Analysis of the Characteristics of a Microburst Event at Urumqi Airport Based on Microwave Radiometer and Doppler Wind Lidar

Microbursts can cause severe low-level wind shear, posing a threat to aviation safety. However, due to their small scale, they are difficult to capture by conventional equipment such as surface Automated Weather Observing Systems (AWOS) and Doppler weather radar. On 25 June 2022, a microburst event occurred at Urumqi Diwopu International Airport. Based on multi-source and high-resolution observation data, including AWOS data, microwave radiometer data and Doppler wind lidar data, an analysis was conducted on the characteristics of this microburst event. The results indicate that before the occurrence of this microburst, the atmosphere was in an unstable state, where the lower atmosphere exhibited a significant dry adiabatic lapse rate, and the temperature and humidity profiles displayed a typical “inverted-V” thermodynamic structure. Approximately 10 min prior to the occurrence of the microburst, the Convective Available Potential Energy (CAPE), Downdraft Convective Available Potential Energy (DCAPE), Microburst Wind Potential Index (MWPI), and WINDEX increased rapidly and reached their peak values, with CAPE and DCAPE reaching 4967 J·kg−1 and 1004 J·kg−1, respectively, MWPI reaching 3.0, and WINDEX reaching 26.2 m·s−1, before subsequently decreasing rapidly. During the transition from rapid accumulation to release of the unstable energy, precipitation particles from aloft passed through the dry and warm low-level region, undergoing evaporative cooling that enhanced negative buoyancy. This effect, combined with precipitation loading, facilitated the accelerated descent and ground impact of the dry-cold air intruding from the mid-to-lower troposphere. The Doppler wind lidar data showed that the downdraft first formed at an altitude of approximately 1.5 km and rapidly extended toward the ground, reaching a maximum descent speed of 4.78 m·s−1. After impinging on the ground, the downdraft produced a pronounced divergent outflow, with the maximum surface wind speed reaching 25.5 m·s−1, which exceeded the operational downburst gust threshold of 17.9 m·s−1. This evolution of the microburst was consistent with the observed ground pressure surge, rapid temperature drop, and downward momentum transport aloft. Integrated observations from microwave radiometers and Doppler wind lidar can effectively reveal the thermodynamic stratification and dynamic characteristics of microburst, offering valuable reference for airport microburst monitoring and nowcasting early warning.