Characteristics of wind speed during rainfall event in the tropical urban city

Abstract

An increasingly recurring recent phenomenon in tropical urban areas is the occurrence of strong winds associated with rainfall. This study investigated the characteristics of strong winds during similar rainfall events. Wind speeds and directions were measured at a sampling frequency of 10 Hz with a high-frequency three-dimensional sonic anemometer from September 2015 until January 2016 during the northeast monsoon season in Kuala Lumpur, Malaysia. Rainfall events were categorised as non-rainfall, during rainfall, before rainfall, and after rainfall. Rainfall amounts were classified as non-rainfall, heavy rainfall, and heavy shower. The results indicated that strong winds (>6.0 m s−1) with slight turbulence (0.3 turbulence intensity) typically occurred 10 min before rainfall during the day from 15:00 to 17:00 LT. Wind speeds began to decline within the first 5 min of rainfall until after the rain had stopped with a range of 2.0–5.0 m s−1. Significantly, heavy rainfall occurred with wind speeds of 8.0–9.5 m s−1 at almost double the likelihood compared to non-rainfall conditions. These findings provide useful information for the design and construction of buildings with good airflow and strong structures in urban areas.