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CR prepress abstract   -  DOI: https://doi.org/10.3354/cr01626

Dimming in the Pearl River Delta of China and the major influencing factors

Yaoxing Liao, Zhaoli Wang, Jinghua Xiong, Chengguang Lai*

*Corresponding author:

ABSTRACT: The sunshine duration (SD) has been attached great attentions to the climatic research under global climate change. This research explored the spatiotemporal variability of SD in the Pearl River Delta (PRD) in mainland China during 1960–2018. A novel equation was proposed to access the relative influence of five climatic variables on variability of SD based on random forest (RF). The dominant variables, their temporal evolution driving SD, and their spatial distribution were discussed. Results show that the SD in the PRD varied significantly both in temporal and spatial scale. At spatial scale, the SD decreased gradually from southeast to northwest; the SD in most areas illustrated a downward trend. Temporally, annual SD significantly decreased at the rate of 57.01 h/decade during 1960–2018 (P < 0.01), suggesting a continuous dimming; an abrupt change occurred in 1981 and a main oscillation period of 3.0 year existed. The annual mean SD showed positive correlation with wind speed (WS) while negative correlation with the other four variables. PRE was detected as the most influence variable with a relative influence rate of 34.46%. The relative influence rates of the five variables changed over time and their spatial distribution demonstrated significant diversity in different regions. The aerosols have a certain impact on driving SD in the PRD, but still could not completely dominate the change of SD in recent years. The ðndings can provide a reference for studying the spatiotemporal variability of SD and detecting its influencing factors in the high urbanization area.