Caroline B. Alden

At regional to global scales, I use inverse modeling with atmospheric measurements of trace gases and stable isotopes to understand atmosphere-biosphere fluxes and biogeochemical cycling. At local scales, I am developing similar techniques to identify and characterize greenhouse gas emissions from industrial sources, for example, methane emissions from oil and gas infrastructure.

Prior to joining CIRES, I worked on connecting climate extremes in the Amazon Basin to variations in net biosphere exchange of CO₂ with the atmosphere as a postdoctoral fellow with Prof. Noah Diffenbaugh at Stanford University. For my PhD, I worked with Prof. Jim White and Dr. John B. Miller (NOAA/ERSL) to develop an inversion framework for delta¹³C of atmospheric CO₂, and explore its potential as a tracer for regional drought stress in North America. I have also published work on global CO₂ sink strength and on atmospheric ¹³CO₂ as a potential indicator of global terrestrial carbon exchange, water stress, and the partitioning of C3/C4 plant productivity.

Teaching Profile

I have taught as a visiting professor at Colorado College and Quest University Canada, and helped develop curriculum for science writing at CU Boulder.

Current Research

My current research projects fall into three main categories.

I work with Greg Rieker in the Mechanical Engineering Department at CU, along with colleagues at the NIST Engineering Laboratory and NOAA, to develop tools for the detection, quantification, and attribution of leaks of methane and other hydrocarbons during natural gas production, distribution and storage. Our team deployed the first fielded dual frequency comb spectrometer for the monitoring of trace gases. We currently have four deployments with industry partners in oil and gas production and underground natural gas storage for testing and prototyping of the observing system. These four systems operate autonomously, providing continuous and low-cost monitoring of active natural gas facilities. This work has resulted in a successful technology transfer to industry with the launching of LongPath Technologies, Inc., which will continue to carry out monitoring and emissions quantification activities in the private sector after the completion of research and development at CIRES and CU's Mechanical Engineering Department.

I also work with the Carbon Cycle Group at NOAA/ESRL in the Global Monitoring Laboratory to better understand what can be learned about regional CO₂ fluxes from measurements made aboard the Orbiting Carbon Observatory 2 (OCO-2) satellite. We are working with colleagues at the University of Illinois and the Carnegie Institution at Stanford to reconcile high-resolution top-down and bottom-up estimates of carbon fluxes across the US corn belt, as part of a NASA Carbon Monitoring System development effort. The results of this effort will be the inclusion of satellite-based observations in the CT-Lagrange inversion framework, and better understanding of information content offered and bias corrections needed when assimilating in situ and remotely sensed information in a regional inversion. This effort will also result in a decadal-length analysis of carbon sequestration in the US corn belt.

Finally, I work with colleagues at CIRES and in the NOAA/ESRL Carbon Cycle Group to investigate global biogeochemical cycling using stable isotope measurements made at the INSTAAR Stable Isotope Laboratory. This global-scale analysis will identify large-scale trends and signals of water use efficiency via a data-constrained model.