Air Quality Modeling in California
Air Quality Modeling in California

Author: Jianlin Hu

Publisher:

Published: 2012

Total Pages:

ISBN-13: 9781267656971

DOWNLOAD EBOOK

A new generation of the source-oriented UCD/CIT air quality model was developed and applied to (1) investigate the impacts of diagnostic vs. prognostic meteorological fields on predicted particulate matter (PM) concentrations, (2) quantify the contribution of volatile organic compounds (VOCs) emitted from livestock feed to ozone (O3) formation, and (3) estimate primary PM exposure fields from ~900 sources for use in epidemiological studies. Diagnostic meteorological fields produced more accurate air quality predictions than the WRF prognostic fields during the winter episode of the California Regional PM10/PM2.5 Air Quality Study (CRPAQS), suggesting that diagnostic meteorological fields generated by a dense measurement network are the preferred choice for air quality model studies during relatively short stagnation periods in locations with complex topography. VOCs emitted from livestock feed contributed ~3.5 tons of the ground level peak O3 (8-hr average) in the San Joaquin Valley (SJV), and mobile VOC contributed ~12 tons in the 2000 summer episode of the Central California Ozone Study (CCOS). Primary PM0.1, PM1., and PM2.5 concentrations from ~900 sources predicted across California for a 7 year period (2000-06) are in good agreement with measured concentrations for EC and 9 trace elements in the PM2.5 size range and for mass and EC in the PM0.1 size range. Source apportionment results from the mechanistic air quality model are likewise in good agreement with receptor-based source apportionment calculations. The continuous PM0.1 and PM2.5 fields predicted by the source-oriented air quality model provide new information on trace composition and source origin of airborne particulate matter that will support future epidemiological studies for the health effects of air pollution.

Meteorological Conditions Surrounding High Ozone Events in California's Central Valley
Meteorological Conditions Surrounding High Ozone Events in California's Central Valley

Author: Samantha Danielle Caputi

Publisher:

Published: 2020

Total Pages: 0

ISBN-13:

DOWNLOAD EBOOK

The San Joaquin Valley has a notorious ozone violation problem that has persisted despite other areas in California trending toward cleaner air at a faster rate in recent decades. Here we synthesize the various synoptic, mesoscale, and microscale meteorological factors that contribute to this problem. In particular, data from the California Baseline Ozone Transport Study (CABOTS) field campaign in the summer of 2016 are analyzed, which include 170 hours of aircraft data, and these aircraft deployments are looked at in the context of background synoptic-scale meteorological conditions. We lastly highlight the importance of measuring synoptic-scale subsidence in mountain-valley systems such as the San Joaquin Valley where air pollution is an issue, assess our current ability to accomplish this, and propose new methods for future research in this domain. Some key findings from these analyses include: 1) Nighttime mesoscale features in the Southern San Joaquin Valley, mainly the low level jet and Fresno Eddy, can either recirculate or deplete ozone from the previous day, and which of these two processes dominate on any given night is determined by the low level jet strength; 2) It is extremely important to track the chemical fate of the Nitrate radical at night as this can have a large effect on the ozone budget; 3) A 3-layer model of the atmosphere is proposed, where a buffer layer exists between the daytime boundary layer and free troposphere above, and the entrainment processes at the top of the boundary layer are important to track as pollutants from the previous day can be injected into the buffer layer by the mountain-valley circulation; 4) A low-cost method of estimating turbulence (specifically the convective velocity scale, turbulent kinetic energy, and eddy dissipation) from aircraft data without a gust probe is developed; 5) The newly developed Micro-Doppler lidar that was used during CABOTS shows promising first results in its ability to measure fair-weather vertical velocities in the lower atmosphere.