China?s state of urbanization in relation to economic development is undeniable, bearing in mind both population growth as well as city to rural ratios. Currently, approximately half of the world lives in the former one and this is set to 67% by the next decade. Due to development of factories, augmented usage of public vehicles, and others of the ilk, a phenomenon has emerged where in which the city centers are significantly warmer than the surrounding rural areas.

This, called the Urban Heat Island (UHI) is commonly characterized by aerosols (fine atmospheric particles) which in turn creates haze pollution, blocking out the path for light to escape back out. Not only does this harm the environment, however, but also public health issues like heat strokes and respiratory problems to name a few.

Previous studies have mainly focused on China?s vegetation land and albedo effects because of the main literal factor of what constitutes the difference between city and country. Surface properties include the following:

• Sunlight reflection based on modern infrastructure

• Evaporative cooling from flora

• Artificial heating (machinery)

• Convection efficiency (open space available)

• Sensible heat dissipation (from electronic devices)

However, details left open-ended in collected data led to more research done, one prominent example done by the Yale School of Forestry and Environmental Science. Further focus on how aerosols and the haze, as stated previously, can impact precipitation patterns in the region, as well as forcing changes in radiation levels. Regarding the latter case, it?s especially interesting.

Two different situations bring two different results: smaller particles scatter shortwave radiation which gives a cooling sensation (and are more prominent in the day) and vice versa. Climate can also correlate with this since density correlated with humidity levels show intensified warming.  Additional climate change model simulations such as the ones below are support of concrete evidence.

1. Winter night time has the highest correlation of UHI (0.29 ?C average) because of cities that have a thick haze layer being mainly prominent. Summer mornings on the other hand would have 0.14 ?C thus, experiments are conducted mainly in earlier times. Accurate results highlight, once more, particulate matter and the classification of rural vs urban as most significant.

2. Satellite data highlights altitude, topography, and city population as a poor indicator for Chinese UHI spatial variations. There is a weak relationship between, for instance, Shanghai, a major city, and Hami, a smaller one.  

Hopefully, in the near future, even more variables can arise and serve as a pinpoint on what to do and what not to do. Rising global temperatures is best to be avoided for the best of our personal wellbeing and biodiversity and perhaps, UHI can be our best bet at this.

Works Cited:

Cao, Chang, et al. ?Urban Heat Islands in China Enhanced by Haze Pollution.? Nature News, Nature Publishing Group, 23 Aug. 2016, www.nature.com/articles/ncomms12509.

Hays, Brooks. ?Study Quantifies Haze's Role in China's Urban Heat Island Effect.? UPI, UPI, 23 Aug. 2016, www.upi.com/Science_News/2016/08/23/Study-quantifies-hazes-role-in-Chinas-urban-heat-island-effect/2051471974660/.

Ouyang, Andrea. Sep 06, 2016. ?Haze Found as Key Element in Urban Heat Island Effect in China.? Yale Daily News Haze Found as Key Element in Urban Heat Island Effect in China Comments, yaledailynews.com/blog/2016/09/06/haze-found-as-key-element-in-urban-heat-island-effect-in-china/.

Wang, Wei-Chiung. ?Urban Heat Islands in China.? Geophysical Research Letters, Dec. 1990. <http://www.informath.org/apprise/a5620/b23.pdf>