My current research involves using multi-platform observations to improve our understanding about the global budget of atmospheric methane (CH4), a potent greenhouse gas.

• Inverse analysis of anthropogenic and natural emissions of methane using satellite and ground-based observations
• Monitor global hydroxyl radical concentration with satelllite observations of atmospheric methane [paper]
• Identification of global oil&gas methane emission hotspot

Previous Project

	Upper Tropospheric Brown Carbon and Its Radiative Impact Nature Geosciences, 2017  Using a unique set of aircraft measurements, we show that atmospheric BrC, a little-understood absorbing agent in the atmosphere, is more dynamic than previously thought. We found BrC is prevalent in the upper troposphere and causes disproportionately strong warming. Evidence suggests that convection may serve as the medium for generating and transporting BrC.
	Long-term Ozone Records and Impact of Climate Proceedings of the National Academy of Sciences, 2016 [paper] Despite the emission reduction in last three decades, surface ozone during October has not seen a decreasing trend over the Southeast US, in constrast to the decreasing trend in the summer. The October surface ozone correlates well with vapor pressure deficit, a humidity measure, suggesting that a humidity-related mechanism controls ozone concentration in the fall season.
	Vertical Distribution of Pollutants Journal of Geophysical Research-Atmospheres, 2016 [paper] In contrast to the popular well-mixed boundary layer assumption, we find a significant gradient of nitrogen oxides, important precursors of ozone pollution, in the boundary layer. The magnitude of the gradient is sensitive to the atmospheric stability. The finding has strong implications to the calculation of ozone production rate and satellite retrieval.
	Marine Sulfur Chemistry Geophysical Research Letters, 2014 [paper] Marine sulfur chemistry is a critical component of global climate system. Our study on a suite of aircraft measurements taken in the Tropical Pacific identifies unknown sources of methanesulfonic acid (MSA), an important yet not-well-studied sulfur-containing compound, near the ocean surface and in the free troposphere.
	Passive PAH Sampler Environmental Pollution, 2011 [paper] This novel design of passive sampler is able to characterize the vertical distribution of polycyclic aromatic hydrocarbons (PAHs) in the gas phase near the soil surface, helping researcher understand the air-soil exchange process.