Special Seminar: The Role of the Ocean in Tropical Pacific Climate Variability and Change
I started my research career in 2005 as a sea-going technician and programmer at NOAA's Atlantic Oceanographic and Meteorological (AOML) laboratory, where I worked collecting ocean observations and developing estimates of upper ocean heat content from in-situ and satellite measurements. In 2007, I started graduate school at the Rosenstiel School where I studied the dynamics of tropical climate change under the supervision of Amy Clement. I obtained an M.Sc. In 2009 and a Ph.D. in Meteorology and Physical Oceanography in 2011, and soon after I received the Young Investigator research fellowship from the School of Ocean and Earth Science and Technology (SOEST) of the University of Hawaii. At SOEST, I have continued to study the dynamics of tropical climate change, in particular the role of the tropics on glacial cycles. I am currently on a seven month long visit at NCAR's Climate and Global Dynamics division, where I am working on two new research projects using the Community Earth System Model (CESM). One aims to determine whether the duration of La Nina events is predictable, along with their effect on North American drought (in collaboration with Clara Deser). The other project has the objective of improving the simulation of tropical rainfall in simulations of the Last Glacial Maximum (in collaboration with Better Otto-‐Bliesner and Brian Mapes).
Analytical Chemistry Seminar: Dr. Andrew Rollins
Jointly sponsored by the Department of Chemistry and Biochemistry, CIRES, and the Environmental Program
Chemical and Physical Processes Controlling Organic Aerosols and Tropopause Cirrus: An Observational Perspective
Dr. Andrew Rollins, NOAA Chemical Sciences Division
Condensed mass in the atmosphere in the form of aerosol and cloud particles is a significant driver of climate and heterogeneous atmospheric chemistry. The processes that control the formation of these particles are complex, and understanding them is frequently limited by the ability to accurately measure the gas and particulate species required to test our theories. In this talk I will discuss results from two recent projects where new analytical instrumentation has been developed and used to inform our understanding of gas/particle partitioning processes involving organic aerosols and cirrus clouds. The first study presented exploits high time resolution measurements of organic nitrate aerosols using a laser induced fluorescence based technique. Laboratory and field measurements using this instrument have been used to probe the influence of nitrogen oxide chemistry on the formation of secondary organic aerosols (SOA) in the troposphere. Observations during the California Nexus (CalNex) field study demonstrate the significance of nitrate radical initiated SOA formation at night, and important nonlinearities in this chemistry.
In the second half of the talk I will discuss measurements of water vapor and ice water content in the tropical tropopause layer (TTL) using a new tunable diode laser based hygrometer operated on the NASA Global Hawk aircraft. Confidence in the accuracy of these historically challenging measurements is strengthened by use of an in-situ calibration system, and excellent agreement with a separate hygrometer operated in parallel. These measurements have provided evidence for the transport of water in excess of saturation through the TTL and into the stratosphere.