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王顼, 张立凤, 王羱, 等. 2024. 西太平洋台风活动对中国西北地区东部夏季降水的影响[J]. 大气科学, 48(2): 507−520. doi: 10.3878/j.issn.1006-9895.2205.22011
引用本文: 王顼, 张立凤, 王羱, 等. 2024. 西太平洋台风活动对中国西北地区东部夏季降水的影响[J]. 大气科学, 48(2): 507−520. doi: 10.3878/j.issn.1006-9895.2205.22011
WANG Xu, ZHANG Lifeng, WANG Yuan, et al. 2024. Influence of Typhoons in the Western Pacific on Summer Precipitation in the Eastern Northwest China [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 48(2): 507−520. doi: 10.3878/j.issn.1006-9895.2205.22011
Citation: WANG Xu, ZHANG Lifeng, WANG Yuan, et al. 2024. Influence of Typhoons in the Western Pacific on Summer Precipitation in the Eastern Northwest China [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 48(2): 507−520. doi: 10.3878/j.issn.1006-9895.2205.22011

西太平洋台风活动对中国西北地区东部夏季降水的影响

Influence of Typhoons in the Western Pacific on Summer Precipitation in the Eastern Northwest China

  • 摘要: 基于1979~2020年(42年)降水及台风资料,利用常用的统计方法和随机森林方法,研究了西太平洋台风对我国西北地区东部(33°N~45°N,93°E~110°E,ENWC)降水的影响。结果发现,在台风频数和降水量都出现峰值的7、8、9月,出现在西北太平洋的台风对台风期间的ENWC平均日降水(TP)有影响。7月份台风的位置和强度对降水影响显著,8月份台风的位置、强度和频数对降水都有影响,9月份影响较小。台风的影响具有地域选择性,不同的月份这种选择性不同,对不同等级降水的影响也不同。其影响主要表现在EOF分解的第二模态以及强降水和极强降水等级上,这说明了台风不是影响TP的主要因素,这种影响是间接的和非线性的,台风的出现是通过影响东亚地区中高纬度的槽脊系统、西太平洋副热带高压以及低纬度低涡的强度和位置来形成有利于降水的条件,从而影响降水的分布和强度。相对于多元线性回归方法,基于随机森林方法建立的降水模型能更好地拟合出降水分布和强度,这说明台风对TP的影响主要是非线性的,且降水强度越强,非线性作用越明显。同时,随机森林模型也显示出台风的位置是影响ENWC降水的最关键因素。

     

    Abstract: Based on the precipitation and typhoon data from 1970 to 2020 (42 years) and traditional statistical methods and random forest, this study investigated the influences of typhoons in the western Pacific on precipitation in the eastern Northwest China (33°N–45°N, 93°E–110°E, ENWC). The results revealed that the peak frequency values for typhoons and precipitation occur in July, August, and September. Typhoons in the western Pacific play an important role in the mean daily precipitation during the typhoon period (TP). The location and intensity of typhoons considerably influence the precipitation in July, and the location, intensity, and frequency of typhoons affect the precipitation in August, while typhoons have little influence on the precipitation in September. The typhoon influence changes with location, time, and precipitation level and is mainly in the second EOF pattern. Furthermore, the heavy and extremely heavy precipitations show that typhoons are not the main factors influencing TP, and their influence is indirect and nonlinear. Typhoons influence precipitation by affecting the location and intensity of the ridges and troughs in the mid-latitude, West Pacific subtropical high, and vortex in the low-latitudes. The random forest model can fit the distribution and intensity of precipitation better than the linear model, demonstrating that the typhoon influence on TP is mainly nonlinear and that influence increases with precipitation intensity. The random forest model also indicates that typhoon location is the most important factor influencing precipitation in the ENWC.

     

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