MJO Modulation and its Predictability of Boreal Summer Tropical Cyclone Genesis over Northwest Pacific in Met Office Hadley Centre and Beijing Climate Center Seasonal Prediction Systems
MJO Modulation and its Predictability of Boreal Summer Tropical Cyclone Genesis over Northwest Pacific in Met Office Hadley Centre and Beijing Climate Center Seasonal Prediction Systems
复制标题
英国气象局哈德利中心和北京气候中心季节预报系统对西北太平洋北方夏季热带气旋成因的MJO调制及其可预报性
DOI：
10.1002/qj.3478
复制
发表时间：
--
影响因子：
8.9
通讯作者：
Craig MacLachlan
中科院分区：
文献类型：
--
作者：
Chongbo Zhao;Hong-Li Ren;Rosie Eade;Yujie Wu;Jie Wu;Craig MacLachlan
目前的许多季节预报系统在MJO预报方面表现出很好的能力，但在TC预报方面能力有限。因此，在业务预测系统中量化MJO对TC的影响对于预测目的是有用的。研究结果表明，英国气象局哈德利中心（MOHC）和北京气候中心（BCC）的季节预报业务系统对北半球夏季TC生成潜力指数（GPI）异常的预报能力显著高于持续4周的预报能力。在MOHC预报系统中，MJO初始条件越强，GPI异常预报效果越好，MJO 4-7期有利于提前11-20天GPI异常预报效果越好。而在BCC预报系统中，MJO对TC预报能力的影响并不显著。两种预报系统均能再现南海和西北太平洋地区MJO 4-5相GPI较强正异常和MJO 8-1相GPI较弱负异常的关系。然而，在BCC_CSM1.2中，MJO对GPI的影响强度通常被低估，这可能是由于南海和西北太平洋上空的上升运动不足和负出射长波辐射伴随着弱MJO的响应。在GloSea 5中，绝对涡度，相对湿度，垂直速度和风切变项在领先的1-10天内相对更接近ERA-Interim。考虑到MJO超过2周的内在可预测性，预测的MJO相位信息对季节内时间尺度上的TC成因预测具有重要意义。
Many of the current seasonal prediction systems show useful skill in Madden–Julian Oscillation (MJO) prediction but limited skill in forecasting tropical cyclones (TC). Quantifying the influences of MJO on TC in an operational prediction system is therefore useful for prediction purposes. The results in this study show that forecast skill of boreal summer TC genesis potential index (GPI) anomaly by operational seasonal prediction systems in Met Office Hadley Centre (MOHC) and Beijing Climate Center (BCC) are significantly higher than persistence out to four weeks. In the prediction system of MOHC, stronger MJO initial conditions are conducive to better GPI anomaly forecast, and MJO phases 4–7 make for higher GPI anomaly skill at lead 11–20 days. However, the MJO influence on TC forecasting skill is not so significant in BCC's prediction system. Both the prediction systems could reproduce the relationship that there are larger positive GPI anomalies in MJO phases 4–5 and negative ones in MJO phases 8–1 over the South China Sea (SCS) and northwest Pacific (WNP). However, the intensity of MJO effect on GPI is generally underestimated in BCC_CSM1.2, which may be due to the response of inadequate ascending motion and negative outgoing long‐wave radiation accompanied by weak MJO over SCS and WNP. In GloSea5, the absolute vorticity, relative humidity, vertical velocity and wind shear terms are relatively closer to ERA‐Interim during lead 1–10 days. Considering the intrinsic predictability of the MJO of more than 2 weeks, the forecasted MJO phase information has significant implications for TC genesis prediction on intraseasonal time‐scales.