Wang Shanshan, Huang Jianping, He Yongli, Guan Yuping
1] Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, China [2] State Key Laboratory of Tropical Oceanography, Chinese Academy of Sciences, South China Sea Institute of Oceanology, Guangzhou, China.
Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, China.
Sci Rep. 2014 Oct 17;4:6651. doi: 10.1038/srep06651.
The effects of natural variability, especially El Niño-Southern Oscillation (ENSO) effects, have been the focus of several recent studies on the change of drought patterns with climate change. The interannual relationship between ENSO and the global climate is not stationary and can be modulated by the Pacific Decadal Oscillation (PDO). However, the global land distribution of the dry-wet changes associated with the combination of ENSO and the PDO remains unclear. In the present study, this is investigated using a revised Palmer Drought Severity Index dataset (sc_PDSI_pm). We find that the effect of ENSO on dry-wet changes varies with the PDO phase. When in phase with the PDO, ENSO-induced dry-wet changes are magnified with respect to the canonical pattern. When out of phase, these dry-wet variations weaken or even disappear. This remarkable contrast in ENSO's influence between the two phases of the PDO highlights exciting new avenues for obtaining improved global climate predictions. In recent decades, the PDO has turned negative with more La Niña events, implying more rain and flooding over land. La Niña-induced wet areas become wetter and the dry areas become drier and smaller due to the effects of the cold PDO phase.
自然变率的影响，尤其是厄尔尼诺-南方涛动（ENSO）的影响，已成为近期几项关于干旱模式随气候变化而变化的研究重点。ENSO与全球气候之间的年际关系并非固定不变，且会受到太平洋年代际振荡（PDO）的调节。然而，与ENSO和PDO组合相关的干湿变化在全球陆地的分布情况仍不明确。在本研究中，我们使用修订后的帕尔默干旱严重度指数数据集（sc_PDSI_pm）对此进行了调查。我们发现，ENSO对干湿变化的影响会随PDO阶段而变化。当与PDO同相位时，ENSO引发的干湿变化相对于典型模式会被放大。当不同相位时，这些干湿变化会减弱甚至消失。PDO两个阶段中ENSO影响的这种显著差异为获得更优的全球气候预测指明了令人兴奋的新途径。在最近几十年里，PDO已转为负值，拉尼娜事件增多，这意味着陆地上降雨和洪水更多。由于冷PDO阶段的影响，拉尼娜引发的湿润地区变得更湿润，而干旱地区变得更干旱且范围缩小。
