Application of Wind Profiler Radar and GroundBased Microwave Radiometer Data in Typhoon Weather Analysis
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Abstract:
Based on the data from conventional ground observation, wind profiler radar, and microwave radiometer data, we analyse the heavy precipitation weather process of Typhoon Hagupit at Pudong Airport during the 4-5th of August 2020. The results show that: (1) The strong and stable subtropical high pressure and the typhoon’s compression led to the long time maintained strong winds at Pudong Airport. (2) After 12:00 on the 4th, the average wind speed stayed stable at over 10 m/s with gusts. Approximately 9 hours before and after reaching the same latitude as the typhoon at Pudong Airport, the wind direction shifted from southeast to south after 21:00 on the 4th, and the cumulative precipitation for 12 hours (from 21:00 on the 4th to 09:00 on the 5th) reached 57.9 mm. (3) Before it landed, the cloud structure primarily maintained a 9-shape, with the spiral cloud belt of Hagupit mainly situated in the southeast quadrant of the typhoon. The northern cloud belt’s boundary was distinct, first moving northwest, gradually affecting the southeast coast of Zhejiang, and then migrating north, impacting Shanghai and Jiangsu. It arrived at the west side of Shanghai at the same latitude at 21:00 on the 4th, and the typhoon’s main structure began to degrade and loosen. (4) When the significant precipitation process took place, the vertical speed below 5 km correlated with a corresponding large value area, and the height of the large vertical velocity area even approached upwards of 5 km. The vertical velocity value also correlated positively with the intensity of precipitation, with the maximum value nearing 9 m/s. (5) When at an altitude below 1 km, a high-value area of the atmospheric refractive index structure constant Cn2 was present. The second-highest value area reached between 2 and 6 km, corresponding with heavy precipitation. As the high-value area gradually weakened, it signalled the tapering or cessation of heavy precipitation. (6) Throughout the continuous heavy precipitation period, the maximum height of the signal-to-noise ratio (SNR) can reached between 5 and 6 km, suggesting that the SNR could serve as an indicator of rainfall intensity. (7) Before the onset of heavy precipitation, the whole atmosphere began to get moist from the middle layer. When precipitation manifested at 21:30, the liquid water content first increased markedly, followed by a significant decrease. When the liquid water content reached 1.25 g/m3, it coincided with the actual heavy rain period at Pudong Airport, and the height was primarily between 700 m and 2200 m. (8) The shortest period of convective effective potential energy (CAPE) overlapped with the period of heavy rainfall, while the KI value remained at 37 ℃ stably, with a negative lifting index. These findings help improve our understanding of the complex meteorological conditions leading to heavy rainfall, and they can aid in the development of more accurate forecasting models.
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Supported by:Beijing E-Tiller Technology Development Co., Ltd.
Supported by:Beijing E-Tiller Technology Development Co., Ltd.