CAREER: Using Tracer Interrelationships to Understand Large-Scale Geophysical Flows and their Changes

Harvard University, Cambridge MA

Investigators

Abstract

This project will explore a new method to understand the history of the large-scale patterns of winds in the stratosphere and currents in the ocean. These winds and currents are important components of the global climate, affecting radiation in the stratosphere, the recovery of the ozone layer, and the storage of heat and carbon in the deep ocean. A tracer is a substance that has a small concentration and follows the flow of a fluid. Wildfire smoke can be a tracer; smoke from fires in the Western United States follows the jet stream, bringing air pollution all the way to the east coast in a large plume that can be seen from space. Carbon dioxide is a trace gas that has no appreciable chemical losses, so it can be used to examine the properties of the winds or currents that are transporting it. The relationships between different tracers have long been used to qualitatively describe winds and currents; for example, measurements of very high salt content and high temperature in the ocean demonstrate that the water started at the surface in the Mediterranean, even if the measurement is taken in the middle of the Atlantic. Just high temperature or high salt content would not lead to the same conclusion. This project involves developing and applying theory to use relationships between different tracers quantitatively to examine trends in the global patterns of winds in the stratosphere and currents in the ocean. Measurements of different tracers go back well over a century in the ocean and nearly 70 years in the stratosphere, and so the ability to use relationships between them to understand the winds and currents potentially unlocks a vast quantity of data to be analyzed in a new way that provides information about the history of global-scale winds and currents. This work will provide new insights into how these winds and currents affect radiation and climate by examining the storage of carbon in the deep ocean and the chemicals that set the rate of the recovery of the ozone layer. Three graduate students will be trained as part of this project. Tracers are one of the best ways to visualize the flow and are therefore excellent for learning about fluid motion. The PI will develop curricula that bring fluid experiments to a range of college-level classes with an inexpensive apparatus made of Lego components and a kitchen turntable. In addition, stratospheric science teaching materials, including a textbook and programming activities, will be developed and made available as part of these efforts. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.