Characteristics of Wind Structure and Nowcasting of Gust Associated with Subtropical Squall Lines over Hong Kong and Shenzhen, China

Abstract

A number of squall line passages over the Pearl River Delta (PRD) are documented for the first time based on the wind data collected by a 356 m-high meteorological tower with high temporal resolution (10 Hz). The mean wind and turbulence characteristics are studied based on a sample of six cases. The mean wind profile is consistent with the international standard for wind engineering, but the turbulence intensity profile has quite significant deviations. Moreover, the energy spectrum of the fluctuating wind is found to be consistent with the −5/3 law, as expected in the inertial subrange. For the purpose of wind gust nowcasting, the performance of a nowcasting algorithm based on upper air wind and thermodynamic profiles is examined using the limited dataset. The results highlight that the mean wind gust estimates are sufficient to nowcast the surface wind gust as measured by the anemometers, but for an extreme squall line case, the maximum wind gust estimates would be useful. The information in this paper is believed to be useful for wind engineering applications and weather nowcasting for wind gusts associated with subtropical squall lines, and, to the best of the authors’ knowledge, this is the first study of its kind for the PRD region.

Nowcasting Irradiance and Wind With Free Data

“…High clouds often mean very active and possibly violent cells. As the name "convective" cloud indicates, they are associated with motion of air, hence wind [2].…”

Characterization of Wind Gusts: A Study Based on Meteorological Tower Observations

“…The distance from the observation tower to the nearest shoreline was approximately 10 km and to the built-up area was about 1 km [30]. The SZMGT is an open lattice structure design with a total height of 365 m, and a cross-section of 2.5 m width [31][32][33]. This is the tallest observation tower in China, and the second tallest lattice observation tower worldwide.…”

“…The terrain conditions around the SZMGT are illustrated in Figure 1, which generally features a suburban condition. To the north and east of SZMGT, the terrain is relatively flat, with 3-m-high broad-leaved evergreen plants, lakes and roads within a radius of 1 km, while the adjacent terrain in the south and west of SZMGT is quite uniform, with forests and lakes within a radius of 5 km as the main terrain [33].…”