AsianScientist (Jan. 7, 2015) – Scientists have found that the annual urban-rural migration for Chinese New Year (CNY) celebrations in China can cause a drop in city temperatures. Their results have been published in the journal Atmospheric and Oceanic Science Letters.
The urban heat island (UHI) phenomenon describes higher temperatures experienced in dense urban centers compared to rural areas caused by increased human activities. During the CNY holiday, many Chinese people leave big cities for family reunions, making the mass movement during the Chinese New Year the largest annual human migration in the world. Scientists from the Institute of Atmospheric Physics under the Chinese Academy of Sciences wanted to know whether mass human migration—such as during the CNY holiday—could affect the urban heat island.
Drs. Wu Lingyun and Zhang Jingyong, together with Dr. Shi Chunxiang, investigated the role of modern human migration for the UHI effects during the CNY holiday for the period of 1992–2006 in Harbin City, Northeast China.
The results show that during the CNY week, the UHI effects expressed as daily mean, maximum, and minimum temperature differences between urban and rural stations averaged over the period of 1992–2006 are 0.65°C (43%), 0.31°C (48%), and 1.14°C (71%) lower than during the background period (four weeks before and four weeks after the CNY week), respectively. These changes are all significant at the 95% confidence level by Student’s t-test.
The reduced population during the CNY holiday in the urban area of Harbin City leads to less human activities, which result in less anthropogenic heat emissions and also affect other processes, thus significantly reducing the UHI effects. The findings identify previously unknown impacts of modern mass human migration on the UHI effects.
The article can be found at: Wu et al. (2014) Mass Human Migration and the Urban Heat Island during the Chinese New Year Holiday: A Case Study in Harbin City, Northeast China.
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Source: Chinese Academy of Sciences.
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