Fronts, Ocean Currents and Topography

Frontal Systems: Shanghai weather is significantly impacted by frontal systems throughout the year. The seasonal shift in the sub solar point and the corresponding shift in continental pressure cause seasonal climatic and frontal variation to occur. October is a transitional month in local weather and predominantly influenced by late summer wind patterns. The current barometric pressure and  image serves to demonstrate the prevailing HIGHER pressure coming from the ocean. (See Figure 1)




 



Ocean Currents: Higher pressure leads to predominantly westerly winds (seaward) , which are generally warmer and influenced by tropical  Kurishio oceanic  currents and tropical air masses in the summer. In the coming months, the sub solar point and the impacts of the shifting ITCZ will allow cooler ocean currents and air masses to push in to the Shanghai area. The Oyashio current forces cooler ocean water move in to the South China Sea during the winter months. The combination of shifting and cooling ocean currents, southward movement of Continental Polar (cP) and Continental Artic (cA) air masses causes the land mass to drastically cool off during the winter (see figure 2). The cooling land mass will change the continental pressure and cause winds to shift to a cold easterly wind. As the cooler air moves toward the Sea, Shanghai weather will cool off and be less influenced by the Sea temperature.


Topography: Shanghai is generally in a basin with several major rivers flowing in to the area. The rivers funnel cold air from higher eastern elevations in the Shanghai region. There is very little topography to the North of Shanghai. The lack of topography will allow cold arctic air masses to move in to Shanghai. The mountain ranges to the South, South West and West of the region can possible serve to keep cold air trapped in the valley. (see Figure 3 and Figure 4).

WebCam: **It always seems to be hazy in Shanghai, part of the haziness is the impact of fog from the ocean. Heavy and rapid industrialization  and mass consumption of coal also contribute greatly to the Shanghai haze.

Shanghai Climate and Seasonality

Shanghai Skyline:
http://www.flickr.com

Introduction: Shanghai is a coastal Mega City with a population over 20 Million people and growing.  The city is one Chinas largest population  centers  and is often referred to as China’s showcase to modernity.   Located at 31 Degrees North Latitude and along the South China Sea; Shanghai’s weather and climate are highly influenced  geographic location and seasonal weather patterns.   

Seasonality:  Shanghai is a northern hemisphere location and seasonal climate paterns similar to what we experience in the United States.  Located at   31 degrees North latitude means Shanghai receives fairly high solar angles throughout the year.  Shanghai, experiences all 4 seasons with receives some temperature moderating impacts from the proximity to the ocean. The relatively low latitude also indicates that Shanghai has a semi-tropical and humid climate.  The humidity is typically higher during the spring and summer months, influenced  by the monsoon season.

Shanghai Climate graph contributed by climatetemp.info

Generalized Monsoon
meted.ucar.edu

High and Low Pressure:  Shanghai is located in the Yangtze River delta and experiences extreme  rainfall runoff  and drought cycles.  These cycles are defined by seasonal variations in atmospheric pressure between the continent and the ocean.  During the winter , cold dry  weather over the Asian continent creates high pressure systems that force westerly air masses toward the South China Sea.  In the summer an opposite effect occurs, low pressure over the Asian continent allows moist air to come inland. This process creates conditions for monsoon season. Monsoons in Shanghai are very pronounced and have detrimental impacts on the lives of the people living in the region.  Shanghai receives most of its annual rainfall in during the late summer months of July and August.