Dr. Meiyun Lin (Research Scholar, Princeton University/CICS)
Office: 250 GFDL Tel: (609) 452-6551 Email: meiyunl at princeton.edu
Meiyun Lin is a Research Scholar (with tenure) at NOAA and Princeton University’s Cooperative Institute for Climate Science. Lin’s research seeks to advance knowledge on the interactions of air quality with weather and climate. Specifically, she investigates how climate variability & change affect large-scale heat waves, intrusions of stratospheric ozone deep into the troposphere, the long-range transport of Asian pollution, and their impacts on ozone air quality at northern mid-latitude regions. Recently, the US Environmental Protection Agency strengthened the National Ambient Air Quality Standard for ground-level ozone from 75 to 70 ppbv. Process-level understanding of US ozone air quality on daily to multi-decadal time scales is thus relevant for effective implementation of the new national ozone standard. Meiyun Lin is also an investigator of the NASA Aura Sciences Team in Atmospheric Composition and the NASA Air Quality Applied Sciences Team. Lin earned her Ph.D. from the University of Tokyo (2007) and completed her postdoctoral work at the University of Wisconsin-Madison (2008-2010).
Citations: | | GFDL Bibliography
RECENT PUBLICATION HIGHLIGHTS!
|Is springtime ozone in the free troposphere over western North America in fact increasing over 1995-2008?
Revisiting the analysis of Cooper et al. [Nature, 2010], we show that sampling biases can substantially influence calculated trends of ozone in the free troposphere over western North America. The model co-sampled in space and time with observations reproduces the observed ozone trend (0.65±0.32 ppb year-1) over 1995-2008 (in simulations either with or without time-varying emissions), whereas the ‘true average’ with continuous temporal and spatial sampling indicates an insignificant trend (0.25±0.32 ppb year-1). While rising Asian emissions in the past decades raise ozone background over North America, attribution of observed trends requires consideration of internal climate variability, particularly for short record length.
|US ozone air quality: Climate and stratospheric links
Exposure to ozone is harmful to human and plant health. There is mounting evidence that intrusions of stratospheric ozone deep into the troposphere can elevate western US surface ozone to unhealthy levels during late spring. This study reveals a connection between these intrusion events in US West and La Niña, an ocean-atmosphere phenomena that affects global weather patterns. Recognizing this link offers an opportunity to forecast ozone several months in advance, which would help western US air quality managers prepare to track these events for public health alert. Identifying these events also have implications for attaining the US national ozone standard.
|Tropospheric ozone: Decadal dynamics
Tropospheric ozone is a greenhouse gas, biological irritant, and significant source of highly reactive hydroxyl radicals. The response of tropospheric ozone to changing atmospheric circulation is poorly understood. This paper shows that over the past four decades, shifts in atmospheric circulation have played a key role in the autumnal ozone increase and the absence of spring ozone change over Hawaii by modulating pollution transport from Asia. This finding implies a need to consider decade-long variability in climate when detecting and attributing trends in tropospheric ozone levels to changes in human-induced emissions.
|Springtime high-ozone events in Western U.S. surface air: Role of stratospheric intrusions.
> Article by Meiyun Lin et al. in J. Geophys. Res. Current guidelines from the U.S. Environmental Protection Agency (EPA) dictate that surface-level air should have no more than 75 ppbv of ozone for 8-hour average. Lin et al  find that intrusions of ozone from the stratosphere can episodically increase surface ozone levels by 20-40 ppbv, pushing observed ozone to exceed the health-based limit at western U.S. high-altitude regions during spring. This finding suggests that stratospheric influence may pose challenges for western states to achieve more stringent ozone air quality standards if such “exceptional events” beyond the control of domestic air agencies are not properly screened out.PDF Full Text | Supplemental Information | Visualization Publicity: JGR most popular articles; US House Environmental Hearing;
|Western U.S. Air Quality: Imported ozone pollution
As Asian countries develop, they are emitting more ozone precursors that pollute surface-level air. This study finds that Asian pollution can contribute as much as 20% of total ozone during springtime pollution episodes observed in western U.S. surface air. NASA satellite observations of carbon monoxide can be used to predict when incoming plumes of polluted air might affect western air quality, one to three days ahead of time. (Read more…)