今年华北雨季为何偏长

Core Viewpoint - The North China rainy season has been notably prolonged this year, lasting 55 days as of August 28, compared to the average of 30 days, influenced by various climatic factors such as sea temperature anomalies and persistent high-pressure systems [1][2][5]. Group 1: Rainy Season Characteristics - The rainy season began on July 5, 13 days earlier than the average start date of July 18, marking the earliest onset since 1961 [2][5]. - Cumulative rainfall in the monitoring area has exceeded the normal seasonal value by 131% as of August 25 [2][3]. - The rainy season has been characterized by high humidity and frequent heavy rainfall events, with 29 significant precipitation events recorded since the onset of the rainy season [3][4]. Group 2: Contributing Factors - Multiple factors contribute to the extended duration of the rainy season, including anomalies in equatorial Pacific sea temperatures, a strong and northward-shifted subtropical high-pressure system, typhoon activity, and geographical features [5][6]. - The subtropical high-pressure system has been particularly strong, reaching its northernmost position since 1961, facilitating the influx of warm, moist air from the south [6][7]. - The interaction between warm, moist air and cold air from higher latitudes has led to increased precipitation in North China [6][7]. Group 3: Climate Change Implications - The record-breaking rainy season is seen as a local manifestation of global climate system changes, with increasing frequency and intensity of extreme weather events attributed to climate change [8]. - Experts suggest that the duration of the rainy season exhibits significant interdecadal variability, with a trend of increasing duration observed since 2011 [7][8]. - There is a call for enhanced disaster prevention and mitigation measures in response to extreme weather, emphasizing the need for societal engagement in climate adaptation strategies [8].