case study: urban microclimates

Question 1

London temperatures (minimum in may)

Answer 1

• highest T in centre: 11 C, in fringe: 5 C
• T constant 15 km W due to urban infrastructure then rapid decline in 5-6 km
• growing season increased 15 days

Question 2

London rainfall

Answer 2

• influenced by topography
• Kenley alt: 170 m avg 800 mm
• London 43 m 550 mm
• humidity is lower in London than surrounding areas, due to higher temperatures (warm air can hold more moisture, hence relative humidity may be lower), and as water is removed from large urban areas due to the combination of drains and sewers, the large amount of impermeable surfaces and the reduced vegetation cover
• However, as air passes over the urban boundary layer it begins to sink, leading to lower precipitation at the leeward rural area.

Question 3

London heat effects

Answer 3

600 heat related deaths in August 2003

Question 4

impact of river restoration in Seoul, South Korea on urban climate

Answer 4

-removal of a large, downtown elevated motorway, and the restoration of a river and floodplain that had been built over
- before: area 5C higher than avg city T
- cool air from stream: avg 7.8 % increase in wind speed
- T decreased 10-30%, 3-4 C during hottest days