Decadal predictability of soil water, vegetation, and wildfire frequency over North America
Decadal predictability of soil water, vegetation, and wildfire frequency over North America
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DOI：
10.1007/s00382-015-2469-5
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发表时间：
2015-10-01
期刊：
影响因子：
4.6
通讯作者：
Langford, Sally
中科院分区：
文献类型：
--
作者：
Chikamoto, Yoshimitsu;Timmermann, Axel;Langford, Sally
使用NCAR社区地球系统模型（CESM）1.0.3版进行的900年工业化前控制模拟，在北美的土地水文和地球化学变量的潜在的十年可预测性进行检查。模拟的北美降水和土壤水储存的主导模式的特征基本上是定性相似的纬向跷跷板模式与西风急流的活动。而相应的降水变率可以被描述为一个白色噪声随机过程，垂直整合的土壤水分的功率谱表现出显着的红色的时间尺度上的几年到几十年，因为土壤水储量的可预测性主要来自降水变率的集成。因此，一阶马尔可夫过程后的阻尼持久性后报是熟练的，前置时间长达几年。这种潜在的多年技能估计与CESM在各种初始条件下进行的集合后报一致。我们的控制模拟进一步表明，土壤水储存的年代际变化也影响植被和野火的发生。土壤水分变化的长期潜在可预测性与植被在重大破坏后的缓慢再生长相结合，导致植被、陆地碳储量和火灾频率在十年时间尺度上的可预测性增强，特别是在美国南部/墨西哥地区。相比之下，美国北方火灾频率的预测技巧仅限于1年。我们的研究结果表明，巧妙的土壤水储量，碳储量和火灾频率的年代际预测是可行的土壤条件的适当初始化。虽然我们理想化的模式框架中的潜在可预测性会高估耦合的气候-土地-植被系统的真实的可预测性，但年代际气候预测可能对水资源管理、林业和农业有益。
The potential decadal predictability of land hydrological and biogeochemical variables in North America is examined using a 900-year-long pre-industrial control simulation, conducted with the NCAR Community Earth System Model (CESM) version 1.0.3. The leading modes of simulated North American precipitation and soil water storage are characterized essentially by qualitatively similar meridional seesaw patterns associated with the activity of the westerly jet. Whereas the corresponding precipitation variability can be described as a white noise stochastic process, power spectra of vertically integrated soil water exhibit significant redness on timescales of years to decades, since the predictability of soil water storage arises mostly from the integration of precipitation variability. As a result, damped persistence hindcasts following a 1st order Markov process are skillful with lead times of up to several years. This potential multi-year skill estimate is consistent with ensemble hindcasts conducted with the CESM for various initial conditions. Our control simulation further suggests that decadal variations in soil water storage also affect vegetation and wildfire occurrences. The long-term potential predictability of soil water variations in combination with the slow regrowth of vegetation after major disruptions leads to enhanced predictability on decadal timescales for vegetation, terrestrial carbon stock, and fire frequency, in particular in the Southern United States (US)/Mexico region. By contrast, the prediction skill of fire frequency in the Northern US is limited to 1 year. Our results demonstrate that skillful decadal predictions of soil water storage, carbon stock, and fire frequency are feasible with proper initialization of soil conditions. Although the potential predictability in our idealized modeling framework would overestimate the real predictability of the coupled climate-land-vegetation system, the decadal climate prediction may become beneficial for water resource management, forestry, and agriculture.