盛夏期间不同路径东北冷涡的分型及对我国气候的影响OA

Based on ERA5 and CPC data from 1980 to 2024,this study employed an improved objective identification algorithm combined with the K-means clustering method to objectively classify the tracks of Northeast Cold Vortices(NECVs)during mid-summer(July-August)into six types:Type Ⅰ:eastward long-distance movement,Type Ⅱ:central localized,Type Ⅲ:central eastward movement,Type Ⅳ:northern,Type Ⅴ:southeastern,and Type Ⅵ:northeastern.This study investigated the spatiotemporal characteristics,atmospheric circulation patterns,and climatic impacts associated with these six vortex track types.Results indicate that NECVs of different track types exhibit significant distinctions in terms of vortex center location,intensity,and life cycle.The configurations of the Western Pacific Subtropical High(WPSH)and the upper-level jet stream are closely related to the NECV types.Types Ⅰ and Ⅲ are associated with a subtropical high ridge line close to its climatic mean.Type Ⅳcorresponds to a weaker WPSH with a southward-displaced ridge line,while other types coincide with an eastward retreat of the WPSH.The upper-level jet stream is continuous over East Asia for most NECV types;however,it exhibits a break near the Sea of Japan for Types Ⅳ and Ⅴ.NECV activity is modulated by 10-30 day subseasonal-scale wave trains.The subseasonal circulation evolution associated with the six NECV track types can be categorized into three patterns:eastward-or southeastward-propagating wave trains,northward-propagating dipoles,and southward-propagating dipoles.The first and third patterns correspond to the generation and movement of NECVs characterized by stable eastward progression and short life cycles,respectively,while the second pattern corresponds to more complex and variable NECV tracks.The impacts of different NECV track types on precipitation and temperature in Northeast China show significant variations.Specifically,Types Ⅰ and Ⅲ can simultaneously cause extensive above-normal precipitation and cooling across Northeast China;Type Ⅳ mainly causes above-normal precipitation in the northern part of the region,while Type Ⅵ mainly causes cooling in the northern and northeastern parts.