2014 Progress Report: Extreme Air Quality Events Using a Hierarchy of Models: Present and FutureEPA Grant Number: R835205
Title: Extreme Air Quality Events Using a Hierarchy of Models: Present and Future
Investigators: Hess, Peter , Berner, Judith , Grigoriu, Mircea Dan , Mahowald, Natalie M. , Samorodnitsky, Gennady
Current Investigators: Hess, Peter , Berner, Judith , Grigoriu, Mircea Dan , Mahowald, Natalie M.
Institution: Cornell University , National Center for Atmospheric Research
EPA Project Officer: Chung, Serena
Project Period: June 1, 2012 through May 31, 2015 (Extended to May 31, 2016)
Project Period Covered by this Report: August 30, 2014 through August 30,2015
Project Amount: $746,825
RFA: Extreme Event Impacts on Air Quality and Water Quality with a Changing Global Climate (2011) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Global Climate Change , Water and Watersheds , Climate Change , Air , Water
This grant funds interdisciplinary research to address the following broad questions:
Under current conditions what is the probability of an extreme pollution event?
During the next century, how are the probability, frequency, duration, and severity of high pollution episodes likely to change under future emission and climate scenarios?
What are the geographic, meteorological, climatological, and chemical conditions that could contribute to extreme pollution episodes in the United States?
What parts of the country are particularly sensitive to extreme pollution events now and in the future?
How do extreme pollution events relate to heat waves? What are the feedbacks between heat waves and severe pollution events?
In the past year we have completed our initial application of extreme value theory to CASTNET ozone measurements (Phalitnonkiat, et al., 2015). We contend that determining the tail parameter of ozone distributions is trickier than it may appear. This is particularly true with limited datasets. We outline a recommended procedure for determining the tail behavior. In some locations, we find that the distribution can be characterized as heavy tailed and is characterized by more extreme behavior. However, in other locations the distributions appear bounded. The locations with bounded distributions have less extreme behavior than those that are unbounded. The upper bound is an additional measure of extreme ozone behavior, addressing the question of how bad it can get. The fact that ozone distributions may have an upper bound dependent on location and emissions has not been well explored in the literature, but likely has implications for pollution policy.
In an additional study, we have analyzed how various meteorological processes and their duration cause ozone to reach extreme values (defined here as the 90th percentile threshold in the cumulative ozone distribution) in CASTNET measurements with implications for future meteorological changes. In contrast to some previous studies, we find little relation between cyclone frequency and an increase in ozone extremes.
We also have analyzed the impact of waviness (quantified through the metric of ‘wave activity’) in the 500 hPa flow on pollutant levels. We are quantifying this relationship in model simulations of the present and future climate and in observations. Wave activity is a dynamically meaningful quantity related to midlatitude circulation and its changes, with a proven relationship to meteorological extremes. Changes in wave activity should encapsulate the meteorological conditions and their future changes that may lead to pollution episodes in a succinct manner.
We expect to complete (1) our joint analysis of ozone-temperature extremes in the CASTNET data and in model simulations; (2) an analysis of the impact of antecedent meteorological conditions on the buildup of high ozone concentrations in the CASTNET data and their impact on ozone extremes; and (3) an analysis of the relation between wave activity and ozone pollution events in observations and model simulations of the present and future climates.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
|Other project views:||All 22 publications||10 publications in selected types||All 10 journal articles|
||Brown-Steiner B, Hess PG, Lin MY. On the capabilities and limitations of GCCM simulations of summertime regional air quality:a diagnostic analysis of ozone and temperature simulations in the US using CESM CAM-Chem. Atmospheric Environment 2015;101:134-148.||
||Phalitnonkiat P, Sun W, Grigoriu MD, Hess P, Samorodnitsky G. Extreme ozone events:tail behavior of the surface ozone distribution over the U.S. Atmospheric Environment 2016;128:134-146.||