Roles of Regional Ocean-Atmosphere Coupling and Remote Forcing in Northwest Pacific Monsoon Variability

区域海气耦合和远程强迫在西北太平洋季风变化中的作用

基本信息

批准号：
1637450
负责人：
Shang-Ping Xie
金额：
$ 61.42万
依托单位：
University of California-San Diego Scripps Inst of Oceanography
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2016
资助国家：
美国
起止时间：
2016-11-01 至 2022-10-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1637450&HistoricalAwards=false
关键词：
Roles Regional Ocean Atmosphere Coupling

项目摘要

Summer is the rainy season for East Asia. The Meiyu-Baiu rain band, extending from the eastern flank of the Tibetan Plateau northeastward through Korea and Japan, is the single most important climate phenomenon of the region. The termination of this summer rain band in late July has been tied to the abrupt onset of tropical convection over the Northwest Pacific east of the Philippines, through a meridional dipole pattern of summer rainfall variability. The abrupt onset of Northwest Pacific convection remains unsolved with local sea surface temperature (SST) rising above 28 degrees C as early as in June. Effort under this project will investigate the hypothesis that the gradual moistening of the lower troposphere via shallow convection leads to a threshold behavior of abrupt convective onset over the tropical Northwest Pacific. During the satellite era starting 1979, interannual variability in tropical Northwest Pacific convection is well correlated with El Nino/Southern Oscillation (ENSO). Specifically, an anomalous anticyclonic circulation (AAC) forms and rainfall decreases over the tropical Northwest Pacific in post-El Nino summers. Through earlier studies a positive feedback has been identified due to interactions between the AAC and Indo-Northwest Pacific SST during summer when the southwest monsoonal winds prevail. We will investigate the mechanisms and predictability of this regional coupled mode. The correlation between the AAC and ENSO breaks down during half of the 20th century from the 1920s and 1970s. Weak ENSO amplitudes are considered to have caused the low correlation. This aspect as well as the role of random noise due to atmospheric internal variability will be explored critically. Locally, Northwest Pacific convection affects the U.S. affiliated Northern Mariana Islands and Guam. Remotely, it affects the South and East Asian monsoon regions, home to three billion people. This research will help improve seasonal forecast and climate change projection in the regions, thereby contributing to several ongoing international research programs. The project trains the next generation of climate scientists by including graduate students and postdocs in the research team, and by exposing them to international collaborations.

夏季是东亚的雨季。梅雨-白雨雨带从青藏高原东翼向东北延伸，穿过韩国和日本，是该地区最重要的气候现象。这个夏季雨带在七月下旬的终止与菲律宾东部西北太平洋热带对流的突然爆发有关，通过夏季降雨变化的经向偶极子模式。西北太平洋对流突然爆发的问题仍未得到解决，当地海面温度（SST）早在6月就升至28摄氏度以上。该项目的工作将调查以下假设：对流层低层通过浅对流逐渐湿润导致热带西北太平洋上空对流突然爆发的阈值行为。在 1979 年开始的卫星时代，热带西北太平洋对流的年际变化与厄尔尼诺/南方涛动 (ENSO) 密切相关。具体来说，厄尔尼诺现象发生后的夏季，热带西北太平洋地区会形成反气旋环流（AAC）异常，降雨量减少。通过早期的研究，在西南季风盛行的夏季，由于 AAC 和印度-西北太平洋海温之间的相互作用，已经确定了正反馈。我们将研究这种区域耦合模式的机制和可预测性。从 20 世纪 20 年代到 1970 年代，AAC 和 ENSO 之间的相关性在 20 世纪上半叶被打破。弱 ENSO 振幅被认为是导致相关性较低的原因。这方面以及由于大气内部变化引起的随机噪声的作用将得到批判性的探讨。局部地区，西北太平洋对流影响美国附属北马里亚纳群岛和关岛。从远处看，它影响着拥有 30 亿人口的南亚和东亚季风地区。这项研究将有助于改善该地区的季节预报和气候变化预测，从而为多个正在进行的国际研究项目做出贡献。该项目通过将研究生和博士后纳入研究团队并让他们参与国际合作来培训下一代气候科学家。