New Observations of the Meteorological Conditions Associated with Particulate Matter Air Pollution Episodes in Santiago, Chile

The meteorological factors of the severe wintertime particulate matter (PM) air pollution problem of the city of Santiago, Chile, are investigated with newly available observations, including a 30 m tower measuring near-surface stability, winds and turbulence, as well as lower-tropospheric vertical...

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Bibliographic Details
Published in:Atmosphere 2023-09, Vol.14 (9), p.1454
Main Authors: Muñoz, Ricardo C., Garreaud, René, Rutllant, José A., Seguel, Rodrigo, Corral, Marcelo
Format: Article
Language:English
Subjects:
Air pollution
Airports
AMDAR data
Atmospheric boundary layer
Atmospheric turbulence
Boundary layers
Chile
Cold season
Commercial aircraft
Distribution
Diurnal
Diurnal cycle
Diurnal variations
Emission standards
Environmental aspects
Environmental monitoring
Evening
Meteorological conditions
Numerical models
Outdoor air quality
Ozone
Particles
Particulate emissions
Particulate matter
particulate matter air pollution
Pollutants
Santiago
subsidence
Surface stability
Surface wind
Suspended particulate matter
Troposphere
Turbulence
Valley winds
Vertical profiles
Winds
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Summary:The meteorological factors of the severe wintertime particulate matter (PM) air pollution problem of the city of Santiago, Chile, are investigated with newly available observations, including a 30 m tower measuring near-surface stability, winds and turbulence, as well as lower-tropospheric vertical profiles of temperature and winds measured by commercial airplanes operating from the Santiago airport (AMDAR database). Focusing on the cold season of the years 2017–2019, high-PM days are defined using an index of evening concentrations measured in the western part of the city. The diurnal cycles of the different meteorological variables computed over 25 PM episodes are compared against the overall diurnal cycles. PM episodes are associated with enhanced surface stability and weaker surface winds and turbulence during the evening and night. AMDAR vertical profiles of temperature and winds during episodes reveal a substantial lower-tropospheric warming attributed to enhanced regional subsidence, which is consistent with the shallower daytime boundary layer depth and the increased surface thermal amplitude observed during these days. An explanation for the weak surface winds during PM episodes was not evident, considering that these are clear days that would strengthen the local valley wind system. Two possible mechanisms are put forward to resolve this issue, which can be tested in the future using high-resolution numerical modeling validated with the new data described here.
ISSN:2073-4433
2073-4433
DOI:10.3390/atmos14091454