the rainfall in beijing during this year's flood season was more than 60% higher than normal, and it continued to rain after the flood season.
2024-09-19
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this year's flood season is over. the reporter learned from the city's meteorological department that during this year's flood season (june 1 to september 15), the city's average rainfall was more than 60% higher than the same period in previous years, ranking third in the same period since 1961. today's forecast shows that there will be another significant rainfall from tonight to tomorrow afternoon. why is there so much rain in beijing during this year's flood season? the reporter conducted an interview.
it rained in beijing on august 9. photo by fang fei, a reporter from beijing daily clientwhat level of rainfall did it reach during the flood season?
"there's so much rain in beijing this year!" the flood season has just ended and many citizens have this feeling, which is also confirmed by statistics.
according to statistics from the meteorological department, the average rainfall in the city during this year's flood season was 666.7 mm, more than 60% more than 408.4 mm in the same period of normal years (1991 to 2020), ranking third in the same period in history since 1961, only lower than the same period in 2021 and 1969.
among the 20 national meteorological stations, the station with the most rainfall was huairou station, which received 929.7 mm, nearly double the normal year and the second highest in the same period since the station was established. during the heavy rainfall from july 30 to 31, huairou's hourly rainfall intensity even ranked first in the country.
why is there so much rain this year?
the reporter learned from the municipal climate center that during this flood season, beijing's rainfall was significantly higher than the same period in previous years, with uneven spatial distribution and high rainfall intensity in some areas. among the 20 national meteorological stations, except for tanghekou station and foyeding station, which were more than 20% higher, the rest of the stations were more than 40% higher, and the observatory station, tongzhou station and huairou station were about twice as high.
according to statistics, during this year's flood season, there were 12 rainfall events in beijing with a cumulative rainfall of more than 100 mm at a single station; there were two rainfall events with a cumulative rainfall of more than 200 mm, namely from july 30 to 31 and from august 9 to 10.
why is there so much rain this year? the relevant person in charge of the municipal climate center said that the abnormal atmospheric circulation at certain stages is the main reason for the heavy rainfall in beijing during this year's flood season. especially after entering the main flood season, the subtropical high pressure in the western pacific ocean advances northward to north china and maintains for a long time. the summer monsoon also advances to north china, guiding the abundant warm and humid air currents from the western pacific ocean, the south china sea, the bay of bengal and other places to be transported northward, providing sufficient water vapor for beijing.
why does rainfall continue after the main flood season?
"the end of july and the beginning of august" (july 20 to august 10) is the period of relatively concentrated heavy rainfall in beijing, which is called the main flood season. once the main flood season ends, the rain is often less frequent. but this year's situation is somewhat special. there was still rainfall until the end of august, and there was a rainstorm on august 26. even the flood season has already begun, and there will be relatively obvious rainfall tonight and tomorrow afternoon. "it is true that we cannot generalize. heavy rainfall does not necessarily occur only in the main flood season. rainfall may also occur before and after the flood season, but the probability of occurrence is relatively low." said a relevant person in charge of the municipal climate center.
statistical data show that the number of days with moderate rain or above at the beijing meteorological observatory during the flood season this year reached 16 days. among them, the number of days with moderate rain or above during the main flood season was relatively large, at 7 days (accounting for 44%). since mid-to-late august, there have been only 4 days with moderate rain or above (accounting for 25%).
the relevant person in charge of the municipal climate center said that the main reason for the "delay" of heavy rainfall this year is that the subtropical high pressure in the western pacific ocean continued to be located to the north and its intensity was relatively strong, resulting in sufficient water vapor being transported to north china after the main flood season, which also gave everyone the feeling that the main flood season was "extended".
