Urban climatology

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Urban climatology is the study of urban climate. It is a branch of climatology that concerns interactions between urban areas and the atmosphere, the effects they have on one another, and the varying spatial and temporal scales at which these processes (and responses) occur.

History

Luke Howard is considered to have established urban climatology with his book The Climate of London, which contained continuous daily observations from 1801 to 1841 of wind direction, atmospheric pressure, maximum temperature, and rainfall.[1]

Urban climatology came about as a methodology for studying the results of

industrialization and urbanization. Constructing cities changes the physical environment and alters energy, moisture, and motion regimes near the surface. Most of these alterations can be traced to causal factors such as air pollution; anthropogenic sources of heat; surface waterproofing; thermal properties of the surface materials; and morphology of the surface and its specific three-dimensional geometry—building spacing, height, orientation, vegetative layering, and the overall dimensions and geography of these elements.[2] Other factors are relief, proximity to water bodies, size of the city, population density, and land-use distributions.[3]

Influential factors

Several factors influence the urban

air quality, wind patterns, and changes in rainfall patterns, but one of the most studied is the urban heat island (UHI) effect.[5]

Temperature and urban heat island effect

Urban environments, and slightly downwind, are typically warmer than their surroundings, as documented over a century ago by Howard.[6] Urban areas are islands or spots on the broader scale compared with more rural surrounding land. The spatial distribution of temperatures occurs in tandem with temporal changes, which are both causally related to anthropogenic sources.

The urban environment has two atmosphere layers, besides the

canopy layer. Fluxes across this plane comprise those from individual units, such as roofs, canyon tops, trees, lawns, and roads, integrated over larger land-use divisions (for example, suburbs). The urban heat island effect has been a major focus of urban climatological studies, and in general the effect the urban environment has on local meteorological conditions. These are sometimes measured by micronets or mesonets, as well as by Earth observation satellites
.

Pollution

The field also includes the topics of

air quality, radiation fluxes, microclimates and even issues traditionally associated with architectural design and engineering, such as wind engineering. Causes and effects of pollution as understood through urban climatology are becoming more important for urban planning.[7]

Precipitation

Changes in winds and convection patterns over and around cities impacts precipitation. Contributing factors are believed to be urban heat island, heightened surface roughness, and increased aerosol concentration.[8]

Climate change

Urban climatology is strongly linked to research surrounding

global warming. As centers for socioeconomic activities, cities produce large amounts of greenhouse gases (GHGs), most notably CO2
as a consequence of human activities such as transport, development, waste related to heating and cooling requirements etc.

Globally, cities are expected to grow into the 21st century (and beyond) [9] - as they grow and develop the landscapes in which they inhabit will change so too will the atmosphere resting above them, increasing emissions of GHGs thus contributing to the global greenhouse effect.

Finally, many cities are vulnerable to the projected

2003 European heat wave that especially deadly in France) and thus are a major focus for urban climatology.[10]

Spatial planning and public health

Urban climatology impacts decision-making for

municipal planning and policy in regards to pollution,[11] extreme heat events, and stormwater modeling.[12]

See also

References

  1. S2CID 54843237
    .
  2. ^ Arnfield, A. John. "Two Decades of Urban Climate Research: A Review of Turbulence, Exchanges of Energy and Water, and the Urban Heat Island." International Journal of Climatology 23.1 (2003): 1-26. Web. [1].
  3. doi:10.1016/0378-7788(88)90026-6
    .
  4. ^ Oke, T.R. 1968: Toward a more rational understanding of the urban heat island. McGill Climate Bulletin. 20pp
  5. ^ Grimmond, CSB. 2006: Prof Sue Grimmond answers questions on urban climatology [2]
  6. ^ Mills, G. 2009: Luke Howard, Tim Oke and the Study of Urban Climates IAUC newsletter
  7. doi:10.1016/S1352-2310(99)00145-4
    .
  8. ^ Han, J. et al. 2014: Urban impacts on precipitation; Asia-Pacific Journal of the Atmospheric Sciences, Volume 50, Issue 1, pp 17-30
  9. ^ United Nations. (2014). World urbanization prospects, the 2014 revision: Highlights [3]
  10. ^ Alexander, Mathews et al
  11. hdl:10.1111/1468-2427.12046
    .
  12. ^ Yen, Ben Chie. "Urban Stormwater Modeling and Simulation." Bulletin of the American Meteorological Society Apr. 1995: 564+. Academic OneFile. Web. 11 Nov. 2014.

External links

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