Based on hourly observation data from 2016 to 2019 and hourly automatic meteorological observation data from 2018 to 2019, we analyzed the annual, monthly and daily variation characteristics of fog days in Ninglang Ai...Based on hourly observation data from 2016 to 2019 and hourly automatic meteorological observation data from 2018 to 2019, we analyzed the annual, monthly and daily variation characteristics of fog days in Ninglang Airport, and diagnosed a case of summer fog. The results show that the average annual fog days in Ninglang Airport are 128 days and the annual characteristic of fog days is bimodal. Analyzed on fog cases in 2019, it was a summer fog process lasting more than 20 hours and visibility less than 500 m. The data from the automatic observational stations around Ninglang airport can describe the near-surface layer features of fog and illustrate the progress of fog. The meteorological elements of automatic observational stations changed suddenly 2 hours before fog, so the data of the automatic observational stations can be used to forscast fog.展开更多
The heaviest rainfall in recent six decades fell in Beijing on 21 July 2012, reaching a record of 460 mm within 18 h. This rainfall was a typical remote precipitation event related to Typhoon Vicente（1208）.Observati...The heaviest rainfall in recent six decades fell in Beijing on 21 July 2012, reaching a record of 460 mm within 18 h. This rainfall was a typical remote precipitation event related to Typhoon Vicente（1208）.Observational analysis indicates that Vicente influenced distant heavy rainfall by transporting water vapor northward to the Beijing area. This moisture transport was mainly driven by the interaction between Vicente and the western Pacific subtropical high（WPSH） associated with the formation of a low-level southeasterly moisture channel. A set of numerical sensitivity experiments were performed with prescribed typhoons of different intensities to investigate the interaction between Vicente and the WPSH and its effects on this rainstorm process. The results indicate that the WPSH interacting with typhoons of different intensities may exert varying degrees of influence on the development of a southeasterly moisture channel, resulting in a change in rain rate and location over the Beijing area. Specifically, in the presence of an enhanced typhoon,the WPSH shows remarkable withdrawal to the east, which is favorable for a northward extension of the southeasterly moisture channel, thereby increasing moisture supply for the rainstorm. The WPSH tends to stretch westward in a zonal pattern if the typhoon is weakened or removed, hindering the northward extension of the moisture channel. Thus, the rainfall area may be expected to expand or contract, with corresponding increases or decreases in rain rate over the Beijing area with a strengthened or weakened typhoon, respectively.展开更多
文摘Based on hourly observation data from 2016 to 2019 and hourly automatic meteorological observation data from 2018 to 2019, we analyzed the annual, monthly and daily variation characteristics of fog days in Ninglang Airport, and diagnosed a case of summer fog. The results show that the average annual fog days in Ninglang Airport are 128 days and the annual characteristic of fog days is bimodal. Analyzed on fog cases in 2019, it was a summer fog process lasting more than 20 hours and visibility less than 500 m. The data from the automatic observational stations around Ninglang airport can describe the near-surface layer features of fog and illustrate the progress of fog. The meteorological elements of automatic observational stations changed suddenly 2 hours before fog, so the data of the automatic observational stations can be used to forscast fog.
基金Supported by the National(Key)Basic Research and Development(973)Program of China(2015CB452804 and 2009CB421504)National Natural Science Foundation of China(91215302,41175063,41275066,and 41475055)
文摘The heaviest rainfall in recent six decades fell in Beijing on 21 July 2012, reaching a record of 460 mm within 18 h. This rainfall was a typical remote precipitation event related to Typhoon Vicente（1208）.Observational analysis indicates that Vicente influenced distant heavy rainfall by transporting water vapor northward to the Beijing area. This moisture transport was mainly driven by the interaction between Vicente and the western Pacific subtropical high（WPSH） associated with the formation of a low-level southeasterly moisture channel. A set of numerical sensitivity experiments were performed with prescribed typhoons of different intensities to investigate the interaction between Vicente and the WPSH and its effects on this rainstorm process. The results indicate that the WPSH interacting with typhoons of different intensities may exert varying degrees of influence on the development of a southeasterly moisture channel, resulting in a change in rain rate and location over the Beijing area. Specifically, in the presence of an enhanced typhoon,the WPSH shows remarkable withdrawal to the east, which is favorable for a northward extension of the southeasterly moisture channel, thereby increasing moisture supply for the rainstorm. The WPSH tends to stretch westward in a zonal pattern if the typhoon is weakened or removed, hindering the northward extension of the moisture channel. Thus, the rainfall area may be expected to expand or contract, with corresponding increases or decreases in rain rate over the Beijing area with a strengthened or weakened typhoon, respectively.
