An Atmospheric General Circulation Model Assessment of Oceanic Impacts on Extreme Climatic Events over Japan in July 2018
An Atmospheric General Circulation Model Assessment of Oceanic Impacts on Extreme Climatic Events over Japan in July 2018
复制标题
DOI：
10.2151/jmsj.2020-041
复制
发表时间：
2020-05
影响因子：
3.1
通讯作者：
K. Nishii;B. Taguchi;H. Nakamura
中科院分区：
文献类型：
--
作者：
K. Nishii;B. Taguchi;H. Nakamura
通过一系列大气环流模型（AGCM）的集合实验，评估了海表温度（SST）异常对2018年7月在日本观测到的两次极端事件的大规模大气环流异常的潜在影响。其中一个是7月初主要在日本西部的强降雨事件，这主要是由与日本西南部的气旋异常和日本东部的反气旋异常相关的极端湿气流入引起的。采用规定的全球海温异常的 AGCM 实验无法重现反气旋异常，导致无法模拟日本西部水汽流入的增强以及降水的增强。另一个极端事件是7月中下旬几乎席卷整个日本的热浪，这是由日本周边强烈的反气旋异常引起的。 AGCM全球海温异常实验可以很好地再现暖反气旋异常。额外的实验证实，热带地区和北太平洋中纬度地区的海温异常有可能迫使北太平洋西部大气变率的主导模式产生热浪。热带和温带海温异常也被发现迫使西太平洋副热带急流轴向极地移动，并导致北半球中纬度地区对流层异常变暖，这两种情况在六月和七月持续存在。
Through a set of ensemble experiments with an atmospheric general circulation model (AGCM), potential influence of sea-surface temperature (SST) anomalies is assessed on large-scale atmospheric circulation anomalies that induced two extreme events observed over Japan in July 2018. One is a heavy rainfall event in early July mainly over western Japan, which was primarily caused by extreme moisture inflow associated with a cyclonic anomaly to the southwest of Japan and an anticyclonic anomaly to the east of Japan. An AGCM experiment with prescribed global SST anomalies cannot reproduce the anticyclonic anomaly, leading to the failure to simulate the enhancement of the moisture inflow and thereby precipitation over western Japan. The other extreme event is heat wave in midand late July almost over the entire Japan, which was caused by a strong anticyclonic anomaly around Japan. The AGCM experiment with global SST anomalies can well reproduce the warm anticyclonic anomalies. The additional experiments have confirmed that SST anomalies in both the tropics and midlatitude North Pacific have potential for forcing the leading mode of the atmospheric variability over the western North Pacific that brought the heat wave. Both the tropical and extratropical SST anomalies are also found to force a poleward shift of the subtropical jet axis over the western Pacific and anomalous tropospheric warming in the midlatitude Northern Hemisphere, both of which persisted in June and July.