Author(s): Demi Xiaocan Sun; Jun Niu; Ji Chen
Linked Author(s): Ji Chen, Jun Niu
Keywords: South Back Phenomenon; High relative humidity; Movement of air mass; Humidity prediction; Statistical model
Abstract: In the spring of south China, there is an extremely humid period lasting for several days. This special weather phenomenon is called ‘South Back Phenomenon’ (SBP) because it usually comes with the suddenly rising up of air temperature along with southerly winds. The occurrence of SBP is due to the movement of warm air mass from the South China Sea to the coastal area of South China. In March and April, the warm southerly winds from the South China Sea meet the cold air above the land, causing the formation of the stationary warm front. Then the water vapor in the air tends to condense, resulting in foggy weather with extremely high relative humidity. During the SBP period, the atmosphere is extremely humid and walls and ground are wet, and it brings an uncomfortable and unsafe living environment. This study aims to develop a reliable method for seasonally projecting SBP occurrence through using the daily weather data for the period from Jan 1968 to Dec 2006. The study period of 39 years (1968 – 2006) are divided into three categories: strong SBP years, weak SBP years and normal SBP years. The relationship between the conditions of SBP period and other weather variables in previous dates is explored. Then, this paper develops an optimal statistical model for seasonal SBP prediction and early SBP warning.