Statistical downscaling of North Atlantic tropical cyclone frequency and the amplified role of the Caribbean low-level jet in a warmer climate
Statistical downscaling of North Atlantic tropical cyclone frequency and the amplified role of the Caribbean low-level jet in a warmer climate
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DOI：
10.1002/2015jd024342
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发表时间：
2016-04-27
影响因子：
4.4
通讯作者：
Campbell, Jayaka D.
中科院分区：
文献类型：
--
作者：
Jones, Jhordanne J.;Stephenson, Tannecia S.;Campbell, Jayaka D.
本研究评估了四种统计模型在后报1950-2008年北大西洋年度热带气旋（TC）频率方面的技能，目的是预测未来的活动。其中三个模型的动机是业务统计预报方案，并在标准飓风预报，包括海面温度（SST）和近地面纬向风。第四个模型使用以前提出的用于加勒比季节性降雨预测的SST梯度指数。从向后回归创建的统计模型解释了1950-2008年TC年频率观测到的24-48%的变异。预测因子的未来状态是从ECHAM 5，HadCM 3，MRI CGCM2.3.2a和MIROC3.2全球气候模式（GCM）模拟耦合模式相互比较项目第3阶段。利用SST和近地面风预测器的模型表明，到2070-2090年，与单一的地面风预测器模型相比，平均年频率显著增加2-8 TC，表明全球变暖下SST的正趋势对预测的相对影响大于地面风变率的变化。只有风的模式表现出TC频率下降，而SST梯度模型产生的变化相对于现今的平均值很小。反向回归重新应用于1990-2008年期间，类似于未来温暖的海洋和大气状态相对于记录中的前几年，只保留加勒比低空急流（CLLJ）型预测因子，解释高达82%的TC频率变异，并建议在气候变暖的CLLJ更占主导地位的作用。使用新模型进行的预测显示，频率的增加或下降更为保守，与更强的CLLJ一致。
This study assesses the skill of four statistical models in hindcasting North Atlantic annual tropical cyclone (TC) frequency over 1950-2008 with the aim of projecting future activity. Three of the models are motivated by operational statistical forecast schemes and are premised on standard hurricane predictors including sea surface temperatures (SSTs) and near-surface zonal winds. The fourth model uses an SST gradient index previously proposed for Caribbean seasonal rainfall prediction. The statistical models, created from backward regression, explain 24-48% of the observed variability in 1950-2008 annual TC frequency. The future state of the predictors is extracted from the ECHAM5, HadCM3, MRI CGCM2.3.2a, and MIROC3.2 global climate model (GCM) simulations under the Coupled Model Intercomparison Project Phase 3. Models utilizing SST and near-surface wind predictors suggest significant increases in mean annual frequency by 2-8 TCs by 2070-2090, compared to a single surface wind predictor model, indicating that positive trends in SSTs under global warming have a larger relative influence on projections than changes in the variability of the surface winds. Wind-only models exhibit declines in TC frequency, while the SST gradient model yields little change relative to the present-day mean. Backward regression reapplied against the 1990-2008 period, analogous to future warmer oceanic and atmospheric state relative to the earlier years in the record, retains only the Caribbean low-level jet (CLLJ)-type predictors, explaining up to 82% of TC frequency variability and suggesting a more dominant role for the CLLJ in a warmer climate. Projections using the new models show either a more conservative increase or a stronger decrease in frequency, consistent with a stronger CLLJ.