Research

Atmospheric transport and jet streams

Gases and particulates are transported on large scales by the atmosphere, affecting atmospheric chemistry, air quality, and climate. I am particularly interested in:

• Long-term changes in the behavior of the jet streams. I am developing an improved jet tracking algorithm (called JetLag) in collaboration with Dr. Jezabel Curbelo to take a new look at this issue.
• Intercontinental transport of urban and biomass burning emissions. I am working with Dr. Arlene Fiore and Dr. Sebastian Eastham to understand how the atmosphere transports and disperses pollutants, using satellite data and advanced techniques in nonlinear dynamics.

Emergence of climate signals

The planet is warming, but certain detailed aspects of the consequences of this warming remain difficult to assess. The primary reasons for this are simple:

1) The climate system is full of random noise, and it is sometimes difficult to separate the signal from the noise;

2) Our observations of the climate system are far from perfect – they have gaps, biases, and their quality changes over time.

Co-authors and I developed a new method to assess the degree of confidence we should place in long-term trends observed in our historical records, accounting for the effects of climate noise and observational uncertainties.

Stratospheric ozone and circulation

The stratospheric ozone layer protects life on Earth from harmful ultraviolet (UV) radiation from the Sun, so it is no surprise that the ozone hole has garnered tremendous scientific concern. My contributions in this area primarily concern:

• Assisting the development of a new satellite mission at Caltech’s Jet Propulsion Laboratory to monitor the circulation of the stratosphere and its connection with its composition;
• Determining whether uncertain, long-term changes in the stratospheric circulation are detectable using observations;
• Re-assessing the degree of confidence we should place in the recovery of the ozone hole as seen by satellites, with collaborators at Caltech’s Jet Propulsion Laboratory, Harvard University, and Princeton’s Geophysical Fluid Dynamics Laboratory.

Tropical cyclones in future climates

As the planet warms globally, regional changes also occur. In the context of tropical cyclones, this could mean that the regions where they form, intensify, and eventually make landfall could change over time. A project in collaboration with Purdue and NOAA will look at future scenarios to inform adaptation and mitigation planning.

Tropical cyclones have historically been studied from the surface up, mostly because of the extensive damage they produce at the surface. However, tropical cyclones also affect the upper atmosphere around them, with climate impacts that are still uncertain. I provided a new detailed look at cold anomalies found above tropical cyclones, and ruled out the effect of clouds as the main driver of these cold anomalies. New studies have delved into mechanisms that explain this cooling, but the effects of the cooling on the cyclones themselves, if any, remain an open question.