems, is currently affected by climate warming and anticipated to undergo further significant changes in this century. The most pronounced changes are expected to occur in the transition zone between the discontinuous and continuous types of permafrost. We apply a transient temperature dynamic model to investigate the spatiotemporal evolution of permafrost conditions on the Seward Peninsula, Alaska—a region currently characterized by continuous permafrost in its northern part and discontinuous permafrost in the south. We calibrate model parameters using a variational data assimilation technique exploiting historical ground temperature measurements collected across the study area. The model is then evaluated with a separate control set of the ground temperature data. Calibrated model parameters are distributed across the domain according to ecosystem types. The forcing applied to our model consists of historic monthly temperature and precipitation data and climate projections based on the Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. Simulated near‐surface permafrost extent for the 2000–2010 decade agrees well with existing permafrost maps and previous Alaska‐wide modeling studies. Future projections suggest a significant increase (3.0°C under RCP 4.5 and 4.4°C under RCP 8.5 at the 2 m depth) in mean decadal ground temperature on average for the peninsula for the 2090–2100 decade when compared to the period of 2000–2010. Widespread degradation of the near‐surface permafrost is projected to reduce its extent at the end of the 21st century to only 43% of the peninsula's area under RCP 4.5 and 8% under RCP 8.5.