| 大气对春季东海黑潮锋响应的气压调整机制分析 |
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| 引用本文： | 李智,刘宣飞,李传浩.大气对春季东海黑潮锋响应的气压调整机制分析[J].大气科学,2015,39(6):1081-1094. |
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| 作者姓名： | 李智 刘宣飞 李传浩 |
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| 作者单位： | 南京信息工程大学气象灾害预报预警与评估协同创新中心/气象灾害教育部重点实验室, 南京 210044 |
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| 基金项目： | 江苏高校优势学科建设工程资助项目PAPD |
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| 摘 要： | 采用美国国家环境预测中心的CFSR(Climate Forecast System Reanalysis)再分析资料和QuickSCAT(Quick Scatterometer)、AVHRR(Advanced Very High Resolution Radiometer)、TRMM(Tropical Rainfall Measuring Mission)高分辨率卫星资料,研究了大气对春季东海黑潮锋响应的气压调整机制及其年际变化。结果表明,春季东海黑潮锋位于黑潮暖舌的西北侧,呈西南-东北走向,与大尺度气压背景场的等压线走向一致,锋区东南侧暖水与西北侧冷水之间产生的局地气压梯度与大尺度气压梯度形成同向叠加,使得锋区附近西北指向东南的气压梯度达到最大,造成该处的海表面10 m矢量风速也最大,在摩擦作用下形成东北偏北风(NNE)。锋区与其东南侧的NNE风之间沿锋区走向(跨锋区走向)的分量差,会在暖舌附近产生气旋性切变涡度(风速辐合),由此产生上升运动和强降水;而在锋区西北侧的冷水区情况正好相反,有反气旋性切变涡度(风速辐散),并伴有下沉运动和弱降水,从而形成跨锋区的次级环流圈。东海黑潮锋区偏强(弱)年,锋区东南侧暖水与西北侧冷水之间的局地气压梯度也偏强(弱),与大尺度气压梯度同向叠加后形成偏强(弱)的NNE风,造成锋区东南侧暖舌附近的气旋性切变涡度、风速辐合、上升运动和降水均偏强(弱),而锋区西北侧冷水区的反气旋性切变涡度、风速辐散和下沉运动均偏强(弱),跨锋区次级环流圈偏强(弱),这表明在年际时间尺度上气压调整机制仍起作用。
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| 关 键 词： | 东海黑潮锋 春季 气压调整机制 海表面风 年际变化 |
| 收稿时间： | 9/3/2014 12:00:00 AM |
| 修稿时间： | 2015/3/19 0:00:00 |
Analysis of the Pressure Adjustment Mechanism in the Atmospheric Response to the Spring Kuroshio Front over the East China Sea |
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| LI Zhi,LIU Xuanfei and LI Chuanhao.Analysis of the Pressure Adjustment Mechanism in the Atmospheric Response to the Spring Kuroshio Front over the East China Sea[J].Chinese Journal of Atmospheric Sciences,2015,39(6):1081-1094. |
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| Authors: | LI Zhi LIU Xuanfei and LI Chuanhao |
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| Institution: | Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters and Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing University of Information Science and Technology, Nanjing 210044 |
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| Abstract: | By using Quick Scatterometer(QuickSCAT), Advanced Very High Resolution Radiometer(AVHRR) and Tropical Rainfall Measuring Mission(TRMM) high-resolution satellite data and Climate Forecast System Reanalysis(CFSR) reanalysis data, the pressure adjustment mechanism in the atmospheric response to the spring Kuroshio front(KF) in the East China Sea is investigated along with its interannual variability. Results show that the spring KF lies to the northwest of the Kuroshio warm tongue with a southwest-northeast orientation, which is parallel to the isobars of large-scale background sea level pressure(SLP). The local SLP gradient between the warm water in the southeast of the KF(SE-KF) and the cold water in the northwest of the KF(NW-KF) will superimpose on the large-scale SLP background gradient, causing the resultant northwest-to-southeast SLP gradient to reach its maximum near the KF, and the 10 m vector wind speed thus being strongest there. Due to the friction factor, such a vector wind will be a north-northeast(NNE) wind. The difference in the component of the NNE wind along(across) the KF will produce cyclonic shear vorticity(convergence in wind speed) over the SE-KF, thereby forming ascending motion and enhanced precipitation. In contrast, over the NW-KF, there is anticyclonic shear vorticity(divergence in wind speed) along(across) the KF and descending motion and weak rainfall. A secondary circulation across the KF is thereby induced. On the interannual timescale, a stronger(weaker) spring KF corresponds to a stronger(weaker) local SLP gradient between the NW- and SE-KF. The stronger(weaker) local SLP gradient, superimposed on the large-scale SLP background gradient, will produce stronger(weaker) NNE wind, thus making cyclonic shear vorticity, convergence in wind speed, ascending motion and precipitation all stronger(weaker) over the SE-KF, and making anticyclonic shear vorticity, divergence in wind speed, and descending motion all stronger(weaker) over the NW-KF, ultimately leading to stronger(weaker) secondary circulation across the KF. This indicates that the pressure adjustment mechanism still exists on the interannual timescale. |
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| Keywords: | Kuroshio front East China Sea Spring Pressure adjustment mechanism Sea surface wind Interannual variability |
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