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Short-term impacts of the megaurbanizations of New Delhi and Los Angeles Between 2000 and 2009

Short-term impacts of the megaurbanizations of New Delhi and Los Angeles Between 2000 and 2009
Short-term impacts of the megaurbanizations of New Delhi and Los Angeles Between 2000 and 2009

Urban areas are expanding worldwide due to increasing population, standard of living, and migration from rural areas. This study uses satellite and road data to quantify the urbanization of two megacities, New Delhi and Los Angeles, between 2000 and 2009. It then estimates, with a three-dimensional nested global-through-urban climate, weather, and air pollution model, Gas, Aerosol, Transport, Radiation, General Circulation, Mesoscale, and Ocean Model, the short-term atmospheric impacts of such urbanization alone. The simulations account for changes in meteorologically driven natural emissions, but not anthropogenic emissions, between 2000 and 2009. New Delhi's urban extent, defined based on the physical existence of its built structures and the transitional gradient from buildings to rural areas rather than on abrupt administrative borders, increased by ~80% and Los Angeles's by ~22.5% between 2000 and 2009. New Delhi experienced a larger increase in its urban extent relative to its population during this period than did Los Angeles. In both megacities, urbanization increased surface roughness, increasing shearing stress and vertical turbulent kinetic energy, decreasing near-surface and boundary layer wind speed, contributing to higher column pollution levels. Urbanization may also have increased downward solar plus thermal infrared radiation fluxes to the ground and consequently upward latent and sensible heat fluxes from the ground to the air, increasing near-surface air temperatures. As such, urbanization alone may have had notable impacts on both meteorology and air quality.

air pollution, climate change, heat island effect, land use change, megacities, urbanization
2169-897X
35-56
Jacobson, Mark Z.
2d2983f0-c280-4bb1-b718-834462d8b187
Nghiem, Son V.
adefb467-c15c-4092-863a-e7833765a6e9
Sorichetta, Alessandro
c80d941b-a3f5-4a6d-9a19-e3eeba84443c
Jacobson, Mark Z.
2d2983f0-c280-4bb1-b718-834462d8b187
Nghiem, Son V.
adefb467-c15c-4092-863a-e7833765a6e9
Sorichetta, Alessandro
c80d941b-a3f5-4a6d-9a19-e3eeba84443c

Jacobson, Mark Z., Nghiem, Son V. and Sorichetta, Alessandro (2019) Short-term impacts of the megaurbanizations of New Delhi and Los Angeles Between 2000 and 2009. Journal of Geophysical Research: Oceans, 124 (1), 35-56. (doi:10.1029/2018JD029310).

Record type: Article

Abstract

Urban areas are expanding worldwide due to increasing population, standard of living, and migration from rural areas. This study uses satellite and road data to quantify the urbanization of two megacities, New Delhi and Los Angeles, between 2000 and 2009. It then estimates, with a three-dimensional nested global-through-urban climate, weather, and air pollution model, Gas, Aerosol, Transport, Radiation, General Circulation, Mesoscale, and Ocean Model, the short-term atmospheric impacts of such urbanization alone. The simulations account for changes in meteorologically driven natural emissions, but not anthropogenic emissions, between 2000 and 2009. New Delhi's urban extent, defined based on the physical existence of its built structures and the transitional gradient from buildings to rural areas rather than on abrupt administrative borders, increased by ~80% and Los Angeles's by ~22.5% between 2000 and 2009. New Delhi experienced a larger increase in its urban extent relative to its population during this period than did Los Angeles. In both megacities, urbanization increased surface roughness, increasing shearing stress and vertical turbulent kinetic energy, decreasing near-surface and boundary layer wind speed, contributing to higher column pollution levels. Urbanization may also have increased downward solar plus thermal infrared radiation fluxes to the ground and consequently upward latent and sensible heat fluxes from the ground to the air, increasing near-surface air temperatures. As such, urbanization alone may have had notable impacts on both meteorology and air quality.

Text
Accepted Version New Delhi LA Including SI - Accepted Manuscript
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More information

Accepted/In Press date: 10 December 2018
e-pub ahead of print date: 14 December 2018
Published date: 3 January 2019
Keywords: air pollution, climate change, heat island effect, land use change, megacities, urbanization

Identifiers

Local EPrints ID: 428268
URI: https://eprints.soton.ac.uk/id/eprint/428268
ISSN: 2169-897X
PURE UUID: 953c3c7b-454f-4ba5-9595-4a2354701937
ORCID for Alessandro Sorichetta: ORCID iD orcid.org/0000-0002-3576-5826

Catalogue record

Date deposited: 19 Feb 2019 17:30
Last modified: 15 Aug 2019 04:01

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