Meso and Micro Scale Climate Controls

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Climate Classification: According  to the Koppen/Geiger climate classification; Shanghai is a humid subtropical climate. This climate occurs primarily because of latitude, proximity of the Pacific Ocean and other dominate oceanic currents.  In addition, there are separate regional and local climate controls that influence climate and weather in Shanghai. 

Meso-Scale: The most important influence on Shanghai weather is China’s monsoon season; one of the most produced monsoons in the world.

Air Mass Dominance: The pairing of the planets larges land mass and the expanse of the Pacific ocean set the conditions for incredibly intense monsoon events.  During the months  of June-August, the continental land mass develops very low pressure. The high temperatures and oceanic currents cause the ocean to develop high-pressure systems pushing warm moist air inland.  This annual cycle defines much of Chinas weather, climate, history  and cultural geography. Modern Chinese history from 1900 to present has been (and likely before), has been plagued by severe flooding.  During the 1930s alone over 4.6 Million people died in flood events that were related to seasonal monsoon rains.  In more recent years, intense monsoon flooding has displaced hundreds of millions of Chinese and caused Billions of dollars in damage.   Current and ongoing research indicates there is a statistically significant link between years of intense monsoon flooding and El Niño years. 

Micro-Scale: Two naturally occurring factors that influence Micro-Scale Climate are local topography and proximity to water. 

Orographic Situation: As a coastal city, Shanghia has a very low elevation and is a drainage basin for air masses from the North and East. The karst topography  and valley regions to the South and West of the city likely serves as a blockade and prevents air masses from passing directly through the city. 

 Proximity to Large Water Bodies: The city of Shanghai is faces the East China Sea part and is bisected by the Huangpo River. The low elevation and abundance of waters sources in the region has several impacts on the Meso-scale climate.  The Huangpo River affects the weather by  serving as a cold air funnel to move cold mountain air from the north toward the East China Sea in the winter. Additionally, area lakes in conjunction with rivers and the ocean cause unbearable humidity in the summer.  The humidity also causes a great deal of fog in the area that interacts with the pollution to create poor air quality. 

Urban Heat Island: Several anthropogenic forces influence Shanghai’s weather.  The most notable is the development of a major heat island. Shanghai has essentially developed from a medium sized city into one of the world larges mega cities in the past 30 years. The rapid rural- to urban demographic shift and drive for industrialization has transformed Shanghai in to a city with a population of over 20 Million.

The rapid development has changed the natural vegetative cover, by replacing productive farming grounds with concrete and sky scrapers.  The change in local albedo will likely make the city retain daytime heat longer, achieve higher temperatures and potentially create uplift and thunderheads.  China has also “re-claimed” swamp and lake areas turned them in to business centers and housing developments.  The rate of growth and the intensity of production has had a entirely negative impact on the air quality and most days the sky is a soot grey soup.  The smog has the capability to influence the climate on its own. The soot can prevent long wave radiation from escaping the local atmosphere. Trapping the heat can further increase the local temperature and local humidity.